Analysis of 46 pesticides in teas of Fuzhou City, Fujian Province, China

Simultaneous determination of 131 pesticides in tea by on-line GPC-GC–MS/MS using graphitized multi-walled carbon nanotubes as dispersive solid phase extraction sorbent

Evaluation of an alternative fluorinated sorbent for dispersive solid-phase extraction clean-up of the quick, easy, cheap, effective, rugged, and safe method for pesticide residues analysis

An inexpensive, effective, and efficient dispersive solid-phase extraction (DSPE) sorbent was developed as an alternative totraditionally used sorbents (primary secondary amine and C18) for fatty matrices using theQuEChERS method. Catalytic chemical vapor deposition grown carbon nanofibers dispersed on activated carbon fibers (Ni-ACF/CNF) having aBET specific surface area of738 (m2/g) were for thefirst time evaluated as a DSPE material for sample cleanup before gas chromatographic analysis. Based on cleanup performance and recoveries, 10mg of Ni-ACF/CNF was found optimalfor the determination of twenty-seven multi-class pesticides in high fat and low water commodities/matrices (peanut, soybean, sesame, and flaxseed). The recoveries obtained for all analytes were in the range ~ 72 to ~ 117%, with relative standard deviation values ≤ 15%. The limits of detection and quantification values were 0.7-4.2ng/g and 2.3-13.9ng/g, respectively. The matrix match calibration curve was linear in the range 20-500ng/g with a correlation coefficient of ≥ 0.993. The results reveal thatthe Ni-ACF/CNF is a competent DSPE sorbent, similar to primary secondary amines and C18sorbent materials, for pesticide determination by QuEChERS methods in high fat and low water commodities. Graphical abstract.

Pesticide Multi-Residue Analysis in Tea Using d-SPE Sample Cleanup with Graphene Mixed with Primary Secondary Amine and Graphitized Carbon Black Prior to LC–MS/MS

基于超高效液相色谱-串联质谱(UHPLC-MS/MS)建立定量分析乙拌磷及其5个代谢物(乙拌磷砜、乙拌磷亚砜、内吸磷-S、内吸磷-S-砜、内吸磷-S-亚砜)的方法,应用该方法分析其在农产品(豌豆、芦笋、小麦、咖啡豆和花生)中的残留量。对样品前处理及色谱条件进行优化,样品经过乙腈涡旋提取(小麦、咖啡豆和花生先加水润湿),经盐析分层,取上清液经50 mg C18、50 mg PSA和50 mg NH2混合分散固相萃取净化后,经Thermo Syncronis C18色谱柱(150 mm×2.1 mm, 5 μm)分离,柱温40 ℃,进样量2 μL,以水和乙腈为流动相梯度洗脱后,采用ESI源,在正离子扫描和多反应监测(MRM)模式下检测,外标法定量。结果表明,乙拌磷及其代谢物在2.0~200.0 μg/L范围内线性关系良好,相关系数(R2)≥0.9981。方法的检出限(LOD)为0.02~2.0 μg/kg,并以最小添加水平5 μg/kg为定量限(LOQ)。乙拌磷及其代谢物在豌豆、芦笋、小麦、咖啡豆和花生中5、100、1000 μg/kg 3个添加水平下的平均回收率为75.0%~110.0%,相对标准偏差(RSD)为0.7%~14.9%,方法的准确度和精密度符合农药残留测定。应用建立的方法对市售的40份小麦样品和40份花生样品进行检测,均低于方法的检出限。该方法具有操作简单、快速、灵敏、准确的特点,适用于谷物、油料、蔬菜等多种农产品中乙拌磷及其代谢物的残留检测。

Development, optimization and validation of QuEChERS based liquid chromatography tandem mass spectrometry method for determination of multimycotoxin in vegetable oil

A multiresidue analytical method for the determination of 250 pesticide residues in vegetables was developed by using QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The target compounds were extracted with acetonitrile containing 1% (v/v) acetic acid, purified by a mixed sorbent of MgSO4, primary secondary amine (PSA), graphitized carbon black (GCB) and C18, separated on a Waters ACQUITY™ UPLC BEH C18 column (100 mm x 2. 1 mm, 1.7 µm) and detected by UPLC-MS/MS. Anhydrous magnesium sulfate was used as a dewatering agent. The effects of the amounts of MgSO4, PSA, GCB and C18 added on the recoveries of 250 pesticides were investigated. The results showed that the purification effect was best when 300 mg MgSO4, 200 mg PSA, 10 mg GCB and 100 mg C18 in 2 mL of the extract were added. For the 250 pesticide residues, the limits of detection (LODs) of the method were from 0. 01 to 50. 00 g/kg. The recoveries obtained ranged from 60. 1% to 120% at three spiked levels in Chinese chives with the relative standard deviations between 3. 5% and 19. 5% using matrix matched external standard method. The results showed that the method is able to meet requirements of the multiresidue detection of the 250 pesticides in vegetable. The method has the advantages of rapidity, simplicity, high sensitivity and better purification effect. It is suitable for the rapid determination of the common pesticides in vegetables, and it provides a strong guarantee for the risk assessments of the quality and safety of vegetables.

