Determination of organochlorine pesticide residues in honey, applying solid phase extraction with RP-C18 material

In this study, a new clean up method was developed for the routine multiresidue determination of organochlorine pesticide residues in honey. The analytical procedure requires sample extraction with methanol, followed by a clean up step through a C18 Sep-Pak cartridge. Finally, pesticides are eluted with hexane. The determination of organochlorine pesticide residues was performed by capillary gas chromatography with electron capture detection. The mean recoveries of 18 organochlorine pesticides were estimated at various concentrations and found very efficient in most cases. The detection limits were found to be between 0.05 and 0.20 microgram kg-1.     

Comparison of solvent extraction and solid-phase extraction for the determination of organochlorine pesticide residues in water.

Solid-phase extraction (SPE) of organochlorine pesticide residues from environmental water samples was evaluated using octadecyl (C18)-bonded porous silica. The efficiency of SPE of these pesticide residues from reagent water samples at 1-5 micrograms dm-3 levels was compared with those obtained by solvent extraction with hexane and Freon TF (trichlorotrifluoroethane). Average recoveries exceeding 80% for these organochlorine pesticides were obtained via the SPE method using small cartridges containing 100 mg of 40 microns C18-bonded porous silica. The average recovery by solvent extraction with hexane and Freon TF exceeded 90% in both instances. It was concluded that the recoveries and precision for the SPE of organochlorine pesticides were poorer than those for the solvent extraction method. Organochlorine pesticide residue levels in environmental water samples from two major rivers flowing through predominantly rice-growing areas were monitored by gas chromatography using the solvent extraction method with hexane. Exceptionally high levels of organochlorine pesticide residues such as BHC, DDT, heptachlor, endosulfan and dieldrin were found in these water samples.     

Supercritical fluid extraction for pesticide multiresidue analysis in honey: determination by gas chromatography with electron-capture and mass spectrometry detection

An analytical procedure using supercritical fluid extraction (SFE) and capillary gas chromatography with electron-capture detection was developed to determine simultaneously residues of different pesticides (organochlorine, organophosphorus, organonitrogen and pyrethroid) in honey samples. Fortification experiments were conducted to test conventional extraction (liquid-liquid) and optimize the extraction procedure in SFE by varying the CO2-modifier, temperature, extraction time and pressure. Best efficiency was achieved at 400 bar using acetonitrile as modifier at 90 degrees C. For the clean-up step, Florisil cartridges were used for both methods LLE and SFE. Recoveries for majority of pesticides from fortified samples of honey at fortification level of 0.01-0.10 mg/kg ranged 75-94% from both methods. Limits of detection found were less than 0.01 mg/kg for ECD and confirmation of pesticide identity was performed by gas chromatography-mass spectrometry in selected-ion monitoring mode. The multiresidue methods in real honey samples were applied and the results of developed methods were compared.     

Simultaneous determination of 109 pesticides in unpolished rice by a combination of gel permeation chromatography and Florisil column purification, and gas chromatography/mass spectrometry

A multi-residue method is described for the simultaneous analysis of 109 pesticides with different properties in unpolished rice. The range covers organophosphorus, organochlorine, carbamate, and synthetic pyrethroid pesticides. The pesticides were extracted from the sample using ethyl acetate. Most higher molecular weight components such as lipids in the co-extractives were removed by gel permeation chromatography (GPC) with a Bio-bead SX-3 column. A Florisil column with ethyl acetate/hexane as the eluting solvents was used for further cleanup. The pesticides were finally simultaneously determined by gas chromatography/mass spectrometry (GC/MS) in selective ion monitoring (SIM) mode. The average recoveries for most pesticides (spiked level 0.02, 0.1 and 1 microg/g) ranged from 70% to 110%, the relative standard deviation (RSD) was below 20% in every case, and the limit of detection (LOD) varied from 1 to 20 ng/g.     

