Residue dynamics of chlorpyrifos and cypermethrin in/on pomegranate (Punica granatum L.) fruits and soil

Study on the residue dynamics of chlorpyrifos and cypermethrin in/on pomegranate (Punica granatum L.) and soil was carried out by conducting supervised field trials as per good agricultural practices. A modified QuEChERS was used to extract the insecticides in pomegranate peel and aril and soil. The limit of quantification (LOQ) of chlorpyrifos and cypermethrin were 0.01 and 0.05 mg kg^?1, respectively. Residues of the insecticides remained on the fruit surface and movement to the edible part (aril) was not observed. The residues after treatment on fruit peel were 2.46 and 3.51 mg kg^?1 and 2.84 and 4.54 mg kg^?1 for chlorpyrifos and cypermethrin, respectively, from recommended and double dose treatments. Chlorpyrifos residues degraded faster compared to cypermethrin. The pre-harvest intervals (PHIs) of chlorpyrifos were 22 and 35 days and those of cypermethrin 50 and 73 days, respectively, at recommended and double dose treatments. In the experimental field soil after the second application chlorpyrifos residues were 0.21 and 0.46 mg kg^?1 and cypermethrin residues 0.15 and 0.36 mg kg^?1. At harvest, both pesticides showed residues below the LOQ. Based on this study, application of cypermethrin towards harvest may be avoided whereas chlorpyrifos can be applied with 22 days PHI.     

Determination of Pesticide Residues in Teas via QuEChERS Combined with Dispersive Liquid–Liquid Microextraction Followed by Gas Chromatography–Tandem Mass Spectrometry

In this study, an effective gas chromatography–tandem mass spectrometry method was developed to determine 47 pesticide residues in tea. Sample preparation involved a quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure, wherein the sample is extracted by acetonitrile and cleaned up with multiwalled carbon nanotubes and primary secondary amine adsorbents; dispersive liquid–liquid microextraction (DLLME) was subsequently performed using carbon tetrachloride as extractive solvent and the extract obtained by QuEChERS as dispersive solvent. Factors influencing DLLME efficiency, including type and volume of extractive solvent, volume of dispersive solvent, and extraction time were evaluated. For validation purposes, recovery studies were performed using matrix blanks fortified with pesticides at three concentrations, namely, 10, 50, and 100 μg kg^?1. Most of the analytes were recovered at an acceptable range of 70?120% and RSDs ≤ 20% were acquired for green tea, oolong tea, black tea, and puer tea. Limits of quantification of pesticides obtained for these teas were sufficiently low, and most pesticides levels were lower than 10 μg kg^?1, which satisfies the requirements for maximum residue levels (MRLs) as prescribed by the European Community. Twenty-four commercially available tea samples were analyzed using this optimized method. Results revealed that the contents of chlorpyrifos and alpha-HCH from different green tea samples exceed the MRLs, and chlorpyrifos, bifenthrin, lambda-cyhalothrin, and cypermethrin are among the most frequently detected pesticides in teas.     

两种叶菜中5种典型手性农药对映体的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法研究

基于手性固定相/超高效液相色谱-串联质谱技术建立了同时拆分2种叶菜类蔬菜(菜心、油麦菜)中5种典型手性农药(多效唑、腈菌唑、甲霜灵、三唑酮和唑菌酮)对映体的分析方法。样品用乙腈提取,N-丙基乙二胺(PSA)粉和石墨化碳黑(GCB)粉净化,经手性色谱柱CHIRALCEL OD-RH拆分后,超高效液相色谱-串联质谱(UPLC-MS/MS)检测。结果表明,5种手性农药在0.005~1.0 mg·L-1范围内均呈良好线性关系;在0.01、0.1、0.5 mg·kg-1加标水平下的平均回收率为68.8%~104%,相对标准偏差(n=6)为1.0%~13.7%。该方法准确、简单、可靠,可以满足叶菜类蔬菜中多种手性农药残留的检测要求,并为这5种手性农药对映体在蔬菜中的残留及消解规律研究提供技术支持。     

Multi-Residue Analysis of 205 Crop Pesticides Using Mini-Solid Phase Extraction–Large Volume Injection–GC–MS

