Determination of pyrethroid pesticide residues in processed fruits and vegetables by gas chromatography with electron capture and mass spectrometric detection

A gas chromatographic method was developed for the simultaneous determination of 12 pyrethroids (tefluthrin, bifenthrin, fenpropathrin, cyhalothrin, permethrin, cyfluthrin, cypermethrin, alpha-cypermethrin, flucythrinate, fenvalerate, fluvalinate, and deltamethrin) in tomato puree, peach nectar, orange juice, and canned peas. A miniaturized extraction-partition procedure requiring small amounts of nonchlorinated solvents is used. Samples are extracted with acetone, partitioned with ethyl acetate-cyclohexane (50 + 50, v/v), and cleaned up on a Florisil cartridge. The final extract is analyzed by gas chromatography with both electron capture and mass spectrometric detection modes. Studies at fortification levels of 0.010-0.100 mg/kg gave mean recoveries ranging from 70.2 to 96.0% and coefficients of variation between 4.0 and 13.9% for all compounds. Quantitation limits were < 0.010 mg/kg for electron capture detection.     

Multiresidue determination of pesticides in honey by matrix solid-phase dispersion and gas chromatography with electron-capture detection

A multiresidue method was developed for the determination of 15 pesticides (organochlorines, organophosphorus compounds, pyrethroids, and other acaricides) in various commercial honeys (eucalyptus, lavender, orange, rosemary, and multifloral). The analytical procedure is based on the matrix solid-phase dispersion of honey in a mixture of Florisil and anhydrous sodium sulfate; the mixture is placed in small plastic columns and extracted with hexane-ethyl acetate (90 + 10, v/v). The pesticide residues are determined by capillary gas chromatography with electron-capture detection. Recoveries with the method at concentrations between 0.15 and 1.5 microg/g ranged from 80 to 113%, and relative standard deviations were <10% for all the pesticides studied. The pesticide detection limits were within the range 0.5-5 microg/kg for organochlorines, around 3 microg/kg for the chlorinated organophosphorus pesticides studied, near 15 microg/kg for fluvalinate, and about 3 microg/kg for the other pyrethroids.     

气相色谱-质谱法测定植物源性食品中残留的联苯菊酯

建立了气相色谱-质谱检测8种植物源性食品中联苯菊酯残留量的方法。粮谷类样品采用乙腈提取、凝胶渗透色谱（GPC）结合Florisil固相萃取柱净化;蔬菜类样品采用乙酸乙酯提取、Florisil固相萃取柱净化,然后采用气相色谱-质谱测定,选择离子监测模式检测。方法的检出限为5 μg/kg（S/N=10）;在0.005～0.5 mg/L范围内呈现良好的线性关系,相关系数为0.9999;在0.005,0.04和0.1 mg/kg 3个添加水平下,联苯菊酯的添加回收率在74%～99%之间,相对标准偏差(RSD)小于13%。该方法灵敏度高,净化效果良好,能有效地消除复杂基质带来的干扰,可以作为日常样品中联苯菊酯残留量的检测和确证方法。     

高效液相色谱法同时测定大豆中12种酰胺类除草剂的残留量

建立了大豆中12种酰胺类除草剂多残留量同时检测的高效液相色谱方法。样品经丙酮提取、弗罗里硅土柱净化后,用高效液相色谱-二极管阵列检测器检测。在0.05～1.0 mg/kg的添加水平范围内,12种酰胺类药物的回收率为75%～102%,相对标准偏差为1.9%～16.1%；12种酰胺类除草剂的测定低限均能达到国家相关的残留限量要求。对样品的前处理条件进行了研究和优化,经商品化的固相萃取柱净化过的样品干扰杂质较少,有利于后续的检测分析和方法的推广应用。该方法能够在35 min内完成一次分析,具有快速、灵敏、准确、可靠的特点。     

Supercritical fluid extraction of macrocyclic lactone mycotoxins in maize flour samples for rapid amperometric screening and alternative liquid chromatographic method for confirmation

A rapid and simple method for the direct screening of macrocyclic lactone mycotoxins (zearalenone, ZON; alpha-zearalenol, alpha-ZOL; and beta-zearalenol, beta-ZOL) in maize flour samples is proposed. The sample screening method comprises supercritical fluid extraction (SFE) and clean-up on Florisil adsorption cartridge of the selected toxic compounds, followed by continuous flow electrochemical detection. Those samples for which the total concentration is close to or above the threshold limit established by legislation (0.200 mg kg(-1)) are subjected to preconcentration on C18 chromatographic material and liquid chromatographic separation for confirmation purposes. This confirmation method allows the determination of ZON, alpha-ZOL and beta-ZOL in the range between 30 and 300 microg kg(-1), with a average relative standard deviation lower than 5.2 in all cases.     

