Simultaneous determination of pyrimethanil,cyprodinil, mepanipyrim and its metabolite in fresh and home-processed fruit and vegetables by a QuEChERS method coupled with UPLC-MS/MS

A QuEChERS procedure for the simultaneous determination of pyrimethanil, cyprodinil, mepanipyrim and its metabolite (M31) in fresh and processed fruit and vegetables was developed using ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). The determination of the four target compounds was achieved in less than 6.0 min using an electrospray ionisation source in positive mode. The limits of detection (LODs) were below 0.4 μg?kg^?1, while the limits of quantification (LOQs) did not exceed 1.5 μg?kg^?1 for all studied matrices. Good linearity of the calibration curves was obtained over the range from 0.002 to 2 mg?kg^?1, with correlation coefficients higher than 0.999. The average recoveries of this method in apple, peach, cabbage and tomato at the five spiked levels (0.002, 0.01, 0.05, 0.20 and 2.0 mg?kg^?1) ranged from 81.5% to 107.3% with relative standard deviations (RSDs) in the range of 1.5–13.9% (n = 5) for all analytes. Residue levels of anilinopyrimidine fungicides in fresh and home-processed apple, peach, cabbage and tomato were also studied. The results indicate that residue levels are significantly reduced following washing, peeling and boiling, and there is no toxic metabolite of mepanipyrim (M31) which is detected during boiling. This study provides a theoretical basis for China to draw up maximum residue limits (MRLs) and protect consumers from the negative health effects of pesticide residues detected in fruit and vegetables.     

A novel method for the simultaneous determination of 14 sweeteners of regulatory interest using UHPLC-MS/MS

An improved, efficient, sensitive method for the determination of 14 non-nutritive sweeteners in food products was developed using electrospray ionisation (ESI) ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in the negative-ion mode. Fourteen sweeteners and three internal standards were separated on a reversed-phase UHPLC column using a simple gradient programme. Analyte quantitation and confirmation were performed with data collection in multiple reaction monitoring (MRM) mode. Limits of detection (LODs) were determined in a representative drink, candy and yogurt sample and ranged from 0.1 to 1.8 ng ml^–1 (drinks) and from 0.1 to 2.5 ng g^–1 (candy and yogurt). Repeatability at the limit of quantitation (LOQ) ranged from 1% to 13% relative standard deviation (RSD). Twenty-seven commercially available food products were tested using the optimised method showing that the majority of products contained sweetener concentrations below their assigned maximum usable dose. Recovery studies were performed and accuracy data are presented.     

Development and validation of an UHPLC-MS/MS method for the determination of mycotoxins in grass silages

An ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) multi-mycotoxin analytical method was developed to simultaneously identify and quantify 20 mycotoxins in grass silages, inclusive of mycotoxins that are currently regulated in European Union feeds. Extraction of mycotoxins from dried grass silages was performed using of a modified QuEChERS extraction employing an acidified aqueous extraction (0.1 N HCl) with no further clean-up. Following chromatographic separation, analytes were detected using a fast polarity-switching MS/MS method that allowed both positive and negative ions to be analysed from a single injection, thus the reducing time and cost of analysis. The limits of detection and quantification ranged between 3 µg kg^–1 DM (aflatoxin B₁, beauvericin and enniatin A and A₁) and 200 µg kg^–1 DM (deoxynivalenol), and between 10 µg kg^–1 DM (aflatoxin B₁, beauvericin and enniatin A₁) and 500 µg kg^–1 DM (deoxynivalenol), respectively. Inter-assay accuracy and precision ranged between 90% and 107% and between 3.9% and 15.0% CV, respectively. The accuracy of the method was assessed through the application to a range of incurred samples in an inter-laboratory study.     

Detection and quantification of 47 antibiotic residues in farmed European sea bass (Dicentrarchus labrax) using a multi-class and multi-residue UHPLC-MS/MS method

In the present study, a multi-class multi-residue method for the simultaneous detection and determination of antibiotics in European sea bass (Dicentrarchus labrax) was developed and validated. The method based on UHPLC-MS/MS proved to be a rapid, highly selective and sensitive tool, requiring minimum sample preparation, for screening and detection of 47 compounds from eight different classes. The validation was performed according to EU regulation 2002/657/EC, proving the method’s suitability for application in routine analysis. The method was applied to the analysis of 30 samples of farmed European sea bass purchased in different supermarkets in Portugal. Antibacterial residues were detected in 6 of the 30 analysed samples, namely enrofloxacin and oxytetracycline, in concentrations ranging from 0.1 to 12 µg kg^?1.     

