Analysis of thiabendazole and procymidone in fruits and vegetables by capillary electrophoresis-electrospray mass spectrometry

A capillary electrophoresis-mass spectrometry method for determining procymidone and thiabendazole in apples, grapes, oranges, pears, strawberries and tomatoes is described. Separation is achieved using a buffer of formic acid-ammonium formate at pH 3.5 with 2% of methanol. Fungicide residues present in the sample are preconcentrated by both solid-phase extraction and injection of large sample volumes into the capillary by a stacking technique, to obtain lower detection limits. Ionization is performed at atmospheric pressure in an electrospray type source and detection is carried out using positive ionization and selected ion monitoring modes. The quantitation limits are 0.005 and 0.05 mg kg(-1), and the mean recoveries are 64 and 75% for thiabendazole and procymidone, respectively, with relative standard deviations below 12% (n=5). Real fruit and vegetable samples are analyzed by the proposed method showing that residues of both fungicides are frequently present.     

Trace analysis of dithiocarbamate fungicide residues on fruits and vegetables by hydrophilic interaction liquid chromatography/tandem mass spectrometry

The simultaneous determination of dithiocarbamate (DTC) fungicide residues on fruits and vegetables was performed by liquid chromatography (LC) on a ZIC-pHILIC column coupled to tandem mass spectrometry (MS/MS). For each DTC subclass, i.e. dimethyldithiocarbamates (DMDs), ethylenebis(dithiocarbamates) (EBDs), and propylenebis(dithiocarbamates) (PBDs), the limits of detection and quantification were approximately 0.001 and 0.005 mg kg(-1), respectively. Recoveries from tomatoes, spiked in the range of 0.05-1 mg kg(-1), averaged between 97 and 101%. Several fruits and vegetables from a local market and different countries of origin (apples, pears, grapes, cherry tomatoes, cocktail tomatoes, cucumbers, tomatoes, tamarillos, papaya, and broccoli) were analyzed by LC/MS/MS, LC/MS, and by the routine CS(2) method. In general, the results obtained by both LC/MS and LC/MS/MS were in good agreement with those obtained by the CS(2) method except for the false positive CS(2) results for broccoli and papaya. The results demonstrate that both LC/MS and LC/MS/MS can be used for routine analyses of DTC residues, whereas LC/MS/MS is more sensitive and selective than LC/MS.     

Development and validation of a routine multiresidue method for determining 140 pesticides in fruits and vegetables by gas chromatography/tandem quadrupole mass spectrometry

A GC/tandem quadrupole MS/MS method was developed and validated for the determination of the residues of 140 pesticides in fruits and vegetables. Pesticides were extracted from samples by using a miniaturized acetonitrile-based extraction technique known as the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. Validation studies were carried out on carrots, tomatoes, and strawberries. In order to reduce systematic errors due to a matrix-induced effect, quantification was carried out using matrix-matched standard calibration curves. The recovery and precision results satisfied the European Union criteria (i.e., average recoveries were in the range 70-120% with RSDs < or = 20%) for 125 of the 140 pesticides at a spiking level of 0.01 mg/kg. At the higher spiking levels, there were just two instances of overall average recovery < 70% (chlorothalonil and captan). The measurement uncertainty was estimated following a "top down" approach as being 21 and 35%, on average, based on validation and ongoing recovery data, respectively (coverage factor k = 2, confidence level 95%). Practical application to 541 samples of apples, tomatoes, strawberries, cucumbers, currants, mushrooms, carrots, peppers, pears, onions, and gooseberries under strict QC conditions demonstrated the ruggedness of the total procedure.     

