Method For Determination Of Residues Research Articles

Efficacy of the traditional and nano-forms of thiocyclam and chlorantraniliprole against Spodoptera littoralis and Agrotis ipsilon and analysis of their residues in tomato fruits

For effective pest control, nano-insecticides have recently been proposed as a promising alternative to traditional ones. Thus, this study aimed to compare the efficacy of the traditional and nano-forms of thiocyclam (a natural toxin-based insecticide) and chlorantraniliprole (a diamide insecticide) against two major insect pests, the cotton leafworm, Spodoptera littoralis (Boisd.), and the black cutworm, Agrotis ipsilon (Hufnagel). The residue levels of the two insecticides in tomato fruits were also assessed. The results showed that chlorantraniliprole was more effective against both insects than thiocyclam, and the nano-forms were more effective than the traditional ones. This higher insecticidal activity of chlorantraniliprole could be attributed to its novel action by binding tightly to ryanodine receptors in insects. The study also optimized and validated an analytical method for residue determination of thiocyclam and chlorantraniliprole in tomato fruits using QuEChERS method and LC-MS/MS. Percentage recovery ranged from 70 to 104%, with good precision and expanded uncertainty of up to ± 23%. The half-life times of thiocyclam and its nano-form in tomatoes were 0.38 and 0.57 days, respectively, compared to 0.7 and 0.38 days for chlorantraniliprole and its nano-form. On the other hand, the calculated pre-harvest intervals for thiocyclam and its nano-form, using the EU maximum residue limit, were 7 and 3 days, respectively, compared to 1 day for both forms of chlorantraniliprole.

High performance liquid chromatography-tandem mass spectrometry method for residue determination of 39 plant growth regulators in root and rhizome Chinese herbs

A simple, rapid, and effective method based on salting-out extraction and LC-MS/MS techniques was developed for the determination of 39 plant growth regulator (PGR) residues in two of the most common root and rhizome Chinese herbs, Codonopsis Radix (Dangshen) and Notoginseng Radix et Rhizoma (Sanqi). The extraction process was performed with acetonitrile-water (5:1) and citrate buffer extraction salt. The performance of the method was validated in accordance with the analytical quality control criteria of SANTE/11813/2017 guidelines. Analyte recoveries of 79.49–109.41% (Dangshen) and 80.17–102.81% (Sanqi) were achieved. The limit of quantifications (LOQs) were determined with the consideration of accuracy and precision. LOQs were lower than the lowest residue limits in EU pesticide regulation (10 µg/kg) for most PGRs. Moreover, the method was successfully applied in the analysis of 35 batches of Dangshen, and 60 batches of Sanqi products. The concentration of eleven PGRs were determined in analyzed samples.

Dissipation and the effects of thidiazuron on antioxidant enzyme activity and malondialdehyde content in strawberry.

Increasing numbers of fruit swelling agents have been used to improve the fruit rate and production yield of strawberries in recent years. The abuse of fruit swelling agents could lead to an increase in the deformation rate and abnormal coloration of strawberry and a decrease in quality at harvest. Therefore, understanding the harmful effects of fruit swelling agents on strawberry will provide guidance for their reasonable use. The residual determination method for measuring thidiazuron (TDZ) in strawberry was developed and validated by liquid chromatography and tandem mass spectrometry (LC-MS/MS). The recoveries of TDZ in strawberry were 97.9-108.5% with relative standard deviations of 0.9% to 5.3%. The dissipation rates of TDZ were different in strawberries cultivated under field and indoor conditions due to the differences in temperature and humidity. The ascorbic acid content increased when TDZ was applied at 2mg kg-1 . The SOD (superoxide dismutase), POD (peroxidase) and CAT (catalase) activities of strawberry tended to decrease and subsequently increase following the application of TDZ, and the opposite changes occurred on the malondialdehyde (MDA) content of TDZ-treated strawberry. The analytical method for measuring TDZ in strawberry that was developed was suitable for dissipation studies on this compound. Antioxidant enzyme activities and the MDA content of strawberry were altered, and some reverse effects, such as membrane damage, were inhibited when TDZ was applied. The data obtained in this study might provide suggestions to reduce the adverse effects of TDZ on strawberry and may help to guide the safe and proper use of TDZ in strawberry. © 2019 Society of Chemical Industry.

