Simultaneous multi-residue pesticide analysis in soil samples with ultra-high-performance liquid chromatography–tandem mass spectrometry using QuEChERS and pressurised liquid extraction methods

To assess soil contamination, it is important to be able to measure different classes of pesticides simultaneously. For this reason we developed a sensitive ultra-high-performance liquid chromatography–tandem mass spectrometry method for the simultaneous analysis of 25 pesticides in soil samples. Multi-class pesticides (triazines, phenylureas, phenoxy acid pesticides etc.) were analysed using a single mass spectrometry method with a fast polarity switching option, allowing the analysis of 19 compounds in the positive ionisation mode and six compounds in the negative ionisation mode. Extraction of pesticides from soil samples was performed employing a pressurised liquid extraction (PLE) and a quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure, recently developed for the extraction of multi-residue pesticides from food matrices. The extraction efficiency, performance and recoveries of these two procedures were evaluated and compared. In addition, we studied the effect of matrix on signal suppression or enhancement. Isotope-labelled internal standards (ILIS) were used to compensate the suppression or enhancement of signal intensities in the extracted samples. The method was validated using reference soil material (EUROSOIL 7) spiked with 50 μg/kg of each pesticide. The average recovery by PLE varied between 65.1% and 122.2% with RSDs of 1.7–23.4%. QuEChERS provided better recoveries for most of the pesticides, the extraction recovery ranging from 79.4% to 113.3% with RSDs of 1.0–12.2%. Limits of quantification for all target compounds were within a range of 0.1–2.9 µg/kg.     

Review of the QuEChERS method for the analysis of organic pollutants: Persistent organic pollutants,polycyclic aromatic hydrocarbons,and pharmaceuticals

In multi-residue pesticide analysis, the quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method has replaced less efficient traditional extraction methods due to its many advantages. In addition to pesticide analysis, this method has been widely used for the detection and analysis of pharmaceuticals, polycyclic aromatic hydrocarbons (PAHs), and several persistent organic pollutants (POPs), including dioxins, polychlorinated biphenyls, perfluoroalkyl substances, and brominated flame retardants in food, biological, and environmental matrices. The analysis of PAHs and POPs is challenging due to the properties of the target compounds and their low concentrations in complex matrices. This review summarizes previously reported the QuEChERS extraction approaches to the analysis of a wide range of analytes. The QuEChERS approaches, which include dispersive solid phase extraction (d-SPE), have generally been combined with either gas chromatography–mass spectrometry (GC–MS) or liquid chromatography–mass spectrometry (LC–MS) analysis. Further on, in recent years, GC and LC-tandem mass spectrometry has been utilized with the QuEChERS extraction due to its high selectivity, sensitivity, and specificity. This enables the extraction methods for target analytes to be modified through the selection of different extraction solvents, salt formulations, and buffers for salting-out partitioning and the selection of different d-SPE and SPE sorbents for the clean-up process. The most significant advantage of this method is that concentration steps are not required. This review aims to provide an up-to-date overview of information regarding the modification of extraction techniques based on target compounds and sample matrices.     

Determination of Pesticide Residues in Cereals by Liquid Chromatography and UV Detection

Abstract

A chromatographic method to determine pesticide residues in cereals by high-performance liquid chromatography (HPLC) and ultraviolet (UV) detection has been described. The study focused on the preliminary purification procedure because of the analytical problems associated with the presence in these food matrices of high-molecular-weight compounds, such as lipids, triglycerides, celluloses, and starch, which can interfere and reduce the chromatographic separation efficiency of the analytes. The method proposed is based on the extraction of pesticide residues from 5 g of sample extracted with the use of petroleum ether and on cleanup with a C18 cartridge. The pesticides were eluted with acetonitrile. The column packed with solid support was eluted with a suitable solvent, and only a portion of flow outlet side of the UV detector was collected. Using the information of standard UV trace, it was possible to establish an appropriate portion and to ensure the collection of all pesticides analyzed. The simple and rapid proposal method has shown good recovery (70–110%) for different spiked levels of samples (0.025–0.1 mg/Kg) and could be applied to other food matrices that containing high-molecular-weight compounds.     