液相色谱-串联质谱法测定蔬菜和水果中硝苯菌酯的残留量

建立了一种通过检测硝苯菌酯(2,4-dinitro-6-(1-methylheptyl) phenyl crotonate, 2,4-DNOPC)相应的水解产物2,4-二硝基-6-(1-甲基庚基)苯酚(2,4-dinitro-6-(1-methylheptyl) phenol, 2,4-DNOP)来测定蔬菜和水果中2,4-DNOPC残留量的液相色谱-电喷雾串联质谱(LC-ESI-MS/MS)检测方法。蔬菜和水果样品用丙酮-甲醇-盐酸的混合液进行液-液分配提取,在碱性条件下超声水解后再进行液-液分配提取,然后进行LC-MS/MS测定。2,4-DNOPC在6种蔬菜和水果中的回收率试验结果表明,2,4-DNOPC在甘蓝中的添加回收率为89.7%～93.3%,相对标准偏差(RSD)为6.3%～8.5%;在黄瓜中的添加回收率为87.7%～95.1%, RSD为5.8%～10.4%;在番茄中的添加回收率为89.3%～96.0%, RSD为6.8%～9.2%;在苹果中的添加回收率为92.0%～98.3%, RSD为5.1%～10.3%;在梨中的添加回收率为89.0%～95.0%, RSD为5.3%～10.2%;在葡萄中的添加回收率为81.2%～95.8%, RSD为5.8%～10.4%。2,4-DNOPC在6种蔬菜和水果的最低检测浓度均为0.01 mg/kg。该检测方法样品前处理简单、快速,分析时间短,灵敏度、准确度和精密度均符合农药残留检测要求,适用于蔬菜和水果中硝苯菌酯残留量的检测。     

Determination of chlorantraniliprole residues in crops by liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry/mass spectrometry

An analytical method is presented for the determination of chlorantraniliprole residues in crops. Chlorantraniliprole residues were extracted from crop matrixes with acetonitrile after a water soak. The extracts were passed through a strong anion-exchange (SAX) SPE cartridge stacked on top of a reversed-phase (RP) polymer cartridge. After both cartridges were rinsed and vacuum-dried, the SAX cartridge was removed, and chlorantraniliprole was eluted from the RP polymer cartridge with acetonitrile. The acetonitrile eluate was evaporated to dryness, reconstituted, and analyzed using an LC/MS/MS instrument equipped with an atmospheric pressure chemical ionization source. The method was successfully validated at 0.010, 0.10, and 10 mg/kg for the following crop matrixes: potatoes, sugar beets (tops), lettuce, broccoli, soybeans, soybean forage, tomatoes, cucumbers, oranges, apples, pears, peaches, almonds (nutmeat), rice grain, wheat grain, wheat hay, corn stover, alfalfa forage, cottonseed, grapes, and corn grain. The average recoveries from all crop samples fortified at the method LOQ ranged from 91 to 108%, with an overall average recovery of 97%. The average recoveries from all crop samples fortified at 10 times the method LOQ ranged from 89 to 115%, with an overall average recovery of 101%. For all of the fortified control samples analyzed in this study, the overall average recovery was 99%.     

Multi-residue determination of plant growth regulators in apples and tomatoes by liquid chromatography/tandem mass spectrometry

A sensitive and rapid multi-residue analytical method for plant growth regulators (PGRs) (i.e., chlormequat, mepiquat, paclobutrazol, uniconazole, ethephon and flumetralin) in apples and tomatoes was developed using high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). A homogenised sample was extracted with a mixture of methanol/water (90:10, v/v) and adjusted to pH <3 with formic acid. Primary secondary amine (PSA) adsorbent was used to clean up the sample. The determination was performed using electrospray ionisation (ESI) and a triple quadrupole (QqQ) analyser. Under the optimised method, the results showed that, except for ethephon, the recoveries were 81.8-98.1% in apples and tomatoes at the spiked concentrations of 0.005 to 2 mg/kg, with relative standard deviations (RSDs) of less than 11.7%. The limits of quantification (LOQs) were lower than their maximum residue limits (MRLs). The procedure was concluded as a practical method to determine the PGR residues in fruit and vegetables and is also suitable for the simultaneous analysis of the amounts of samples for routine monitoring. The analytical method described herein demonstrates a strong potential for its application in the field of PGR multi-residue analysis to help assure food safety.     