Development, validation and application of a sensitive analytical method for residue determination and dissipation of imidacloprid in sugarcane under tropical field condition.

A simple and sensitive analytical method has been developed and validated for the determination of trace amounts of imidacloprid in/on sugarcane sett, stalk and leaf. The method optimized in the present study requires less volume of organic solvent and time. Hence, this method is suitable for high-throughput analyses involving large number of samples. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.003 and 0.01mg/kg, respectively. The recovery and relative standard deviation were more than 93% and less than 4%, respectively. Thus, it is obvious that the analytical method standardized in this study is more precise and accurate enough to determine the residues of imidacloprid in sugarcane sett, stalk and leaf. The dissipation and translocation of imidacloprid residues from treated cane setts to leaf and stalk were studied by adopting this method. In sugarcane setts, the residues of imidacloprid persisted up to 120days with half-life of 15.4days at its recommended dose (70g a.i./ha). The residues of imidacloprid were found to be translocated from setts to stalk and leaf. The imidacloprid residues were detected up to 105days in both leaf and stalk. Dipping of sugarcane setts in imidacloprid at its recommended dose may result in better protection of cane setts and established crop because of higher initial deposit (>100mg/kg) and longer persistence (>120days).

Analysis of Pesticide Residues and Their Variability in Cabbage Using QuEChERS Extraction in Combination with LC-MS/MS

An analytical method for the simultaneous determination of residues of five insecticides and two fungicides in cabbage was developed and validated. Pesticide residues were extracted from the samples using QuEChERS extraction and the analysis was performed by liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS). The performance of the method was investigated in terms of accuracy, precision, linearity, limit of detection (LOD), and limit of quantification (LOQ). The average recoveries ranged from 80 to 110 % with RSDr ≤ 16 % for all the analytes at four fortification levels of 0.01, 0.05, 0.10, and 0.20 mg/kg. The LOD values ranged from 0.001 to 0.003 mg/kg, and the LOQ for all the analytes was set at 0.01 mg/kg. The linearity was very good and coefficient of determination was ≥ 0.997 for all the analytes when matrix-matched calibration standards were used. Matrix effect was estimated and it was found prominent for cabbage with cypermethrin and deltamethrin (+49 and +97 %, respectively). The method was applied very satisfactorily for the residue analysis of 132 fresh cabbage samples collected from different market places in Thessaloniki, Greece. Among the analyzed samples, 41 (31 % of the total no. of samples) had pesticide residues, of which, two had multiple pesticide residues and 39 had a single pesticide residue. Only one sample was found contaminated with deltamethrin at a level above the European Union maximum residue levels (EU-MRLs). Variability of pesticide residues originated from the samples of cabbage purchased from different market places of Thessaloniki in Greece were also estimated in this study. The estimated variability factors ranged from 1.00 to 6.75 and the average VFs was 5.00.

A trace analysis method based on HPLC-MS/MS for the simultaneous determination of residues of the two isomers of pyrisoxazole in tomato fruit and soil

A simple, sensitive and accurate method for the simultaneous determination of residues of the two isomers of pyrisoxazole in tomato fruit and soil was established using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).

Rapid determination of residues of pesticides in honey by µGC-ECD and GC-MS/MS: Method validation and estimation of measurement uncertainty according to document No. SANCO/12571/2013

