Negative chemical ionization gas chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry and automated accurate mass data processing for determination of pesticides in fruit and vegetables.

Gas chromatography coupled to high resolution hybrid quadrupole time-of-flight mass spectrometry (GC-QTOF MS), operating in negative chemical ionization (NCI) mode and combining full scan with MSMS experiments using accurate mass analysis, has been explored for the automated determination of pesticide residues in fruit and vegetables. Seventy compounds were included in this approach where 50 % of them are not approved by the EU legislation. A global 76 % of the analytes could be identified at 1 μg kg(-1).

Validation of a multiclass multiresidue method and monitoring results for 210 pesticides in fruits and vegetables by gas chromatography-triple quadrupole mass spectrometry.

A rapid, sensitive, accurate and reliable multiresidue method for the identification and quantification of 210 relevant pesticides in four representative fruit and vegetable commodities (tomato, potato, spring onion and orange) has been developed and validated by gas chromatography in tandem with triple quadrupole mass spectrometry. The method has been fully validated and applied to 292 samples from different countries. Prior to instrumental analysis, an extraction procedure based on a sample extraction of multiclass analytes, using the ethyl acetate method was employed.

Evaluation of zirconium dioxide-based sorbents to decrease the matrix effect in avocado and almond multiresidue pesticide analysis followed by gas chromatography tandem mass spectrometry.

Two sorbents containing ZrO₂ (Z-Sep and Z-Sep+) were tested as a d-SPE clean-up in combination with the QuEChERS and ethyl acetate multiresidue method in the pesticide residues extraction in avocado. All extracts were analysed using gas chromatography coupled with a triple quadrupole mass spectrometer working in multi-reaction monitoring mode. GC QToF was used to compare the amount of matrix compounds present in the final extracts, prepared according to different protocols.

Processing factor for a selected group of pesticides in a wine-making process: distribution of pesticides during grape processing.

The processing factors (the pesticide concentration found in the wine/pesticide concentration found in grapes) of acetamiprid, azoxistrobin, carbaril, carbendazime, cyprodinil, dimethoate, dimethormorf, imazalil, imidacloprid, kresoxim methyl, penconazole, procymidone and thiabendazole were determined in a wine-making process. Pesticide analysis was performed using a multi-residue method for the determination of different pesticides both in wine and in grapes by extraction with acetonitrile followed by LC/MS. The pesticide distribution was studied for each step of the process, and the pesticide processing factors were calculated and found to vary among the different pesticides studied.

Prediction of the processing factor for pesticides in apple juice by principal component analysis and multiple linear regression.

The main objective of this work was to establish a mathematical function that correlates pesticide residue levels in apple juice with the levels of the pesticides applied on the raw fruit, taking into account some of their physicochemical properties such as water solubility, the octanol/water partition coefficient, the organic carbon partition coefficient, vapour pressure and density. A mixture of 12 pesticides was applied to an apple tree; apples were collected after 10 days of application. After harvest, apples were treated with a mixture of three post-harvest pesticides and the fruits were then processed in order to obtain apple juice following a routine industrial process.

Comparison of three multiresidue methods to analyse pesticides in green tea with liquid and gas chromatography/tandem mass spectrometry.

The aim of the present work was to compare and choose the best method to extract pesticide residues from green tea. Three different multiresidue methods were tested on blank green tea samples fortified with 86 pesticides (insecticides, fungicides and herbicides) at the 100 μg kg(-1) level - modified QuEChERS (in order to limit the amount of coextractives, MgSO(4) was replaced with calcium chloride in the clean-up step); ethyl acetate extraction (not SweEt) and miniLuke. Due to matrix complexity, samples were diluted five times.

Analysis of synthetic endocrine-disrupting chemicals in food: a review.

This work focuses on a revision of analytical methodologies for the determination of industrial chemicals that have an endocrine-disrupting effect on food commodities. These food commodities have been divided into two major categories: crops and food of animal origin. The reviewed methods have been commented on in terms of sample preparation, analytical methods, and the occurrence of the studied compounds.

Pesticide analysis in teas and chamomile by liquid chromatography and gas chromatography tandem mass spectrometry using a modified QuEChERS method: validation and pilot survey in real samples.

This paper presents the validation of a modified QuEChERS method in four matrices - green tea, red tea, black tea and chamomile. The experiments were carried out using blank samples spiked with a solution of 86 pesticides (insecticides, fungicides and herbicides) at four levels - 10, 25, 50 and 100 μg/kg. The samples were extracted according to the citrate QuEChERS protocol; however, to reduce the amount of coextracted matrix compounds, calcium chloride was employed instead of magnesium sulphate in the clean-up step.

A sensitive and selective method for the determination of selected pesticides in fruit by gas chromatography/mass spectrometry with negative chemical ionization.