A simple, rapid, and sensitive multi-residue method has been developed for the determination of 205 pesticides commonly used for crop protection. Pesticide residues were extracted from samples with acetonitrile and a mini-solid phase extraction filter. No additional concentration or clean-up steps were necessary. Analyses were performed via large volume gas chromatography injection using a stomach-shaped inlet liner. The developed method was linear over the range assayed (5–50 μg L^?1), with determination coefficients >0.99. The limits of quantification were in the range 0.0005–0.6 mg kg^?1 and the limits of detection were between 0.00015 and 0.2 mg kg^?1. The majorities of them were lower than the maximum residue set by the Japanese government in “Positive System for Agricultural Chemical Residues in Food” directive in apple. This method was applied to determine pesticide levels in vegetables, fruits, and beans.     

Pesticide residue determination in vegetables from western China applying gas chromatography with mass spectrometry

In this study,an effort has been made to evaluate the pesticide residues in vegetables from western China. Fifty‐one pesticides, including organophosphorus, organochlorine, carbamate and pyrethroid, were detected in 369 commonly used vegetables by GC‐MS. Concentrations of organophosphorus pesticides were detected ranging from 0.0008 to 18.8200 mg/kg, among which organophosphorus pesticide concentrations exceeded their maximum residue levels (MRLs) in five samples. Carbamate and organochlorine pesticides were determined to have concentrations in the range of 0.0012–0.7928 mg/kg. The residual concentrations of carbamate pesticides in six samples and organochlorine pesticides in four samples exceeded their MRLs. The residual concentrations of five pyrethroid pesticides were within the range of 0.0016–6.0827 mg/kg and the pyrethroid residues in two samples exceeded their MRLs. The results revealed that pesticide residues in 70.73% of the vegetables samples were not detected, while in the rest of vegetables there were one or more pesticide residues and some even exceeded their MRLs, which would threaten the health of consumers. Our work provides significant information for the food safety regulations to control the excessive use of some pesticides on those kinds of vegetables from western China. Copyright © 2016 John Wiley & Sons, Ltd.     

Behaviour of selected pesticide residues in blackcurrants (<Emphasis Type="Italic">Ribes nigrum</Emphasis>) during technological processing monitored by liquid-chromatography tandem mass spectrometry

In this experiment, the behaviour of ten pesticides on field-sprayed blackcurrants (Ribes nigrum) after washing, juicing and cooking was investigated. The concentration level changes in two acaricides (fenazaquin, propargite), three insecticides (alpha-cypermethrin, deltamethrin and lambdacyhalothrin) and five fungicides (boscalid, bupirimate, difenoconazole, pyraclostrobin, thiophanate-methyl) were quantified. Analysis was carried out using the QuEChERS method followed by chromatographic analysis based on LC-MS/MS. The matrix effects ranged from —(17.4 ± 8.1) % to (15.9 ± 7.8) %. The limits of detection and limits of quantification were 0.003 mg kg^?1 and 0.01 mg kg^?1, respectively. The mean recoveries of the analytes ranged between 71 % and 109 %. The processing factors of all the blackcurrant products were determined. Washing reduced the pesticide residues up to 71 %. Juicing significantly reduced all the pesticide residues (processing factors (PFs) ranged 0.14–0.47). Cooking resulted in a decrease in residues up to 82 %. The residue levels of alpha-cypermethrin, deltamethrin and lambda-cyhalothrin in blackcurrant jam increased, and PFs > 1 were noted as PF = 1.38, 1.66 and 1.04, respectively. Cluster analysis was performed to find any similarity in the behaviour of pesticides after processing. The results confirmed that solubility, polarity and mode of action could be used to explain differences in the behaviour of pesticides.     

