Aflatoxins and zearalenone (ZEN) are highly common mycotoxins in maize and maize-based products. This study aimed to report a time-resolved fluorescence immunochromatographic assay (TRFICA) developed using two idiotypic nanobodies for rapid, quantitative, and simultaneous detection of aflatoxin B1 (AFB1) and ZEN in maize and its products. A novel Eu/Tb(III) nanosphere with enhanced fluorescence was prepared as a label and conjugated to anti-idiotypic nanobody (AIdnb) and monoclonal antibody (mAb). On the basis of nanosphere–antibody conjugation, two patterns of competitive time-resolved strip methods (AIdnb–TRFICA and mAb–TRFICA) were established and compared. The half inhibition concentration of AIdnb–TRFICA was 0.46 and 0.86 ng·mL–1 for AFB1 and ZEN, which was 18.3- and 20.3-fold more sensitive than that of mAb–TRFICA for AFB1 and ZEN, respectively. Under optimal conditions, AIdnb–TRFICA for dual mycotoxin was established and provided a quantitative relationship ranging from 0.13 to 4.54 ng·mL–1 for AFB1 and 0.20 to 2.77 ng·mL–1 for ZEN, with a detection limit of 0.05 and 0.07 ng·mL–1 in the buffer solution, respectively. AIdnb–TRFICA showed good recoveries (72.6%–106.6%) in samples and was applied to detect dual mycotoxin in maize samples with satisfying results. To the best of our knowledge, it is the first report about a time-resolved strip method based on AIdnbs for dual mycotoxin.

•Magnetic solid phase extraction has been used in the sesame oil sample preparation.•Graphene oxide and hydroxylated Fe3O4 are combined.•A detection method is established for sesamol, sesamin and sesamolin in sesame oil.•The extraction conditions are optimized.•This method has a good application prospect in detection of main lignans in sesame oil.Graphene oxide was fabricated by a simple method and applied to magnetic solid-phase extraction. In a pretreatment procedure before the sesamol, sesamin and sesamolin in sesame oil were detected by high performance liquid chromatography. Several parameters affecting the extraction efficiency were investigated, including the type and volume of desorption solvent, desorption time and the amount of sorbent. Under the optimized conditions, the detection limits of sesamol, sesamin, and sesamolin were 0.05 μg/g, 0.02 μg/g, and 0.02 μg/g, respectively. The limits of quantification were all 0.2 μg/g. The average recoveries of sesamol, sesamin, and sesamolin were 84.55%, 85.47%, 86.83%, respectively and their relative standard deviations were 1.23%, 1.33%, and 0.84%, respectively.

•A time-resolved fluorescent strip was developed based on double-label immunoprobes.•The quantitative TRFICA’s LODs may reach 0.04 mg L−1 in apple extraction solution.•Strip assay sensitivity is increased or similar to the previous GNP strip assays.•The spiked recoveries of carbofuran in the agro-products were 81–103%.•The TRFICA’s results were in good agreement with a standard HPLC method.A rapid and quantitative time-resolved fluorescent immunochromatographic assay (TRFICA) for detecting carbofuran residues in agro-products was reported in this paper. This assay was developed based on double-label immunoprobes, one of which was a carbofuran-specific antibody coupled with europium microbeads for the test (T) line signal while the other was mouse IgG coupled with europium microbeads for the control (C) line signal. Quantitative relationships between carbofuran concentrations and T/C ratios were established to determine the analyte concentration. To increase assay accuracy, four standard curves were established for the agro-products (green bean, cabbage, apple, and pear). The limits of detection (LODs) ranged from 0.04 to 0.76 mg L−1. The spiked recoveries of carbofuran in the agro-products were in the range of 81–103%, which was in good agreement with a standard HPLC method. Therefore, we provided a new and reliable method for determination of N-methylcarbamate pesticide carbofuran residues in agro-products including vegetables and fruits.

•Authentication model was built by one-class classification and metabolomics for VOOs.•The MCOCPLS classifiers could effectively detect the adulterated oils.•The lowest adulteration level of the model was determined Monte Carlo method.•Risk analysis and assessment for authentic virgin olive oils were conducted.To develop effective adulteration detection methods is essential as food quality and safety draw particular concern all over the world. In this study, Monte Carlo one-class partial least squares (MCOCPLS) was proposed and employed as a novel one class classification model for authentication identification by using virgin olive oil (VOO) as an example. Monte Carlo sampling was proposed for selecting variable subspace to improve the performance of one-class partial least squares (OCPLS) classifier. MCOCPLS was used to establish a one-class model, the performance of which was validated by an independent test set consisting of 5000 adulterated oils simulated by the Monte Carlo method. The prediction for the best model of MCOCPLS reaches a correct rate of 99.10%. Moreover, authentic VOOs were analyzed and assessed for the adulteration risk. In conclusion, the proposed MCOCPLS method could be used to effectively detect olive oils adulterated with other vegetable oils at a concentration of as low as 3%. Therefore, MCOCPLS provides an effective tool and new insights in adulteration detection for edible oils and other foods.

Fluorescence polarization immunoassays (FPIA) were developed for the determination of pesticides triazophos and carbaryl in wheat grains using the portable FPIA device Sentry 200 (Ellie). FPIA of carbaryl was developed first. Tracers for FPIA were synthesized and their structures were confirmed via mass spectrometry. The influence of tracer cross-linking bridge length on the assay sensitivity was estimated. The use of tracers labeled with ethylenediamine fluorescein thiocarbamyl (EDF) resulted in the best assay sensitivity with minimal reagent consumption. A rapid and easily performed sample preparation technique that allowed the parallel determination of both analytes in aliquots of the same sample was developed. The detection limits for triazophos and carbaryl were 40 and 20 μg kg−1, respectively, and the measurement ranges were 40–200 and 60–650 μg kg−1, respectively. A recovery test was performed using FPIA and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), and the results obtained showed good correlation (r2 = 0.9843 for triazophos, r2 = 0.9916 for carbaryl).

•A high sensitive novel monoclonal antibody against fumonisin B1 was achieved.•A indirect competitive enzyme-linked immunosorbent assay (icELISA) was established for fumonisin B1 detection.•A gold nanoparticles-based gray imaging quantification immunoassay (GNPs-GI) was developed for fumonisin B1 detection.•The icELISA and GNPs-GI performed rapidly assay for fumonisin B1 in agricultural products.Fumonisins (FBs) are widely found in rice, maize, peanut, wheat, and other agricultural products. These have been detected using a chromatography technique, whereas the rapid assay by a highly sensitive monoclonal antibody is minimally reported. Herein, a highly sensitive monoclonal antibody (7A11) was successfully developed by hybridoma technique. The 50% inhibition concentration (IC50) of 7A11 monoclonal antibody was 0.32 ng/mL in an optimized buffer. The cross-reactivity between fumonisin B1 and fumonisin B2, B3 was 4.3% and 12.8%, respectively. Based on the newly developed 7A11 antibody, a high sensitivity indirect competitive enzyme-linked immunosorbent assay (icELISA) and gold nanoparticles-based gray imaging quantification immunoassay (GNPs-GI) were established. The analytical range of icELISA was 0.08–1.38 ng/mL and that for GNPs-GI was 0.24–15 ng/mL. Both the methods showed adequate recoveries (80.0–105.8% for icELISA and 78.5–115.2% for GNPs-GI) in spiked samples. Compared to high-performance liquid chromatography (HPLC), icELISA and GNPs-GI indicated reliability that could be used for further detection of fumonisin B1 in agricultural products.

