Determination of pesticide residues in olives and olive oil by matrix solid-phase dispersion followed by gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry

A novel analytical approach has been developed and evaluated for the quantitative analysis of a selected group of widely used pesticides (dimethoate, simazine, atrazine, diuron, terbuthylazine, methyl-parathion, methyl-pirimiphos, endosulfan I, endosulfan II, endosulfan sulphate, cypermethrin and deltamethrin), which can be found at trace levels in olive oil and olives. The proposed methodology is based on matrix solid-phase dispersion (MSPD), (with a preliminary liquid-liquid extraction in olive oil samples) using aminopropyl as sorbent material with a clean-up performed in the elution step with Florisil, followed by mass spectrometric identification and quantitation of the selected pesticides using both gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode and liquid chromatography tandem mass spectrometry (LC-MS-MS) in positive ionization mode. The recoveries obtained (with mean values between 85 and 115% (obtained at different fortification levels) with RSD values below 10% in most cases, confirm the usefulness of the proposed methodology for the analyses of these kind of complex samples with a high fat content. Moreover, the obtained detection limits, which were below 5 microg kg(-1) by LC-MS analyses and ranged from 10 to 60 microg kg(-1) by GC-MS meet the requirements established by the olive oil pesticide regulatory programs. The method was satisfactorily applied to different olives and olive oil samples.     

Analytical methods for pesticide residues in rice

Rice consumption has increased worldwide over recent decades, as it has become one of the most common foods. Although the analysis of environmental samples coming from rice areas has been well documented, there is less information regarding the analysis of pesticide residues in rice-grain samples.Rice (paddy, brown and white) can be considered a complex matrix, leading to difficulties in the application of the different multiresidue methods described in the literature. This review addresses and compares the principal extraction and clean-up methodologies [e.g., liquid-liquid extraction, solid-phase extraction, pressurized-liquid extraction, QuEChERS (quick, easy, cheap, effective, rugged and safe), gel-permeation chromatography and supercritical-fluid extraction - with QuEChERS-based methods being the most frequently employed].Traditionally, the determination of pesticide residues in rice has been based on gas chromatography with mass spectrometry (MS). But the application of new classes of pesticides has driven laboratories to increase the use of liquid chromatography with tandem MS. The limits of detection and quantification are in the ranges 0.09-90 μg/kg and 1-297 μg/kg, respectively, for the methodologies reported. These values agree with the current internationally-accepted maximum residue limits (MRLs).Based on the European Union (EU) database, more than 3000 analyses of pesticide residues in rice have been performed by official EU laboratories over the past decade. Of these, 6% reported pesticide residues above the MRLs.Physico-chemical properties can explain the occurrence of pesticides in rice commodities: lipophilic pesticides are frequently found in brown rice, whereas fungicides are mainly found in milled rice. Carbendazim, malathion, iprodione, tebuconazole, quinclorac and tricyclazole are the pesticides most frequently found in white rice, while buprofezin, hexaconazole, chlorpyrifos and edifenphos are most commonly found in paddy rice.Pesticide-residue concentrations can be affected during rice processing - with concentrations generally lower in the final products. However, few studies focusing on primary processing have addressed the setting of precise values applicable for the processing factors.     

Analytical methods applied to the determination of pesticide residues in foods of animal origin. A review of the past two decades

Pesticides are widely used in agriculture and can be transferred to animals in a number of ways. Consequently, reliable analytical methods are required to determine pesticide residues in foods of animal origin. The present review covers published methods and research articles (1990-2010) in which pesticide residues have been extracted from meat and meat products, milk and dairy products, fish and seafood, and eggs, then cleaned up, and isolated by chromatographic techniques to be identified and quantified by various detection methods. Recovery rates, quantification limits, the matrix effect and related parameters have all been considered. Lastly, future developments in this field are outlined.     

气相色谱-负化学离子源质谱联用法测定植物性产品中多组分农药残留量

通过气相色谱-负化学离子源质谱技术建立了同时检测18种农药残留的分析方法. 样品经正己烷和丙酮混合溶剂及正己烷提取后, 用活性炭-中性氧化铝混合小柱净化, 再由气相色谱-负化学离子源质谱分时段选择离子监测技术进行测定. 一次进样就能得到18种农药残留结果;各农药在0.005、 0.01和0.02 mg/kg 3个添加水平的平均回收率在70.2%～115.3%之间, RSD<12%, 检出限为0.01～6 μg/kg, 方法可应用于8种植物性产品中的农残检测.     