Rapid determination of acrylamide contaminant in conventional fried foods by gas chromatography with electron capture detector

Gas chromatography coupled with electron capture detector (GC-ECD) was successfully developed and applied for the rapid determination of acrylamide in conventional fried foods, such as potato crisps, potato chips, and fried chicken wings. The method included defatting with n-hexane, extraction with aqueous solution of sodium chloride (NaCl), derivatization with potassium bromate (KBrO3) and potassium bromide (KBr), and liquid-liquid extraction with ethyl acetate. The final acrylamide extract was analyzed by GC-ECD for quantification and by GC-MS for confirmation. The chromatographic analysis was performed on the HP-INNOWax capillary column, and good retention and peak response of acrylamide were achieved under the optimal conditions (numbers of theoretical plates N = 83,815). The limit of detection (LOD) was estimated to be 0.1 microg kg(-1) on the basis of ECD technique. Recoveries of acrylamide from conventional samples spiked at levels of 150, 500 and 1000 microg kg(-1) (n = 4 for each level) ranged between 87 and 97% with relative standard deviations (RSD) of less than 4%. Furthermore, the GC-ECD method showed that no clean-up steps of acrylamide derivative would be performed prior to injection and was slightly more sensitive than the MS/MS-based methods. Validation and quantification results demonstrated that this method should be regarded as a new, low-cost, and robust alternative for conventional investigation of acrylamide.     

Development of an analytical method for the determination of the residues of four pyrethroids in meat by GC–ECD and confirmation by GC–MS

The development of an analytical method for the determination of four selected pyrethroid insecticides at residue level in beef meat is presented. Acetone and petroleum ether at 40-60 degrees C were chosen as extraction solvents. A two-step clean-up was performed using an Extrelut NT3-C(18) system followed by a Florisil column, with disposable, ready-to-use cartridges. Instrumental analysis was carried out on a gas chromatograph equipped with an electron capture detector (GC-ECD), using matrix-matched and internal standard calibration techniques. Confirmatory analysis by GC-MS was performed. Recoveries at the EU Maximum Residue Limit (MRL), 0.5 x MRL and 1.5 x MRL levels and the repeatabilities were widely satisfactory. The main advantage of the method was the reduction of analysis time as compared with previously published works. The applicability of the method to different matrices and pesticide classes will be investigated.     

液相色谱-串联质谱法同时测定贝类中大田软海绵酸、鳍藻毒素、蛤毒素和虾夷扇贝毒素

建立了同时测定贝类中大田软海绵酸(okadaic acid, OA)及其衍生物鳍藻毒素(dinophysistoxin-1, DTX-1)、蛤毒素(pectenotoxin-2, PTX-2)和虾夷扇贝毒素(yessotoxin, YTX)的液相色谱-串联质谱分析方法。样品经甲醇提取,固相萃取柱净化,C18色谱柱分离,经含甲酸和甲酸铵的乙腈-水溶液为流动相梯度洗脱,选择反应监测(SRM)模式检测,正、负离子切换扫描,基质标准校正,外标法定量。结果表明,OA、DTX-1和YTX的线性范围为2.0～200.0 μg/L,定量限(以信噪比(S/N)≥10计)为1.0 μg/kg; PTX-2的线性范围为1.0～100.0 μg/L,定量限为0.5 μg/kg;几种化合物的添加平均回收率为83.1%～105.7%,相对标准偏差(RSD)为3.16%～9.29%。成功应用本法对黄海灵山湾海域采集的贝类样品进行了分析,发现部分样品中含有大田软海绵酸、鳍藻毒素、蛤毒素和虾夷扇贝毒素。     

Determination of antifouling pesticides and their degradation products in marine sediments by means of ultrasonic extraction and HPLC-APCI-MS