•Magnetic carboxylated multi-walled carbon nanotubes were successfully prepared.•The extraction procedure can be achieved in 12 min without tedious steps.•Phenolic compounds in lipid matrix were simultaneously quantified by LC–MS/MS.•This method was simple and sensitive to analyze phenolic compounds in oil samples.A novel magnetic carboxylated multi-walled carbon nanotubes (c-MWCNT-MNPs) was proposed for magnetic solid-phase extraction coupled with liquid chromatography–tandem mass spectrometry to determine phenolic compounds in sesame oil. In this study, c-MWCNT-MNPs were acquired by simply dispersing Fe3O4 magnetic nanoparticles into carboxylated multi-walled carbon nanotubes. The major parameters affecting extraction efficiency were optimized, including the type and volume of desorption solvents, extraction and desorption time, washing solution, and sorbent amount. The limit of quantifications and limit of detections were from 0.03 μg/kg to 43.00 μg/kg and from 0.01 μg/kg to 13.60 μg/kg, respectively. The recoveries of phenolic compounds in vegetable oils were in the range of 83.8–125.9% with inter-day and intra-day precisions of less than 13.2%. It was confirmed that this method was simple, rapid and reliable with an excellent potential for routine analysis of phenolic compounds in oil samples.

•A simple and rapid IMS fingerprint was developed for adulteration of sesame oil.•Discriminant model for adulteration detection was built by R-SVM and RF.•R-SVM model could identify adulterated sesame oils with an accuracy of 94.2%.•IMS fingerprint was an effective method to detect the counterfeit sesame oils.A simple and rapid detection technology was proposed based on ion mobility spectrometry (IMS) fingerprints to determine potential adulteration of sesame oil. Oil samples were diluted by n-hexane and analyzed by IMS for 20 s. Then, chemometric methods were employed to establish discriminant models for sesame oils and four other edible oils, pure and adulterated sesame oils, and pure and counterfeit sesame oils, respectively. Finally, Random Forests (RF) classification model could correctly classify all five types of edible oils. The detection results indicated that the discriminant models built by recursive support vector machine (R-SVM) method could identify adulterated sesame oil samples (⩾10%) with an accuracy value of 94.2%. Therefore, IMS was shown to be an effective method to detect the adulterated sesame oils. Meanwhile, IMS fingerprints work well to detect the counterfeit sesame oils produced by adding sesame oil essence into cheaper edible oils.

Cadmium (Cd) in 8698 peanut samples collected from China in 2009–2014 was studied to evaluate its contamination level, distribution, and health risk. The average Cd concentration was 0.1684 mg kg–1; the range of 2.5–97.5% was 0.0191–0.4762 mg kg–1, indicating the cadmium-contaminated peanut level was even lower. Some peanut strains for which protein contents had a significant correlation (Pearson correlation coefficient r = 0.86**) with the Cd concentration level should be of concern. Under the same soil Cd background, the difference in Cd contents in different peanut varieties is extremely significant. For example, the Cd concentration of Silihong is about 0.4522 mg kg–1, being 7 times higher than that of Zhonghua 6. According to the exposure assessment using the probabilistic simulation method, the target hazard quotients (THQs) of all groups should be below 1. The THQ range in this study was from 0.0035 to 0.0202, suggesting that there were no potential noncinogenic effects in any group.Keywords: cadmium; contamination; dietary exposure; peanut; THQ;

•IMCOD was proposed to detect outliers based on Monte Carlo sampling.•IMCOD could overcome masking effect by taking dubious samples as test set.•The performance of IMCOD outperforms MCOD and EMOCD.Highly predictive multivariate calibration model depends on samples in training set. In this study, we introduced an outlier detection method and developed its improvement for shorter run time. Improved Monte-Carlo outlier detection (IMCOD) was proposed to establish cross-prediction models for determining normal samples, which were subsequently used to analyze the distribution of prediction errors for all of dubious samples together. Four real datasets were employed to illustrate and validate the performance of IMCOD. After sample selection for training set of NIR of soy flour samples, the Root Mean Square Error of Prediction (RMSEP) of PLS model decreased from 1.4811 to 0.7650. This method benefits the establishment of a good model for QSAR and NIR datasets.

•We developed simultaneous detection for 7 mycotoxins by a multiple IAC-HPLC–MS/MS.•We developed a one-step sample preparation combining sample grinding and extraction.•Multiple IAC was fabricated using home-made monoclonal antibodies against mycotoxin.•It provided an alternative with high throughput detection method in food safety.Mycotoxins usually found in agricultural products such as peanut, corn, and wheat, are a serious threat to human health and their detection requires multiplexed and sensitive analysis methods. Herein, a simultaneous determination for aflatoxin B1, B2, G1, G2, ochratoxin A, zearalanone and T-2 toxin was investigated using high performance liquid chromatography coupled with tandem mass spectrometry in a single run via a home-made multiple immunoaffinity column. Four monoclonal antibodies were produced in our lab against aflatoxins, ochratoxin A, zearalanone and T-2 toxin, respectively, then combined as a pool and bound to Sepharose-4B for affinity chromatography. Seven mycotoxins were effectively extracted from the agricultural product samples by using acetonitrile/water/acetic acid (80:19:1, v/v/v) Then, the extraction was cleanup by multiple immunoaffinity column. This method demonstrated a considerable linear range of 0.30–25, 0.12–20, 0.30–20, 0.12–20, 0.60–30, 0.30–25, and 1.2–40 μg kg−1and lower limits of detection at 0.1, 0.04, 0.1, 0.04, 0.2, 0.1 and 0.4 μg kg−1 for AFB1, AFB2, AFG1, AFG2, OTA, ZEN and T-2, respectively, in comparison with previously reported methods, as well as excellent recoveries. The mIAC capacity for AFB1, AFB2, AFG1, AFG2, OTA, ZEN, and T-2 were 187, 181, 153, 151, 105, 130, 88 ng, respectively. It was found that all of the 7 mycotoxins were present in 90 agricultural product samples. The proposed method meets the requirements for rapid sample preparation and highly sensitive identification of multiple mycotoxins in agricultural product and food safety. This method provides a promising alternative with high throughput and high sensitivity for rapid analysis of seven mycotoxins in the monitoring of food safety.

•The IAC column for selective extraction of capsaicinoids from oil was developed.•The major parameters affecting IAC extraction efficiency were optimized.•The IAC column was characterized including binding capacity, accuracy, etc.•Accurate quantification was performed with deuterium-labeled internal standards.•Capsaicinoids in spiked oil was extracted by IAC column and analysed by LC–MS/MS.Capsaicin and dihydrocapsaicin were selected as adulteration markers to authenticate vegetable oils. In this study, a method of immunoaffinity chromatography (IAC) combined with liquid chromatography–tandem mass spectrometry was established for the determination of capsaicin and dihydrocapsaicin in vegetable oils. In this method, immunosorbents were obtained by covalently coupling highly specific capsaicinoid polyclonal antibodieswith CNBr-activated Sepharose 4B, and then packed into a polyethylene column. In this paper, the major parameters affecting IAC extraction efficiency, including loading, washing and eluting conditions, were also investigated. The IAC column displayed high selectivity for capsaicin and dihydrocapsaicin with the maximum capacity of 240 ng. The limit of detection (LOD) and limit of quantification (LOQ) for capsaicin were calculated as 0.02 and 0.08 μg kg−1, and for dihydrocapsaicin were 0.03 and 0.10 μg kg−1. The recoveries of capsaicin and dihydrocapsaicin in oil samples were in the range of 87.3–95.2% with the relative standard deviation (RSD) of less than 6.1%. The results indicated that capsaicinoid compounds could not be found in edible vegetable oils. Therefore, the proposed method is simple, reliable and adequate for routine monitoring of capsaicinoid compounds in vegetable oils and has an excellent potential for detection of adulteration with inedible waste oil.