Chapter 2.3 - The Evaluation of the Cleanup Efficiency of SPE Cartridge Newly Developed for Multiresidues in Tea

A comparative study was conducted over three stages on the cleanup efficiency of SPE cartridge Cleanert TPT, newly developed for multigroups of pesticide residues in tea. In Stage I, different SPE cartridges C18, graphite carbon black (GCB), primary secondary amine (PSA), and amino (NH2) were purchased and combined into 12 different sequences. Through the comparative test on cleanup efficiency of 84 representative pesticides in tea, Envi-Carb GCB + PSA with a good cleanup effect was selected. In Stage II, GC/MS test results from the comparative study of the extraction efficiency of 201 pesticides spiked into green tea and Woolong tea with Cleanert TPT and Envi-Carb + PSA SPE showed that average recoveries fell within 70-110% and RSD <20% for 193 and 184 pesticides, respectively, for green tea, accounting for 96.0 and 91.0% of the total number, respectively. GC/MS/MS test results also found 193 and 184 pesticides, respectively, meeting the recovery and RSD conditions, accounting for 96.0 and 91.5%, respectively, of the total number. For Woolong tea samples, GC/MS results showed that with Cleanert TPT and Envi-Carb + PSA SPE for cleanup, there were 192 and 177 pesticides, respectively, meeting the conditions, accounting for 95.5 and 88.1% of the total number, respectively. GC/MS/MS results demonstrated that there were 195 and 184 pesticides, respectively, meeting the conditions, accounting for 97.0 and 91.5% of the total number, respectively. It was seen that Cleanert TPT was superior to Envi-Carb + PSA in cleanup efficiency, whether for green or Woolong tea samples, or GC/MS or GC/MS/MS determination. In Stage III, 61104 results of the average content value of pesticides and RSD (two teas xtwo Youden pair concentrations x two kinds of SPE cartridges x two instruments x 19 tests x 201 pesticides) were derived from the 19 times stability tests over 3 months by paralleling three samples every 5 days via two instruments with two kinds of SPE cartridges for cleanup, respectively, against Youden Pair samples of the 201 incurred pesticides from green and Woolong teas. The statistical analysis found that detected values from the target pesticides of the incurred Youden pair samples showed no marked differences with cleanup by either Cleanert TPT or Envi-Carb + PSA, whether for green or Woolong tea, or G/IMS or G/IM/IMS. The test results using the two aforementioned kinds of SPE cleanup for above 93% pesticides had a tolerance less than 15%, which testifies that both cartridge cleanups met the requirement for pesticide residue analysis.

Multiclass pesticide residue analysis in fish muscle and liver on one-step extraction-cleanup strategy coupled with liquid chromatography tandem mass spectrometry

Perchlorate is an environmental contaminant interrupting thyroid hormone production, and perchlorate in tea has raised wide concern recently. In this study, an accurate method was developed for the determination of perchlorate in tea using hydrophilic interaction chromatography-tandem mass spectrometry and a simplified QuEChERS procedure. The method utilized a zwitterion HILIC column for separation, and the optimal gradient eluents consisted of acetonitrile and aqueous solution with 0.1% formic acid and 20 mmol L-1 ammonium formate. Calibration curves were fitted by the quadratic model with 1/x weight instead of the linear model. As perchlorate was only partially extractable when using acetonitrile or methanol as the extraction solvent, acetonitrile/water (1 : 1, v/v) was chosen to extract perchlorate from tea samples. Graphitized carbon black was used as the dispersive solid phase extraction sorbent to clean up tea extracts. The method exhibited satisfactory accuracy with recoveries of 81.4-100.9% and relative standard deviations of 1.3-14.5% for green and black teas. The limit of quantitation was 0.005 mg kg-1, while the limits of detection were 0.0011 mg kg-1 for green tea and 0.0013 mg kg-1 for black tea, indicating an excellent sensitivity of this method. A 100% positive rate of perchlorate was found in 100 real tea samples, and the concentrations ranged from 0.0030 mg kg-1 to 0.78 mg kg-1. This accurate, sensitive and rapid method would be suitable for monitoring, risk assessment and source identification of perchlorate in tea.