A method has been developed for the simultaneous determination of antifouling pesticides and some of their degradation products, e.g. dichlofluanid, diuron, demethyldiuron, 1-(3,4-dichlorophenyl)urea, sea-nine, Irgarol 1051 and one of its metabolites (2-methylthio-4-tert-butylamino-s-triazine) in marine sediments. The determination of these compounds in sediment samples was performed by means of methanolic ultrasonic extraction then clean-up on an Isolute ENV+ solid phase extraction (SPE) cartridge. The resulting extract was then analyzed by reversed-phase high-performance liquid chromatography coupled with atmospheric-pressure chemical-ionization mass spectrometry in negative and positive ion modes (HPLC-APCI-MS). Recovery ranged from 54-109% for the antifouling agents and their degradation products. The determination limits for the different compounds varied between 0.2 and 1.6 microg kg(-1) dry sediment. The analytical procedure was successfully applied to the determination of these pesticides and their degradation products in marine sediment samples from different marinas of the Catalan coast. The compounds detected were: diuron, dichlofluanid, demethyldiuron, sea-nine, and Irgarol 1051. The highest concentrations were those of diuron and Irgarol 1051--136 and 88 microg kg(-1), respectively.     

Determination of enrofloxacin and its metabolite ciprofloxacin in goat milk by high-performance liquid chromatography with diode-array detection. Optimization and validation

A high-performance liquid chromatography-diode array detection method (HPLC-DAD) combined with liquid chromatography-mass spectrometry was developed for the determination of enrofloxacin and its metabolite ciprofloxacin in goat milk. The HPLC-DAD method validation was compliant with the "DG SANCO 1805/2000" European regulation. The residues were extracted from milk with phosphate buffer, purified on a C18 Speedisk cartridge SPE (Baker) and then analysed using HPLC-DAD set at 277 nm. The decision limit (CCa) calculated by spiking samples at 100 microg/kg with both analytes, taking into account the maximum residue limit (MRL) of 100 microg/kg established by the European Union for the sum of enrofloxacin and its metabolite ciprofloxacin in milk, was 105.3 microg/kg for enrofloxacin and 105.5 microg/kg for ciprofloxacin. The detection capability (CCbeta) was 110.7 and 110.9 microg/kg for enrofloxacin and ciprofloxacin, respectively. The mean recoveries of the method, calculated by spiking samples at 50, 100 and 150 microg/kg were 84% for enrofloxacin and 88% for ciprofloxacin. The limit of quantification was 20 microg/kg for both analytes. The HPLC-DAD validated method was successfully applied for the first time in goats milk, and proved to be suitable for the sensitive and accurate quantification and confirmation analysis of enrofloxacin and ciprofloxacin for regulatory purposes.     

气相色谱-质谱法分析蜂蜜中的多种农药残留

开展了蜂蜜中23种农药残留的气相色谱-电子轰击离子源质谱(GC-EI/MS)分析方法的研究,并对其中3种农药的EI/MS碎片离子的断裂机理与结构进行了初步解析。探讨了蜂蜜试样前处理条件的优化与选择。将蜂蜜试样用乙酸乙酯提取剂超声提取、Florisil硅藻土色谱柱净化和正己烷-乙酸乙酯(体积比为7∶3)混合洗脱剂洗脱后,以PCB103为内标物,采用选择离子监测(SIM)方式下的GC-EI/MS分析。当试样的加标浓度为50,100和200 μg/kg时,加标回收率为82%～120%,相对标准偏差小于11.0%。23种农药的检测限都小于10.0 μg/kg,线性范围为10～500 μg/kg,相关系数都大于0.995。此分析方法已成功地应用于蜂蜜中23种痕量农药残留的分析。     

Determination of chloramphenicol in bovine milk by liquid chromatography/tandem mass spectrometry

A rapid confirmatory liquid chromatographic/tandem mass spectrometic method was developed for determination of chloramphenicol in bovine milk. Chloramphenicol was extracted directly from milk by solid-phase extraction on a C18 cartridge. The extract was further cleaned up on neutral aluminium oxide. Three transition products were monitored in negative ion mode after atmospheric pressure chemical ionization. The detection capability related to the transition product of lowest abundance was 0.03 microg/kg. The mean recovery was 90% at levels of 0.1-0.2 microg/kg. The relative repeatability standard deviations were 4.3, 3.8, and 2.8% at levels of 0.1, 0.2, and 1.0 microg/kg, respectively.     

Liquid chromatographic determination of triasulfuron in soil

Two extraction methods were developed for the determination of triasulfuron in soil. Method I included extraction with methanol-phosphate buffer at pH 7 (2 + 1, v/v), liquid-liquid partition with dichloromethane, and cleanup on a liquid chromatographic Si adsorption solid-phase extraction tube. In Method II, Extrelut was added and the sample was then extracted with acetonitrile. In both cases, the extracts were analyzed by liquid chromatography (LC) with UV detection and the LC peak was confirmed by LC/mass spectrometry (MS). The 2 methods were tested on 3 soils having different physicochemical characteristics. Method I gave 83% average recovery and a determination limit of 0.4 microg/kg soil. Method II gave 67% average recovery and a determination limit of 2 microg/kg soil. Examples of application of Method I to field samples are reported.     