•Novel monoclonal antibodies against deterrent capsaicinoids were achieved.•A competitive indirect ELISA (icELISA) was established for capsaicinoids detection.•A time-resolved fluorescent ICA (TRFICA) was developed for capsaicinoids detection.•The icELISA and TRFICA performed rapidly assay for major capsaicinoids in serum.To monitor capsaicinoids in serum on-site, three new monoclonal antibodies (mAbs) were firstly proposed using a conjugate of 4-[(4-hydroxy-3-methoxybenzyl) amino]-4-oxobutanoic acid as the immunogen. Among them, the YQQD8 mAb showed the highest sensitivity and cross-reactivity to major capsaicinoids, such as capsaicin, dihydrocapsaicin and N-vanillylnonanamide. A competitive indirect enzyme-linked immunosorbent assay (icELISA) and a time-resolved fluorescent immunochromatographic assay (TRFICA) were established based on this mAb. The linear range was 1.1–27.0 ng mL−1 for icELISA and 1.9–62.5 ng mL−1 for TRFICA and the limit of detection (LOD) of TRFICA was 1.5 ng mL−1. To decrease the interference of sample components and increase accuracy, serum samples were diluted four times before assays. As a result, the linear range of serum samples was 4.6–107.9 ng mL−1 for icELISA and 7.6–250.0 ng mL−1 for TRFICA. Both icELISA and TRFICA showed good recoveries (91.0–112.8% for icELISA and 87.6–111.5% for TRFICA) and concordant results in spiked experiments. Overall, this is the first report of immunoassay based on the mAbs for quantitative determination of major capsaicinoids, and the results demonstrate that both methods can meet the demands of rapid on-site assay for capsaicinoids in serum samples.

•Determination of cholesterol level used as indicator by GC × GC–TOF/MS.•The baseline separation of cholesterol and cholestanol (i.s.) was achieved.•Reliable method for authenticating the purity of virgin coconut oils (VCO).•Possibly to detect the presence of animal fats in VCO at a level as little as 0.25%.A new method based on the cholesterol level was developed to detect the presence of animal fats in virgin coconut oil (VCO). In this study, the sterols in VCO and animal fats was separated using conventional one-dimensional gas chromatography (1D GC) and comprehensive two-dimensional gas chromatography (GC × GC). Compared with 1D GC, the GC × GC system could obtain a complete baseline separation of the sterol trimethylsilyl ethers derived from cholesterol and cholestanol, so that the cholesterol content in pure VCO and false VCO adulterated with animal fats could be accurately determined. Cholesterol, a main sterol found in animal fats, represented less than 5 mg/kg of VCO. The study demonstrated that the determination of the cholesterol level in VCO could be used for reliable detection of the presence of lard, chicken fat, mutton tallow, beef tallow, or their mixture in VCO at a level as little as 0.25%.

•Magnetic hydrophilic multiwalled carbon nanotubes were successfully prepared.•The extraction procedure can be achieved in 10 min without tedious steps.•Magnetic absorbents were applied to extract trans-resveratrol from oil samples.•The method is simple and sensitive to analyze trans-resveratrol in lipid matrix.In the present work, a rapid and simple procedure was developed and validated for the analysis of trans-resveratrol in vegetable oils based on magnetic hydrophilic multi-walled carbon nanotubes (h-MWCNT-MNPs) combined with liquid chromatography–tandem mass spectrometry (LC–MS/MS). h-MWCNT-MNPs were simply obtained by wrapping amine-functionalized Fe3O4 magnetic nanoparticles into previously oxidized hydrophilic multi-walled carbon nanotubes. The major parameters affecting extraction efficiency were investigated, including the type and volume of desorption solvents, extraction and desorption time, washing solution, and sorbent amount. The limit of detection (LOD) and the limit of quantification (LOQ) were calculated as 0.6 and 2.0 μg/kg, respectively. The recoveries of trans-resveratrol in oil samples were in the range of 90.0–110.0% with RSDs of less than 17.5%. The results showed that only peanut oil contained trans-resveratrol, ranging from 8 ± 1 to 103 ± 12 μg/kg. The proposed method is reliable and robust, having an excellent potential for the analysis of trans-resveratrol in edible oils.

•Mixed-mode SPE LC-MS/MS method was developed for isoflavones and resveratrols.•The extraction procedure can be achieved in 15 min and  avoiding tedious steps.•The method was simple and applicable to quantify analytes in lipid matrix.•Characteristic components could assess adulteration and quality of vegetable oils.To ensure authenticity of vegetable oils, isoflavones (genistein, genistin, daidzein and daidzin) and resveratrols (cis-resveratrol and trans-resveratrol) were selected as the putative markers for adulteration of soybean and peanut oils. Firstly, mixed mode solid-phase extraction coupled with liquid chromatography tandem mass spectrometry (mixed-mode SPE LC–MS/MS) method was developed to analyze isoflavones and resveratrols in vegetable oils. The concentration of marker compounds in vegetable oils were 0.08–1.47 mg kg−1 for daidzein, ND-78.9 μg kg−1 for daidzin, 0.40–5.89 mg kg−1 for genistein, 1.2–114.9 μg kg−1 for genistin, 3.1–85.0 μg kg−1 for trans-resveratrol and 1.9–51.0 μg kg−1 for cis-resveratrol, which are compatible with the raw materials for oil press. Additionally, the applicability of this method has been successfully tested in thirteen vegetable oils from the market. Mixed-mode SPE LC–MS/MS method can simultaneously detect isoflavones and resveratrols in vegetable oils and assess adulteration and quality of soybean and peanut oils.

Developing a method of identifying oil authenticity is becoming critical for protecting customers' rights as adulteration of edible oils is a particular concern in food quality. Since adulterants in edible oils are usually unknown, the authenticity identification is a one-class classification problem in chemometrics. In this study, a one-class classification model was built to identify the authenticity of peanut oils by fatty acid profiles. Based on previous studies, 28 fatty acids were identified and quantified for peanut oils. The authenticity identification model was built by one-class partial least squares (OCPLS) classifier for peanut oils. Subsequently, the established model was validated by independent test sets. The results indicated that the OCPLS classifier could effectively detect adulterated oils and was therefore employed for authenticity assessment. Moreover, counterfeit oils adulterated with different levels of other edible oils were simulated by the Monte Carlo method and employed to test the lowest adulteration level of this one-class classifier. As a result, the model could identify peanut oils and sensitively detect adulteration of edible oils with other vegetable oils at adulteration level of more than 4%.

A highly-sensitive time-resolved fluorescent immunochromatographic assay (TRFICA) was developed to detect aflatoxin M1 (AFM1) in raw milk samples within 6 minutes without any sample pretreatments. This method could meet the requirement for rapid and sensitive milk monitoring in dairy farms and milk industries. Based on a competitive format and the home-made monoclonal antibody 2C9 against AFM1, this assay enhanced the sensitivity from 0.3 ng mL−1 (by using nanogold-strip method previously reported) to 0.03 ng mL−1 (by using this TRFICA method). The improved sensitivity could probably result from the increases in both the higher affinity of monoclonal antibody 2C9 against AFM1 and detection signals of immunoassay probes (with each europium microbead coupled with numbers of 2C9 antibodies). The TRFICA method showed a considerable dynamic range of 0.1–2.0 ng mL−1 and spiked recoveries of 80–110% for AFM1 quantification in raw milk. The results via TRFICA method was found to be high consistency (R2 = 0.988) with results via standard high-performance liquid chromatography (HPLC) method, when detecting AFM1 in 17 blind milk samples.