Study on pesticide residues in apples,apple-based baby food,and their behaviour during processing using fast GC–MS multiresidue analysis

Food-processing experiments using apples were conducted to obtain more knowledge on the behaviour of pesticides during apple-based baby-food production. The residues were determined in raw material (apples), in intermediate products at different steps of the processing procedure (baby food production) and in final products (apple purée) using a rapid GC–MS method in combination with two different sample-preparation approaches. During 2 years of a monitoring programme, 84 analyses of apple samples and 102 of baby food sample apple purée intermediate and final product samples from baby food production were performed. A pesticide-residue search revealed that residues in fresh apples do not exceed the maximum residue limit for the adult population, but there were some positive findings concerning apples as baby food. The maximal pesticide concentration (fluquinconazole) found in apples was 0.099?mg?kg^?1. In the processed apple-based baby food the concentration of pesticide residues were mostly below 0.010?mg?kg^?1.     

Analysis of Phosmet and Azinphos-Methyl in Apples by High-Performance Liquid Chromatography

Abstract

A high-performance liquid chromatography (HPLC) method has been developed to analyze two organophosphate insecticides (phosmet and azinphosmethyl) in apples. The procedure includes a novel extraction whereby whole apples are sonicated for 2 min in 100 ml of MeOH to remove the pesticides. Reversed-phase HPLC separation was accomplished with an Ultremex C18 column and acetonitrile:methanol:water as the eluent. Detection was at 224 nm for phosmet and 300 nm for azinphos-methyl. For both pesticides the limit of detection was 0.5 ppb and the linearity was from 1 to 405 ng injected. Average recoveries were 80% for phosmet and 86% for azinphos-methyl. Thirteen apple varieties comprising 240 apples were analyzed from supermarkets and roadside stands for phosmet (amount found ranged from none detected to 1233 ppb) and azinphos-methyl (amount found ranged from none detected to 388 ppb). Confirmation of phosmet and azinphos-methyl was made by UV spectral scans.     

Ethylene production from fruits measured by a simple field-effect structure and compared with a gas chromatographic method

The determination of ethylene from various fruits by a PtTMOSFET (platinum thin metal film-oxide-semiconductor field-effect transistor) is described. The limit of detection of ethylene is about 1 ppm (v/v); the selectivity and response characteristics of the sensor are discussed. Ethylene production from tomatoes, green apples and bananas was followed both with the sensor and with a gas chromatograph. Data obtained from the two methods correlated well. The applicability of the PtTMOSFET in practical measurements is discussed.     

High-performance liquid chromatography and capillary supercritical-fluid chromatography separation of vegetable carotenoids and carotenoid isomers

Carotenoids from carrots and tomatoes were separated with high-performance liquid chromatography (HPLC) and capillary supercritical fluid chromatography (SFC). All trans alpha- and beta-carotene were separated from their respective cis-isomers with capillary SFC. Carotenoids extracted from tomatoes included xanthophyll, lycopene and beta-carotene, while alpha- and beta-carotene were extracted from carrots. The HPLC separations were accomplished isocratically with a 25-cm column containing 5-microns ODS and methanol-acetonitrile-chloroform (47:47:6) or acetonitrile-dichloromethane (80:20). beta-Carotene cis-isomers were separated with SFC with a SB-cyanopropyl-25-polymethylsiloxane column, while alpha-carotene isomers were separated with two SB-cyanopropyl-50-polymethylsiloxane columns. Carotenoids from carrots and tomatoes were separated with a SB-phenyl-50-polymethylsiloxane column. Carbon dioxide with 1% ethanol was the SFC mobile phase. The eluent was monitored at 461 nm for HPLC and either 453 or 461 nm for SFC.