Analytical methods for the determination of bisphenol A in food

Food constitutes the primary route for human exposure to bisphenol A (BPA), one of the highest volume chemicals produced worldwide. The estrogenic properties of BPA, its wide dispersive use and the recent extensive literature describing low-dose BPA effects in animals, have raised concerns about its possible adverse effects on human health. A reliable health risk assessment of BPA relies basically on its unambiguous identification and accurate quantification in food, and the aim of the present review is to give an overview of the analytical methods reported so far for the determination of BPA in these matrices. Emphasis is placed on the main strategies developed for sample treatment, which usually consists of several laborious and time-consuming steps in order to achieve the required sensitivity and selectivity. Separation, identification and quantitation of BPA is today reliably made with mass spectrometric methods, namely liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS), and thus main attention is devoted to these techniques, but other methods using LC coupled to fluorescence or electrochemical detection, as well as immunochemical methods are also covered. Recent and expected future developments are discussed.     

Comparison of QuEChERS sample preparation methods for the analysis of pesticide residues in fruits and vegetables

This article describes the comparison of different versions of an easy, rapid and low-cost sample preparation approach for the determination of pesticide residues in fruits and vegetables by concurrent use of gas and liquid chromatography (GC and LC) coupled to mass spectrometry (MS) for detection. The sample preparation approach is known as QuEChERS, which stands for “quick, easy, cheap, effective, rugged and safe”. The three compared versions were based on the original unbuffered method, which was first published in 2003, and two interlaboratory validated versions: AOAC Official Method 2007.01, which uses acetate buffering, and European Committee for Standardization (CEN) Standard Method EN 15662, which calls for citrate buffering. LC–MS/MS and GC–MS analyses using each method were tested from 50 to 1000 ng/g in apple–blueberry sauce, peas and limes spiked with 32 representative pesticides. As expected, the results were excellent (overall average of 98% recoveries with 10% RSD) using all 3 versions, except the unbuffered method gave somewhat lower recoveries for the few pH-dependent pesticides. The different methods worked equally well for all matrices tested with equivalent amounts of matrix co-extractives measured, matrix effects on quantification and chemical noise from matrix in the chromatographic backgrounds. The acetate-buffered version gave higher and more consistent recoveries for pymetrozine than the other versions in all 3 matrices and for thiabendazole in limes. None of the versions consistently worked well for chlorothalonil, folpet or tolylfluanid in peas, but the acetate-buffered method gave better results for screening of those pesticides. Also, due to the recent shortage in acetonitrile (MeCN), ethyl acetate (EtOAc) was evaluated as a substitute solvent in the acetate-buffered QuEChERS version, but it generally led to less clean extracts and lower recoveries of pymetrozine, thiabendazole, acephate, methamidophos, omethoate and dimethoate. In summary, the acetate-buffered version of QuEChERS using MeCN exhibited advantages compared to the other tested methods in the study.     

Critical review of the application of liquid chromatography/mass spectrometry to the determination of pesticide residues in biological samples

A critical review is made on the use of hyphenated liquid chromatography/mass spectrometry (LC–MS) for the identification and quantification of pesticides and their metabolites in human biosamples (whole blood, plasma, serum and urine). The first applications of LC–MS in this field began in the early 1990s. Since then, increasing interest has been shown in applying this powerful technique, with most applications dealing with the determination of a variety of chemically diverse metabolites in urine. The use of different LC–MS interfaces and mass spectral detection modes are discussed. Special attention is given to tandem mass spectrometry (MS/MS) due to its inherent advantages of increased sensitivity and selectivity, as well as its advantages for identification and confirmation of analytes in samples. Quantification can be severely affected by matrix effects, the most common being inhibition of the ionisation of analytes in the mass spectrometer, which leads to unacceptable errors if no correction is made. Different approaches can be employed to minimise this undesirable matrix effect, the preferred being the use of labelled internal standards (when available) in isotope dilution methods or the application of an efficient clean-up, performed off-line or automated on-line. Adequate criteria for confirming the identities of residues detected are required in order to avoid false positives. The criterion most commonly used with a triple quadrupole instrument is the monitoring of two MS/MS transitions together with the ion abundance ratio. TOF mass analysers are seldom used in pesticide residue analysis despite their improved resolution and mass accuracy characteristics, which makes them very suitable for confirmation purposes. The main reasons for the relative unpopularity of TOF MS in residue analysis are its limited sensitivity and its high acquisition cost. In this paper, we present a critical assessment on current techniques, trends and future developments, and give illustrative examples to point out the main characteristics of LC–MS for pesticide residue analysis in biological fluids.     