Immunochromatographic (IC) assays are considered suitable diagnostic tools for the determination of mycotoxins. A europium nanospheres-based time-resolved fluorescence immunoassay (Eu-Nano-TRFIA), based on a monoclonal antibody and a portable TRFIA reader, was developed to determine total aflatoxin (including aflatoxins B1, B2, G1, and G2) levels in feed samples. Under optimized conditions, the Eu-Nano-TRFIA method detected total aflatoxin within 12 min. It showed good linearity (R2 > 0.985), LOD of 0.16 μg/kg, a wide dynamic range of 0.48–30.0 μg/kg, recovery rates of 83.9–113.9%, and coefficients of variation (CVs) of 3.5–8.8%. In the 397 samples from company and livestock farms throughout China, the detection rate was 78.3%, concentrations were 0.50–145.30 μg/kg, the highest total aflatoxin content was found in cottonseed meal, and corn was found to be the most commonly contaminated feed. This method could be a powerful alternative for the rapid and ultrasensitive determination of total aflatoxin in quality control and meet the required Chinese maximum residue limits.

The adulteration of olive oils based on advanced sensors has attracted high interest owing to its health benefits in the prevention and treatment of certain pathologies. Concerning its health and commercial aspects, lower grade oil blending and other illegal additives in virgin olive oil can negatively affect the nutritive value of olive oil. This review focuses on the advances in the sensing and identification of adulteration of olive oil. Optical sensing, chromatography (usually coupled with mass spectrometry), and nuclear magnetic resonance are discussed in detail. Other methods including a DNA-based method, dielectric spectroscopy, differential scanning calorimetry, thermogravimetric analysis and electronic nose among others, are overviewed as well.

A method of lateral flow time-resolved fluoroimmunoassay (LF-TRFIA) was developed for rapid and ultrasensitive detection of T-2 toxin with TRFIA strips and an assorted portable TRFIA reader. Quantitative detection of T-2 toxin was realized by recording fluorescence intensities of the mAb–Eu(III) probes captured on the test line (T line) and control line (C line) of the assay strips. Quantitative standard curves for determining T-2 toxin in rice, maize, and feed were established by plotting T/C ratio against the logarithmic concentration of T-2 toxin with the linear range of 0.125–200 ng g−1 for rice and maize and 0.25–200 ng g−1 for feed. The limit of detection (LOD) was 0.09 ng g−1 for rice and maize and 0.17 ng g−1 for feed. The recovery of the standard spike ranged from 94.2% to 111.0%, and the coefficient of variation (CV) was less than 15%. The results obtained by LF-TRFIA within 15 minutes showed a good correlation with the LC-MS/MS results, indicating that the LF-TRFIA method was reliable and suitable for rapid testing.

•Developing a sensitive and quantitative immunochromatographic assay for ochratoxin A.•Using antibody conjugated gold nanoparticles as label for detection.•Using a rapid color intensity portable strip reader for quantifying the method.•The assay was used for ochratoxin A detection in agro-products.•The results were reliable and in accordance with those obtained using HPLC.In most cases of mycotoxin detection, quantitation is critical while immunochromatographic strip tests are qualitative in nature. Moreover, the sensitivity of this technique is questioned. In order to overcome these limitations, an ultrasensitive and quantitative immunochromatographic assay (ICA) for rapid and sensitive quantitation of ochratoxin A (OTA) was developed. The assay was based on a competitive format and its sensitivity was improved by using a sensitive and selective OTA monoclonal antibody (OTA-mAb). The visible ICA results were obtained within 15 min, and in addition to visual examination, they were read by the rapid color intensity portable strip reader. The visual and computational detection limits (vLOD and cLOD, respectively) for ochratoxin A were 0.2 and 0.25 ng mL−1, respectively. These values were lower than those reported by previous studies in a range 5–2500 folds. For validation, contaminated samples including wheat, maize, rice and soybean were assayed by ICA and a standard high performance liquid chromatography (HPLC). The results were in good agreement for both ICA and HPLC methods. The average recoveries of the HPLC were in the range 72–120% while the ICA values were from 76 to 104%, confirming the accuracy and sensitivity of this method.

A phage-displayed library of variable domain of heavy chain of the heavy chain antibody (VHH) or nanobody (Nb) was constructed after immunizing an alpaca with aflatoxin B1 (AFB1) conjugated with bovine serum albumin (AFB1–BSA). Two AFB1-specific nanobodies were selected. The obtained nanobodies were compared to an aflatoxin-specific monoclonal antibody B5 with respect to stability under organic solvents and high temperature. The two nanobodies could bind antigen specifically after exposure to temperatures as high as 95 °C. Besides, the nanobodies showed better or similar tolerance to organic solvents. A competitive ELISA with nanobody Nb26 was developed for the analysis of AFB1, exhibiting an IC50 value of 0.754 ng/mL (2.4 μM), linear range from 0.117 to 5.676 ng/mL. Due to the high tolerance to methanol, sample extracts were analyzed by nanobody-based ELISA without dilution. The recovery from spiked peanut, rice, corn and feedstuff ranged from 80 to 115%. In conclusion, the isolated nanobodies are excellent candidates for immunoassay application in aflatoxin determination.

Aflatoxins are a group of extremely toxic small molecules that have been involved in human hepatic and extrahepatic carcinogenesis as causative agents. Herein, we developed a real-time immuno polymerase chain reaction (IPCR) assay for the accurately quantitative detection of aflatoxins in agri-products base on a M13 phage containing aflatoxin anti-idiotypic nanobody and its encoding DNA which was used to design the specific primers. The limit of detection (LOD) of the assay is 0.02 ng/mL, which exhibits a 4-fold improvement over traditional phage ELISA. The developed method was successfully validated with the samples of corn, rice, peanut, and feedstuff, which are major aflatoxin-contaminated agri-products. And the recoveries were from 77.05 to 122.16%. For further validation, the developed assay was also compared with a reference HPLC method for the analysis of aflatoxins in corn and peanuts, and concordant results (R2 = 0.991) were obtained. In this context, this study provides a novel opportunity to analyze aflatoxins in agri-products.

•Selected ion monitoring mode was proposed to untargeted fatty acid profiles.•Mass spectra and equivalent chain length were used to identify fatty acids.•The developed method could analyze 28 fatty acids in vegetable oils.Fatty acids are potential biomarkers of some diseases and also key markers and quality parameters of different dietary fats and related products. Thus, untargeted fatty acid profiles are important in the study of dietary fat quality and fat-related diseases, as well as in other fields such as bioenergy. In addition, accurate identification of unknown components is a technological breakthrough for the selected ion monitoring (SIM) mode for untargeted profiles. In this study, we developed untargeted fatty acid profiles based on SIM. We also investigated mass spectral characteristics and equivalent chain lengths (ECL) to eliminate the influence of non-FAMEs for identifying fatty acids in samples. As an application example, fatty acid profiles were used to classify three edible vegetable oils. The results indicated that SIM-based untargeted fatty acid profiles could yield accurate qualitative and quantitative results for more fatty acids and benefit related studies of metabolite profiles.

•Ozone can detoxify most of aflatoxins under the optimised condition.•Exposure time and ozone concentration are two important factors on detoxification.•The nutrition and quality of treated peanuts have not changed significantly.Aflatoxins are a group of secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus with carcinogenicity, teratogenicity, and mutagenicity. Aflatoxins may be found in a wide range of agri-products, especially in grains, oilseeds, corns, and peanuts. In this study, the conditions for detoxifying peanuts by ozonation were optimised. Aflatoxins in peanuts at moisture content of 5% (w/w) were sensitive to ozone and easily degraded when reacted with 6.0 mg/l of ozone for 30 min at room temperature. The detoxification rates of the total aflatoxins and aflatoxin B1 (AFB1) were 65.8% and 65.9%, respectively. The quality of peanut samples was also evaluated in this research. No significant differences (P > 0.05) were found in the polyphenols, resveratrol, acid value (AV), and peroxide value (PV) between treated and untreated samples. The results suggested that ozonation was a promising method for aflatoxin detoxification in peanuts.