The goal of this study was to develop a method for simultaneous determination of acrylamide (AA) and 5-hydroxymethylfurfural (5-HMF) in heat-processed foods by liquid chromatography-tandem mass spectrometry analysis. Several cleanup methods for the quick, easy, cheap, effective, rugged, and safe (QuEChERS) protocol were investigated and compared: (a) dispersive solid-phase extraction (d-SPE) with Enhanced Matrix Removal-Lipid (EMR-Lipid), (b) d-SPE with primary secondary amine, (c) without the cleanup step, and (d) cleanup with n-hexane. It is the first time that EMR-Lipid sorbent has been used as a d-SPE material to detect AA and 5-HMF in heat-processed foods, and among the four cleanup methods, the EMR-Lipid method provided the best cleanup of co-extracted matrix interferences and the highest extraction efficiency. Validation experiments were carried out for the method using EMR-Lipid as the d-SPE sorbent. Excellent linearity ( R2 > 0.999) was achieved, and the limits of detection (LODs) of AA and 5-HMF were 2.5 and 12.5 μg/kg, respectively. The recoveries of AA and 5-HMF levels obtained were in the ranges of 87.3-103.3 and 83.2-104.3%, with precision [relative standard deviations (RSDs)] of 1.2-6.8 and 1.4-7.4% ( n = 3), respectively. The method is accurate and reliable and was successfully applied to analyze the AA and 5-HMF in eight categories of Chinese heat-processed foods.

ABSTRACTNanosheets of graphitic carbon nitride (GCN) were used as the dispersive solid-phase extraction (d-SPE) sorbent for the first time. GCN successfully purified complex matrices of soil, wheat, and wheat straw utilising a simple QuEChERS (quick, easy, cheap, effective, rugged, and safe) method with liquid chromatography tandem mass spectrometry. Pesticides recoveries in the range of 80–110%, small matrix effect, and decreased amounts guaranteed and distinguished this new sorbent. The application of a real formulation of pesticides under field conditions during 2015 in the wheat ecosystem illustrated the clean-up effect and application potential of GCN. It is a valuable and potential substitute for C18 according to the results comparison between two sorbents, including recoveries, matrix-matched calibration, and dissipation kinetics of pesticides. The new use of GCN also enriched the knowledge of d-SPE and sample preparation furthermore.

This study demonstrated the application of nanosized γ-aluminum oxide as dispersive solid-phase extraction (d-SPE) sorbent to pesticides multi-residue analysis in cereal grains by gas chromatography combined with orbitrap mass spectrometry (GC-Orbitrap-MS). The influence of structural phase, particle size, and usage amount of nanosized aluminum oxide were investigated on d-SPE cleanup performance. The ability of nanosized γ-aluminum oxide to clean up interfering substances from ethyl acetate extracts of cereal grains was also evaluated. Compared with common d-SPE sorbents (i.e., primary secondary amine (PSA), basic alumina, neutral alumina, acidic alumina, octadecylsilane (C18), florisil, graphitized carbon black (GCB), and nanosized ferroferric oxide (Fe3O4)), 10 nm γ-aluminum oxide was cost-effective and exhibited much better cleanup performance with 99.72% removal of eluting matrix components for wheat kernel. Meanwhile, a multiresidue method was validated on 24 representative pesticide residues in three cereal grains (wheat kernel, rice, and corn). Acceptable average recoveries of 71.1-117.0% and relative standard deviations (RSDs) &lt; 12.7% were obtained for all target pesticides. The method met the 5-10 μg L−1 limit of detection and 10-20 μg kg−1 limit of quantification. The results indicated that 10 nm γ-aluminum oxide represented an affordable and effective d-SPE adsorbent for pesticides multiresidue analysis in cereal grains.

A multi-residue analytical method was validated for 24 representative pesticides residues in onion, garlic and leek. The method is based on modified QuEChERS sample preparation with a mixture of graphene, primary secondary amine (PSA), and graphitised carbon black (GCB) as reversed-dispersive solid-phase extraction (r-DSPE) material and LC-MS/MS. Graphene was first used as an r-DSPE clean-up sorbent in onion, garlic and leek. The results first show that the mixed sorbent of graphene, PSA and GCB has a remarkable ability to clean-up interfering substances in the r-DSPE procedure when compared with the mixture of PSA and GCB. Use of matrix-matched standards provided acceptable results for tested pesticides with overall average recoveries between 70.1% and 109.7% and consistent RSDs <15.6%. In any case, this method still meets the 1–10 μg kg–1 detection limit needed for pesticide testing and may be used for qualitative screening applications in which any identified pesticides can be quantified and confirmed by a more intensive method that achieves >70% recovery.