Method validation and analysis of nine dithiocarbamates in fruits and vegetables by LC-MS/MS

An analytical method for separation and quantitative determination of nine dithiocarbamates (DTCs) in fruits and vegetables by using LC-MS/MS was developed, validated and applied to samples purchased in local supermarkets. The nine DTCs were ziram, ferbam, thiram, maneb, zineb, nabam, metiram, mancozeb and propineb. Validation parameters of mean recovery for two matrices at two concentration levels, relative repeatability (RSD_r), relative within-laboratory reproducibility (RSD_R) and LOD were obtained for the nine DTCs. The results from the analysis of fruits and vegetables served as the basis for an exposure assessment within the given commodities and a risk assessment by comparing the calculated exposure to the acceptable daily intake and acute reference dose for various exposure groups. The analysis indicated positive findings of DTCs in apples, pears, plums, table grapes, papaya and broccoli at concentrations ranging from 0.03 mg/kg to 2.69 mg/kg expressed as the equivalent amount of CS₂. None of the values exceeded the Maximum residue level (MRL) set by the European Union, and furthermore, it was not possible to state whether illegal use had taken place or not, because a clear differentiation between the various DTCs in the LC-MS/MS analysis was lacking. The exposure and risk assessment showed that only for maneb in the case of apples and apple juice, the acute reference dose was exceeded for infants in the United Kingdom and for children in Germany, respectively.     

气相色谱-串联质谱法同时测定肉制品中氯霉素、甲砜霉素残留

建立了肉制品中氯霉素、甲砜霉素的气相色谱串联质谱检测方法。样品经均质后,用乙酸乙酯提取,正己烷脱脂,弗罗里硅土小柱净化,衍生后用气相色谱串联质谱法检测,内标法定量。优化了二级质谱条件,包括离子对及碰撞电压。该方法检出限为氯霉素(CAP)0.02μg/kg,甲砜霉素(TAP)0.1μg/kg,加标回收率均在86%~97%之间,相对标准偏差(RSD)在3.8%~12.3%之间,在0.1~20 ng/mL范围内都呈现出良好线性关系。     

Rapid multi-residue and multi-class qualitative screening for veterinary drugs in foods of animal origin by UHPLC-MS/MS

Multi-class UHPLC-MS/MS was developed for the analysis of more than 160 regulated or banned compounds of various classes: anthelmintics including benzimidazoles, avermectins and others; antibiotics including amphenicols, beta-lactams, macrolides, pyrimidines, quinolones, sulphonamides and tetracyclines; beta-agonists; corticosteroids; ionophores; nitroimidazoles; non-steroidal anti-inflammatory agents; steroids; and tranquillisers. Samples were extracted with acetonitrile, without any additional purification step, and analysed by using UHPLC-MS/MS. Validation was done in accordance with the guidelines laid down by European Commission Decision 2002/657/EC for qualitative screening methods. This simple method proved applicable to routine screening for residues in egg, honey, milk and muscle samples at half the maximum concentration permitted by the European Union for each drug. In most cases, the target value was set at 5?µg?kg^?1 for unauthorised compounds.     

Simultaneous determination of nine acaricides and two metabolites in comb honey by LC/MS/MS