The detection of adulteration of high priced oils is a particular concern in food quality and safety. Therefore, it is necessary to develop authenticity detection method for protecting the health of customers. In this study, fatty acid profiles of five edible oils were established by gas chromatography coupled with mass spectrometry (GC/MS) in selected ion monitoring mode. Using mass spectral characteristics of selected ions and equivalent chain length (ECL), 28 fatty acids were identified and employed to classify five kinds of edible oils by using unsupervised (principal component analysis and hierarchical clustering analysis), supervised (random forests) multivariate statistical methods. The results indicated that fatty acid profiles of these edible oils could classify five kinds of edible vegetable oils into five groups and are therefore employed to authenticity assessment. Moreover, adulterated oils were simulated by Monte Carlo method to establish simultaneous adulteration detection model for five kinds of edible oils by random forests. As a result, this model could identify five kinds of edible oils and sensitively detect adulteration of edible oil with other vegetable oils about the level of 10%.

To prevent the potential adulteration of flaxseed oil with high amounts of nutritional components, a simple and rapid adulteration detection method was proposed based on ion mobility spectrometry (IMS). After dilution in n-hexane, the edible oil sample was analyzed by IMS for 20 s. Subsequently, the multivariate statistical methods, including principal component analysis (PCA) and recursive support vector machine (R-SVM), were employed to establish a discriminant model for authentic and adulterated flaxseed oils. The cross validation results indicated that the R-SVM model could identify adulterated flaxseed oil samples (≥5%) with a high accuracy of 93.1%. Therefore, IMS could be used as an important tool to protect customers from adulterated flaxseed oil.

Adulteration of high-price edible oils has become a focus of attention and a tough problem in food trade and consumption all over the world. Therefore, there is a great demand for detecting oil adulteration to protect interests and rights of customers and safeguard their health. In this study, free phytosterol profiles of peanut, soybean, rapeseed, and sunflower seed oils were established by SPE-multidimensional gas chromatography coupled with time-of-flight mass spectrometry (GC-GC-TOF/MS) and employed to classify the four edible oils with the help of unsupervised (principal component analysis and hierarchical clustering analysis) and supervised (random forests) multivariate statistical methods. The results indicated that free phytosterol profiles of edible oils could help classify the four edible oils into four groups completely, and therefore, could be used as important markers of the oils studied. Moreover, a simulated data test revealed that free phytosterol profiles could also be used to detect adulteration of peanut oil with 5% soybean oil, which was simulated by the Monte Carlo method.

A simple, directly applicable and label-free immunoassay was proposed based on a specific immune binding reaction induced fluorescence quenching of an analyte. Aflatoxin B1 (AFB1) was taken as the model analyte, whose intrinsic fluorescence was quenched by the specific anti-AFB1 monoclonal antibody. This immunoreaction-induced fluorescence quenching was utilized to quantitatively determine AFB1.

•VOCs in four kinds of edible oils were analyzed by Headspace GC×GC–TOF/MS.•The selective volatile components were screened out for four classes of edible oils.•Classification models of four kinds of edible oils were built by PCA, HCA and RF.Edible oil adulteration is the biggest source of food fraud all over the world. Since characteristic aroma is an important quality criterion for edible oils, we analyzed volatile organic compounds (VOCs) in four edible vegetable oils (soybean, peanut, rapeseed, and sunflower seed oils) by headspace comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (Headspace–GC×GC-TOFMS) in this study. After qualitative and quantitative analysis of VOCs, we used unsupervised (PCA) and supervised (Random forests) multivariate statistical methods to build a classification model for the four edible oils. The results indicated that the four edible oils had their own characteristic VOCs, which could be used as markers to completely classify these four edible oils into four groups.

Anti-idiotypic antibodies recognize the antigenic determinants of an antibody, thus they can be used as surrogate antigens. Single-domain antibodies from camlid heavy-chain antibodies with the benefit features of small size, thermostability, and ease in expression, are leading candidates to produce anti-idiotypic antibodies. In this work, we constructed an antibody phage library from the mRNA of an alpaca immunized with an antiaflatoxin monoclonal antibody (mAb) 1C11. Three anti-idiotypic VHH antibodies were isolated and applied to immunoassay toward aflatoxin as a coating antigen. The best immunoassay developed with one of these VHH antibodies shows an IC50 of 0.16 ng/mL toward aflatoxin B1 and cross-reactivity toward aflatoxin B2, G1, and G2 of 90.4%, 54.4%, and 37.7%, respectively. The VHH-based immunoassay was successfully applied to the analysis of peanuts, corn, and rice, which are the predominant commodities regularly contaminated by aflatoxins. A good correlation (r2 = 0.89) was found between the data obtained from the conventional ELISA and the ELISA based on a VHH coating antigen for the analysis of aflatoxins in peanuts and feedstuff. The use of biotechnology in developing the surrogate, the absence of standard aflatoxin and organic solvents in the synthesis procedures, and the reproducibility of the VHH antibody makes it an ideal strategy for replacing conventional synthesized antigens.

•Graphene oxide (GO) was successfully synthesized and used as an adsorbent for extraction of four aflatoxins.•The aflatoxins extraction efficiency for GO has been investigated.•A method of HPLC-FLD coupled with GO as adsorbent has been developed for the simultaneous determination of four aflatoxins in peanut samples.In this paper, graphene oxide (GO) was synthesized and specifically selected by centrifugation to extract four aflatoxins (B1, B2, G1, and G2) as an effective adsorbent. Then, the amount of aflatoxins was quantitatively measured by high-performance liquid chromatography (HPLC). The GO was characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), and ultraviolet (UV) spectrophotometer. Several parameters that could affect the extraction efficiency, including the GO amount, methanol concentration in the extraction solvent, spiked amount, extraction time, and elution cycle, were also investigated and optimized in this work. Under optimal conditions, good linear relationships were achieved with the correlation coefficient (r) ranging from 0.99217 to 0.99995. The detection limit of this method for the four aflatoxins ranged from 0.08 to 0.65 ng/g. Finally, the proposed method has been successfully applied to determine aflatoxins in peanut samples. The results show that the recoveries of the four aflatoxins range from 85.1% to 100.8% with the relative standard deviations between 2.1% and 7.9%.

To search for an alternative to using protein conjugated aflatoxin as a coating antigen in aflatoxin detection by an ELISA method, a random-8-peptide library was constructed and used as a source of peptides that mimic aflatoxins (termed as mimotopes). Five mimotope peptides were obtained by panning-elution from the library and were successfully used in an indirect competitive ELISA for analyzing total aflatoxin concentration. The assay exhibited an IC50 value of 14 μg/kg in samples (with 1 in 7 dilution of sample extract) for aflatoxins. The linear range is 4–24 μg/kg. Further validation indicated relatively good recovery (60–120%) in peanut, rice and corn. Natural contaminated samples (peanut and feedstuff) were analyzed for aflatoxin concentration by both conventional ELISA and phage ELISA. The results showed good correlation. It can be concluded that the mimotope preparation is an effective substitute for the aflatoxin based coating antigen in ELISA and can be used in real sample analysis.

