Qualitative and quantitative analysis of polar pesticide multiresidues in leaf samples with a liquid chromatography–ion-trap mass-selective detector

Since 1995, in Austria, an agricultural programme (ÖPUL) has promoted an environmentally friendly and extensive production with restricted pesticide use. To observe the achievement of this goal, the pesticides in leaf samples are monitored. This study aimed to develop a multiresidue method for the qualitative and quantitative analysis of 46 pesticides in leaf samples with HPLC-IT-MS equipped with an electrospray ionization in positive mode after extraction with the QuECheRS method. The method has been validated for leaf samples based on the SANCO European Guideline at two fortification levels (LOQ and 10 times LOQ). The recoveries of the pesticides, with a few exceptions, were between 70 and 110% at both fortification levels and modes (full scan and selected reaction monitoring, SRM) with acceptable precision (RSD??1 and between 4.8 and 725?µg?kg^?1 in full scan, respectively) compared with the Austrian authorized value of 100?µg?kg^?1 fresh leaf sample defined in the ÖPUL programme.     

Simultaneous Analysis of Hexaconazole, Myclobutanil, and Tebuconazole Residues in Apples and Soil by SPE Clean-Up and GC with Nitrogen–Phosphorus Detection

A facile and sensitive method utilizing capillary gas chromatography with nitrogen phosphorus detection (GC–NPD) has been developed and validated for simultaneous analysis of hexaconazole, myclobutanil, and tebuconazole, three broad-spectrum systemic fungicides, in apples and soil. Two samples were fortified with the three pesticides and subjected to ultrasonic extraction, followed by solid-phase extraction (SPE) to remove coextractives, before analysis by GC–NPD. SPE procedures were performed on PSA cartridges (500 mg, 3 mL), the analytes being eluted with n-hexane–acetone (9:1 v/v, 2 mL). Recovery of three pesticides from the fortified apple and soil samples ranged from 94.5 to 107.3% with relative standard deviations less than 9.7% at the three spike levels (0.01, 0.1, and 0.5 mg kg^?1). Limits of quantification of the method for apple and soil were 0.01 mg kg^?1, sufficiently below the maximum residue limits. Direct confirmation of the analytes in samples was achieved by gas chromatography–mass spectrometry (GC–MS).     

Multielement Analysis of South Serbian Strawberry Cultivars by Inductively Coupled Plasma—Optical Emission Spectrometry

The contents of 17 elements in thirteen strawberry cultivars grown in the five districts of Southern Serbia were determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The most abundant elements are K (875–1148 mg?·?kg^?1 fresh weight), P (307–664 mg?·?kg^?1 fresh weight), Ca (192–256 mg?·?kg^?1 fresh weight), and Mg (111–189 mg?·?kg^?1 fresh weight) in all samples. Strawberries were also found to be a good source of Sr (8.05–18.6 mg?·?kg^?1 fresh weight) and Fe (3.09–10.4 mg?·?kg^?1 fresh weight). The contents of As and Cd were below the detection limit (0.0828 mg?·?kg^?1 and 0.0205 mg?·?kg^?1, respectively) in all strawberry samples, while the contents of Ni, Cr, and Cu were below the recommended tolerable levels proposed by Joint Food and Agriculture Organization of the United Nations and World Health Organization Expert Committee on Food Additives, and did not a pose a health risk for the consumer. The application of Duncan’s test showed significant differences between contents of analyzed elements in all strawberry cultivars. The highest mean levels of analyzed elements were detected in strawberries grown in the Topli?ki, Jablani?ki, and P?injski districts. The spike recovery test was used to verify the accuracy of the method, and the spike recovery was in the range 93.8–107.8%. The contents of the metals in strawberry samples were also comparable with values previously reported in the literature.     