Multiresidue methods (MRMs) for pesticides residues determination in fruit and vegetables, based on GC-MS, are mainly performed in electron impact ionization mode. However an important group of them provide much better response working in negative chemical ionization mode due to the elimination of a high percentage of background signal. Considering that a selective and sensitive method has been developed for the determination of multiclass pesticide residues in different commodities by GC-MS with a triple stage quadrupole analyzer (GC-TSQ-MS); the pesticide signal has been optimized in MS-MS whilst working in negative chemical ionization mode using methane as the reagent gas.

Determination of chlorothalonil in difficult-to-analyse vegetable matrices using various multiresidue methods.

The molecular characteristics of chlorothalonil can cause particular determination difficulties in some vegetable commodities such as leek or garlic. These difficulties are mainly related to the low recoveries obtained using common multi-residue methods (MRMs)--a consequence of the very high interaction level with natural components in the matrix. These shortcomings were pointed out in the last European Proficiency Test for Pesticide Residues on Fruits and Vegetables, where false negatives for chlorothalonil in leek were observed at around 50%.

Evaluation of relevant time-of-flight-MS parameters used in HPLC/MS full-scan screening methods for pesticide residues.

An automatic screening method based on HPLC/time-of-flight (TOF)-MS (full scan) was used for the analysis of 103 non-European fruit and vegetable samples after extraction by the quick, easy, cheap, effective, rugged, and safe method. The screening method uses a database that includes 300 pesticides, their fragments, and isotopical signals (910 ions) that identified 210 pesticides in 78 positive samples, with the highest number of detection being nine pesticides/sample. The concentrations of 97 pesticides were <10 microg/kg, 53 were between 10 and 100 microg/kg, and 60 were at a concentration of >100 microg/kg.

Determination of selected pesticides by GC with simultaneous detection by MS (NCI) and μ-ECD in fruit and vegetable matrices.

A gas chromatography-mass spectrometry method in negative chemical ionization mode has been developed incorporating simultaneous detection using a micro-electron capture detector (μ-ECD) for the determination of pesticides in fruits and vegetables. This instrument configuration uses a three-way splitter device which divides the effluent from the analytical column between the two detectors with the split ratio 1:0.1 (MSD/μ-ECD) in each run.

Determination of nicotine in mushrooms by various GC/MS- and LC/MS-based methods.

Due to the basic properties of nicotine, it is not easily integrated into commonly used multiresidue methods. The present work investigates the application of two commonly employed multiresidue methods-the QuEChERS method and the ethyl acetate method-for determining nicotine in mushrooms. Both methods are employed in a modified form and an unmodified form: the former to address the special properties of nicotine and the latter, combined with the use of isotopically labelled nicotine, to compensate for poor recoveries.

Benefits and pitfalls of the application of screening methods for the analysis of pesticide residues in fruits and vegetables.

The goal of this study was to expand knowledge on the performance of screening methods based on accurate mass measurements using a liquid chromatography electrospray quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS) system operating in full scan mode and with automatic identification based on the use accurate-mass databases. The study involved the analysis of 97 pesticides, in five matrices (tomato, pepper, zucchini, orange and leek) and at three concentration levels (20, 50 and 100 μg kg(-1)). Aspects concerning optimization of the search parameters, sensitivity, matrix effects, efficiency of the algorithm search, usefulness of fragment ions, etc.

Chemical and toxicological evolution of the antibiotic sulfamethoxazole under ozone treatment in water solution.

This work studied the elimination paths of the sulfonamide antibiotic sulfamethoxazole by ozonation in fast kinetic regime. The ozonation runs were performed in conditions favouring either the direct attack of the ozone molecule or the indirect attack by ozone-generated radical species with initial concentration of 0.150 mM.

Comparative study of the main top-down approaches for the estimation of measurement uncertainty in multiresidue analysis of pesticides in fruits and vegetables.

Practical "top-down" approaches appear to be the most suitable for the evaluation of measurement uncertainty in pesticide residue testing laboratories, where analytical procedures are routinely applied to a large number of pesticide/food combinations. The opposite approach, "bottom-up" evaluation of measurement uncertainty, leads to great difficulties in evaluating all of the pesticides in a consistent way. Among the top-down approaches, there are two main ways in which measurement uncertainty can be estimated: One is based on default values, which are based on previous extensive interlaboratory experience and the proven accuracy of the laboratory; these include the Horwitz equation or the fit-for-purpose relative standard deviation (FFP-RSD).

Rapid automated screening, identification and quantification of organic micro-contaminants and their main transformation products in wastewater and river waters using liquid chromatography-quadrupole-time-of-flight mass spectrometry with an accurate-mass database.