An enhanced facile strategy using a green chemistry method for the surface modification of poly(dimethylsiloxane) (PDMS) was developed via an in situ bulk free radical polymerization to resist nonspecific protein adsorption and to reduce electroosmotic flow (EOF). After silanization by 3-methacryloxypropyltrimethoxysilane, allyl-polyethylene glycol (PEG) was conjugated onto the PDMS surface with the aid of sodium persulfate. The surface properties of PDMS were characterized with Fourier transform infrared absorption by attenuated total reflection (ATR-FTIR) and contact angle experiments. EOF measurements and a nonspecific protein adsorption assay revealed a stable EOF suppression and remarkable protein-repelling properties for more than 30 days. Separation of FITC-labeled amino acids demonstrated a high reproducibility (migration time, RSD 2.2%). Further separation of fluorescence-labeled proteins using PDMS microchips before and after the surface modification showed that the PEG-modified PDMS microchip had an improved electrophoretic performance with a RSD of 1.49% for the migration time. In summary, a convenient strategy was developed for the modification of a PDMS microchip to prevent nonspecific protein adsorption and to enhance the electrophoretic performance. This improved environmentally friendly surface modification method will be useful for protein separation especially in batch production.

•A multi-component immunochromatographic assay (ICA) was established for multiple mycotoxins detection.•The ICA gave visible results for sensitive and simultaneous detection of three mycotoxins.•This ICA strip could analyze the agro-food samples in easy, rapid, onsite and low-cost way.Mycotoxins are highly toxic contaminants and have induced health threat to human and animals. Aflatoxin B1 (AFB1), ochratoxin A (OTA) and zearalenone (ZEA) commonly occur in food and feed. A multi-component immunochromatographic assay (ICA) was developed for rapid and simultaneous determination of these three mycotoxins in agro-food. The strategy was performed based on the competitive immunoreactions between antibody-colloidal gold nanoparticle conjugate probes and mycotoxins or mycotixin antigens. Each monoclonal antibody specially recognize its corresponding mycotoxin and antigen, and there was no cross reactivity in the assay. Three mycotixin antigens were immobilized as three test lines in the nitrocellulose membrane reaction zone, which enable the simultaneous detection in one single test. The visible ICA results were obtained in 20 min. The visual detection limits of this strip test for the AFB1, OTA and ZEA were 0.25 ng/mL, 0.5 ng/mL and 1 ng/mL, respectively. The assay was evaluated using spiked and naturally contaminated peanuts, maize and rice samples. The results were in accordance with those obtained using enzyme-linked immunosorbent assay. In summary, this developed ICA could provide an effective and rapid approach for onsite detection of multi-mycotoxin in agro-food samples without any expensive instrument.

Recent trend toward semiquantitative strip tests has been driven by a strong demand for rapid screening of toxic or harmful substances in food. Here, a detector-free semiquantitative immunochromatographic assay (ICA) has been developed. In the assay, the test zone is formed by dispensing three test lines [TLs (TL-I, TL-II and TL-III)] with the same capture reagent onto a nitrocellulose membrane. The competition between the migrating analyte and the immobilized capture reagent on three TLs for the limited number of antibody binding sites causes less nanogold–Ab probe to accumulate on TLs, which provides an easily visible color owing to the red color itself. When analyte concentration is up to the threshold level, no color appears on the TL. That's to say, the appearing number of color bands after a reaction indicates the content (range) of analyte. Analyte concentration levels can thus be determined by observing the number of TLs developed in the test zone. Taking major aflatoxins as target analytes, the threshold levels for TL-I–III and the visual detection limit of the detector-free semiquantitative strip (DFQ-strip) assay were determined, respectively. Results show that the DFQ-strip assay is superior to traditional ICAs because it offers multiple dynamic detection ranges and semiquantitative analytical capability.

We screened and established seven hybridoma cell lines that secrete anti-aflatoxin monoclonal antibodies with different sensitivities. Among these antibodies, 1C11 exhibited the highest sensitivity against all four major kinds of aflatoxins (AFB1, AFB2, AFG1, and AFG2) (IC50 0.0012–0.018 ng mL–1 in the enzyme linked immunosorbent assay (ELISA) system, visual limit of detection of 0.03–0.25 ng mL–1). To better understand the interactions between these antibodies and aflatoxins, as well as to guide their potential sensitivity improvement in recombinant antibodies, we used multiple sequence alignment and molecular modeling combined with molecular docking to clarify the molecular mechanism of the highest sensitivity of 1C11 against aflatoxins. Our results show that hydrogen bond and hydrophobic interaction formed by Ser-H49 and Phe-H103 in the antibody with the hapten played the most important roles in determining the binding affinity. Further experiments performed on antibody mutants, designed on the basis of the computational models, supported the prediction of the interaction mode between the antibody and the hapten. Although the factors that influence antibody sensitivity are highly interdependent, our experimental and modeling studies clearly demonstrate how structural differences influence the binding properties of antibodies against the target hapten with different sensitivities.

It is critical to develop a cost-effective quantitative/semiquantitative assay for rapid diagnosis and on-site detection of toxic or harmful substances. Here, a naked-eye based semiquantitative immunochromatographic strip (NSI-strip) was developed, on which three test lines (TLs, TL-I, TL-II and TL-III) were dispensed on a nitrocellulose membrane to form the test zone. Similar as the traditional strip assay for small molecule, the NSI-strip assay was also based on the competitive theory, difference was that the analyte competed three times with the capture reagent for the limited number of antibody binding sites. After the assay, the number of TLs developed in the test zone was inversely proportional to the analyte concentration, thus analyte content levels could be determined by observing the appeared number of TLs. Taking aflatoxin B1 as the model analyte, visual detection limit of the NSI-strip was 0.06 ng mL−1 and threshold concentrations for TL-I–III were 0.125, 0.5, and 2.0 ng mL−1, respectively. Therefore, according to the appeared number of TLs, the following concentration ranges would be detectable by visual examination: 0–0.06 ng mL−1 (negative samples), and 0.06–0.125 ng mL−1, 0.125–0.5 ng mL−1, 0.5–2.0 ng mL−1 and >2.0 ng mL−1 (positive samples). That was to say, compared to traditional strips the NSI-strip could offer more parameter information of the target analyte content. In this way, the NSI-strip improved the qualitative presence/absence detection of traditional strips by measuring the content (range) of target analytes semiquantitatively.Graphical abstractTo offer semiquantitative analytical ability for a single analyte, the naked-eye based strategy used three test lines (TL-I–III) instead of the traditional application of a single test line per analyte or multi-test lines for multi-analyte in simultaneous detection strips. The three test lines, containing the same capture reagent, was the key point of the strategy and also the basis of semiquantitative analytical ability of the NSI-strip. In the assay, with the increase of concentration, the analyte caused the TLs to disappear in a graduated sequence due to competition between the analyte and the immobilized capture reagent to bind with the nanogold-Ab probe, in other words, the disappearance of each test line represented a threshold level of analyte concentration. Analyte concentration levels could thus be determined by observing the number of TLs developed in the test zone. In this way, the NSI-strip assay improved the qualitative presence/absence detection of traditional strip by measuring the content (range) of target analytes semiquantitatively.Highlights► A novel naked-eye based strategy for semiquantitative immunochromatographic assay was described by dispensing three test lines (TLs) on a nitrocellulose membrane to form the test zone and validated with aflatoxin B1 as a model analyte. ► Compared to traditional strips, the naked-eye based semiquantitative immunochromatographic strip (NSI-strip) could offer more parameter information of analyte content, these parameters were: three threshold concentrations, five detection ranges and a visual detection limit. ► The NSI-strip improved the qualitative presence/absence detection of traditional strip by measuring the content (range) of target analytes semiquantitatively.