Analytical methods for estimation of organophosphorus pesticide residues in fruits and vegetables: A review

Use of pesticides has turned out to be an obligatory input to agriculture and public health. Versatile use of pesticides had resulted in contamination of all basic necessities of life, i.e. air, water and food. Among various pesticides, organophosphorus pesticides (OPPs), derivative of phosphoric acid, are the most extensively used insecticides or acaricides in many crops. Due to low persistency and high killing efficiency of OPPs, many agriculturalists regularly use this group of pesticides for various vegetables and fruits crops. The continuous use of pesticides has caused the deleterious effects to ecosystem. In response to this, a number of methods have been developed by several regulatory agencies and private laboratories and are applied routinely for the quantification and monitoring of multi pesticide residues in vegetables and crops. The present review pertains to various extraction and quantification procedures used world wide to analyze OPPs residues in various vegetables and fruits.     

Capillary electromigration methods for fatty acids determination in vegetable and marine oils: A review

Fatty acids determination is of paramount importance for quality control and suitable labeling of edible oils, required by regulatory agencies in several countries, and fast methods for this determination are worldly desired. This review article aimed to explore the available analytical methods for vegetable and marine oils analyses employing CE, which can be a straightforward and faster alternative than GC methods for fatty acid determination, considering some purposes. CE usually offers the possibility of a rapid analysis with a simple preparation of the sample, without requiring specific columns, which are inherent advantages of the technique. Instrumental conditions and the key points about fatty acids determination employing the technique are highlighted, and the main challenges and perspectives are also approached. Potential use of CE for edible oil analyses has been demonstrated for research and routine, which can be of interest for industries, regulatory agencies, and edible oil researchers. Therefore, we have explored the analytical approaches described in the last decades, intending to spread the interest of CE methods for fatty acid monitoring, label accuracy assessment, and food authenticity evaluation of edible oils.     

Determination of organochlorine pesticide residues in fatty foods: a critical review on the analytical methods and their testing capabilities

Organochlorine pesticide (OCP) residues in foods have been of concern for several decades. However, the analysis of some of the OCPs and their metabolites or derivatives, such as endrin aldehyde, endrin ketone, nonachlor, etc. in fatty foods (including foods of animal and plant origin), was not commonly included in routine monitoring programme. Recently, the Stockholm Convention introduced nine plus one new persistent organic pollutants (POPs) that included chlordecone and some other OCPs. Is there a method available that can analyze both traditional OCPs, together with their metabolites and derivatives in fatty foods? Furthermore, is there a suitable method that can monitor OCPs and the newly added POPs including chlordecone in fatty foods together in a pot? This review aims to provide some background information to answer these questions.     

Quaternary ammonium pesticides: A review of chromatography and non-chromatography methods for determination of pesticide residues in water samples

The monitoring of pesticide residues in water sources is essential because of their increased worldwide demand in agriculture and their subsequent detection in waters. Pesticide residues in water matrices are traditionally determined by multiresidue methodologies based on chromatography coupled to mass spectrometry. However, for quaternary ammonium pesticide residues, as highly polar compounds, the chromatographic approach frequently fails, requiring modifications in the separation method, or even an alternative technique for analyte quantification. Therefore, to solve this analytical limitation for these residues, several authors proposed unusual methodologies, such as those based on spectroscopic or electroanalytical approaches. This review intends to offer an overview of the analysis of quaternary ammonium pesticide residues in different water sources, focusing on advances in sample preparation before chromatographic separations and alternative analytical techniques, such as spectroscopy and electroanalytical methods.     

Rapid determination of BTEXS in olives and olive oil by headspace-gas chromatography/mass spectrometry (HS-GC-MS)

In this work, a straightforward, reliable and effective automated method has been developed for the direct determination of monoaromatic volatile BTEXS group (namely benzene, toluene, ethylbenzene, o-, m- and p-xylenes, and styrene) in olives and olive oil, based on headspace technique. Separation, identification and quantitation were carried out by headspace-gas chromatography-mass spectrometry (HS-GC-MS) in selected ion monitoring (SIM) mode. Sample pretreatment or clean-up were not necessary (besides olives milling) because the olives and olive oil samples are put directly into an HS vial, automatically processed by HS and then injected in the GC-MS for chromatographic analysis. The chemical and instrumental variables were optimized using spiked olives and olive oil samples at 50 μg kg⁻¹ of each targeted species. The method was validated to ensure the quality of the results. The precision was satisfactory with relative standard deviations (RSD (%)) in the range 1.6-5.2% and 10.3-14.2% for olive oil and olives, respectively. Limits of detection were in the range 0.1-7.4 and 0.4-4.4 μg kg⁻¹ for olive oil and olives, respectively. Finally, the proposed method was applied to the analysis of real olives and olive oil samples, finding positives of the studied compounds, with overall BTEXS concentration levels in the range 23-332 μg kg⁻¹ and 4.2-87 μg kg⁻¹ for olive oil and olives, respectively.     