超声波溶剂提取-气相色谱法测定烟草及烟草制品中19种有机氯农药残留

建立了超声波溶剂提取-气相色谱法同时测定烟草及其制品中19种有机氯农药残留。样品采用正己烷-丙酮超声提取,经Florisil固相萃取柱净化后,采用气相色谱-电子捕获检测法(GC-ECD)进行检测。结果发现,19种有机氯农药加标回收率均在72%以上,相对标准偏差(RSD)在0.1%～9.0%,能满足当前烟草中有机氯农药残留的同时快速检测要求。     

Organochlorine residue analysis of commercial milks by capillary gas chromatography

The determination of organochlorine pesticides and polychlorinated biphenyls in milks requires the use of efficient extraction methods. A rapid procedure has been developed, based on extraction of organochlorine residues from milk on to octadecylsilica solid phase extraction cartridges and elution with hexane. The addition of different organic solvents to the milk before solid phase extraction has been studied. The use of methanol to disrupt the fat globules enables almost complete recovery of the residues with minimum extraction of fatty substances. Recovery experiments were performed for eighteen compounds present at ppb levels in whole, two per cent, and skimmed milks. The average recoveries of the compounds from two per cent and skimmed milks were 73–84%; values for whole milk were lower. The residues were determined by gas chromatography using two kinds of capillary column (non-polar and semi-polar) and electron capture detection. The procedure shows low lipid carry over, and extraneous interferences are minimal. The method has been applied to the detection of organochlorine pesticides and nine individual polychlorinated biphenyls in commercial milks. The results obtained demonstrated the presence of very low levels of organochlorine residues in the commercial milks analyzed.     

Multi-residue determination of organochlorine pesticides in vegetables in Kirklareli,Turkey by gas chromatography–mass spectrometry

The aim of this study was to investigate the level of organochlorine pesticides use for treatment of tomatoes, eggplants and cucumbers in Kirklareli, Turkey. Eighteen organochlorine pesticides were identified in vegetable samples using microwave or Soxhlet extraction, and results were obtained by gas chromatography–mass spectrometry. The optimized conditions were 1 mL/min for flow rate in the mobile phase, 1 μL for injection volume and 70 V for fragmentation potential. The analytical parameters show that the microwave oven extraction procedure provided the best results when compared to the Soxhlet extraction procedure. Samples were prepared for analysis with hexane?dichlormethane (1: 1, v/v, 40 mL) using a solid-phase extraction method. The limits of detection and quantitation for the eighteen analytes were between 0.02–0.26 and 0.06–0.87 μg/L, respectively, and the relative standard deviations of the migration time ranged from 2.4 to 8.9%. The recoveries of surrogate spiked in vegetable samples ranged from 70 to 116%, respectively. The obtained concentrations of pesticides in all vegetables studied were proved in the range of ND–123 μg/kg. The organochlorine pesticide sum was below the legal limit, except for Endrin and Methoxychlor, which requires a further elucidation of the organochlorine pesticides pollution sources in the region. These studies on accumulation of organochlorine pesticides were necessary for accomplishing a comprehensive ecological risk assessment.     

Microwave-assisted extraction versus Soxhlet extraction in the analysis of 21 organochlorine pesticides in plants

A method to determine 21 organochlorine pesticides in vegetation samples using microwave-assisted extraction (MAE) is described and compared with Soxhlet extraction. Samples were extracted with hexane–acetone (1:1, v/v) and the extracts were cleaned using solid-phase extraction with Florisil and alumine as adsorbents. Pesticides were eluted with hexane–ethyl acetate (80:20, v/v) and determined by gas chromatography and electron-capture detection. Recoveries obtained (75.5–132.7% for Soxhlet extraction and 81.5–108.4% for MAE) show that both methods are suitable for the determination of chlorinated pesticides in vegetation samples. The method using microwave energy was applied to grass samples from parks of A Coruña (N.W. Spain) and to vegetation from the contaminated industrial area of Torneiros (Pontevedra, N.W. Spain).     

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.     

Solid phase extraction GC/ECD method for the analysis of organochlorine pesticides in wildlife plasma

A gas chromatographic method for the analysis of nine organo-chlorine pesticides in wildlife plasma is described. Reversed-phase solid phase extraction is utilized to extract the organochlorine pesticides from plasma. This is followed by a normal phase solid phase extraction clean-up as the pesticides are recovered by elution with hexane:ethyl ether (1:1) and quantified by gas chromatogra-phy/electron capture detection. Method limits of detection range from 7.0–25 μg/L. The mean recovery for all pesticides is 81%.     

