For the first time, C₈-functionalized magnetic graphene (magG) has been designed and synthesized with a polydopamine (PDA) coating. The magG prepared by a solvothermal reaction was encapsulated in a layer of PDA through the oxidative polymerization of dopamine in alkaline buffer, and C₈ groups were grafted onto magG/PDA composites through a silanization method. The as-prepared material integrates the merits of graphene, magnetic microspheres, PDA, and C₈ chains; thus possessing an ultrahigh specific area, strong magnetic responsiveness, excellent solubility, and an extraordinary enrichment capability. The C₈-functionalized magnetic composites were employed in the enrichment and identification of low-concentration standard peptides, peptides in standard protein digest solutions, and endogenous peptides in human urine. The enriched peptides were eluted and analyzed by MALDI-TOF MS. The MS results indicated that the C₈-functionalized material exhibited the distinguished ability to enrich hydrophobic peptides mainly through hydrophobic–hydrophobic interactions. Moreover, thanks to the enrichment approach based on magG@PDA@C₈, the limit of detection of the standard peptide decreased to as low as 50 pM. The experimental results demonstrate that the magG@PDA@C₈ composite is a promising candidate for the enrichment of low-abundance peptides in biological samples.

A novel hierarchically ordered macro/mesoporous silica was functionalized with polyboronic acid (HOMMS@PolyVPBA). This composite possesses the attractive features of high surface area and large accessible porosity, and was applied to enrich glycopeptides. Here the HOMMS material was introduced into glycoproteome for the first time. The HOMMS@PolyVPBA gave remarkable selectivity for glycopeptides even at a low molar ratio of glycopeptides/nonglycopeptides (1:50) with a very rapid enrichment speed (only 10 min) and low detection (1 ng μL⁻¹). Therefore the synthetic HOMMS@PolyVPBA might be a promising selective enrichment material for glycoproteome analysis.

Feasible design is essential to achieve ideal chemical and biological properties of nanomaterials. For the first time, new nanocomposites with a polydopamine coating on hierarchically ordered macro-/mesoporous silica functionalized with titanium ions (denoted as HOMMS-PD-Ti⁴⁺) were prepared through a facile reaction route at room temperature. The applicability of as-synthesized HOMMS-PD-Ti⁴⁺ for the selective enrichment of phosphopeptides was tested. The experimental results demonstrate that, by taking advantage of the pure phosphate–Ti⁴⁺ interface and high loading amount of Ti⁴⁺, HOMMS-PD-Ti⁴⁺ presents remarkable selectivity for phosphopeptides, even at a low molar ratio of phosphopeptides/non-phosphopeptides (1:1000) with a very rapid enrichment speed (within 1 min). The superior sensitivity for low-abundant phosphopeptides and the high selectivity and effectiveness for the enrichment of phosphopeptides from human serum are also proven. These outstanding features demonstrate that HOMMS-PD-Ti⁴⁺ exhibits great potential in phosphoproteome research in the future.

In this work, magnetic multiwalled carbon nanotubes were synthesized through a facile hydrothermal process, and then successfully used as magnetic solid-phase extraction sorbents for the determination of p-hydroxybenzoates in beverage. The prepared magnetic multiwalled carbon nanotubes presented both satisfactory superparamagnetism and strong capacity of absorption, with magnetic Fe₃O₄ beads of 200 nm average diameters decorated at either ends of the tubes. The hybrid nanocomposites showed a high efficiency in the extraction and enrichment of p-hydroxybenzoates via π–π stacking of targeted molecules onto the polyaromatic composed surface of multiwalled carbon nanotubes, which entitled them promising magnetic solid-phase extraction sorbents for p-hydroxybenzoates at trace level from complex drink samples. By using an external magnetic field, p-hydroxybenzoates adsorbed on magnetic multiwalled carbon nanotubes could be rapidly isolated in only 30 s, and subsequently analyzed by liquid chromatography-diode array detector after elution with organic solvents. Extraction conditions such as eluting solvent, the amounts of magnetic sorbents added, pH values, adsorption and desorption time were investigated and optimized to achieve the best effect. Method validations including linearity, detection limit, and precision were also studied. The linearities were in the wide range of 0.05–500 μg/mL with correlation coefficients higher than 0.9983 for all p-hydroxybenzoates. The limits of detection were less than 20 ng/mL. Acceptable RSDs were achieved within 5–8% for all analytes. The results indicated that the proposed method based on magnetic multiwalled carbon nanotubes as magnetic solid-phase extraction absorbents was rapid, efficient, and convenient for the analysis of the targeted compounds of p-hydroxybenzoates in beverage sample.