Multiplex bead-array competitive immunoassay for simultaneous detection of three pesticides in vegetables

We report on a multiplex bead-based competitive immunoassay using suspension array technology for the simultaneous detection of the pesticides triazophos, carbofuran and chlorpyrifos. Three hapten-protein conjugates were covalently bound to carboxylated fluorescent microspheres to serve as probes. The amount of conjugates and antibodies were optimized. The new multi-analyte assay has dynamic ranges of 0.02–50 ng?mL^?1, 0.5–500 ng?mL^?1 and 1.0–1000 ng?mL^?1 for triazophos, carbofuran and chlorpyrifos, respectively, and the detection limits are 0.024, 0.93 and 1.68 ng?mL^?1. This new multiplex assay is superior to the traditional ELISA in possessing a wider detection range, better reproducibility and the feature of multi-target detection. Cross-reactivity studies indicated that the bead-array method is highly selective for the three target pesticides, and that individual analyses have no significant influence between each other, also without cross-reactions from other structurally related pesticides. The method was applied to analyze vegetables spiked with the three pesticides, and the recoveries were in ranges of 78.5–112.1 %, 72.2–120.2 % and 70.2–112.8 %, respectively, with mean coefficients of variation of <15 %.

Pesticide residues in groundwaters and soils of agricultural areas in the Águeda River Basin from Spain and Portugal

This research has evaluated the agricultural impact of the use of pesticides in small agricultural areas in the Águeda river basin, which straddles the Spanish-Portuguese border. Sixteen pesticides frequently used in the area, including herbicides, fungicides and insecticides and some of their degradation products, were monitored in 52 groundwater samples and 42 soil samples taken around them, using a developed multi-residual analytical method based on SPE-LC-MS. Sampling was carried out in two different seasons (winter and summer). The results indicated the presence of pesticides at several levels, both in groundwaters and soils. Thirteen of the pesticides studied were detected in one or more of the groundwater samples analysed, but only three pesticides were detected in the soil samples. Terbuthylazine, cyprodinil, tebuconazole and chlorpyrifos were the pesticides most frequently detected in groundwaters, whereas terbuthylazine, metalaxyl and tebuconazole were the sole compounds detected in soils. The distribution of the concentrations in groundwaters indicated that up to 80% and 70% of the samples collected in the summer on the Spanish and Portuguese sides, respectively, exceed the quality standards of 0.1 µg L^?1 for one or more individual compounds and, in turn, up to 64% and 40% exceed the quality standards of 0.5 µg L^?1 for all compounds. The presence of pesticide residues in the groundwaters and soils analysed may well be explained by the use of these compounds in agricultural practices.     

Determination of imidacloprid and benzimidazole residues in fruits and vegetables by liquid chromatography-mass spectrometry after ethyl acetate multiresidue extraction

A simple and sensitive method based on liquid chromatography-atmospheric pressure ionization-mass spectrometry is described for the determination of 4 benzimidazole pesticides (carbendazim, thiabendazole, benomyl, and thiophanate-methyl) and imidacloprid in vegetables and fruits. Food samples were typically extracted with ethyl acetate to draw the analytes into the organic phase. No cleanup step was necessary before injection into the liquid chromatographic (LC) system with electrospray mass spectrometric detection. The analytes were separated on a reversed-phase C8LC column. Limits of detection for the compounds were in the microg/L range. Results are reported for validation studies with fortified pear and tomato samples and for residues of the target compounds found in the pesticide residue monitoring program during 1998.     

QuEChERS Technique for the Gas Chromatographic Determination of Organophosphate Residues in Strawberries

This study describes the validation of an analytical method employing gas chromatography with flame photometric detection for the determination of organophosphate pesticides (diazinon, disulfoton, parathion, chlorpyrifos, and malathion) in strawberries. The method employed a QuEChERS dispersive solid phase extraction for the sample preparation. QuEchERS is inexpensive, fast, and easy for the separation of the analytes from the matrix. In addition, the method provided linear calibration curves, ranging from 0.10–1.00 µg g^?1, for diazinon, disulfoton, parathion, and chlorpyrifos, and 0.10–2.00 µg g^?1 for malathion. Recovery studies yielded values in the range from 81.64 to 100.00%. These results demonstrated the potential of the technique for the determination of organophosphate residues in strawberries.     