Determination of 21 organochlorine pesticides in tree leaves using solid-phase extraction clean-up cartridges

A method to determine 21 organochlorine pesticides (OCPs) in tree leaves [chestnut (Castanea sativa), hazel (Corylus avellana), oak (Quercus robur) and walnut tree (Juglans regia)] based on microwave-assisted extraction (MAE) followed by solid-phase extraction (SPE) clean-up is described. After extraction with hexane:acetone (50:50), four different sorbents (Florisil, tandem Florisil + alumina, silica and ENVI-Carb) were assayed for the clean-up step. Pesticides were eluted with 5 mL of hexane:ethyl acetate (80:20) and determined by gas chromatography and electron capture detection (GC-ECD). Carbon was the sorbent, which provided colourless eluates and chromatograms with less interferent compounds. Analytical recoveries obtained were ca. 100% for all the studied pesticides with this sorbent.     

Application of dispersive liquid–liquid microextraction followed by gas chromatography/mass spectrometry as effective tool for trace analysis of organochlorine pesticide residues in honey samples

A dispersive liquid–liquid microextraction (DLLME) method followed by gas chromatography/mass spectrometry (GC/MS) was applied for the trace determination of organochlorine pesticides in honey samples. The type and volume of organic extraction and disperser solvents, pH, effect of added salt content and centrifuging time and speed were optimized to find the appropriate extraction conditions. In DLLME, 30 µL of 1,2-dibromomethane (serving as extractant) and 1.5 mL of acetonitrile (serving as disperser) were applied. The limit of detection (3 s) and limit of quantification (10 s) for all the analytes of interest (organochlorine pesticides) varied from 0.004 to 0.07 and from 0.02 to 0.3 ng g^?1, respectively. The extraction recovery ranged from 91 to 100 %, and the enrichment factors ranged from 171 to 199. The relative standard deviation was <6 % for intraday (n = 6) and <8 % interday (n = 4) measurements. The proposed DLLME–GC/MS method was confirmed to be fast, simple to perform, friendly to environment and suitable for analysis of organochlorine pesticide residues at trace levels in honey samples.     

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。     

固相萃取-气相色谱法同时测定花生中18种有机氯农药残留

利用气相色谱(GC)建立了花生中18种有机氯农药同时测定的方法。花生中有机氯农药残留通过乙腈提取,减压浓缩后过弗罗里固相萃取柱净化,采用正己烷-丙酮(体积比为9∶1)溶液淋洗,淋洗液氮吹近干后以正己烷定容,应用微池电子捕获检测器(μECD)检测。氟氯氰菊酯和溴氰菊酯的检出限分别为50和100g/kg,其余16种有机氯农药检出限均为10μg/kg。在花生样品中添加检测限水平有机氯混标溶液,加标回收率为71.28%～116.58%,测定结果的相对标准偏差为4.08%～18.16%(n=4或5)。     

凝胶渗透色谱-气相色谱同时测定糙米中拟除虫菊酯、有机氯农药和多氯联苯的残留量

基于凝胶渗透色谱（GPC）对脂类和色素的优良分离能力,系统研究了其对有机氯农药、拟除虫菊酯农药、多氯联苯和糙米基体的分离行为。介绍了一种可同时测定糙米中35种拟除虫菊酯、有机氯农药和多氯联苯的方法。样品用乙酸乙酯提取,凝胶渗透色谱净化,气相色谱-电子捕获检测法(GC-ECD)检测,外标法定量。在低、中、高浓度3个添加水平上的回收率分别为70.1%~107.4%,70.3%~109.9%和70.8%~109.5%,相对标准偏差（RSD）为2.3%~13.3%;有机氯农药和多氯联苯的检出限为0.07 μg/k     

Determination of Pesticides in the Rhizome of Traditional Chinese Medicines by Gas Chromatography with Electron Capture Detection