The comparison of solid phase microextraction-GC and static headspace-GC for determination of solvent residues in vegetable oils

The objective of these investigations has been the determination of volatile organic compounds including residue solvents present in vegetable oil samples. Some olive oil, rape oil, sunflower oil, soy-bean oil, pumpkin oil, grape oil, rice oil as well as hazel-nut oil samples were analysed. Among residue solvents the following compounds have been mentioned: acetone, n-hexane, benzene, and toluene. Some experiments for the solid phase microextraction (SPME)-GC-flame ionisation detection (FID) were performed to examine extraction conditions such as fiber exposure time, temperature of extraction, and temperature of desorption. Various SPME fibers such as polydimethylsiloxane, Carboxen/polydimethylsiloxane and polydimethylsiloxane/divinylbenzene coatings were used for the isolation of tested compounds from vegetable oil samples. After optimisation of SPME, real vegetable oil samples were examined using SPME-GC/MS. Based on preliminary experiments the qualitative and quantitative analyses for the determination of acetone, n-hexane, benzene and toluene were performed by SPME-GC-FID and static head-space (SHS)-GC-FID methods. The regression coefficients for calibration curves for the examined compounds were R(2) > or = 0.992. This shows that the used method is linear in the examined concentration range (0.005-0.119 mg/kg for SPME-GC-FID and 0.003-0.728 mg/kg for SHS-GC-FID). Chemical properties of analysed vegetable oils have been characterised by chemometric procedure (cluster analysis).     

Direct, reagent-free determination of free fatty acid content in olive oil and olives by Fourier transform Raman spectrometry

Fourier transform (FT) Raman spectrometry in combination with partial least squares (PLS) regression was used for direct, reagent-free determination of free fatty acid (FFA) content in olive oils and olives. Oils were directly investigated in a simple flow cell. Milled olives were measured in a dedicated sample cup, which was rotated eccentrically to the horizontal laser beam during spectrum acquisition in order to compensate sample heterogeneity. Both external and internal (leave-one-out) validation were used to assess the predictive ability of the PLS calibration models for FFA content (in terms of oleic acid) in oil and olives in the range 0.20-6.14 and 0.15-3.79%, respectively. The root mean square error of prediction (RMSEP) was 0.29% for oil and 0.28% for olives. The predicted FFA contents were used to classify oils and olives in different categories according to the European Union regulations. Ninety percent of the oil samples and 80% of the olives were correctly classified. These results demonstrate that the proposed procedures can be used for screening of good quality olives before processing, as well as, for the on-line control of the produced oil.     

Determination of pesticides and veterinary drug residues in food by liquid chromatography-mass spectrometry: A review

Monitoring of pesticides and veterinary drug residues is required to enforce legislation and guarantee food safety. Liquid chromatography-mass spectrometry (LC-MS) is the prevailing technique for assessing both types of residues because LC offers a versatile and universal separation mechanism suitable for non-gas chromatography (GC) amenable and the majority of GC-amenable compounds. This characteristic becomes more relevant when LC is coupled to MS because the high sensitivity and specificity of the detector allows to apply generic sample preparation procedures, which simultaneously extract a wide variety of residues with different physico-chemical properties. Determination of metabolites and degradation products, non-target suspected screening of an increasing number of residues, and even unknowns identification are also becoming inherent LC-MS advantages thanks to the latest advances. For routine analysis and, in particular, for official surveillance purposes in food control, analytical methods properly validated following strict guidelines are needed. After a brief introduction and an outline of the legislation applicable around the world, aspects such as improvement of specificity of high-throughput methods, resolution and mass accuracy of identification strategies and quantitative accuracy are critically reviewed in this article. In them, extraction, separation and determination are emphasized. The main objective is to offer an assessment of the state of the art and identify research needs and future trends in determining pesticide and veterinary drug residues in food by LC-MS.     

Determination of pesticide transformation products: A review of extraction and detection methods

Pesticides are widely applied and they can produce a variety of transformation products (TPs), through different pathways and mechanisms. Nowadays there is a growing interest related to the determination of pesticide TPs in several matrices (environmental, food and biological samples), due to these compounds can be more toxic and persistent than parent compounds, and some of them can be used as markers of exposure to different pesticides. Although solid-phase extraction (SPE) is mainly used for the extraction of TPs, alternative techniques such as solid-phase microextraction (SPME) and liquid-phase extraction (LPE) can be used. These TPs are mainly determined by liquid chromatography (LC) due to the recent developments in this technique, especially when it is coupled to mass spectrometry (MS) detectors, allowing the determination of known and/or unknown TPs. Furthermore, MS is a very valuable tool for the structural elucidation of unknown TPs. This review discusses all phases of analytical procedure, including sample treatment and analysis, indicating the main problems related to the extraction of TPs from several matrices due to their high polarity, as well as the different alternatives found for the simultaneous determination of parent compounds and TPs, using chromatographic techniques coupled to MS detection.     