A green enzyme-linked immunosorbent assay (ELISA) to measure aflatoxin M1 (AFM1) in milk was developed and validated with a surrogate calibrator curve. Polyclonal anti-idiotype (anti-Id) antibody, used as an AFM1 surrogate, was generated by immunizing rabbits with F(ab′)2 fragments from the anti-AFM1 monoclonal antibody (mAb). The rabbits exhibited high specificity to the anti-AFM1 mAb, and no cross-reactivity to either of the other anti-aflatoxin mAbs or the isotype matched mAb was observed. After optimizing the physicochemical factors (pH and ionic strength) that influence assay performance, a quantitative conversion formula was developed between AFM1 and the anti-Id antibody (y = 31.91x − 8.47, r = 0.9997). The assay was applied to analyze AFM1 in spiked milk samples. The IC50 value of the surrogate calibrator curve was 2.4 μg mL−1, and the inter-assay and intra-assay variations were less than 10.8%; recovery ranged from 85.2 to 110.9%. A reference high-performance liquid chromatography method was used to validate the developed method, and a good correlation was obtained (y = 0.81x + 9.82, r = 0.9922).Graphical abstractHighlights► Polyclonal anti-idiotype antibodies were used as surrogate of AFM1. ► An excellent correlation was obtained between AFM1 and anti-idiotype antibodies. ► The anti-idiotype antibody was successfully used as surrogate calibrator curve for AFM1 in immunoassays. ► The recovery and accuracy results demonstrated that the method was feasible and reliable for the analysis of samples.

A sensitive and specific monoclonal antibody (Mab) against aflatoxin M1 (AFM1), named as 2C9, was selected by semi-solid HAT medium. It exhibited high affinity for AFM1 of 1.74 × 109 L/mol and no cross-reactivity to aflatoxin B1, B2, G1 and G2. Based on the antibody, an ultra-sensitive competitive enzyme-linked immunosorbent assay (ELISA) was developed for AFM1 in milk and infant milk products. Assays were performed in the AFM1-BSA coated (0.0625 μg/mL) ELISA format in which the antibody was diluted 1:10,000. Several physicochemical factors (pH, ionic strength and blocking solution) that influence assay performance were optimised. Finally, the limits of detection were 3 ng/L for milk and 6 ng/L for milk-based cereal weaning food, inter-assay and intra-assay variations were less than 10%, and the recovery ranged from 91% to 110%. Thirty samples were analysed, and concordant results were obtained when the data were compared with a reference high-performance liquid chromatography method.Research highlights► In our experiments, a novel semi-solid complete medium was applied to select single clone. Hybridoma colonies obtained from this medium are monoclonal from the start. It avoids the step of recloning and saves much time. ► The monoclonal antibodies described in this paper are the most specific for AFM1 so far. It exhibited high affinity for AFM1 of 1.74 × 109 L/mol and no cross-reactivity to aflatoxin B1, B2, G1 and G2. ► Based on the monoclonal antibodies described in this paper, an ultra-sensitive competitive enzyme immunoassay for aflatoxin M1 was developed. This method showed a detection limit of 3 ng/L, rather below the EU maximum level. Several physicochemical factors (pH, ionic strength and blocking solution) that affect assay performance were studied and optimized. ► The ultra-sensitive method was validated, by recovery test and comparing with reference HPLC method. The recovery and accuracy results demonstrated that the method was feasible and reliable for the analysis of real samples.

An ultrasensitive immunochromatographic (IC) assay for simultaneous detection of total aflatoxins (AFB1, AFB2, AFG1, and AFG2) was developed to meet the requirement for rapidly monitoring aflatoxins in agro-products. The assay was based on a competitive format and its sensitivity was improved by using a novel criterion to screen the optimal amount of monoclonal antibody (MAb) labeled to nanogold particles. The visual detection limits (VDLs) for aflatoxins B1, B2, G1, and G2 in peanut matrix were 0.03, 0.06, 0.12, and 0.25 ng mL−1, respectively, which were lower than those of published literatures. The results of IC assay were in good agreement with those of high performance liquid chromatography (HPLC) in the analysis of aflatoxins in peanuts, demonstrating the practical applicability of the developed assay in real samples. This qualitative test based on the visual evaluation of results did not require any equipment. Overall, to our knowledge, this is the first report of qualitative detection for total aflatoxins by immunochromatographic assay.

This paper describes the establishment of an immunoaffinity chromatography (IAC) for selective extraction of fenvalerate from vegetable samples. The IAC column was constructed by covalently coupling monoclonal antibody (mAb) against fenvalerate to CNBr-activated Sepharose 4B and packed into a cartridge. The extraction conditions were carefully optimized, including loading, washing and eluting solutions. Under the optimal conditions, the IAC column was able to capture fenvalerate with the maximum capacity of 4000 ng. An average recovery of 94.5% and a RSD of 8.8% were obtained with six IAC columns prepared on six different days. Three vegetable samples spiked with fenvalerate at four different concentrations were extracted with IAC column and determined by gas chromatography with electron capture detection (GC–ECD). Chromatograms of final extracts were clean and fenvalerate could be easily detected without the interferences. The extraction recoveries and RSD were 74.7–96.5% and 2.5–5.2%, respectively, and the calculated limit of detection of the whole method was 0.008–0.012 ng g−1.Highlights► An immunoaffinity chromatography was developed for extraction of fenvalerate from vegetables. ► The extraction conditions were carefully optimized. ► High recoveries of fenvalerate were obtained by using IAC combined with GC detection. ► The calculated LOD of the whole developed method towards different vegetables were all acceptable.

With a screening hemisolid stem-cell culture, four positive hybridomas 2B12, 2C1, 2F1, and 3D4 were screened and used to prepare four correspondent monoclonal antibodies (McAbs) against the pyrethroid insecticide deltamethrin. These McAbs showed I50 values in a range of 17−94 ng mL−1, from among which the antibody 2B12 with the lowest I50 value was selected to develop an optimized enzyme-linked immunosorbent assay (ELISA). In the developed ELISA, the I50 of deltamethrin was 17.0 ± 3.3 ng mL−1 and the limit of detection (LOD) was 1.2 ± 1.3 ng mL−1. There seemed to be little or no cross-reactivity with other tested pyrethroids and their metabolites. For validation of the assay method, environmental water samples fortified with deltamethrin were analyzed with the ELISA and gas chromatography (GC) methods. The recoveries of the developed ELISA ranged from 82 to 117%, which were close to those of the GC method (94−103%). These results suggested that the developed ELISA based on the McAb 2B12 could be used for the rapid and sensitive determination of deltamethrin in environmental water.

Monoclonal antibodies (McAbs) cross-reactive with four major aflatoxins were achieved using a modified two-step screening procedure. The first step was twice modified indirect enzyme-linked immunosorbent assay (ELISA) and resulted in positive hybridomas and hapten-specific antibodies. The modified indirect competitive ELISA (ciELISA) was the second step, in which the competition incubation time was decreased to 30 min, aflatoxin B1, B2, G1 and G2 were all used as competitors, the concentrations of four aflatoxins were gradiently decreased in each screening. 2–3 subclonings were performed after every modified fusion and resulted in eight hybridomas that secreted antibodies with good cross-reactivity and high affinity to four aflatoxins. Five McAbs were chosen for further analysis. Of the five, two antibodies had similar reaction efficiency with aflatoxin B1, B2 and G1 but showed a weak cross-reaction to G2. Another two had almost identical reaction capability with four aflatoxins. One clone 1C11 exhibited the highest sensitivity for all four aflatoxins. The concentrations of aflatoxin B1, B2, G1 and G2 at 50% inhibition for 1C11 were 1.2, 1.3, 2.2 and 18.0 pg mL−1 respectively. This is the most sensitive for all four major aflatoxins described so far. The results indicated that the modified two-step screening procedure had superiority and these antibodies could be used for simultaneous analysis of total aflatoxins.