Determination of Organophosphorus Pesticides in Leeks (Allium porrum L.) by GC-FPD

A method was validated for the analysis of organophosphorus pesticides in leeks. The leek sample was cut into about 2 cm lengths and heated in a microwave oven for 50 s to inactivate enzymes. The sample was extracted with 50 mL acetonitrile using an Ultra-turrax T18 blender and cleaned up by solid phase extraction. The target analytes were determined by GC with a flame photometric detector. Average recoveries were 73–118% and limits of detection ranged from 1.1 to 10.0 μg kg^?1. The uncertainty of the analysis for each pesticide was evaluated as below 16%. The method was applied to determine organophosphorus pesticides in real samples. The GC–MS was used as confirmatory tool for positive samples.     

Simplified Determination of Organophosphorus Pesticides in Camellia Oil

A rapid, simple, and economical analytical approach has been developed and evaluated for the determination of six organophosphorus pesticides in camellia oil. This method is based on dispersive liquid?liquid microextraction (DLLME) following simple extraction. Oil was extracted with methanol by a high-speed blender and filtered with glass paper to remove fat. The filtrate was incorporated in the DLLME procedure. Acetonitrile was used as the dispersive solvent and chloroform as the extraction solvent. The residues were analyzed by gas chromatography–mass spectrometry. Under the optimized conditions, the recoveries were between 78.4 and 112.8% with relative standard deviations less than 12.3%. The limits of detection for the analytes were from 0.0003 to 0.0056?mg?·?kg^?1. The optimized method was used for the determination of organophosphorus pesticides in camellia oil.     

Study on pesticide residues in apples,apple-based baby food,and their behaviour during processing using fast GC–MS multiresidue analysis

Food-processing experiments using apples were conducted to obtain more knowledge on the behaviour of pesticides during apple-based baby-food production. The residues were determined in raw material (apples), in intermediate products at different steps of the processing procedure (baby food production) and in final products (apple purée) using a rapid GC–MS method in combination with two different sample-preparation approaches. During 2 years of a monitoring programme, 84 analyses of apple samples and 102 of baby food sample apple purée intermediate and final product samples from baby food production were performed. A pesticide-residue search revealed that residues in fresh apples do not exceed the maximum residue limit for the adult population, but there were some positive findings concerning apples as baby food. The maximal pesticide concentration (fluquinconazole) found in apples was 0.099?mg?kg^?1. In the processed apple-based baby food the concentration of pesticide residues were mostly below 0.010?mg?kg^?1.     

Pesticide residues analysis in honey using ethyl acetate extraction method: validation and pilot survey in real samples

This paper presents a cost-effective and validated multi residue confirmatory method for the determination of 167 chemically different pesticides and a survey study on Cyprus honey samples. This method uses ethyl acetate for the extraction of pesticides from honey and the determination is performed with liquid chromatography (LC) coupled to mass spectrometry (MS) operating in tandem mode (MS/MS) and with GC–ECD (gas chromatography with electron capture detector) analysis. The LC-MS/MS analytical system is especially important in the analysis of polar and non-volatile pesticides. For the validation of the method, blank honey samples were spiked with 146 pesticides (organophosphorous, carbamates, triazoles, amides, neonicodinoids, strobilurines, phenylureas, bendimidazoles and others) for the LC-MS/MS analysis at three levels: 0.01, 0.05 and 0.1 mg kg^?1 and with 21 pesticides for the GC-ECD analysis at two levels: 0.01 and 0.05 mg kg^?1for organochlorines and 0.05 and 0.2 mg kg^?1for the pyrethroids. As blank sample, a sample of honey which did not contain detectable levels of the analytes sought was used. The validation study was in accordance to the DG SANCO guidelines. The scope of validation included recovery, linearity, limits of quantification and precision. Linearity is demonstrated all along the range of concentration that was investigated with correlation coefficients ≥0.98. Recoveries of the majority of compounds were in the 70%–120% range and were characterised by precision lower or equal to 20%. The validated method was used for a survey of 36 samples of honey produced in different areas of Cyprus and this is the first work on Cypriot honey samples investigating a broad range of pesticides. Only coumaphos was detected at concentrations higher than 0.01 mg kg^?1 in the 58.6% of the honey samples analysed for Coumaphos. The results were evaluated in accordance to the provisions of the Commission Regulation (EU) No 37/2010 on pharmacologically active substances and their classification regarding maximum residue limits (MRLs) in foodstuffs of animal origin. The concentrations of coumaphos in all positive samples were at levels much lower than the MRL.     