对比3种不同的QuEChERS前处理方式在气相色谱-串联质谱检测分析烟草中上百种农药残留中的应用

以气相色谱-串联质谱(GC-MS/MS)技术为基础,建立了适合烟草中上百种农药残留分析的3种QuEChERS前处理方法:溶剂转换法、提取液稀释法和正己烷液液萃取法。以烟草中的有机磷、有机氯、拟除虫菊酯类、酰胺类、氨基甲酸酯类、二硝基苯胺类等共155种农药为研究对象,从基质效应、共萃取基质、色谱峰干扰、回收率和定量限等方面对3种前处理方式进行对比分析。经考察发现,3种方法各有优缺点,正己烷液液萃取法得到的提取液中共萃取基质含量最少,但只能保证约100种目标物的回收率在70%~120%;溶剂转换法和提取液稀释法对绝大部分目标物都能保证回收率在70%~120%,适合用于多农药残留分析检测。对不同种类农药进行对比,发现有机磷、酰胺类和氨基甲酸酯类农药的基质效应相对较强,而有机氯和拟除虫菊酯类目标物的基质效应相对较弱,因此,对有机磷农药单独分析时,建议使用提取液稀释法;对有机氯和拟除虫菊酯类农药单独分析时,建议使用正己烷液液萃取法。     

Influence of pH and Matrix Components in the Chromatographic Response of Pesticides

The pH effect of potato, apple, and soil matrices on the chromatographic response of nine pesticides was evaluated. All chromatographic analyses were performed in duplicate on a gas chromatograph with electron capture detection. The matrix effect observed in the chromatographic response of the pesticides was evaluated by comparison. We compared the chromatographic response of each pesticide in pure solvent and in organic extract obtained for the matrices. The organic extracts were obtained by solid–liquid extraction with partition at low temperature. Depending on the matrix pH, a greater or lesser amount of co-extractives can be extracted into the organic phase, which affects the matrix effect. The pH of the samples before the extraction process was modified in order to check their influence on pesticide responses. Statistical analyses involving principal component analysis and marginal means revealed that, in the potato and apple matrices, the co-extractives exerted positive effects on the chromatographic response of the analytes. At lower pH, the extraction of co-extractives from potato and apple was favored, thus increasing the matrix effect for these samples.     

Rapid analysis of multiple pesticide residues in fruit-based baby food using programmed temperature vaporiser injection-low-pressure gas chromatography-high-resolution time-of-flight mass spectrometry

A rapid method using programmed temperature vaporiser injection-low-pressure gas chromatography-high-resolution time-of-flight mass spectrometry (PTV-LP-GC-HR-TOF-MS) for the analysis of multiple pesticide residues in fruit-based baby food was developed. The fast and inexpensive buffered QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction method and "conventional" approach that employs ethyl acetate extraction followed by gel permeation chromatography (GPC) cleanup were employed for sample preparation. A PTV injector in solvent venting mode was used to reduce volume of acetonitrile and acetic acid (from the buffered QuEChERS extracts) that caused higher column bleed without their elimination. Otherwise, the time-to-digital converter would become saturated in HR-TOF-MS. For fast GC separation allowing analysis of 100 analytes within a 7 min runtime, both a high temperature programming rate and vacuum conditions in a megabore GC column were employed. The use of HR-TOF-MS allowed the unbiased identification and reliable quantification of target analytes through the application of a narrow mass window (0.02 Da) for extracting analyte ions and the availability of full spectral information even at very low levels. With only a few exceptions, the lowest calibration levels for the pesticides tested were 相似文献   

Solid-phase microextraction in pesticide residue analysis

The applications of solid-phase microextraction (SPME) for sample preparation in pesticide residue analysis are reviewed in this paper taking into account the different approaches of this technique coupled mainly to gas chromatography but also to high-performance liquid chromatography. A complete revision of the existing literature has been made considering the different applications divided according to the pesticide families (organochlorine, organophosphorus, triazines, thiocarbamates, substituted uracils, urea derivatives and dinitroanilines among others) and the sample matrices analysed which included environmental samples (water and soil), food samples and biological fluids. Details on the analytical characteristics of the procedures described in the reviewed papers are given, and new trends in the applications of SPME in this field are discussed.     