ABSTRACTA simple and straightforward method for simultaneous determination of residues of 13 pesticides in honey samples (acrinathrin, bifenthrin, bromopropylate, cyhalothrin-lambda, cypermethrin, chlorfenvinphos, chlorpyrifos, coumaphos, deltamethrin, fluvalinate-tau, malathion, permethrin and tetradifon) from different pesticide classes has been developed and validated. The analytical method provides dissolution of honey in water and an extraction of pesticide residues by n-Hexane followed by clean-up on a Florisil SPE column. The extract was evaporated and taken up by a solution of an injection internal standard (I-IS), ethion, and finally analyzed by capillary gas chromatography with electron capture detection (GC-µECD). Identification for qualitative purpose was conducted by gas chromatography with triple quadrupole mass spectrometer (GC-MS/MS). A matrix-matched calibration curve was performed for quantitative purposes by plotting the area ratio (analyte/I-IS) against concentration using a GC-µECD instrument. According to document No. SANCO/12571/2013, the method was validated by testing the following parameters: linearity, matrix effect, specificity, precision, trueness (bias) and measurement uncertainty. The analytical process was validated analyzing blank honey samples spiked at levels equal to and greater than 0.010 mg/kg (limit of quantification). All parameters were satisfactorily compared with the values established by document No. SANCO/12571/2013. The analytical performance was verified by participating in eight multi-residue proficiency tests organized by BIPEA, obtaining satisfactory z-scores in all 70 determinations. Measurement uncertainty was estimated according to the top-down approaches described in Appendix C of the SANCO document using the within-laboratory reproducibility relative standard deviation combined with laboratory bias using the proficiency test data.

Liquid Chromatography–Mass Spectrometry Method for the Quantitative Determination of Residues of Selected Veterinary Hormones in Powdered Ingredients Derived from Bovine Milk

A rugged, quantitative liquid chromatography-tandem mass spectrometry method with modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation for 17 selected veterinary hormones in six different powdered ingredients derived from bovine milk was developed and comprehensively validated. A universal post-extraction spiked matrix-matching approach based on whole milk powder has been successfully implemented. Three validation runs based on four levels of pre-extraction spiked quality control (QC) samples have been conducted. Overall accuracy (86-117%), overall precision (<20% RSD), selectivity, absolute extraction recovery (62-82%), matrix effect (<15% for most compounds), limits of detection (0.1-0.8 μg/kg, except for diethylstilbestrol at 3.8 μg/kg), limits of quantitation (0.2-2.0 μg/kg, except for diethylstilbestrol at 10.0 μg/kg), and extract stability (48 h) have been determined. The method is proposed for the routine analysis of hormones potentially present in powdered ingredients derived from bovine milk.

Determination of Residues of Three Triphenylmethane Dyes and Their Metabolites (Malachite Green, Leuco Malachite Green, Crystal Violet, Leuco Crystal Violet, and Brilliant Green) in Aquaculture Products by LC/MS/MS: First Action 2012.25

During the AOAC Annual Meeting held from September 30 to October 3, 2012 in Las Vegas, NV, the Expert Review Panel (ERP) on Veterinary Drug Residues reviewed data for the method for determination of residues of three triphenylmethane dyes and their metabolites (malachite green, leuco malachite green, crystal violet, leuco crystal violet, and brilliant green) in aquaculture products by LC/MS/MS, previously published in the Journal of Chromatography A 1218, 1632-1645 (2006). The method data were reviewed and compared to the standard method performance requirements (SMPRs) found in SMPR 2009.001, published in AOAC's Official Methods of Analysis, 19th Ed. (2012). The ERP determined that the data were acceptable, and the method was approved AOAC Official First Action. The method uses acetonitrile to isolate the analyte from the matrix. Then determination is conducted by LCIMS/MS with positive electrospray ionization. Accuracy ranged from 100.1 to 109.8% for samples fortified at levels of 0.5, 0.75, 1.0, and 2.0 microg/kg. Precision ranged from 2.0 to 10.3% RSD for the intraday samples and 1.9 to 10.6% for the interday samples analyzed over 3 days. The described method is designed to accurately operate in the analytical range from 0.5 to 2 microg/kg, where the minimum required performance limit for laboratories has been fixed in the European Union at 2.0 microg/kg for these banned substances and their metabolites. Upper levels of concentrations (1-100 microg/kg) can be analyzed depending on the different optional calibrations used.