Development and Validation of LC Coupled with SPE for Simultaneous Determination of Lamivudine, Oxymatrine and its Active Metabolite Matrine in Dog Plasma

A simple and highly selective method, based upon solid-phase extraction (SPE), ion-pair HPLC and UV absorbance detection, was developed and validated to determine lamivudine, oxymatrine and its active metabolite matrine in dog plasma. The analytes and famotidine (internal standard) were simultaneously extracted from plasma samples by SPE, and separated on a C18 column. The mobile phase consisted of acetonitrile-water (13:87, v/v, 5 mmol L^?1 sodium heptanesulfonate, at pH 3.2). The lower limit of quantification of the method was 0.1 mg L^?1 for these analytes. The linear calibration curves of the analytes were obtained in the concentration range of 0.1–40 mg L^?1. This method was successfully applied to the quantitative determination of plasma concentration of lamivudine, oxymatrine and its active metabolite matrine in dogs after single oral co-administration of 5.0 mg kg^?1 lamivudine and 30.0 mg kg^?1 oxymatrine.     

Determination of carbamates at trace levels in water and cucumber by capillary liquid chromatography

A sensitive and reliable method using capillary HPLC with UV-diode array detection (DAD) has been developed and validated for trace determination of carbamate pesticides in cucumber and environmental water samples. The analytes, including carbofuran, carbaryl, methiocarb, promecarb, benthiocarb and fenoxycarb, present legal residue levels regulated by the EU Council Directive 98/83/EC on drinking water and by the Regulation (EC) No. 396/2005 on vegetables. A previous off-line solid-phase extraction (SPE) procedure was required for preconcentration and sample clean-up. The separation was achieved using a C₁₈ column (150?mm?×?0.5?mm I.D, 5?µm particle size) and a mobile phase consisting of ACN?:?water using gradient mode, with a flow rate of 10?µl min^?1. Taking advantages of the characteristics of capillary HPLC, low volume of sample and solvents were required, achieving limits of detection for the studied compounds ranged from 10.0–29.6?ng l^?1 for water samples and 1.8–5.6?µg kg^?1 for cucumber, using UV-detection. Recoveries studies for fortified samples, at three different concentration levels, were carried out obtaining recoveries ranging from 70.0 to 111.1% and relative standard deviations (RSDs) lower than 10.6%.     

Survey of low-level endocrine disrupting pesticides in food matrices in Slovakia

The search on endocrine disrupting chemicals (EDCs) in non-fatty food was evaluated. A fast, high-throughput, accurate, multiresidue method for the analysis of selected EDC pesticides in fruit and vegetable food samples was developed. The QuEChERS technique was used for sample preparation. Fast GC-MS was performed with a narrow-bore capillary column and a quadrupole benchtop detector with electron ionization (EI) and negative chemical ionization (NCI). A part of the work was devoted to the comparison of NCI versus EI approach concerning the sensitivity of detection and to the study of selectivity enhancement in NCI mode. Matrix-matched standard solutions were utilized for calibration. The methods validation was performed. Fortification studies at 1, 5, 10 and 250?µg?kg^?1 for 35 pesticides in EI mode and 0.1, 1, 5 and 250?µg?kg^?1 for 28 pesticides in NCI mode were performed. Average recoveries for each fortification level ranged from 70 to 110% with >80% of recoveries between 90 and 110%. Limits of quantification (LOQs) were established at 5?µg?kg^?1 for EI and at 1?µg?kg^?1 for NCI mode, which is lower than the lowest maximum residue level (MRL) value set by the European Commission in fruit and vegetables. The developed and validated fast GC-MS method was successfully applied to the search of EDC pesticides at ultratrace concentration level in real fruit and vegetable samples in Slovakia. Thirty-four samples of 20 different commodities were analyzed. Seven samples contained residues of three or more EDCs pesticides.     