ABSTRACT

We developed a method for the simultaneous determination of acaricides in comb honey using LC/MS/MS. Because methods for honey analysis had not previously been applied to comb honey, we modified three techniques for sample preparation and LC/MS/MS conditions. First, we used a modified QuEChERS method that changed the extraction solution from ethyl acetate to acetonitrile. Second, we replaced the InertSep® MA-1 (30 mg, 1 ml) clean-up cartridge with an Oasis® HLB (60 mg, 3 ml). Third, we changed the ionisation mode from ESI to atmospheric pressure chemical ionisation (APCI). With these modifications, sample matrices had no effect on the identification and quantification of analytes, using an external solvent calibration curve. We verified this new method with nine acaricides and two metabolites on comb honey and honey samples from three different honey origins. The trueness ranged from 74.0 to 99.4%. The relative standard deviation of repeatability (RSD_r) ranged from 0.8 to 14.8% and that of within-laboratory reproducibility (RSD_WR) ranged from 1.3 to 14.8%. All criteria met Japanese validation guidelines. The LOQ was 1.0 μg kg^–1 for all analytes. We applied this method to 10 comb honey and 31 honey samples commercially available in Tokyo. From the results of the analysis of 41 samples, we observed that amitraz remained as N-(2,4-dimethylphenyl)-N-methylformamidine (DMPF) in 9 comb honey and 23 honey samples and that their residual concentrations were less than 20 μg kg^–1. Using this new method, we improved recovery and precision, which enabled precise quantitative determination. Furthermore, the residual amitraz value in honey determined by both this new and the previous method were in good agreement.     

Simultaneous determination of cyromazine and dicyclanil in animal edible tissues using UPLC-MS/MS

Cyromazine and dicyclanil are both used as insect growth regulators. This paper describes an easy and innovative simultaneous extraction method for residues of cyromazine and dicyclanil in food of animal origin, and a confirmation procedure using UHPLC-MS/MS. The sample was extracted, deproteinised by 1% trichloracetic acid in water-acetonitrile, followed by selective defatting using hexane based on the degree of matrix complexity; cleaned-up on an mixed-mode cation exchange (MCX) cartridge; and quantified by using matrix-matched calibration. The mean recoveries were all between 62.0% and 99.2%, and the RSDs were all below 9.94%. The present method was rapid, sensitive and reliable, which was applied to the quantitative analysis of these residues in animal tissues.     

HPLC-MS联用测定果冻等食品中的3种甜味剂和苯甲酸

建立食品中糖精钠、甜蜜素、安赛蜜和苯甲酸的高效液相色谱-质谱（HPLC-MS）检测方法。色谱柱为Spherigel C18（5μm,4．6×200Mm）,流动相为：（A）甲醇-（B）甲酸-三乙胺缓冲盐,梯度洗脱;电喷雾负离子（ESI^-）采集模式,流速为1．0mL／min,进样量为10μL;以华法林钠为内标,质谱定性定量;安赛蜜、糖精钠、甜蜜素、苯甲酸的线性范围分别为：5．4～135,5．4～135,7．4～111,10～150μg／mL,加样回收率为93．19％～100．90％,RSD为1．05％～2．04％．该方法具有选择性好、分析时间短、定性定量准确等优点,可用于果冻等食品中的4种目标物定性定量检测。     

Routine approach to qualitatively screening 300 pesticides and quantification of those frequently detected in fruit and vegetables using liquid chromatography tandem mass spectrometry (LC-MS/MS)

This paper describes an efficient and effective analytical scheme to first screen for 300 pesticides in fruit and vegetables samples using liquid chromatography tandem mass spectrometry (LC-MS/MS) with a commercially enhanced product ion method. Then presumed positive extracts are analysed using a quantitative and confirmatory LC-MS/MS method optimized for 55 pesticides. A quick, easy, cheap, effective, rugged, and safe (QuEChERS) method with acetate buffering (AOAC Official Method 2007.01) was used for sample preparation, which has been previously shown to yield high-quality results for hundreds of pesticide residues in foods. The advantages and disadvantages of both the qualitative screening and quantitative/confirmatory methods and their combination are critically discussed. No false-negatives for the 55 pesticides occurred above 10 ng g^?1 for extracts analysed by both LC-MS/MS methods, and the no false-positives were encountered from the screening analysis (after analyst review) because all presumptive identifications were confirmed in the second analysis. The monitoring scheme was applied during a one-year period on 200 fruit and vegetable samples from Hungarian markets. No pesticide residues were found in half the samples, and twelve violations of European maximum residue limits were detected.     