A capillary electrophoresis-tandem mass spectrometry methodology for the determination of non-protein amino acids in vegetable oils as novel markers for the detection of adulterations in olive oils

A new analytical methodology based on capillary electrophoresis-mass spectrometry (CE-MS(2)) is presented in this work, enabling the identification and determination of six non-protein amino acids (ornithine, β-alanine, GABA, alloisoleucine, citrulline and pyroglutamic acid) in vegetable oils. This methodology is based on a previous derivatization with butanol and subsequent separation using acidic conditions followed by on-line coupling to an ion trap analyzer for MS(2) detection established through an electrospray-coaxial sheath flow interface. The electrophoretic and interface parameters were optimized obtaining the separation of all compounds in less than 15 min and with resolutions higher than 5. The proposed method was validated by assessing its accuracy, precision (RSD<7% for corrected peak areas), LODs and LOQs (between 0.04-0.19 ng/g and 0.06-0.31 ng/g, respectively) and linearity range (R(2)>0.99), and it was used in order to identify the selected non-protein amino acids in soybean oils, sunflower oils, corn oils and extra virgin olive oils. MS(2) experiments performed the fingerprint fragmentation of these compounds allowing to corroborate ornithine and alloisoleucine in seed oils but not in olive oils. The method was applied to identify and quantify olive oil adulterations with soybean oil detecting in a single run the amino acids in mixtures up to 2% (w/w). The results showed a high potential in using these compounds as novel markers for the detection of adulterations of extra virgin olive oils with seed oils. Thus, the developed method could be considered a simple, rapid and reliable method for the quality evaluation of extra virgin olive oil permitting its authentication.     

Analytical methods for the assessment of endocrine disrupting chemical exposure during human fetal and lactation stages: A review

In the present work, a review of the analytical methods developed in the last 15 years for the determination of endocrine disrupting chemicals (EDCs) in human samples related with children, including placenta, cord blood, amniotic fluid, maternal blood, maternal urine and breast milk, is proposed. Children are highly vulnerable to toxic chemicals in the environment. Among these environmental contaminants to which children are at risk of exposure are EDCs —substances able to alter the normal hormone function of wildlife and humans—. The work focuses mainly on sample preparation and instrumental techniques used for the detection and quantification of the analytes. The sample preparation techniques include, not only liquid–liquid extraction (LLE) and solid-phase extraction (SPE), but also modern microextraction techniques such as extraction with molecular imprinted polymers (MIPs), stir-bar sorptive extraction (SBSE), hollow-fiber liquid-phase microextraction (HF-LPME), dispersive liquid–liquid microextraction (DLLME), matrix solid phase dispersion (MSPD) or ultrasound-assisted extraction (UAE), which are becoming alternatives in the analysis of human samples. Most studies focus on minimizing the number of steps and using the lowest solvent amounts in the sample treatment. The usual instrumental techniques employed include liquid chromatography (LC), gas chromatography (GC) mainly coupled to tandem mass spectrometry. Multiresidue methods are being developed for the determination of several families of EDCs with one extraction step and limited sample preparation.     

Development of an ultrasound‐assisted emulsification microextraction method for the determination of chlorpyrifos and organochlorine pesticide residues in honey samples using gas chromatography with mass spectrometry

A simple, rapid, and efficient ultrasound‐assisted emulsification microextraction method followed by gas chromatography mass spectrometry in selected ion monitoring mode was developed for the determination of organochlorine pesticides in honey samples. The type and volume of organic extraction solvent, pH, effect of added salt content, and centrifuging time and speed were investigated. Under the optimum extraction conditions, 30 μL of 1, 2‐dibromoethane (extraction solvent) was immersed into an ultrasonic bath for 1 min at 40°C. The limits of detection and quantification for all target pesticides were 0.003–0.06 and 0.01–0.2 ng/g_, respectively. The extraction recovery was 91–100% and the enrichment factors were 168–192. The relative standard deviation for the method was <6% for intraday (n = 6) and <8% for interday precision (n = 4). The proposed method was successfully applied for the analysis of organochlorine pesticides in honey samples.