A simple and efficient gas chromatography method for the determination of 27 organochlorine and pyrethroid pesticides in traditional Chinese medicine was developed. Pesticide residues were extracted from the samples by oscillation and ultrasound, and purified by gel permeation chromatography and florisil solid phase extraction. The analysis was performed by gas chromatography with micro-electron capture detection. The purification conditions, such as the extraction and elution solvents, extraction methodology, and gel permeation chromatography conditions, were optimized. Traditional Chinese medicines were purified by different methods based on their composition. Under optimized conditions, the calibration graph was linear from 10 to 500 µg/L and the correlation coefficients varied from 0.9958 to 0.9997. The detection limits of these pesticides were between 0.09 and 1.82 µg/kg. The recovery of the pesticides spiked in various samples at four concentrations ranged from 73.2% to 106.4%, with relative standard deviations between 1.0% and 14.0%. This study indicates that the method is useful for determining pesticides in rhizome traditional Chinese medicines.     

Comparison of different sample pre‐treatments for multi‐residue analysis of organochlorine and pyrethroid pesticides in chrysanthemum by gas chromatography with electron capture detection

The widespread use of insecticides in Chinese herbal medicines has created a compelling need for the development of a multiresidue analytical method to help assure herbs safety. The operating variables affecting the performance of the multiresidue analysis of 34 organochlorine and 12 pyrethroid pesticides in chrysanthemum, a widely used kind of Chinese herbal medicines, were evaluated. Three different extraction solvents including n‐hexane and its mixtures with acetone and petroleum ether were compared, and n‐hexane was found to be an appropriate option. A combination of gel permeation chromatography and SPE was selected as the optimum cleanup, in comparison with dispersive SPE, or the two former methods alone. The determination of the 46 pesticide residues in the spiked chrysanthemum samples was performed by GC with electron capture detection. The average recoveries ranged from 71.3 to 102.6% with RSDs of 1.4–15.7% for all of the pesticides. The LOQs were in the range of 0.0015–0.2 mg/kg, while the LODs were between 0.0005 and 0.1 mg/kg. The satisfactory accuracy, and precision, in combination with a good separation and few interferences, have demonstrated the strong potential of this technique for its application in chrysanthemum analysis.     

超声波萃取-SPE净化-双柱双检测器测定土壤和沉积物中的20种有机氯

建立了超声波萃取-SPE硅胶小柱净化-双柱双检测器气相色谱法测定土壤和沉积物中20种有机氯农药的方法。样品中添加高纯铜粉除硫,二氯甲烷超声萃取9 min,使用SPE硅胶小柱,9 mL丙酮:正己烷(1:9)洗脱净化。采用单进样口,双色谱柱双μ-ECD同时分离测定。土壤和沉积物样品中的方法检出限为0.001 mg/kg,平均回收率为73.17%～112.5%,相对标准偏差为0.33%～16%。     

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。     

Analysis of 28 insecticides in curry leaves (Murraya koenigii L.) by gas chromatography and gas chromatography–mass spectrometry

A simple and efficient method was developed for analysis of 28 insecticides (organochlorines, organophosphates and synthetic pyrethroids) in curry leaves (Murraya koenigii L.). The extraction of the analytes was carried out with acidified acetonitrile and purification with magnesium sulphate, primary secondary amine along with graphitised carbon black to remove excess chlorophyll content in curry leaves. Acetonitrile extracts were changed into hexane + acetone (9 + 1) and hexane + toluene (9 + 1) in the final step. In another method ethyl acetate was used for extraction and purification was carried out as above. The analytes in the samples were determined by gas chromatography (GC) and confirmed by gas chromatography–mass spectrometry (GC–MS). Use of ethyl acetate increased the recovery of the analytes, but co-extractive interference led to higher GC maintenance. Acidified acetonitrile was found to be a better extraction solvent compared with ethyl acetate. The use of hexane:toluene (9:1) as exchange solvent increased the recovery of organochlorine insecticides compared with hexane:acetone (9:1). The limit of quantification (LOQ) of the method was 0.01 mg kg^?1 for organochlorine insecticides and 0.05 mg kg^?1 for organophosphates and synthetic pyrethroids. The recoveries of organochlorines were within 70.36–82.45%; organophosphates, 82.54–90.93% and synthetic pyrethroids, 88.45–90.71% at the LOQ level. The method developed was found suitable for analysis of real samples of curry leaves. The pesticides detected in curry leaves collected from the retail market were mainly organophosphates and synthetic pyrethroids.