Analysis of pesticides in surface water in remote areas in Vietnam: Coping with matrix effects and test of long-term storage stability

During the last years, the increased use of pesticides and growing awareness of associated environmental and health problems have led to the implementation of various monitoring programmes in South-East Asia. The introduction of numerous new active ingredients and commercial pesticide formulations in connection with reports on pesticide-related health problems strongly indicate that the analytical procedures should be tested and evaluated for currently used pesticides. Coping with matrix effects and ensuring pesticide stability when samples are taken in remote areas are paramount. In the present study, we tested an analytical method that targets nine currently used pesticides in surface water in northern Vietnam. The method consists of solid phase extraction, storage at ?18°C in the adsorbed state, and capillary gas chromatography with nitrogen-phosphorus-detection of five insecticides (dichlorvos, fenobucarb, dimethoate, fenitrothion, and chlorpyrifos), three fungicides (chlorothalonil, metalaxyl, and edifenphos) and one herbicide (atrazine). We evaluated the potential analytical bias caused by matrix effect and investigated its possible causes. We also tested the long-term stability (up to 9 months) of pesticides adsorbed to Carbopack SPE cartridges when stored at temperatures below ?18°C. Adopting a matrix-matched calibration technique considerably improved the recovery values of seven of the nine tested pesticides. At spiking levels of 0.1?µg?L^?1 and 1?µg?L^?1 and after storage of 119 days at ?18°C, recovery values of these pesticides ranged from 67% to 107% and from 67% to 155%, respectively. For the remaining two pesticides recovered at 53–55% at both spiking levels – dichlorvos and chlorothalonil – the method could still be useful for semi-quantitative analysis or as a screening tool. Even though the general recommendation is to minimise storage time to reduce pesticides degradation, our results showed that storage times up to nine months can be adopted for atrazine, metalaxyl, fenitrothion, and chlorpyrifos.     

Multiresidue determination of 256 pesticides in lavandin essential oil by LC/ESI/sSRM: advantages and drawbacks of a sampling method involving evaporation under nitrogen

The determination of 256 multiclass pesticides in lavandin essential oil has been performed by liquid chromatography–electrospray ionization tandem mass spectrometry using the scheduled selected reaction monitoring mode available on a quadrupole-linear ion trap mass spectrometer. With the aim of improving the limits of quantification (LOQs) of the target molecules, a sampling step based on evaporation of the essential oil under a nitrogen flow assisted by controlled heating was tested. The LOQs determined in this case were compared with the values obtained with the classic dilution preparation method. With sampling by dilution, 247 pesticides were detected and quantified at low concentration, with 74 % of the pesticides having LOQs of 10 μg L^-1 or less. With the evaporation method, a global improvement of the LOQs was observed, with lower LOQs for 92 active substances and LOQs of 10 μg L^-1 or less for 82.8 % of the pesticides. Almost twice as many active substances had an LOQ of 1 μg L^-1 or less when the evaporation method was used. Some pesticides exhibited poor recovery or high variance caused by volatilization or degradation during the evaporation step. This behavior was evidenced by the case of thiophanate-methyl, which is degraded to carbendazim.

Oxidized Multiwalled Carbon Nanotubes as an SPME Fiber Coating for Rapid LC–UV Analysis of Benzimidazole Fungicides in Water

The potential of oxidized multiwalled carbon nanotubes as a fiber coating for solid-phase microextraction of carbendazim, thiabendazole, and thiophanate-methyl from aqueous solution has been investigated, and the mechanism of adsorption has been explored. When an analytical method combining SPME with high-performance liquid chromatography was applied to real environmental water samples, recoveries of the spiked compounds was 75.7–104.5%, the linear range was 5–500 ng mL^?1, the squared correlation coefficients (r ²) were from 0.9978 to 0.9984, LOD were from 0.3 to 1.5 ng mL^?1, and RSD were from 2.3 to 10.5%.     

