A novel in-syringe chitosan-assisted dispersive micro-solid phase extraction method was established for the determination of anthraquinones in three kinds of traditional Chinese medicinal oral liquids containing rhubarb. Some parameters, including the concentration and molecular weight of chitosan, extraction time, pH of the solution, and the type and volume of eluent, affecting the extraction recovery were evaluated. Under the optimum conditions, i.e. 0.6 μg mL−1 chitosan (Mr 3000), extraction time 2 min, pH 5.0, and 800 μL of methanol as the eluent for the extraction of emodin, chrysophanol and physcion from 10 mL of the sample solution, the extraction yield reached the highest value. A good linearity was obtained for the three anthraquinones (R2 > 0.9983). The limit of quantitation was in the range of 1.8–3.0 ng mL−1 and the relative standard deviations for intra- and inter-day precision were less than 4.68% and 5.36%, respectively. The method was successfully applied towards the determination of the content of the three anthraquinones in Huangzhihua oral liquid, Children's heat-clearing oral liquid, and Magnolia exhaust mixture. Satisfactory recoveries for the three anthraquinones were in the range of 85.9–120.3%. In this study, the use of chitosan as a sorbent material is reported for the first time for in-syringe dispersive micro-solid phase extraction combined with HPLC/UV to analyze anthraquinones in rhubarb-based oral liquids.

•Methylamine modified graphene (CH3NH-G) was synthesized and used to pack SPE cartridge.•CH3NH-G packed SPE cartridge was used for the clean-up of sunflower seed extracts.•Neonicotinoid insecticide residues in sunflower seed samples were analyzed by UPLC-MS/MS.•Regeneration and reusability of the CH3NH-G packed SPE cartridge were studied.In this paper, methylamine modified graphene (CH3NH-G) was synthesized and used as solid-phase extraction (SPE) sorbent to cleanup the acetonitrile extract of sunflower seeds for the determination of neonicotinoid insecticides by UPLC-MS/MS. The effects of the type of extraction solvent, pH, the amount of CH3NH-G sorbent as well as the type and volume of eluent on the extraction efficiency were evaluated. Good linearity was obtained for the analytes with coefficient of determination (R2) in the range of 0.9986–0.9998. LOD (S/N=3) and LOQ (S/N=10) were below 6 and 20 ng kg−1, respectively. Method recoveries were between 74.3% and 119.1%. Relative standard deviations (RSD) for eight replicate determinations were in the range of 1.7–2.9%. The proposed method has been applied to the analysis of 3 kinds of sunflower seed samples from local market.

In this paper, salting-out assisted liquid–liquid extraction was coupled with low-temperature purification for the analysis of five kinds of endocrine-disrupting chemicals (EDCs) in milk and infant formula by ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Acetonitrile and potassium hydrogen phosphate were used for the extraction of EDCs and the precipitation of protein. After the extract’s being frozen at −35 °C in the freezer for 2 h to remove fat, the remaining liquid phase was passed through a neutral alumina cartridge for further purification. Some important parameters, such as the extraction solvent and protein precipitant, the species and amount of salting-out reagent, the volume ratio between sample solution and acetonitrile, the freezing temperature and freezing time, as well as the amount of adsorbent, were carefully investigated and optimized to achieve the best extraction efficiency. Under the optimal conditions, good linearity was obtained with coefficient of determination ≥0.9995 except for 17β-estradiol (R2 = 0.9950). Satisfactory recoveries were obtained for the five EDCs in the range of 73.5–119.2 %. Limits of detection were in the range of 0.03–0.23 ng mL−1. Relative standard deviations for intraday and interday precision were in the range of 4.5–9.0 and 2.7–6.0 %, respectively. The proposed method has been successfully applied to the analysis of seven kinds of market-purchased milk and two kinds of infant formula.

A well-defined Pd nanoparticles@polyoxometalates/macroporous carbon (Pd@POMs/MPC) tri-component nanohybrid has been developed using a facile, green, and one-pot synthesis method. The polyoxometalates were used as both reductant and bridging molecules. The novel nanohybrids of Pd@POMs/MPC can provide new features for electro-catalytic applications, because of the synergetic effects of Pd nanoparticles and MPC materials. The successful fabrication of Pd@POMs/MPC holds great promise for the design of electrochemical sensors, and is a promising material to promote the development of new electrode materials.