In this study we have developed and evaluated an analytical method for a rapid automated screening and confirmation of a large number of organic micro-contaminants (almost 400) and also the quantification of the positive findings in water samples of different types (surface and wastewaters) using liquid chromatography-electrospray quadrupole-time-of-flight mass spectrometry (LC-QTOFMS) based on the use of an accurate-mass database. The created database includes data not only on the accurate masses of the target ions but also on the characteristic in-source fragment ions, isotopic pattern and retention time data. This customized database was linked to commercially available software which extracted all the potential compounds of interest from the LC-QTOFMS raw data of each sample and matched them against the database to search for targeted compounds in the sample.

Method development and validation for determination of thiosultap sodium, thiocyclam, and nereistoxin in pepper matrix.

This work reports a method for extraction and analysis of thiosultap sodium, thiocyclam, and nereistoxin in pepper. Different extraction methods were tested to attain the best recoveries. The final extraction method combines acetonitrile extraction in an acidic medium with ultrasonic extraction followed by a cleanup step with anhydrous MgSO(4).

Laboratory assessment by combined z score values in proficiency tests: experience gained through the European Union proficiency tests for pesticide residues in fruits and vegetables.

The obligation for accredited laboratories to participate in proficiency tests under ISO 17025, performing multiresidue methods (MRMs) for pesticide residues, involves the reporting of a large number of individual z scores making the evaluation of the overall performance of the laboratories difficult. It entails, time and again, the need for ways to summarise the laboratory's overall assessment into a unique combined index. In addition, the need for ways to continually evaluate the performance of the laboratory over the years is equally acknowledged.

Efficiency evaluation of the main multiresidue methods used in Europe for the analysis of amitraz and its major metabolites.

This paper compares the performance of the three most widely employed multiresidue methods [quick, easy, cheap, effective, rugged, and safe (QuEChERS), mini-Luke, and ethyl acetate] currently used for the determination of amitraz residues in fruits. A fast and differentiated analysis of amitraz and its two main metabolites, N-2,4-dimethylphenyl-N-methylformamidine and 2,4-dimethylformanilide, was performed by HPLC-electrospray ionization-MS/MS using a triple quadrupole mass spectrometer in the positive mode. A test of the stability of the standard solutions showed a rapid hydrolysis of amitraz to the amide and amidine derivatives in solutions containing water, including QuEChERS extracts of crops that were previously acidified.

Multi-residue determination of pesticides in fruit-based soft drinks by fast liquid chromatography time-of-flight mass spectrometry.

This work reports a rapid and reliable method for the determination of 33 multi-class pesticides in fruit-based soft drinks. The proposed method consists of a sample treatment step based on solid-phase extraction using hydrophilic-lipophilic balanced polymer-based reverse-phase SPE cartridges, followed by identification and quantitation of the target pesticides by rapid resolution liquid chromatography using a short C(18) column (4.6mm x 50mm) with 1.

Simultaneous screening and target analytical approach by gas chromatography-quadrupole-mass spectrometry for pesticide residues in fruits and vegetables.

A full-scan GC/quadrupole/MS method has been developed to perform large-scale screenings of pesticides and simultaneous quantification of 95 target compounds in a single run of 21 min. The screening method was performed by using a deconvolution of the spectrum of the full-scan data files acquired under a retention time locked method. The identification performance of the screening method was evaluated in eight different food matrixes at three different concentrations.

A new gas chromatography/mass spectrometry method for the simultaneous analysis of target and non-target organic contaminants in waters.

In this study we developed a GC-MS method for the analysis of priority pollutants, personal care products (PCPs) and other emerging contaminants in waters using large volume injection with backflushing. Analyses are performed in the SIM/scan mode, so that in addition to the targeted organic contaminants, this method allows the simultaneous screening of non-target compounds. The scan data are analysed using Deconvolution Reporting Software (DRS) which screens the results for 934 organic contaminants.

Accurate-mass databases for comprehensive screening of pesticide residues in food by fast liquid chromatography time-of-flight mass spectrometry.

Because of the international trade of fruits and vegetables and the lack of harmonized regulations on the use of pesticides worldwide, the development of comprehensive screening methods for analyzing hundreds of pesticides and other banned chemicals is very convenient. This work reports the development and evaluation of a rapid automated screening method for determining pesticide residues in food using liquid chromatography electrospray time-of-flight mass spectrometry (LC-TOFMS) based on the use of an accurate-mass database. The database created includes data not only on the accurate masses of the target ions but also the characteristic in-source fragment ions (over 400 fragments included) and retention time data.

Environmental risk assessment of pharmaceutical residues in wastewater effluents, surface waters and sediments.

Pharmaceutical residues in the environment, and their potential toxic effects, have been recognized as one of the emerging research area in the environmental chemistry. The increasing attention, on pharmaceutical residues as potential pollutants, is due that they often have similar physico-chemical behaviour than other harmful xenobiotics which are persistent or produce adverse effects. In addition, by contrast with regulated pollutants, which often have longer environmental half-lives, its continuous introduction in the environment may make them "pseudopersistents".