Evaluation of the Effect of Pear Stone Cells on the Recovery of Multi-Class Pesticides

The widespread sample preparation method for the extraction of pesticide residues, the QuEChERS method, sometimes yields different pesticide recovery values for different food matrices. Pear (Pyrus communis L.) is an example of a matrix that can be characterized with somewhat lower pesticide recoveries. In order to investigate the reason for this result, the most characteristic structural feature of pears, the stone cells, possessing a specific surface due to their greater cellulose and lignin contents, were isolated and purified. The isolated stone cells were used for the preparation of a model sample in combination with tomato, a food matrix showing high pesticide recovery values, in a pesticide spiking experiment. Eleven multi-class pesticides were selected for the study where the quantification was carried out with HPLC-ESI-MS/MS. No significant differences were found between the pesticide recoveries obtained from the tomato and the combined tomato-pear stone cells matrices, which indicates the reason behind the lower pesticide recoveries in pear matrices is still to be determined.     

Sorptive extraction of pesticides from food and environmental samples using metal organic framework-based adsorbents

Sorptive pre-concentration of pesticide residues in food and environmental samples is increasingly gaining momentum. This can be attributed to fact that most sorptive extraction techniques are solvent-free as well as the availability of emerging sorbents with relatively high adsorption capacities. Metal organic frameworks (MOFs) are among the emerging sorbents that have captured the interests of many researchers during pesticide analysis. There are many types of MOFs that have been used by researchers to pre-concentrate pesticides in food and environmental samples. Some researchers have successfully used MIL-based MOFs during sorptive extraction of pesticides in complex matrices. This review gives a detailed discussion of their application during pesticide pre-concentration. Other researchers have used the ZIF series of MOFs for the sorptive pre-concentration of pesticides in food and environmental samples. The utilisation of the ZIF series of MOFs during pesticide pre-concentration is well-articulated in this review. The review also devoted to the application of UiO and HKUST series of MOFs during the pre-concentration of pesticides in food and environmental samples. In addition, the challenges associated with the use of MOFs during sorptive pre-concentration of pesticides are also discussed in this review.     

A review of sample preparation methods for the pesticide residue analysis in foods

The pesticide residues in foods have received increasing attention as one of the most important food safety issues. Therefore, more strict regulations on the maximum residue limits (MRLs) for pesticides in foods have been established in many countries and health organizations, based on the sensitive and reliable analysis methods of pesticide residues. However, the analysis of pesticide residues is a continuing challenge mainly because of the small quantities of analytes as well as the large amounts of interfering substances which can be co-extracted with them, often leading to experimental errors and damage to the analytical instruments. Thus, extensive sample preparation is often required for the pesticide residue analysis for the effective extraction of the analytes and removal of the interferences. This paper focuses on reviewing the recent development in the sample preparation methods for the pesticide residue analysis in foods since 2006. The methods include: liquid-liquid extraction (LLE), supercritical-fluid extraction (SFE), pressurized-liquid extraction (PLE), microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), gel permeation chromatography (GPC), solid-phase extraction (SPE), molecularly imprinted polymers (MIPs), matrix solid-phase dispersion (MSPD), solid-phase micro-extraction (SPME), QuEChERS, cloud point extraction (CPE) and liquid phase micro-extraction (LPME), etc. Particularly their advantages, disadvantages and future perspectives will be discussed.     

Evaluation of common organic solvents for gas chromatographic analysis and stability of multiclass pesticide residues

In this study, we evaluated the suitability of six common organic solvents for gas chromatographic (GC) analysis of pesticides. Three of these, acetone, acetonitrile (MeCN) and ethyl acetate (EtAc), represent extraction solvents commonly used in multiresidue methods for determination of pesticides in produce. The other three, isooctane, hexane and toluene, often serve as exchange solvents before a GC analysis. An ideal solvent for GC analysis of multiclass pesticide residues should be compatible with: the analytes, sample preparation, and GC analysis. This study addresses each aspect with emphasis placed on stability of selected pesticides in the given solvents. In this respect, the exchange solvents proved to be superior to the more polar extraction solvents. Degradation of N-trihalomethylthio fungicides (e.g., captan, folpet, dichlofluanid) in MeCN was observed only in certain lots of the tested MeCN, but even if it occurred, the stability of these analytes as well as that of dicofol and chlorothalonil was dramatically improved by the addition of 0.1% (v/v) acetic acid. Dicofol and chlorothalonil were also unstable in acetone, and pesticides with a thioether group (e.g., fenthion, disulfoton) degraded in the tested EtAc. Formation of isomers of certain pyrethroids (deltamethrin, lambda-cyhalothrin) was recorded in the chromatograms from MeCN and acetone solutions, but this effect more likely occurred during the GC injection than in solution. For several reasons, MeCN was found to be the most suitable solvent for extraction of a wide polarity range of pesticide residues from produce. After acidification, the stability of problematic pesticides in MeCN is acceptable, and MeCN can also serve as a medium for GC injection; therefore solvent exchange is generally not required before GC analysis. If sensitivity is an issue in splitless injection, then toluene was demonstrated to be the best exchange solvent due to its miscibility with MeCN and stronger responses of relatively more polar pesticides (e.g., acephate, methamidophos) as compared to hexane and isooctane.     