Determination of Pesticides in Organic Carrots by High-Performance Liquid Chromatography/High-Resolution Mass Spectrometry

Food contamination by pesticide residues, which may cause serious human health problems, is an ongoing challenge. Safer organically grown food is therefore needed. However, best practices are not always followed for farming organic foods, necessitating analytical testing. To this end, this report describes an analytical method for the evaluation of 82 pesticides by high-performance liquid chromatography–high-resolution mass spectrometry in organically grown carrots. The method was validated in terms of linearity, precision, and limits of detection and quantification that ranged from 0.3 to 5 and 5–40?µg?kg^?1, respectively. From the 82 pesticides evaluated in this multiresidue method, three were detected in real samples, with bendiocarb detected at the highest concentration (199.11?µg?kg^?1), which was above the maximum residue limit. Chlorpyriphos (43.20?µg?kg^?1) and amitraz (11.22?µg?kg^?1) were also detected. Measurement of contaminants in organic foods should be a standard practice, which would contribute to improved food safety. It is observed that even organic foods can be contaminated by pesticides, intentionally or unintentionally, perhaps by cross-contamination. Pesticides in organic foods are a public health problem because consumers expect organic foods to be free of pesticide contamination, but this is not necessarily the case.     

Simultaneous determination of 118 pesticide residues in Chinese teas by gas chromatography-mass spectrometry

An efficient and sensitive method for simultaneous determination of 118 pesticide residues in teas has been established and validated. A multi-residue analysis of pesticides in tea involved extraction with ethyl acetate-hexane, clean-up using gel permeation chromatography (GPC) and solidphase extraction (SPE), and subsequent identification and quantification of the selected pesticides by gas chromatography-mass spectrometry (GC-MS). For most of the target analytes, optimized pretreatment processes led to no significant interference with analysis of sample matrix, and the determination of 118 compounds was achieved in about 60 min. In the linear range of each pesticide, the correlation coefficient was R ² ≥ 0.99. At the low, medium and high three fortification levels of 0.05–2.5 mg kg⁻¹, 118 pesticides average recoveries range from 61 % to 121 % and relative standard deviations (RSD) were in the range of 0.6–9.2 % for all analytes. The limits of detection for the method were 0.00030-0.36 mg kg⁻¹, depending on each pesticide.     

Dissipation of insect growth regulators in fresh and canned fruits

The objective of the study was to determine the dissipation of insect growth regulators in fresh and canned mandarin and apricot to determine the exposure to them. Field studies were carried out in the preharvest period with good agricultural practices (GAP) and in critical agricultural practices. The processing studies were carried out in each relevant step in a pilot plant. A validated methodology was developed (limit of quantification of 0.05?mg?kg^?1 for apricots, 0.10?mg?kg^?1 for mandarin) including acetone–dichloromethane extraction, cleanup, and liquid chromatography-diode array detection. The pesticides complied with the maximum residue limits (MRLs) except pyriproxyfen, which has not been authorized in apricots, and it did not comply with its MRL for peaches. The dissipation rates (t _1/2) with GAP were fenoxycarb-apricot?>?pyriproxyfen-apricot?>?fenoxycarb-mandarin?>?pyriproxyfen-mandarin. In the processing studies, there was only residue transference in the canning of apricots. All final cans contained residues much lower than the MRLs.     