Development and validation of a method for determination of residues of 15 pyrethroids and two metabolites of dithiocarbamates in foods by ultra-performance liquid chromatography–tandem mass spectrometry

This paper reports a novel approach for the detection, confirmation, and quantification of 15 selected pyrethroid pesticides, including pyrethins, and two metabolites of dithiocarbamates in foods by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS). The proposed method makes use of a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure that combines isolation of the pesticides and sample cleanup in a single step. Analysis of pyrethroids and dithiocarbamate metabolites was performed by UPLC-MS-MS operated with electrospray and atmospheric pressure chemical ionization, respectively. Two specific precursor-product ion transitions were acquired per target compound in multiple reaction monitoring (MRM) mode. Such acquisition achieved the minimum number of identification points according to European Commission (EC) document no. SANCO/10684/2009, thus fulfilling the EC point system requirement for identification of contaminants in samples. The method was validated with a variety of food samples. Calibration curves were linear and covered from 1 to 800μg kg(-1) in the sample for all target compounds. Average recoveries, measured at mass fractions of 10 and 100μg kg(-1) for pyrethroids and 5 and 50μg kg(-1) for dithiocarbamate metabolites, were in the range of 70-120% for all target compounds with relative standard deviations below 20%. Method limits of quantification (MLOQ) were 10μg kg(-1) and 5μg kg(-1) for pyrethroids and dithiocarbamate metabolites, respectively. The method has been successfully applied to the analysis of 600 food samples in the course of the first Hong Kong total diet study with pyrethroids and metabolites of dithiocarbamates being the pesticides determined.

LC-MS/MS Analysis of Neonicotinoid Insecticides in Honey: Methodology and Residue Findings in Austrian Honeys

An analytical method for the simultaneous determination of residues of eight neonicotinoid insecticides and two metabolites in honey using LC-MS/MS was developed and validated. Two approaches of sample preparation were investigated, with the final method involving acetonitrile extraction and subsequent cleanup by dispersive solid-phase extraction (QuEChERS type). Validation was based on quintuplicate analysis at three fortification levels and showed satisfactory recoveries (60-114%) and high precision (RSDs between 2.7 and 12.8%). Low limits of detection and quantification could be achieved for all analytes ranging from 0.6 to 5 μg/kg and from 2 to 10 μg/kg, respectively. Investigations of Austrian honey samples revealed the presence of acetamiprid, thiacloprid, and thiamethoxam residues in honey; however, no sample exceeded the maximum residue limits. On average, flower honey samples contained neonicotinoid residues in higher quantities compared to forest honey samples.

Investigation of different commercial fining agents by SDS-PAGE and immunoblot

Allergenic fining agents and processing aids from hen's egg and cow's milk used in wine production are hidden allergens and could demonstrate a health threat for allergic persons. Hence, the European parliament adopted Directive 2003/89/EC amending 2000/13/EC to declare ingredients, contaminations and processing aids which are known to trigger allergic reactions. The Amendment Directive 415/2009/EC excludes the labeling of wine which are processed with eggs or milk and products thereof until the 31st of December 2010. In 2006 Rolland et al. did a double-blind, placebo-controlled trial and basophil activation analysis about potential food allergens in wine including 5 egg-allergic and 1 milk-allergic patients. Among others they collected 24 egg white-fined or whole egg-added red wines, 34 milk-fined white wines and 25 casein-fined white wines. In this study no anaphylaxis was induced by wine consumption. But adverse reactions against treated wines could not be excluded. Due to the rarity of adult milk or egg-allergic patients reliable statistical analysis of allergic reactions against milk or egg-fined wines is inhibited. Casein, ovalbumin/hen's egg white and lysozyme products of different commercial producers were investigated by SDS-PAGE and immunoblot. These investigations show that every product contains beside casein, ovalbumin or lysozyme other milk or egg allergens respectively in different amounts. The investigations show the necessity to have analytical methods for determination of residues of fining agents or stabilizers in wine which are able to detect not only casein, ovalbumin and lysozyme but also take into account the other milk and egg allergens. This could be guaranteed by certain antibodies used in ELISA systems binding not only to casein, ovalbumin or lysozyme but also to the other allergens in processed casein, ovalbumin or lysozyme for wine production. Therefore polyclonal antibodies raised against fining agents casein and ovalbumin and stabilizer lysozyme of one fining agent producer were used in this study.