•Synthesize graphene in the lab, and to use it as SPE adsorbent after characterization.•Optimize the SPE conditions for the extraction and preconcentration of six carbamate pesticides.•Establish fast, sensitive and efficient UPLC–MS/MS method for the quantification of the carbamates.•Apply the proposed method to the determination of carbamate pesticide residues in environmental water samples.In this paper, graphene, a new sorbent material, was synthesized and used for solid-phase extraction (SPE) of the six carbamate pesticides (pirimicarb, baygon, carbaryl, isoprocarb, baycarb and diethofencarb) in environmental water samples. The target analytes can be extracted on the graphene-packed SPE cartridge, and then eluted with acetone. The eluate was collected and dried by high purity nitrogen gas at room temperature. 1 mL of 20% (v/v) acetonitrile aqueous solution was used to redissolve the residue. The final sample solution was analyzed by ultra performance liquid chromatography-tandem quadrupole mass spectrometry (UPLC–MS/MS) system. Under optimum conditions, good linearity was obtained for the carbamates with correlation coefficient in the range of 0.9992–0.9998. The limits of detection (S/N = 3) for the six carbamate pesticides were in the range of 0.5–6.9 ng L−1. Relative standard deviations (RSD) for five replicate determinations were below 5.54%. RSD values for cartridge-to-cartridge precision (n = 7) were in the range of 1.27–8.13%. After proper regeneration, the graphene-packed SPE cartridge could be re-used over 100 times for standard solution without significant loss of performance. The enrichment factors for the target analytes were in the range of 34.2–51.7. The established method has been successfully applied to the determination of carbamate pesticide residues in environmental water samples such as river water, well water and lake water.

A sandwich-type spontaneous injection for capillary electrophoresis is proposed in this paper. Three nitrophenols, namely p-nitrophenol, o-nitrophenol, 2,4-dinitrophenol, were chosen as the model compounds to validate the possibility of sandwich-type spontaneous injection. This sandwich-type spontaneous injection for the analysis of the three nitrophenols was performed in three steps. The first step was to fill up the whole capillary with the alkaline background solution of sodium borate (pH = 9.2). The second step was to inject a small volume of n-octanol (approximately 1.47 nL). The third step was to insert the inlet of the capillary into the sample vial where the pH was adjusted to acidic conditions for a desired time period (of less than 42 min). The sample vial was then refilled with background solution reservoir and a high voltage was applied across the whole capillary to enable the capillary electrophoretic analysis. Several experimental conditions influencing the efficiency of sandwich-type spontaneous injection were investigated, such as voltage, volume of n-octanol, cartridge temperature and waiting time for the inlet of the capillary inserted into the sample vial. Experimental results showed that the waiting time was the dominant factor influencing sandwich-type spontaneous injection. The enrichment factors for p-nitrophenol, o-nitrophenol and 2,4-dinitrophenol were 26, 28 and 15, respectively. The corresponding detection limits were 1.9 × 10−6, 5.0 × 10−6 and 1.7 × 10−6 mol L−1. The proposed method was successfully applied to the determination of three compounds in samples of spiked tap water.

In this paper, a cloud-point extraction method was developed for the determination of five anthraquinone derivatives in Chang-Qing tea by high-performance liquid chromatography. The optimum conditions for micelle extraction were obtained as follows—15% (w/v) Genapol X-080 as extractant, pH 3.5, liquid/solid ratio 80, and extraction time, 40 min. For cloud point preconcentration, 20% (w/v) NaCl was added, and the solution was incubated at 55 °C for 30 min. The detection limits for the five anthraquinone derivatives were in the range of 0.55–3.30 ng ml−1. Average recoveries for the anthraquinone derivatives at three spiked levels were in the range of 84.3–104.1%. Relative standard deviations for six replicate determinations of Chang-Qing tea sample were below 2.39. The established method has been successfully applied to the determination of anthraquinone derivatives in Chang-Qing tea products from three different manufacturers.

The reproducibility in migration time is essential in the use of capillary electrophoresis to identify components in a complex sample or compare constituent differences for different botanical drug samples. A powerful one-marker technology for correcting migration time was proposed in this paper. This technology is practically simple compared with the multi-marker technologies developed in literature, due to only one marker required. Paeoniae Radix which is a crude drug used in many traditional prescriptions in China and Japan was selected as an example to verify the effectiveness of the powerful one-marker technology in analyzing complex botanical samples. Relative standard deviations in migration times treated with the powerful one-marker technology were below 0.5% for Paeoniae Radix analyzed during three different days. The technology was successfully applied to classify Paeoniae Radix from nine different growing regions. Based on their corrected electropherograms, Paeoniae Radix was classified into three groups which were in agreement with their real origins.