Three class-specific monoclonal antibodies against aflatoxins were screened by a designed strategy in which aflatoxin G2 was used as competitor in the screening ELISA system. With a high cross-reactivity (65%) to aflatoxin G2, antibody 10C9 had the most similar sensitivity for five aflatoxins (AFB1, AFB2, AFG1, AFG2 and AFM1), whose I50 values were in a range of 2.1–3.2 ng ml−1. So, antibody 10C9 was selected to develop an ELISA for determination of aflatoxin B1, B2, G1, G2 and total of them in peanut samples. And spiked recoveries were from 87.5% to 102.0%. The results indicate that the ELISA developed can accurately determine total aflatoxins in samples of peanuts after the simple and rapid extraction procedure.

To determine the influences of early-stage diabetes mellitus on methionine sulfoxide reductases (Msrs) expression in lenses, streptozocin (STZ)-induced diabetic mice as animal models were used in this study. The results showed that the contents of methionine sulfoxide (MetO), protein carbonyl (PC) and Malondialdehyde (MDA) in the lenses of STZ-induced diabetic mice after 14 days were significantly higher than that in the normal control, level of total sulfhydryl groups (TSH) was 60% of normal control, and mRNA expressing levels of the MsrA and MsrBs were significantly decreased compared with normal group, as was the expression of MsrB1 protein. These results suggest that STZ not only causes increased oxidative stress, but also suppresses Msr mRNA and MsrB1 protein expression during early-stage diabetes in mice. However, the mechanism remains to research.Highlights► The contents of methionine sulfoxide, protein carbonyl and malondialdehyde in the STZ-induced diabetic mouse lenses were significantly higher than that in the normal control. ► The levels of total sulfhydryl groups, the MsrA and MsrBs mRNA expression were significantly decreased compared with normal group, as was the expression of MsrB1 protein. ► The STZ-induced diabetic mice result in not only increasing oxidative stress but also suppressing Msrs mRNA and MsrB1 protein expression in the lens.

To determine the influences of early-stage diabetes mellitus on methionine sulfoxide reductases (Msrs) expression in lenses, streptozocin (STZ)-induced diabetic mice as animal models were used in this study. The results showed that the contents of methionine sulfoxide (MetO), protein carbonyl (PC) and Malondialdehyde (MDA) in the lenses of STZ-induced diabetic mice after 14 days were significantly higher than that in the normal control, level of total sulfhydryl groups (TSH) was 60% of normal control, and mRNA expressing levels of the MsrA and MsrBs were significantly decreased compared with normal group, as was the expression of MsrB1 protein. These results suggest that STZ not only causes increased oxidative stress, but also suppresses Msr mRNA and MsrB1 protein expression during early-stage diabetes in mice. However, the mechanism remains to research.Highlights► The contents of methionine sulfoxide, protein carbonyl and malondialdehyde in the STZ-induced diabetic mouse lenses were significantly higher than that in the normal control. ► The levels of total sulfhydryl groups, the MsrA and MsrBs mRNA expression were significantly decreased compared with normal group, as was the expression of MsrB1 protein. ► The STZ-induced diabetic mice result in not only increasing oxidative stress but also suppressing Msrs mRNA and MsrB1 protein expression in the lens.

•Multivariate adulteration detection for sesame oil by one-class support vector machine.•Lowest adulteration levels of the OC-SVM model were calculated.•One-class model is promising tool to identify authenticity of edible oil and food.Multivariate and untargeted adulterations are real cases of oil adulteration in practice. In this study, one-class support vector machine (OC-SVM) was used to build the model for detecting multivariate and untargeted adulterations of sesame oil. The predictive model was subsequently validated by an independent test set. The results indicated that the OC-SVM model could completely detect the adulterated oils. Moreover, oils adulterated with different levels of mixed edible oils were simulated by Monte Carlo method and employed to determine the lowest adulteration level of the predictive model. Compared with earlier studies, the OC-SVM model proposed for sesame oil in this study is more robust to detect untargeted and multivariate adulteration.

Adulteration of high-price edible oils has become a focus of attention and a tough problem in food trade and consumption all over the world. Therefore, there is a great demand for detecting oil adulteration to protect interests and rights of customers and safeguard their health. In this study, free phytosterol profiles of peanut, soybean, rapeseed, and sunflower seed oils were established by SPE-multidimensional gas chromatography coupled with time-of-flight mass spectrometry (GC-GC-TOF/MS) and employed to classify the four edible oils with the help of unsupervised (principal component analysis and hierarchical clustering analysis) and supervised (random forests) multivariate statistical methods. The results indicated that free phytosterol profiles of edible oils could help classify the four edible oils into four groups completely, and therefore, could be used as important markers of the oils studied. Moreover, a simulated data test revealed that free phytosterol profiles could also be used to detect adulteration of peanut oil with 5% soybean oil, which was simulated by the Monte Carlo method.

A simple, directly applicable and label-free immunoassay was proposed based on a specific immune binding reaction induced fluorescence quenching of an analyte. Aflatoxin B1 (AFB1) was taken as the model analyte, whose intrinsic fluorescence was quenched by the specific anti-AFB1 monoclonal antibody. This immunoreaction-induced fluorescence quenching was utilized to quantitatively determine AFB1.

An enhanced facile strategy using a green chemistry method for the surface modification of poly(dimethylsiloxane) (PDMS) was developed via an in situ bulk free radical polymerization to resist nonspecific protein adsorption and to reduce electroosmotic flow (EOF). After silanization by 3-methacryloxypropyltrimethoxysilane, allyl-polyethylene glycol (PEG) was conjugated onto the PDMS surface with the aid of sodium persulfate. The surface properties of PDMS were characterized with Fourier transform infrared absorption by attenuated total reflection (ATR-FTIR) and contact angle experiments. EOF measurements and a nonspecific protein adsorption assay revealed a stable EOF suppression and remarkable protein-repelling properties for more than 30 days. Separation of FITC-labeled amino acids demonstrated a high reproducibility (migration time, RSD 2.2%). Further separation of fluorescence-labeled proteins using PDMS microchips before and after the surface modification showed that the PEG-modified PDMS microchip had an improved electrophoretic performance with a RSD of 1.49% for the migration time. In summary, a convenient strategy was developed for the modification of a PDMS microchip to prevent nonspecific protein adsorption and to enhance the electrophoretic performance. This improved environmentally friendly surface modification method will be useful for protein separation especially in batch production.

To prevent the potential adulteration of flaxseed oil with high amounts of nutritional components, a simple and rapid adulteration detection method was proposed based on ion mobility spectrometry (IMS). After dilution in n-hexane, the edible oil sample was analyzed by IMS for 20 s. Subsequently, the multivariate statistical methods, including principal component analysis (PCA) and recursive support vector machine (R-SVM), were employed to establish a discriminant model for authentic and adulterated flaxseed oils. The cross validation results indicated that the R-SVM model could identify adulterated flaxseed oil samples (≥5%) with a high accuracy of 93.1%. Therefore, IMS could be used as an important tool to protect customers from adulterated flaxseed oil.

The adulteration of olive oils based on advanced sensors has attracted high interest owing to its health benefits in the prevention and treatment of certain pathologies. Concerning its health and commercial aspects, lower grade oil blending and other illegal additives in virgin olive oil can negatively affect the nutritive value of olive oil. This review focuses on the advances in the sensing and identification of adulteration of olive oil. Optical sensing, chromatography (usually coupled with mass spectrometry), and nuclear magnetic resonance are discussed in detail. Other methods including a DNA-based method, dielectric spectroscopy, differential scanning calorimetry, thermogravimetric analysis and electronic nose among others, are overviewed as well.