QuEChERS-高效液相色谱-串联质谱法测定黄瓜和土壤中甲基硫菌灵和多菌灵

建立了黄瓜和土壤样品中甲基硫菌灵和多菌灵的QuEChERS-高效液相色谱-电喷雾串联质谱(HPLC-ESI-MS/MS)检测方法。样品用乙腈溶液提取,经QuEChERS方法净化,以Agilent ZORBAX SB-C18色谱柱(30 mm×2.1 mm, 5 μm)进行HPLC分离,以电喷雾电离串联质谱正离子多反应监测(MRM)模式进行测定。对甲基硫菌灵和多菌灵在黄瓜和土壤中4个添加水平(0.01、0.05、0.1和1.0 mg/kg)下的回收率进行了测定,甲基硫菌灵在黄瓜中的添加回收率为87.3%～96.0%(相对标准偏差(RSD)为8.0%～9.3%),在土壤中的添加回收率为88.8%～93.4%(RSD为5.3%～9.9%);多菌灵在黄瓜中的添加回收率为87.1%～92.3%(RSD为5.2%～7.5%),在土壤中的添加回收率为85.8%～90.9%(RSD为5.3%～13.2%)。该方法样品前处理简单、快速,分析时间短,灵敏度、准确度和精密度均符合农药残留检测要求,适用于黄瓜和土壤中甲基硫菌灵和多菌灵残留的检测。     

气相色谱-四极杆飞行时间质谱准确鉴定常见水果蔬菜中的农药残留

建立了一种新型农药多残留检测方法。采用气相色谱-四极杆飞行时间质谱（GC-QTOF MS）结合Carbon NH₂柱固相萃取净化可对不同类别的152种农药残留进行准确的鉴定。一级（MS¹）精确质量数据库评价3~5个特征离子,以3个及以上特征离子检出且离子丰度比（Q/q_i）合适作为一级质谱定性依据。对部分特征离子数不足及特征离子检出情况不符合条件的农药进行二级（MS²）确证,应用二级谱图库检索及镜像结果对比分析实现疑似农药确证。本文对梨、甘蓝、番茄3种代表性果蔬在5.0和10.0 μg/kg 2个添加水平的152种农药进行测定,回收率在70%~120%范围的比例分别为甘蓝91.45 %、94.08%,番茄88.20%、88.80%,梨86.84%、92.10%。本方法为常见果蔬中农药残留的准确判断提供了可靠依据,扩大了分析范围。     

超高效液相色谱-串联质谱法快速检测番茄酱中吡虫啉等6种农药残留

建立了番茄酱中吡虫啉、多菌灵、甲基硫菌灵、霜霉威、灭多威和烯酰吗啉等农药残留的超高效液相色谱-串联质谱(UPLC-MS/MS)检测方法。样品用含0.1%(体积分数)乙酸的甲醇-水(1:1, v/v)混合溶液提取,采用Waters Acquity UPLC BEH C18色谱柱,以甲醇和10 mmol/L乙酸铵溶液为流动相进行梯度洗脱分离,经电喷雾正离子(ESI+)电离及多反应监测(MRM)模式来测定目标化合物,采用基质标准溶液曲线法进行定量。结果表明: 6种农药在0.005～0.2 mg/L的范围内线性关系良好(r＞0.995);当标准添加水平为0.02、0.05和0.2 mg/kg时,回收率为66.8%～102.9%;相对标准偏差均小于15%; 6种农药的定量限（以信噪比（S/N）＞10计）均为0.02 mg/kg。该方法简便、快速、灵敏和准确,非常适合番茄酱中这6种农药残留的快速检测及定量分析。     

Multi-residue analysis of 30 currently used pesticides in fine airborne particulate matter (PM 2.5) by microwave-assisted extraction and liquid chromatography–tandem mass spectrometry

A confirmatory and rapid procedure has been developed for the determination of 30 currently used pesticides (CUP) in fine airborne particulate matter (PM 2.5) at trace level. The proposed method includes extraction of PM 2.5-bound pesticides by microwave-assisted extraction (MAE) followed by a direct injection into LC–MS/MS. The main parameters affecting the MAE extraction (time, temperature and volume of solvent) were optimised using statistical design of experiments (DoE). The matrix effect was also evaluated. Recoveries ranged from 72 to 109% and the limit of quantification (LoQ) was 32.5 pg m⁻³ for chlorpyrifos, 13.5 pg m⁻³ for fenhexamid, imazalil and prochloraz, and 6.5 pg m⁻³ for the rest of pesticides, when air volumes of 760 m³ were collected. The method was applied to 54 samples collected from three stations of the atmospheric monitoring network of the Regional Valencia Government (Spain) during April–July 2009. Nineteen out of 30 pesticides investigated were found in at least one sample: omethoate, carbendazim, acetamiprid, thiabendazole, malathion, flusilazole, metalaxyl, azoxystrobin, iprovalicarb, myclobutanil, tebuconazole, triflumizole, cyprodinil, tebufenpyrad, buprofezin, pyriproxyfen, hexythiazox, flufenoxuron and fenazaquin. The measured concentrations ranged from 6.5 to 1208 pg m⁻³. To our knowledge, 11 of the pesticides detected have been reported for the first time in ambient air.     