Multiresidue pesticide analysis of fruits by ultra-performance liquid chromatography tandem mass spectrometry

Ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC–MS–MS) has been used for screening and quantification of 32 pesticides and metabolites in two fruit matrices. The compounds investigated belonged to different chemical families of insecticides, acaricides, fungicides, and herbicides; several metabolites were also included. Quantification was conducted using matrix-matched standards calibration; response was a linear function of concentration in the range tested (10–500 ng mL⁻¹). The method was validated with blank samples of lemon and raisin spiked at 0.01 and 0.1 mg kg⁻¹, and recoveries were satisfactory, between 70 and 110%, for most of the pesticides tested and relative standard deviations were below 15% (n = 5 at each spiking level). Excellent sensitivity resulted in limits of detection for all compounds well below 0.01 mg kg⁻¹, with the limit of quantification being validated at 0.01 mg kg⁻¹. The UPLC system generates narrow peaks (approx. 5 s), thus increasing peak height and improving sensitivity. This improved separation efficiency facilitates adequate resolution not only of the analytes but also of matrix interferences compared with conventional HPLC. The method developed could also resolve some geometric isomers. The main advantage of this approach is the high sample throughput achieved because of the short analysis time, which enables satisfactory separation of all the compounds in less than 5 min per sample.     

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.     

Development and validation of a SPE-GC-MS method for the determination of pesticides in surface water

A method for analysis of 20 commonly used pesticides in surface water based on solid-phase extraction and gas chromatography-mass spectrometry was proposed. During method development the key parameters that can affect SPE extraction and determination such as selection of efficient SPE sorbent, pH of water sample, type and volume of elution solvent, breakthrough volume and matrix effects were investigated. The method was validated using spring water spiked with appropriate concentration of pesticides. The obtained correlation coefficients were in range 0.9972–1.000, limits of detection (LOD) were 0.001–0.5?µg?L^?1 and the limits of quantification (LOQ) were 0.005–1?µg?L^?1 depending on a pesticide. Much higher LOD (20?µg?L^?1) and LOQ (50?µg?L^?1) values were obtained for bentazone. The influence of matrix was assessed using real water samples spiked with appropriate concentration of pesticide standards solution. Both signal enhancement and suppression were observed, depending on a pesticide, therefore standard addition method was used for pesticides determination. The developed method was applied on real water samples taken in close vicinity of agricultural fields. Many of the targeted pesticides were found in the samples and the results are presented in this article.     

Development and validation of a multiresidue method for determination of 37 pesticides in soil using GC-NPD

In this study, a multiresidue analytical method for the detection of 37 pesticides in a soil matrix was developed and validated. The soil sample was fortified with a known quantity of pesticides at two different concentration levels (0.1 and 0.01 µg/g) and the analytes were extracted via a liquid–solid extraction method. The pesticides were separated on an HP5 capillary column and were analyzed with a gas chromatograph coupled to a nitrogen–phosphorous detector (GC‐NPD). Method validation was accomplished with good linearity (r² = 0.994–0.999) within a considerable range of concentrations. Satisfactory recoveries (70.5–110.4%) were obtained with 32 pesticides at both spiking concentration levels, whereas five pesticides—dimepiperate, buprofezin, prometryn, pirimicarb, and fludioxonil—were recovered at relatively low levels (43.6–61.8%). The applicability of the method was demonstrated by analyzing field samples collected from 24 different sites around Yeongsan and Sumjin rivers in the Republic of Korea. No residues of the selected pesticides were detected in any of the samples. The developed method could be employed as a simple and cost‐effective method for the routine detection and analysis of 37 pesticides in soil samples. Copyright © 2010 John Wiley & Sons, Ltd.     