In capillary electrophoresis (CE) analysis, acetonitrile-salt stacking (ASS) is an efficient way for enhancing the response signal of the analyte which is dissolved in the aqueous medium of acetonitrile and NaCl. The higher volume fraction of acetonitrile (60 to 80%) in the sample medium is strictly demanded if ASS is conducted. Consequently, it is necessary to develop a convenient method for converting the water-based sample to the acetonitrile-based sample without any dilution of the analyte during the sample preparation procedure. Acetonitrile subzero temperature liquid-liquid extraction (ASTLLE) is the best choice for this purpose. ASTLLE is based on the unique property of acetonitrile that a phase separation can occur if the homogenous mixture solution of acetonitrile and water is kept at a subzero temperature for a short period. The upper layer is the acetonitrile-rich phase, and the lower layer is the water phase. Accompanying the phase separation, the analytes of relatively weak polarity such as mononitrophenol isomers (at acidic condition) can be transferred to acetonitrile-rich phase. The volume fraction of acetonitrile in the formed acetonitrile-rich phase was estimated on the basis of its viscosity which was determined by CE instrument. It was confirmed that the volume fraction of acetonitrile in the formed acetonitrile-rich phase was in the range of 70 – 80% (v/v), indicating that the sample processed by ASTLLE met the ASS demand for high volume fraction of acetonitrile. The combination of ASTLLE and ASS was successfully applied to the analysis of mononitrophenol isomers in acidic aqueous solution. The precisions (RSD) of the migration time and peak area for six replicate runs of the three mononitrophenol isomers were in the range of 1.1∼1.3% and 5.5∼8.5% respectively. The lowest detection limit of mononitrophenol isomers was 1×10-4 μg-mL-1.The recovery ranged from 96.1 to 113.4%

A pre-column derivatization RP-HPLC assay was established for the simultaneous determination of 12 kinds of amino acids in Asparagi Radix before and after heating process. PITC was used as pre-column derivatization reagent. The obtained amino acid derivatives were separated on C18 column (250 × 4.6 mm i.d., 5 μm) by using gradient elution with 0.1 mol/L pH6.5 acetate buffer solution-acetonitrile (93:7,v/v) as mobile phase A and acetonitrile-water (4:1,v/v) as mobile phase B. 12 kinds of amino acids could be detected at 254 nm in 40 min with a flow rate of 0.9 mL/min. Linear range was between 0.5-500 μg/mL and average recovery was between 75.4% -100.1%. Experimental results showed that the amino acid content in Asparagi Radix was decreased after heating process.

A sandwich-type spontaneous injection for capillary electrophoresis is proposed in this paper. Three nitrophenols, namely p-nitrophenol, o-nitrophenol, 2,4-dinitrophenol, were chosen as the model compounds to validate the possibility of sandwich-type spontaneous injection. This sandwich-type spontaneous injection for the analysis of the three nitrophenols was performed in three steps. The first step was to fill up the whole capillary with the alkaline background solution of sodium borate (pH = 9.2). The second step was to inject a small volume of n-octanol (approximately 1.47 nL). The third step was to insert the inlet of the capillary into the sample vial where the pH was adjusted to acidic conditions for a desired time period (of less than 42 min). The sample vial was then refilled with background solution reservoir and a high voltage was applied across the whole capillary to enable the capillary electrophoretic analysis. Several experimental conditions influencing the efficiency of sandwich-type spontaneous injection were investigated, such as voltage, volume of n-octanol, cartridge temperature and waiting time for the inlet of the capillary inserted into the sample vial. Experimental results showed that the waiting time was the dominant factor influencing sandwich-type spontaneous injection. The enrichment factors for p-nitrophenol, o-nitrophenol and 2,4-dinitrophenol were 26, 28 and 15, respectively. The corresponding detection limits were 1.9 × 10−6, 5.0 × 10−6 and 1.7 × 10−6 mol L−1. The proposed method was successfully applied to the determination of three compounds in samples of spiked tap water.