UNE-EN ISO/IEC 17025:2005-accredited method for the determination of pesticide residues in fruit and vegetable samples by LC-MS/MS

A rapid, simple and sensitive multi-residue method was developed and validated for the simultaneous quantification and confirmation of 69 pesticides in fruit and vegetables using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted following the quick, easy, cheap, effective, rugged and safe method known as QuEChERS. Mass spectrometric conditions were individually optimised for each analyte in order to achieve maximum sensitivity in multiple reaction monitoring (MRM) mode. Using the developed chromatographic conditions, 69 pesticides can be separated in less than 17 min. Two selected reaction monitoring (SRM) assays were used for each pesticide to obtain simultaneous quantification and identification in one run. With this method in SRM mode, more than 150 pesticides can be analysed and quantified, but their confirmation is not possible in all cases according to the European regulations on pesticide residues. Nine common representative matrices (zucchini, melon, cucumber, watermelon, tomato, garlic, eggplant, lettuce and pepper) were selected to investigate the effect of different matrices on recovery and precision. Mean recoveries ranged from 70% to 120%, with relative standard deviations (RSDs) lower than 20% for all the pesticides. The proposed method was applied to the analysis of more than 2000 vegetable samples from the extensive greenhouse cultivation in the province of Almería, Spain, during one year. The methodology combines the advantages of both QuEChERS and LC-MS/MS producing a very rapid, sensitive, accurate and reliable procedure that can be applied in routine analytical laboratories. The method was validated and accredited according to UNE-EN-ISO/IEC 17025:2005 international standard (accreditation number 278/LE1027).     

Simultaneous determination of three pesticides and their metabolites in unprocessed foods using ultraperformance liquid chromatography-tandem mass spectrometry

We have developed a rapid, multi-compound analytical method for measuring residues of the pesticides thiamethoxam and its metabolite, clothianidin; fipronil and its three metabolites, fipronil sulfone, fipronil sulfide, and fipronil desulfinyl; and pyraclostrobin in unprocessed foods (rice, corn, cucumbers, tomatoes, apples, and bananas) by ultra-performance liquid chromatography coupled to tandem mass spectrometry. Acetonitrile was used as the extraction solvent, and an octadecylsilane-dispersive SPE was used to clean up the analytes, which were then separated through a UPLC HSS T3 column connected to a tandem mass spectrometer via an electrospray ionisation source. The linearity of this method for the target analytes was excellent (R² ≥0.990) in the concentration range of 5–1000 μg kg^–1. The average recoveries of the seven compounds at concentrations of 10, 100, and 1000 μg kg^–1 from six spiked matrix samples ranged from 73.6 to 110.6%, all with RSD values of ≤19.7%. The limit of quantification was 10 μg kg^–1. The method validated the effectiveness of the method for routine monitoring the residue of these pesticides and their metabolites in foods.     

果蔬脯水分活度降低剂选择研究

对低糖果蔬脯水分活度降低剂进行了选择研究。试验结果表明,降低水分活度的能力大小为:柠檬酸>磷酸二氢钠>氯化钠;丙二醇>丙三醇;琼脂>卡拉胶>明胶。复合水分活度降低剂比单一的降低Aw的能力强。     

SPE-LC/MS/MS法同时测定烟叶中5种新烟碱类杀虫剂残留

通过比较硅胶柱、石墨化碳柱、C18柱和聚合物柱对分析物的保留能力,建立了20％甲醇水溶液超声萃取、Pesticarb石墨化碳柱固相萃取、LC-MS/MS同时测定烟叶中5种新烟碱类杀虫剂“烯啶虫胺”、“噻虫嗪”、“吡虫啉”、“啶虫咪”和“噻虫啉”残留的方法.结果表明,方法的检测限为0.005～0.009 μg/mL,平均回收率为80％～92％,RSD为2.50％ ～ 4.08％.该方法适用于烟叶中这5种新烟碱类杀虫剂残留的快速检测.     

Rapid multiresidue determination of pesticides in livestock muscle and liver tissue via modified QuEChERS sample preparation and LC-MS/MS