Validation of a high-performance liquid chromatography method for the determination of oxytetracycline,tetracycline, chlortetracycline and doxycycline in bovine milk and muscle

High-performance liquid chromatography with diode-array detection (HPLC-DAD) was optimised and validated for the determination of tetracyclines in bovine milk and tissues. Milk and tissue samples were extracted and purified using a solid-phase extraction HLB Oasis cartridge and analysed using HPLC-DAD set at 365 nm. The analyses were carried out using the mobile phase of 0.01 M oxalic acid-acetonitrile-methanol (60:25:15, v/v/v) on a C8 column (250 x 4.6 mm I.D., 5 microm). Recoveries of tetracyclines from spiked samples at the three concentrations (0.5, 1 and 1.5) of the maximum residues limits (corresponding to 100 microg/kg for milk and the muscle) were higher than 81.1% in milk and 83.2% in muscle. The method was successfully validated for bovine milk and muscle in compliance with requirements set by draft SANCO/ 1805/ 2000 European Decision. The decision limit (CCalpha) was in the range 113.2-127.2 microg/kg and 107.7-129.9 micro/kg for all compounds in milk and muscle, respectively. The detection capability (CCbeta) was in the range 117.2-131.3 microg/kg and 114.9-133.1 microg/kg for all compounds in milk and muscle, respectively.     

Multiresidue determination of pesticides in sediment by ultrasonically assisted extraction and gas chromatography/mass spectrometry

A gas chromatographic/mass spectrometric (GS/MS) method was developed for the multiple determination of pesticides in sediment. The investigated pesticides included 85 compounds, i.e., 13 fungicides, 43 herbicides, and 29 insecticides. The pesticides were extracted from sediment samples by an ultrasonically assisted procedure. The extract was cleaned up by using reversed-phase column chromatography followed by normal-phase column chromatography. A styrene-divinylbenzene copolymer cartridge and a silica gel cartridge were used as the reversed-phase column and the normal-phase column, respectively. The compounds were determined by GC/MS with 2 internal standard compounds. The overall recoveries were 70-105%, and the relative standard deviations ranged from 1.5 to 18%. The minimum detectable concentrations were 2-10 microg/kg. This method was successfully applied to sediment samples from the Shin River in Niigata, Japan. Twenty-five pesticides (6 fungicides, 11 herbicides, and 8 insecticides) were detected in the sediment samples. The concentrations of the detected pesticides ranged from 3 to 69 microg/kg. Herbicides were found May through July; insecticides and fungicides were found July through August, and during July through September, respectively. The presence of pesticides in the river sediment was correlated with the time of pesticide application in the Shin River basin.     

气相色谱-质谱法同时测定粮谷及油籽中多种酰胺类除草剂残留量

粮谷及油籽样品经丙酮-水提取,经去脂和弗罗里硅土固相萃取小柱净化,气相色谱-质谱(GC-MS)选择离子监测模式(SIM)对净化液进行检测;一次进样,便可对粮谷及油籽样品中的9种酰胺类除草剂及常混用的莠去津和嗪草酮等除草剂残留进行准确定量和确证。除草剂回收率为63%~96%;相对标准偏差为2.1%~11.2%;定量下限为0.02~0.05 mg/kg。该法快速、灵敏、准确,各项技术指标均满足农药残留检测的要求。     

Determination of acetanilide herbicides in cereal crops using accelerated solvent extraction, solid-phase extraction and gas chromatography-electron capture detector

A method was developed to determine eight acetanilide herbicides from cereal crops based on accelerated solvent extraction (ASE) and solid-phase extraction (SPE) followed by gas chromatography-electron capture detector (GC-ECD) analysis. During the ASE process, the effect of four parameters (temperature, static time, static cycles and solvent) on the extraction efficiency was considered and compared with shake-flask extraction method. After extraction with ASE, four SPE tubes (graphitic carbon black/primary secondary amine (GCB/PSA), GCB, Florisil and alumina-N) were assayed for comparison to obtain the best clean-up efficiency. The results show that GCB/PSA cartridge gave the best recoveries and cleanest chromatograms. The analytical process was validated by the analysis of spiked blank samples. Performance characteristics such as linearity, limit of detection (LOD), limit of quantitation (LOQ), precision and recovery were studied. At 0.05 mg/kg spiked level, recoveries and precision values for rice, wheat and maize were 82.3-115.8 and 1.1-13.6%, respectively. For all the herbicides, LOD and LOQ ranged from 0.8 to 1.7 μg/kg and from 2.4 to 5.3 μg/kg, respectively. The proposed analytical methodology was applied for the analysis of the targets in samples; only three herbicides, propyzamid, metolachlor and diflufenican, were detected in two samples.     

