Automatic Multi-Plug Filtration Cleanup Tip-Filtration with Ultra-Performance Liquid Chromatography/Tandem Mass Spectrometry Detection For 22 Pesticide Residues in Typical Vegetables.

An automatic multi-plug filtration cleanup (m-PFC) tip-filtration method was developed to reduce the manual operation workload in sample preparation. In this work, m-PFC was based on multi-walled carbon nanotubes mixed with primary secondary amines and anhydrous magnesium sulfate (MgSO4) in a packed column for analysis of pesticide residues followed by ultra-performance liquid chromatography coupled with tandem mass spectrometry. Method validation was performed on 22 pesticide residues in carrot, spinach and leek, at spiked levels of 5, 10 and 50 µg/kg, respectively. The average recoveries were between 70.1 and 119.5% with associated relative standard deviations <20% (n = 6) indicating satisfactory accuracy and repeatability. Matrix-matched calibration curves were performed with the correlation coefficients (R2) higher than 0.9903 within a linearity range of 5-100 ng/mL. The limits of quantification were 5 µg/kg for all the pesticides in carrot, spinach and leek matrices. The developed method was successfully used to determine pesticide residues in market samples.

[Determination of 44 foodborne stimulants and 6 progestogens in meat by QuEChERS and ultra-performance liquid chromatography-tandem mass spectrometry].

To ensure the success of large-scale sporting events, prevent the contamination of food by prohibited substances, and evaluate the risk of foodborne stimulants and other hormones in food, it is necessary to establish a high-throughput, rapid, and accurate detection method for foodborne stimulants and other hormones. In this study, a QuEChERS method is proposed for the simultaneous determination of 44 foodborne stimulants and 6 progestogens using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The analyzed foodborne stimulants include 19 ß2-agonists, 3 ß-blockers, 11 anabolic agents, 8 glucocorticoids, and 3 diuretics. A meat sample was crushed and homogenized, following which the internal standard was added. Subsequently, the sample was shaken and extracted with water and an acetonitrile solution containing 0.5% acetic acid, then dehydrated and centrifuged with sodium chloride and anhydrous magnesium sulfate. The supernatant was purified by PSA, C18, neutral alumina, and anhydrous magnesium sulfate. It was then dried with nitrogen and concentrated. The concentrated extracts were separated using an ACQUITY BEH C18 column (100 mm×2.1 mm, 1.7 µm) with gradient elution using 0.1% formic acid-5 mmol/L ammonium acetate solution and methanol as mobile phases. The target compounds were detected by ultra-performance liquid chromatography-tandem mass spectrometry with electrospray ionization and positive ion scanning (ESI+) in the multiple reaction monitoring (MRM) mode, and quantified by the internal standard method. The linear ranges of ß2-agonists and ß-blockers were 0.1-20 µg/L, the linear ranges of glucocorticoids were 0.5-200 µg/L, and those of the others were approximately 0.2-50 µg/L. The linear relationships of 50 compounds were good, with correlation coefficients >0.99 in the linear ranges, and limits of quantification (LOQs) in the range of 0.1-0.4 µg/kg. The recoveries of the 50 target compounds spiked in chicken, pork, beef, lamb samples at three levels ranged from 50.3% to 119.9%, while the relative standard deviations (RSDs, n=6) ranged from 0.42% to 15.1%. Nine meat samples (including 3 beef, 3 pork, 2 chicken, and duck samples) were tested by this method and the national standard method (GB/T 21981-2008). The t test was used for statistical analysis of the hydrocortisone and cortisone contents, and no significant difference was found between the results obtained by the two methods. The developed method was used to analyze 12 beef samples from a farm. In all, 4 compounds were detected, while the other 46 were not detected. The content ranges and detection rates of the compounds were as follows: hydrocortisone: 3.3-22.6 µg/kg, 100%; cortisone: 1.5-2.1 µg/kg, 67%; androstenedione: 0.7-1.2 µg/kg, 17%; and testosterone: 0.6-1.5 µg/kg, 42%. In conclusion, the proposed method is simple, accurate, and sensitive, and hence, is suitable for the detection of foodborne stimulants and progestogens in different kinds of raw meat.

Determination of 12 Carbamate Insecticides in Typical Vegetables and Fruits by Rapid Multi-Plug Filtration Cleanup and Ultra-Performance Liquid Chromatography/Tandem Mass Spectrometry Detection.

A multiresidue method for determining 12 carbamate pesticides in purple cabbage, orange, watermelon, cucumber, cowpea and Lactuca sativa L. employing multi-plug filtration cleanup (m-PFC) and ultra-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) was developed. M-PFC was carried out by cleanup at dispersive solid phase extraction (d-SPE), one m-PFC tip-filtration, two m-PFC tip-filtration and other methods (1-3 m-PFC cleanups). Results demonstrated that filtration simplified the cleanup method compared with d-SPE and other m-PFC methods (1-3 m-PFC cleanups). The method validation results showed that the method was linear, selective and accurate. The limits of quantification (LOQs) were 0.05-5.0 µg/kg, and the recoveries were in the range of 70.1-119.9% in different matrices. Although matrix effects were observed, they were successfully compensated using matrix-matched calibration. Finally, the developed method was successfully applied to detect pesticides in real samples.

[Simultaneous determination of 24 industrial dyes in grain and meat products by ultra performance liquid chromatography-tandem mass spectrometry].

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS) analytical method was established for the simultaneous determination of 24 forbidden industrial dyes in grain and meat products. The sample was extracted with methanol and acetonitrile, and cleaned-up by a WAX solid phase extraction column. The solution was separated on an ACQUITY UPLC BEH C18 column eluted with a mixture of 10 mmol/L ammonium acetate-0.2% formic acid aqueous solution and methanol-acetonitrile (7:3, v/v) as the mobile phases, and then analyzed in multiple reaction monitoring (MRM) mode. The correlation coefficients were above 0.99, the average recoveries were 61%-116%, and the relative standard deviations (RSD, n = 6) were lower than 13%. The quantification limits were 0.1-4.0 microg/kg. This method is simple, effective, sensitive, and suitable for the determination and confirmation of the 24 forbidden industrial dyes in grain and meat products.