ABSTRACT

Many multiresidue methods for the determination of pesticides in vegetables and fruits have been reported to date. However, few such methods have been employed to investigate pesticide residues in animal tissue. In this study, an LC-MS/MS multiresidue method coupled with modified QuEChERS extraction was developed and validated for the investigation of eight pesticide residues: prallethrin (PR), resmethrin (RMT), imidacloprid (IMC), diflubenzuron (DFB), cyromazine (CYR), etofenprox (EFP), dinotefuran (DNT) and phthalthrin (PTLT). This method involves initial extraction in a water/acetone system, the addition of salts and a subsequent extraction/partitioning step and, finally, a clean-up step utilising dispersive solid-phase extraction (SPE). The mean recoveries of seven of the pesticides (the exception being CYR) ranged between 74.7% and 113.5%, and the CVs of the livestock tissue – bovine, swine, and chicken muscle and liver tissue spiked at 10 ng g^–1 (50 ng g^–1 for RMT and DNT) and 100 ng g^–1 – were < 13.8%. The recoveries of CYR in all muscle and liver spiked samples ranged from 56.9% to 78.3%, while those of RMT in swine liver were > 120%. Therefore, this method was considered as being unsuitable for the investigation of these samples. The limits of quantitation (LOQs) of seven of the investigated pesticides (the exception being swine liver) in the tissue samples ranged from 0.9 to 15.2 ng g^–1. We therefore concluded that this LC-MS/MS multiresidue method is a valid and suitable for the investigation of seven pesticides in animal tissue, but it is unsuitable for the analysis of CYR in all animal tissues and RMT in swine liver tissue.     

果蔬中二甲戊乐灵、氟乐灵、双丁乐灵残留测定

采用基质分散固相萃取(MSPD)为样品前处理方法,建立气相色谱-串联四极杆质谱快速检测蔬菜、水果中二甲戊乐灵、氟乐灵、双丁乐灵残留分析方法。果蔬类样品经乙腈提取,乙二胺-N-丙级甲烷(PSA)分散固相(DSPE)净化后,应用气相色谱/四级杆质谱仪多离子反应监测(MRM)定量检测。结果表明,在0.005 mg/kg～0.2 mg/kg添加水平内二甲戊乐灵、氟乐灵、双丁乐灵的平均添加回收率在78.5%～109.3%之间,相对标准偏差不大于8.8%。     

Evaluation of an analytical methodology using QuEChERS and GC-SQ/MS for the investigation of the level of pesticide residues in Brazilian melons

A multiresidue method based on the sample preparation by modified QuEChERS and detection by gas chromatography coupled to single quadruple mass spectrometers (GC-SQ/MS) was used for the analysis of 35 multiclass pesticides in melons (Cucumis melo inodorus) produced in Ceara-Brazil. The rates of recovery for pesticides studied were satisfactory (except for the etridiazole), ranging from 85% to 117% with a relative standard deviation (RSD) of less than 15%, at concentrations between 0.05 and 0.20 mg kg⁻¹. The limit of quantification (LOQ) for most compounds was below the MRLs established in Brazil. The combined relative uncertainty (Uc) and expanded uncertainty (Ue) was determined using repeatability, recovery and calibration curves data for each pesticide. Analysis of commercial melons samples revealed the presence of pesticides bifenthrin and imazalil at levels below the MRLs established by ANVISA, EU and USEPA.     

LC/MS/MS detection of fungicide guazatine residues for quality assessment of commercial citrus fruit

An analytical protocol was developed for investigating guazatine occurrence in citrus fruit with the aim of controlling the import of treated fruits in countries where the use of this fungicide is forbidden. The main constituents of guazatine mixture (GN, GG, GNG, GGN, GGG, GGGN and GGGG) and the internal standard (dodine) were separated by high performance liquid chromatography using a hydrophilic end-capped Aquasil C₁₈ column and detected by ESI/MS/MS of parent ions, operating in positive mode. Extraction from citrus peels was performed with 1% HCOOH in water/acetone (1:2 v/v). The analytical method was statistically validated on three of the main constituents (GG, GGN and GGG) representing more than 65% of the total content. The regression lines, ranging from 0.100 to 3.750 mg/L of total guazatine, showed r ² > 0.990. Recoveries of about 81, 90 and 104% were obtained on average for the fortification level of 0.010, 0.035 and 0.060 mg/kg, respectively; the relative standard deviations ranged from 2 to 8% (n = 6). The limit of detection was below 0.0050 mg/kg, while the limit of quantification did not exceed 0.0065 mg/kg. The method was successfully applied to 77 samples of extra-European citrus fruit collected in the Italian market during the summer 2007. The results demonstrated that 64% of the investigated citrus samples contained guazatine over the residue limit value of 0.010 mg/kg for not allowed pesticides, evidencing the alarming illicit employ of this fungicide in citrus post-harvest treatments.