An analytical method for prohexadione in Chinese cabbage and apple

A residual determination method as a regulatory residue method was developed using HPLC-UVD for prohexadione residues in Chinese cabbage (Brassica pekinensis) and apple (Malus domestica). The developed method consisted of solid-liquid extraction with acidic acetonitrile and ion-suppression liquid-liquid partitioning, followed by anion exchange cartridge cleanup. The limits of detection and quantitation for the method were 0.005 and 0.02 mg/kg, respectively. The method gave good linearity in the range of 0.02-2.5 mg/kg. Accuracy and precision ranged from 84.1 to 94.1% and from 2.4 to 6.9%, respectively. Additionally, the confirmative conditions of LC-MS/MS for prohexadione were set in negative electrospray ionization mode with transitions of m/z 211.4 → 167.5 and m/z 211.4 → 123.5 in the selected reaction monitoring mode. The applicability of the method was demonstrated by analyzing real samples collected from local markets in Seoul, Republic of Korea. This developed method fully deserves consideration in accordance with its sensitivity, accuracy and precision required for residue analysis of prohexadione in Chinese cabbages and apples.

Dynamics of residues from a novel nano-imidacloprid formulation in soyabean fields

Imidacloprid has been widely used to control vegetable pests in China. This research was conducted to establish a method for preparing a novel imidacloprid nano-formulation and develop a simple and efficient method for determination of residues of the novel imidacloprid formulation in soyabean fields. Imidacloprid micro-crystals were directly encapsulated with chitosan and sodium alginate through layer-by-layer self-assembly. The coated colloids and photocatalysts were characterized using confocal laser scanning microscopy and scanning electron microscopy. Residues of the novel imidacloprid were determined by HPLC equipped with a UV detector. The results showed that imidacloprid micro-crystals were obtained by association and had a mean length of 7 μm and a zeta potential of −37.5 mV. The pesticide loading and encapsulation efficiency were 56.2 ± 0.96% and 81.6 ± 0.96%, respectively. Degradation of the nano-imidacloprid and the suspension concentrate imidacloprid formulations in soil coincided with C = 0.227e −0.152t and C = 0.544e −0.177t with half lives of about 2.8 d and 6.2 d, respectively. Degradation of the two imidacloprid formulations in soyabean plants coincided with C = 6.644e −0.475t and C = 8.585e −0.573t with half lives of about 1.9 d and 4.5 d, respectively. Thus, in soil, the degradation rate of the nano formulation was faster than that of the suspension concentrate, but the degradation rates were vice versa in the plant. The final residue of the nano imidacloprid formulation after 35 days was below the limit of detection but in the soyabean plant, the final residue was 0.003 mg kg −1, much lower than the USA Environment Protection Agency’s Maximum Residue Level. Therefore, a dosage of 900 ml hm −2 is suggested for the nano-imidacloprid concentrate, which could be considered as safe to fields.

Simple analytical method for determination of pesticide residues in human serum by liquid chromatography tandem mass spectrometry

The aim of this study was to develop an analytical method for the determination of residues of organophosphorus and carbamate pesticides which are widely used in Tunisia. This method involves a liquid-liquid extraction procedure followed by liquid chromatography tandem mass spectrometry (LC/MS/MS) for the identification and quantification of compounds. Ionization of molecules was performed by the electrospray mode. Multiple reactions monitoring (MRM) was the acquisition mode used for the monitoring of two MS/MS transitions for each compound. The average recoveries obtained, at three different fortification levels, ranged between 65% and 106% for most of the pesticides studied, except for methamidophos (lower than 25%).The linearity of the method was in the range of 5 to 50 μ g/L with a correlation coefficient from 0.995 to 0.999, depending on the analyte. The estimated limit of detection and limit of quantification were 2 μ g/L and 5 μ g/L, respectively. The precision of the analytical procedure was satisfactory and the coefficients of variation, evaluated at three concentration levels were lower than 15% for most pesticides studied. The application of the method was investigated in a population of agricultural workers chronically exposed to various pesticides some of which, such as carbofuran, carbendazim, methomyl and pirimicarb, were detected in some serum samples.