Liquid chromatographic analysis of cinchona alkaloids in beverages

A method for the determination of Cinchona extract (whose main components are the alkaloids cinchonine, cinchonidine, quinidine, and quinine) in beverages by liquid chromatography was developed. A beverage with an alcohol content of more than 10% was loaded onto an OASIS HLB solid-phase extraction cartridge, after it was adjusted to pH 10 with 28% ammonium hydroxide. Other beverages were centrifuged at 4000 rpm for 5 min, and the supernatant was loaded onto the cartridge. The cartridge was washed with water followed by 15% methanol, and the Cinchona alkaloids were eluted with methanol. The Cinchona alkaloids in the eluate were chromatographed on an L-column ODS (4.6 mm id x 150 mm) with methanol and 20 mmol/L potassium dihydrogen phosphate (3 + 7) as the mobile phase. Cinchona alkaloids were monitored with an ultraviolet (UV) detector at 230 nm, and with a fluorescence detector at 405 nm for cinchonine and cinchonidine and 450 nm for quinidine and quinine (excitation at 235 nm). The calibration curves for Cinchona alkaloids with the UV detector showed good linearity in the range of 2-400 microg/mL. The detection limit of each Cinchona alkaloid, taken to be the concentration at which the absorption spectrum could be identified, was 2 microg/mL. The recovery of Cinchona alkaloids added at a level of 100 microg/g to various kinds of beverages was 87.6-96.5%, and the coefficients of variation were less than 3.3%. A number of beverage samples, some labeled to contain bitter substances, were analyzed by the proposed method. Quinine was detected in 2 samples of carbonated beverage.     

Simultaneous determination of seventeen glucocorticoids residues in milk and eggs by ultra-performance liquid chromatography/electrospray tandem mass spectrometry

A comprehensive analytical method has been developed and validated for the simultaneous determination of seventeen glucocorticoid residues in eggs and milk. The mass spectrometer parameters, the composition of the mobile phase and the sample preparation method were firstly optimized to obtain maximum sensitivity. The samples were deconjugated with beta-glucuronidase/arylsulfatase enzyme and concentrated using an Oasis HLB solid-phase extraction cartridge, followed by cleanup with a dual Sep-pak silica and aminopropyl cartridge. The analytes were quantified by ultra-performance liquid chromatography (using a C18 column)/electrospray ionization tandem mass spectrometry (UPLC/ESI-MS/MS) operating in the negative ion mode. The assay for the 17 glucocorticoids was linear over the range of 1-200 microg/L for milk and egg samples with a high correlation coefficient (>0.99). The limits of quantification (LOQs) for the target analytes were 0.04-1.27 microg/kg for the egg samples and 0.03-0.73 microg/kg for the milk samples. The average extraction recoveries of the glucocorticoids from eggs and milk at two concentration levels (spiked at 0.40 and 2.00 microg/kg) were 65.6-118.7% and 61.5-119.6%, respectively, with relative standard deviations between 1.8-17.0% and 2.4-18.4%, respectively. Because of its high sensitivity, good precision and specificity, the method was found to be suitable for trace analysis of synthetic and natural glucocorticoids in complex biosamples such as eggs and milk.     

Determination of malathion, coumaphos, and fluvalinate residues in honey by gas chromatography with nitrogen-phosphorus or electron capture detectors

A rapid, reliable, and inexpensive extraction method was developed to determine acaricide residues in honey by gas chromatography (GC) with nitrogen-phosphorus (NP) or electron capture (EC) detectors. Because of the high selectivity of the NP detector, no interfering peaks were present and no cleanup was necessary. A simple cleanup step is proposed for the GC-ECD analysis. Recoveries from spiked honey samples ranged from 79 to 94.4%, with coefficients of variation of 0.3-18.5%. The quantitation limit obtained was 0.015 mg/kg for malathion, 0.020 mg/kg for coumaphos, and 0.005 mg/kg for fluvalinate. The method was used to determine the disappearance of malathion and coumaphos residues from honey samples collected from beehives treated with these acaricides. The disappearance of both acaricides was rapid and followed a first-order model for the duration of the experiment.