In this work, the interior-walls decyl-perfluorinated functionalized magnetic mesoporous microspheres (F₁₇–Fe₃O₄@mSiO₂) were synthesized for the first time, and applied as adsorbents to extract and concentrate perfluorinated compounds (PFCs) from water samples. The fluorous functionalized interior pore-walls contributed to the high-selective preconcentration of PFCs due to fluorous affinity; and abundant silanol groups on the exterior surface of microspheres contributed to the good dispersibility in water sample. Four kinds of PFCs were selected as model analytes, including perfluorooctanoic acid, perfluorononanoic acid, perfluorododecanoic acid, and perfluorooctane sulphonate. In addition, UHPLC-ESI/MS/MS was introduced to the fast and sensitive detection of the analytes after sample pretreatment. Important parameters of the extraction procedure were optimized, including salinity, eluting solvent, the amount of F₁₇–Fe₃O₄@mSiO₂ microspheres, and extraction time. The optimized procedure took only 10 min to extract analytes with high recoveries and merely 800-μL acetonitrile to elute analytes from the magnetic adsorbents. Validation experiments showed good linearity (0.994–0.998), precision (2.6–7.6%), high recovery (93.4–105.7%) of the proposed method, and the limits of detection were from 0.008 to 0.125 μg/L. The F₁₇–Fe₃O₄@mSiO₂ magnetic microspheres have the advantages of great dispersibility in aqueous solution, high specificity of extraction, large surface area, and efficient separation ability. The results showed that the proposed method based on F₁₇–Fe₃O₄@mSiO₂ microspheres is a simple, fast, and sensitive tool for the analysis of PFCs in water sample.

In this work, the novel technique based on headspace single-drop microextraction with in-syringe derivatization followed by GC-MS was established to determine the volatile organic acids in tobacco. The parameters for headspace single-drop microextraction and in-syringe derivatization were optimized, including extraction time, and volume of derivatization reagent and in-syringe derivatization time. The method validations including linearity, precision, recovery and LOD were also studied. The obtained results illustrated that the optimized technique was easy, highly efficient and sensitive. Finally, the proposed method was successfully applied to the analyses of volatile organic acids in tobacco samples with seven different brands. It was further demonstrated that the present technique developed in this study does offer a simple and fast approach to determine volatile organic acids in tobacco.

In this work, for the first time, microwave-assisted extraction (MAE) followed by CE was developed for the fast analysis of catechin and epicatechin in green tea. In the proposed method, catechin and epicatechin in green tea samples were rapidly extracted by MAE technique, and then analyzed by CE. The MAE conditions and the method's validation were studied. It is found that the extraction time of 1 min with 400 W microwave irradiation is enough to completely extract catechin and epicatechin in green tea sample, whereas the conventional ultrasonic extraction (USE) technique needs long extraction time of 60 min. The method validations were also studied in this work. The calibration curve shows good linearity in 0.01–3 mg/mL for catechin (R²=0.993), and 0.005–3 mg/mL for epicatechin (R²=0.996), respectively. The RSD values for catechin and epicatechin are 0.65 and 2.58%, respectively. This shows that the proposed method has good reproducibility. The proposed method has good recoveries, which are 118% for catechin and 120% for epicatechin. The proposed method was successfully applied to determination of the catechin and epicatechin in different green tea samples. The experiment results have demonstrated that the MAE following CE is a simple, fast and reliable method for the determination of catechin and epicatechin in green tea.

In this work, for the first time, headspace (HS) single-drop microextraction and simultaneous derivatization followed by GC-MS was developed to determine the aliphatic amines in tobacco samples. In the HS extraction procedure, the mixture of derivatization reagent and organic solvent was employed as the extraction solvent for HS single-drop microextraction and in situ derivatization of aliphatic amine in the samples. Fast extraction and simultaneous derivatization of the analytes were performed in a single step, and the obtained derivatives in the microdrop extraction solvent were analyzed by GC-MS. The optimized experiment conditions were: sample preparation temperature of 80°C and time of 30 min, HS extraction solvent (the mixture of benzyl alcohol and 2,3,4,5,6-pentafluorobenzaldehyde) volume of 2.0 μL, extraction time of 90 s. With the optimal conditions, the method validations were also studied. The method has good linearity (R² more than 0.99), accepted precision (RSD less than 13%), good recovery (98–104%) and low limit of detection (0.11–0.97 μg/g). Finally, the proposed technique was successfully applied to the analyses of aliphatic amines in tobacco samples of seven different brands. It was further demonstrated that the proposed method offered a simple, low-cost and reliable approach to determine aliphatic amines in tobacco samples.

A novel method is firstly presented for field and rapid analysis of short-chain aliphatic amines in water as their pentafluorobenzaldehyde (PFBAY) derivative using solid-phase microextraction (SPME) and portable GC. In the proposed method, short-chain aliphatic amines in water rapidly reacted with PFBAY, and then were headspace extracted and concentrated by SPME. The formed amines derivatives were analyzed by portable GC. The SPME parameters of fiber selection, extraction temperature, extraction time, and stirring rate were studied. The method validations including LOD, recovery, precision, and linearity were studied. It was found that the proposed method required the whole analysis time 22 min, and provided low LOD of 1.2–4.6 ng/mL, good recovery of 91–106%, good precision of RSD value 3.5–9.3%, and linear range 20.0–500 ng/mL (r² >0.99). The obtained results demonstrated that the SPME-portable GC is a simple, rapid, and efficient method for the field analysis of short-chain aliphatic amines. Finally, the proposed method was further applied to the quantification of ethylamine, propylamine, and butylamine in environmental water.