基于QuEChERS提取方法优化的液相色谱-串联质谱法测定蔬菜中51种氨基甲酸酯类农药残留

采用气相色谱-质谱（GC-MS）全扫描结合NIST谱库检索方法分析6种蔬菜（番茄、青刀豆、大葱、青花菜、姜、胡萝卜）提取液中的基质干扰物,以蒸发残渣重量法探讨乙二胺N-丙基硅烷（PSA）、十八烷基硅烷（C18）及两者组合对6种蔬菜提取液基质干扰物的净化效果及吸附机理,考察了原创QuEChERS方法及AOAC 2007.01方法对蔬菜中51种氨基甲酸酯类农药提取的适用性,并建立了液相色谱-串联质谱法测定蔬菜中51种氨基甲酸酯类农药残留的方法。结果表明,C18与PSA组合进行分散固相萃取的净化效果最好;AOAC 2007.01方法适用于二氧威以外的50种农药残留的提取,而原创QuEChERS方法对二氧威残留的提取可获得满意结果。经电喷雾正离子电离及多反应监测模式来测定目标化合物,采用基质匹配标准溶液曲线法进行定量。结果表明：51种农药在6种基质中3个添加水平（10、20、100 μg/kg）的回收率为58.4%~126%,相对标准偏差为3.3%~26%;以信噪比（S/N）≥10计,久效威及杀螟丹的定量限（LOQ）为50 μg/kg,其他49种农药的LOQ为0.2~10 μg/kg。本文方法有效、灵敏,适用于不同蔬菜基质中51种氨基甲酸酯类农药残留的测定。     

Assessment of priority pesticides,degradation products,and pesticide adjuvants in groundwaters and top soils from agricultural areas of the Ebro river basin

Gas chromatography-mass spectrometry (GC/MS) was employed for the determination of 30 widely used pesticides including various transformation products and alkylphenols in water and agricultural soils with the aim of assessing the impact of these compounds in agricultural soils and the underlying aquifer. The extraction, clean-up, and analytical procedures were optimized for both water and soil samples to provide a highly robust method capable of determining target analytes at the ppb–ppt level with high precision. For water samples, different solid-phase extraction cartridges and conditions were optimized; similarly, pressurized liquid extraction conditions were tested to provide interference-free extracts and high sensitivity. Instrumental LODs of 3–4 pg were obtained. The multi-residue extraction procedures were applied to the analysis of groundwaters and agricultural soils from the Ebro river basin (NE Spain). Most ubiquitous herbicides detected were triazines but some acetanilides and organophosphorus pesticides were also found; the pesticide additive tributylphosphate was found in all water samples. Levels varied between 0.57 and 5.37 μg/L in groundwater, whereas nonylphenol was the sole compound detected in soil. Alkylphenols are used as adjuvants in pesticide formulations and are present in sludges employed as soil fertilizers. Occurrence was found to be similar to other environmental studies.     

A rapid multiresidue method for determination of pesticides in fruits and vegetables by using acetonitrile extraction/partitioning and solid-phase extraction column cleanup

A modification of a rapid and inexpensive multiresidue method for determination of pesticides in fruits and vegetables (QuEChERS method) is presented. Samples were extracted by shaking with acetic acid-acetonitrile (1 + 99). Water was removed by liquid-liquid partitioning with magnesium sulfate and sodium acetate. The extract was subjected to a single solid-phase extraction (SPE) column cleanup, which produced a cleaner extract than did the dispersive SPE cleanup used in the original QuEChERS method. Recovery data were obtained for 316 pesticide residues, at levels ranging from 20 ppb to 1.0 ppm. Data were provided by 3 different laboratories. The modified QuEChERS method resulted in a 65% reduction in solvent usage, when compared with the traditional multiresidue methods previously used in our laboratories.     

