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Hollow fiber-solid phase microextraction combined with micro sample collector assisted injection technique was developed for the detection of trace fatty acid methyl esters in biodiesel wastewater. Polypropylene hollow fiber was employed as extraction material to absorb fatty acid methyl esters in biodiesel wastewater. After the adsorption, hollow fiber was sleeved on the needle core of a micro sample collector and introduced directly into a GC injector for thermal desorption of the analytes. The selectivity of polypropylene hollow fiber on fatty acid methyl esters was investigated by extracting common pollutants in wastewater. Under the optimal conditions, the enrichment factors of polypropylene hollow fiber for methyl palmitate, methyl linoleate, methyl oleate, and methyl stearate were tested as high as 471, 287, 527, and 801, respectively. The quantitative method was validated and the linearity was satisfactory over a concentration range of 10-2000 µg/L with the correlation coefficients more than 0.9990 for 4 fatty acid methyl esters. The limits of detection and quantification were 0.04-0.40 µg/L and 10.0 µg/L, respectively. The recoveries were in the range of 92.0-116.7% by analyzing actual spiked samples. The results showed that the established method was suitable for the analysis of trace fatty acid methyl esters in water samples, with simple operation, low cost and environmental friendliness.

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A method for the determination of polyvinyl chloride was developed by the use of a micro sample pretreatment technique combined with ion chromatography. Polyvinyl chloride sample was placed in a sealed glass capillary containing 10 µL deionized water. As a micro pyrolysis reactor, the sealed glass capillary was maintained at 300 °C for 2 min in an oven. Under the above temperature, polyvinyl chloride was pyrolyzed rapidly and released hydrogen chloride, which was easily absorbed by deionized water. Subsequently, the absorption liquid was transferred to a volumetric flask and diluted to 10 mL. Ion chromatography was utilized to detect the content of chloride ion in the diluted absorption liquid for the quantification of polyvinyl chloride in samples. Good linear correlation coefficient (r = 0.9999) was obtained over a range of 0.02-2.00 mg polyvinyl chloride. Appropriate precision with the relative standard deviation below 16.4% and good recoveries between 86.0 and 119.4% were achieved in this work. The limits of detection and quantification were 0.004 mg and 0.012 mg for polyvinyl chloride respectively. The contents of polyvinyl chloride in real samples determined by the micro sample pretreatment technique were consistent with the results obtained by the referenced oxygen flask combustion method. It proved that the proposed method is simple, rapid and accurate for the determination of polyvinyl chloride in real samples.

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Tyrosine phosphorylation is one of the important protein phosphorylations in eukaryotes responsible for a variety of biological processes including cell signaling transduction, cell migration, and apoptosis. In the study of phosphoproteomics, due to the low stoichiometry of tyrosine phosphorylation (pTyr) proteins and sometimes limited initial sample, traditional phosphoproteomics enrichment technology is inefficient for the enrichment of pTyr peptides. Here, we review the substantial progress in tyrosine phosphoproteomics by preparation of limited amount sample and the newly introduced SH2 superbinder.

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One of the most cited limitations of biochemical detection is its poor sensitivity, owing to the relatively high complexity of micro-samples. Moreover, some samples cannot be easily self-replicated and their abundance cannot be increased through traditional technologies. Therefore, the preconcentration of low-abundance samples is a key requirement for microfluidic biological analysis. In recent years, the ion-concentration polarization phenomenon has aroused widespread interest in the application of microfluidic technology. In addition, paper-based materials are readily available, easy to modify, and exhibit good hydrophilicity. The study of the ion-concentration polarization preconcentration of micro-samples in paper-based microfluidic chips is of considerable significance. In this review, we discuss the development and applications of ion-concentration polarization paper-based preconcentrator in the past 5 years, with emphasis on key progresses in chip fabrication and performance optimization under different conditions. The current needs and development prospects in this field have also been discussed.

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Tyrosine phosphorylation is one of the important protein phosphorylations in eukaryotes responsible for a variety of biological processes including cell signaling transduction, cell migration, and apoptosis. In the study of phosphoproteomics, due to the low stoichiometry of tyrosine phosphorylation (pTyr) proteins and sometimes limited initial sample, traditional phosphoproteomics enrichment technology is inefficient for the enrichment of pTyr peptides. Here, we review the substantial progress in tyrosine phosphoproteomics by preparation of limited amount sample and the newly introduced SH2 superbinder.

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A rapid, sensitive, selective and validated reverse phase high-performance liquid chromatography (RP-HPLC) method for the estimation of paclitaxel in micro-sample of rat plasma and in culture of cancer cells was performed in this study. The mobile phase consisted of an optimized mixture of methanol:water: trifluroacetic acid (80: 20: 0.1, v/v/v). Column elution at a flow rate of 1 mL/minute with UV detection at 225 nm at room temperature was used. The RP-HPLC method was successfully applied for the determination of paclitaxel in plasma samples and in culture of cancer cells with nano-quantity of estimation. The validation studies were performed in accordance with the International Conference on Harmonization (ICH) guidelines. The intra- and inter-day precision showed that the coefficients of variation ranged from 1.07% to 4.27% at different levels of concentrations. To the best of our knowledge, this study also reported for the first time the optimization of different solvents for effective extraction of paclitaxel wherein tert.-butyl methyl ether (TBME): diethyl ether (DEE) in 50: 50 v/v composition was found most efficient with extraction efficiency ranging between 77.99% and 91.74% and between 76.14 and 93.66% in the plasma and cell culture, respectively. This proposed method was successfully applied to study the pharmacokinetics of paclitaxel and the influence of verapamil and all-trans retinoic acid (atRA) on paclitaxel pharmacokinetics in rat models. This proposed method might emerge as a valuable aid in the laboratory monitoring of paclitaxel in a variety of in vitro as well as in vivo scenarios.