Multi-Walled Carbon Nanotubes as Matrix Solid-Phase Dispersion Extraction Adsorbent for Simultaneous Analysis of Residues of Nine Organophosphorus Pesticides in Fruit and Vegetables by Rapid Resolution LC�CMS�CMS

A method for simultaneous analysis of residues of nine organophosphorus pesticides in fruit and vegetables has been developed. It involves matrix solid-phase dispersion (MSPD) for preconcentration before rapid resolution liquid chromatography?Ctandem mass spectrometry (RRLC?CMS?CMS). In the MSPD pre-concentration step, the adsorptive performance of multi-walled carbon nanotubes (MWCNT) as MSPD adsorbent and elution with four solvents were investigated; in the LC separation step, a rapid resolution high-throughout LC column was used with gradient elution. The results of the research showed that the linear correlation coefficients (r ²) of the method for the nine target analytes varied between 0.9942 and 0.9996, mean recovery was in the range 71.2?C102.8%, with relative standard deviations (RSD) 2.0?C11.8%, and limits of detection were all below 0.2 ??g kg^?1. The method was used for simultaneous analysis of the nine pesticides in eight different fruit and vegetable samples.     

Use of a Headspace Solid-Phase Microextraction-Based Methodology Followed by Gas Chromatography–Tandem Mass Spectrometry for Pesticide Multiresidue Determination in Teas

This study reports on the development of a fast and efficient method based on headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography–tandem mass spectrometry (GC–MS/MS) for simultaneous analysis of 128 volatile or semi-volatile pesticide residues belonging to nine classes of pesticides. The important factors related to HS-SPME performance were optimized; these factors include fiber types, water volume, ion strength, extraction temperature, and extraction time. The best extraction conditions include a PDMS/DVB fiber, and analytes were extracted at 90 °C for 60 min from 1 g of tea added to 5 mL of 0.2 g mL^?1 NaCl solution. The methodology was validated using tea samples spiked with pesticides at three concentration levels (10, 50, and 100 μg kg^?1). In green tea, oolong tea, black tea, and puer tea, 82.8, 88.3, 79.7, and 84.3% of the targeted pesticides meet recoveries ranging from 70 to 120% with a relative standard deviation of?≤?20%, respectively, when spiked at a level of 10 μg kg^?1. Limits of quantification in this method for most of the pesticides were 1 or 5 μg kg^?1, which are far below their maximum residue limits prescribed by EU. The optimized method was employed to analyze 30 commercial samples obtained from local markets; 17 pesticide residues were detected at concentrations of 2–452 μg kg^?1. Chlorpyrifos was the most detected pesticide in 80% of the samples, and the highest concentration of dicofol (452 μg kg^?1) was found in a puer tea. This is the first time to find that the optimized extraction temperature for pesticide residues is 90 °C, which is much higher than other reported HS-SPME extraction conditions in tea samples. This developed method could be used to screen over one hundred volatile or semi-volatile pesticide residues which belong to multiple classes in tea samples, and it is an accurate and reliable technique.     

A comparative study of biochar,multiwalled carbon nanotubes and graphitized carbon black as QuEChERS absorbents for the rapid determination of six triazole fungicides by UPLC-MS/MS

A rapid, effective and sensitive method to quantitatively determine six fungicide residue was developed using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC–MS/MS). The target compounds were extracted by using acetonitrile and the sorbent used for clean-up in this modified QuEChERS analytical method were biochar, multiwalled carbon nanotubes (MWCNT) and graphitized carbon black (GCB). Results indicated that the MWCNT (10 mg) was the most effective sorbent in removing pigment. This method was validated on spinach, tomato, cucumber, celery, lettuce, rape, pakchoi, romaine lettuce and eggplant matrices spiked at three concentration levels of 0.01, 0.1 and 1 mg kg^?1. It exhibited recoveries between 73.1% and 118.2% with RSD values below 20%. Matrix-matched calibrations were performed with the coefficients of determination >0.9901 between concentration levels of 0.01–1 mg kg^?1. The limit of quantity (LOQ) for six pesticides ranged from 0.0036 to 0.011 mg kg^?1. The developed method was satisfactorily applied to determine pesticide residues in market vegetable samples.