Determination of Diacylhydrazines-Type Insect Growth Regulator JS-118 Residues in Cabbage and Soil by High Performance Liquid Chromatography with DAD Detection

JS-118 is a diacylhydrazines-type insect growth regulator used extensively in China now. An analytical method for residues determination of JS-118 in cabbage and soil samples by high performance liquid chromatography with DAD detection was established and optimized. Primary secondary amine solid phase extraction cartridge was used for sample preparation. Mean recoveries for the analyte ranged from 96.6% to 107.0% with CV value less than 4.7%. The limit of quantification is 0.01 mg/kg. Direct confirmation of JS-118 residues in samples was realized by high performance liquid chromatography-mass spectrometry. The proposed method is simple, rapid and reliable to perform and could be utilized for monitoring of pesticides residues.

Large volume injection for the direct analysis of ionophores and avermectins in surface water by liquid chromatography–electrospray ionization tandem mass spectrometry

A simple method for the direct determination of residues of ionophore antibiotics and avermectin antiparasitics in surface water is reported. Using a large volume injector, a mixture of methanol and surface water is injected into an analytical liquid chromatography (LC) column and subsequently screened for residues of these veterinary pharmaceuticals using electrospray ionization tandem mass spectrometry. On-line sample enrichment and chromatographic separation are achieved using a single, short (20 mm) octadecylsilane LC column. The method permits the detection of four ionophores and two avermectins in surface water samples at low ng L −1 concentrations. Minimal matrix effects were observed for a variety of surface water samples which permitted the use of reagent-based standards for quantitation.

Determination of Organophosphorus Pesticides in Soybean Oil, Peanut Oil and Sesame Oil by Low-Temperature Extraction and GC-FPD

A low-temperature clean-up method for residue determination was developed and validated for 14 organophosphorus pesticides in soybean oil, peanut oil and sesame oil by gas chromatography with flame photometric detector (GC-FPD). A different matrix influenced the response and retention time of pesticides. Hence matrix-matched calibration standards were used to counteract the matrix effect. The pesticide responses in blank samples of soybean oil, peanut oil and sesame oil were within the linear range of 0.02–1 mg kg−1 and the correlation coefficients were higher than 0.9989. Average recoveries obtained from different oil samples at three fortified levels were higher than 50% with relative standard deviations (RSDs) of less than 15%. The limit of detections (LODs) of studied pesticides ranged from 2 to 5 μg kg−1. Thirty-nine commercial samples were analyzed, and the results were confirmed by gas chromatography–mass spectrometry (GC–MS) in selective ion monitoring (SIM) mode.

Proposal of an analytical method for determination of residues of organophosphorus pesticides in milk by GLC-NPD.

G. Pagliuca*, T. Gazzotti, E. Zironi, N. Pavoncelli and R. Rosmini Department of Veterinary Public Health and Animal Pathology – Alma Mater Studiorum – University of Bologna *Correspondence: Dipartimento di Sanita Pubblica Veterinaria e Patologia Animale – Sezione di Igiene e T ecnologia Alimentare – Alma Mater Studiorum – Universita di Bologna, via T olara di Sopra, 50 – 40064 Ozzano dell’Emilia, Bologna, Italy E-mail: pagliuca@vet.unibo.it

New gas chromatographic method for residue determination of dithiopyr in soil, wheat grain and straw

A gas chromatographic method has been developed for a new pyridine herbicide, dithiopyr, utilising an electron capture detector. The method makes use of a column (10 m×0.534 mm I.D.; 1 μm film thickness) containing HP-1 with nitrogen as a carrier gas at a flow rate of 15 ml min −1 at temperatures of 190, 210, 270°C for oven, injector port and detector, respectively. Soil, wheat grain and straw samples fortified with dithiopyr were extracted with acetone–0.2 M HCl (95:5) and cleaned up by partitioning with hexane. The technique has a sensitivity of 0.05 μg ml −1 and the recovery of dithiopyr from soil, wheat grain and straw ranged between 80 and 99%.