Validation of short run time LC-ESI (+) MS/MS method for determination of twenty recommended pesticide residues in food based on QuEChERS extraction technique

Food is expected to contain pesticide residues that might have many problems due to their toxicities for human and animals. So, it is very important to detect and quantify the pesticides contamination levels to increase food safety for the human. The target of our study is to analyse a 20 new pesticides including different pesticide classes such as 1 acaricide, 3 fungicides, 2 plant growth regulators, 11 herbicides, 1 insecticide, 1 rodenticide, and 1 metabolite which were selected according to their modern application in the Egyptian agriculture as well as the recommendation of the Egyptian Agriculture Pesticides Committee (APC). The research is focused on the method validation for the routine analysis of the targeted pesticide residues according to the European SANTE/11,813/2017 guideline. The validation was carried out by fortifying of three levels at 0.01, 0.05 and 0.1 mg/kg in four blank matrices: apple, green beans, fennel seeds and rice which represent different classes of food. The most common citrate buffered QuEChERS extraction method and liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS) device were used. The mass spectrometer was operated in the positive electrospray ionisation ESI (+) mode and the non-scheduled multiple reactions monitoring (MRM) method in a short run time of 16.0 min. The limits of quantifications (LOQs) for all pesticides ranged between 0.01 and 0.05 mg/kg. Good linearity of the method was in the concentration range 0.001–0.5 μg/ml with acceptable correlation coefficients (r²) ≥ 0.99 for all analytes. The average recoveries for all the target pesticide residues were in the range of 70–120% with relative standard deviations RSDs ≤ 20%. The matrix effect was compensated by using the standard addition method. This short run time LC ESI (+) MS/MS Method may help laboratories which deal with the routine pesticide residues analysis in different food samples.     

Pressurized liquid extraction in environmental analysis

A critical evaluation of recent literature utilizing pressurized liquid extraction (PLE) for environmental analysis is presented by compound class. Overall, the extraction efficiency of PLE, using the appropriate solvent, temperature and pressure for extraction, is similar to that of Soxhlet extraction. PLE has been used for some classes of compounds that are thermally labile (e.g., explosives) and may require acidic conditions for extraction (e.g., organometallic compounds). References to recent applications are presented emphasizing studies which utilize unspiked, natural matrices and studies that compare PLE to alternate extraction techniques.     

Supercritical fluid extraction in herbal and natural product studies - a practical review

Due to increasingly stringent environmental regulations, supercritical fluid extraction (SFE) has gained wide acceptance in recent years as an alternative to conventional solvent extraction for separation of organic compounds in many analytical and industrial processes. In the past decade, SFE has been applied successfully to the extraction of a variety of organic compounds from herbs and other plants. This review article presents the practical aspects of SFE applications in sample preparation, selection of modifiers, collection methods, on-line coupling techniques, means for avoiding mechanical problems, and approaches to optimization of SFE conditions. SFE can also be used to clean up pesticides from herb medicines. SFE processes can be modeled to acquire useful information for better understanding of the extraction, mechanisms and optimization of the extraction procedures. With increasing public interest in natural products, SFE may become a standard extraction technique for studying herbal, food and agricultural samples.     

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

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

Flow-Injection Methods in Water Analysis—Recent Developments

Widespread demand for the analysis and control of water quality and supply for human activity and ecosystem sustainability has necessitated the continuous improvement of water analysis methods in terms of their reliability, efficiency, and costs. To satisfy these requirements, flow-injection analysis using different detection methods has successfully been developed in recent decades. This review, based on about 100 original research papers, presents the achievements in this field over the past ten years. Various methodologies for establishing flow-injection measurements are reviewed, together with microfluidics and portable systems. The developed applications mostly concern not only the determination of inorganic analytes but also the speciation analysis of different elements, and the determination of several total indices of water quality. Examples of the determination of organic residues (e.g., pesticides, phenolic compounds, and surfactants) in natural surface waters, seawater, groundwater, and drinking water have also been identified. Usually, changes in the format of manual procedures for flow-injection determination results in the improvement of various operational parameters, such as the limits of detection, the sampling rate, or selectivity in different matrices.