Gas chromatography analysis of organophosphorous pesticides in plant samples

Summary The work presents a GC method for the determination of six organophosphorous pesticide residues in cabbage. Chopped cabbage was blended with acetone, then extracted with the mixture of n-hexane:methylene chloride (1:1). The extract was purified on a GPC column packed with BioBeads SX-3 gel. The pesticides were eluted with the mixture of methylene chloride:cyclohexane (1:1) at the flow rate of 0.5 mL min⁻¹. After concentrating the extract was analysed by GC. Nearly 100 samples of cabbage were analysed; trace residues of dimethoate (about 0.05 ppm) were found in 10 samples. The average recoveries of the pesticides were above 80% with a relative standard deviation mostly less than 10%. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997.     

Determination of pesticide residues in peaches by using gas chromatography and mass spectrometric detection

ABSTRACT

A multi-residue method using selected ion monitoring mode GC-MSD has been developed for the quantitative analysis of 30 widely used pesticides in fresh peaches produced in Swat Malakand, Pakistan. The planned methodology involved a sample extraction procedure using liquid-liquid partition with acetonitrile followed by a clean-up step based on solid-phase extraction (SPE). Method validation was performed in accordance with European Union guidelines. The European Union criteria (recovery 70–120%, RSD <20%) were met for majority of pesticides. For most of the pesticides, signal-to-noise ratios were good and background-corrected mass spectra often contained sufficient diagnostic to enable identity and confirmation. The limits of quantification (LOQs) were in the range 0.01–1.0 mg/kg. The above method was successfully applied to the analysis of peach samples (n = 30) from the field. Pesticide concentration in real peach samples was compared with the maximum residue levels (MRLs). Pesticide residues were detected in 73% of the peach samples. Most frequent residues were metalaxyl, α-cypermethrin, azoxystrobin, dimethoate, tebuconazol, λ-cyhalothrin and spiromesifin in peach samples.     

Presence of pesticides in breast milk and infants’ formulae in Himachal Pradesh,India

This study documents the levels of pesticide residues in milk samples of mothers from Himachal Pradesh, India, and time trend comparison of pesticide load based on various studies conducted around the world. The regional difference in xenobiotic levels of breast milk varied with demographic characteristics of mothers and altitudinal variations. The single or multiple pesticides contamination of p,p′-DDE, p,p′-DDT and chlorpyrifos was revealed in 27.45% mothers’ milk samples. Among these p,p′-DDE was the major contaminant found in 26.79% samples followed by p,p′-DDT (1.31%) and chlorpyrifos (0.65%). However, residues of other 26 pesticides comprising organochlorines, organophosphorus and synthetic pyrethroids included in this study were below detectable limit (BDL). The determination of a low DDT/DDE ratio (0.050) indicated past exposure of mothers to DDT from the environment. The pesticide residues level in samples drawn from 14 branded infant formulae was BDL. The calculated infants’ daily intake (DI) of DDT was 0.0015 mg kg^?1 body weight per day compared with a decade-old study (0.021 mg kg^?1 body weight per day) suggesting a sharp decline in the residue levels of these pesticides in the Himalayan region. The trend comparison with past studies conducted around the world indicate a decline in the levels of organochlorine pesticide residues in mothers’ milk and further drop of DI in infants. However, such comparisons confer very limited utilisation of data generated on pesticide load in mothers’ milk and simultaneous infants’ DI due to lack of proper research protocol.