Automated sample clean-up and fractionation of organochlorine pesticides and polychlorinated biphenyls in human milk using NP-HPLC with column-switching

A method has been developed for the automated sample pretreatment of organochlorine pesticides (OCP's) and polychlorinated biphenyls (PCB's) in extracts of human milk. This work was part of a regular monitoring program presently carried out at our institute. In this program several hundreds of human milk samples have to be analyzed for the occurrence of PCB's and OCP's. With a normal bore straight phase HPLC system, utilizing column switching we are able to separate the fat from the compounds of interest and, moreover, complete separation of the PCB fraction from the OCP's can be achieved. Under the conditions used to separate the PCB fraction from intefering OCP's column-switching is essential since the retention times for the OCP's vary from 4 minutes for hexachlorobenzene (HCB) to more than 2 hours for dieldrin. 1 ml of an extract containing 45 mg of fat is injected on the first (pre)column, the fat is retained on this column and the early eluting HCB, the PCB fraction, and the DDT complex are transferred to the second (analytical) column. Compounds eluting later than p,p′-DDT are collected directly from the precolumn. Meanwhile, the PCB fraction is separated from the rest of the OCP's on the analytical column. Contrary to conventional gravity-controlled chromatography or solid phase extraction the clean-up process can be monitored on-line by UV-detection, thus rendering a fast and reliable optimization of the system. The OCP-fractions collected from the LC are pooled before they are transferred to a high resolution gas chromatograph equipped with a large volume option. The PCB-fraction is injected directly in a HRGC equipped with a concurrent solvent evaporation injection device. The limits of detection for the OCP's (HCB, α-,β- and γ-HCH, β-Hepo (heptachlorepoxide), dieldrin, p,p′-DDE, o,p′-DDT p,p′-DDT and TDE) and the PCB's investigated are at sub-ppb level (fat basis); the recoveries vary from 80 to 100%.     

Simplified method for the determination of organochlorine pesticides in honey.

A method is described for the detection and quantitative determination of organochlorine pesticides in honey. After extraction with hexane, the pesticides were cleaned-up by adsorption chromatography on a Florisil Sep-Pak cartridge and eluted with 15% diethyl ether in hexane. The detection of organochlorine pesticides was performed by capillary gas chromatography with electron-capture detection. The quantification limit obtained for different pesticides ranged from 0.56 to 2.78 micrograms kg-1 and recoveries from fortified honey samples averaged 89.6%.     

气相色谱-质谱法测定茶叶中的25种有机氯农药残留

利用气相色谱-质谱(GC-MS)联用技术建立了茶叶中25种有机氯农药残留同时测定的方法。茶叶样品中有机氯农药残留通过正己烷-丙酮(体积比为2∶1)溶液提取,浓缩后过弗罗里硅土柱净化,采用正己烷-乙酸乙酯(体积比为9∶1)溶液淋洗,GC-MS选择离子监测模式(SIM)检测。方法的线性范围为0.010～0.500 mg/L。在茶叶样品中0.01～0.20 mg/kg加标水平下有机氯混标的加标回收率为70.8%～105.5%,相对标准偏差为1.6%～12.7%。除硫丹Ⅰ和硫丹Ⅱ的定量限为0.02 mg/kg以外,其余23种有机氯农药的定量限均为0.01 mg/kg。     

固相萃取-毛细管气相色谱法测定枇杷花中有机氯农药残留量

建立了枇杷花中有机氯类农药残留量的固相萃取-毛细管气相色谱(SPE-CGC)分析方法。对采自福建蒲田等12地的枇杷花中六六六(4种异构体)、滴滴涕(4种异构体)、五氯硝基苯共9种有机氯农药的残留量进行了测定。样品采用丙酮超声波提取,浓缩后过Florisil固相萃取小柱净化,洗脱剂为V(正己烷)∶V(丙酮)100∶1。用DB-1701弹性石英毛细管气相色谱柱分离样品,微电子捕获检测器进行检测。9种有机氯农药的峰面积与其质量浓度均有良好的线性关系,相关系数均大于0.999,最低检测限为0.016~0.125μg/L,样品的加标回收率为85.4%~106.9%,相对标准偏差为1.8%~9.8%。该方法能够满足农药残留检测的要求。     

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.     

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.     

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.     

Determination of selected persistent organochlorine pollutants in human milk using solid phase disk extraction and narrow bore capillary GC-MS

Summary A simple and rapid procedure based on solid phase disk extraction (SPDE), adsorption chromatography on acidified silica gel and GC-MS analysis was developed for the determination of 8 organochlorine pesticides and 19 PCB congeners in human milk. By using the SPDE procedure, a high throughput and parallel sample processing could be achieved. Method variables were optimized on whole cow's milk (3.5% fat) fortified at levels close to concentrations found in human milk. Recoveries of target analytes were acceptable and ranged from 69 to 102% and 86 to 120% for whole and skimmed milk, respectively. By the use of two stage clean-up and narrow bore capillary columns, detection limits as low as 20 pg mL⁻¹ could be obtained. The method was used for the determination of organochlorine pollutants in human milk from 19 individuals from Romania. The concentrations of PCBs were low, whereas those of organochlorine pesticides were higher than the values reported from other European countries.     

Application of SiO2 hollow fibers for sorptive microextraction and gas chromatography–mass spectrometry determination of organochlorine pesticides in herbal matrices

A method involving simultaneous extraction and sample clean-up procedure: hollow fiber sorptive microextraction, coupled with gas chromatography–mass spectrometric detection for quantification of seven organochlorine pesticides in Radix et Rhizoma Rhei is described. SiO₂ hollow fiber with porous structure was synthesized for the first time. The internal diameter of SiO₂ hollow fiber is 380 μm and average wall thickness is 100 μm. Aggregated SiO₂ particles deposited on the surface of the hollow fiber in a regular array lead to porous structure. SiO₂ hollow fiber was applied to the determination of organochlorine pesticides in Radix et Rhizoma Rhei to avoid sample clean-up and minimize the matrix effects. Extraction solvent, extraction temperature and equilibration time were optimized. Fiber to fiber repeatability over the concentration ranges were less than 10%. Recoveries were satisfactory (between 63% and 115%) for most of organochlorine pesticides at spiking levels. Furthermore, the proposed method was also applied to determine seven organochlorine pesticides in 43 commercial Radix et Rhizoma Rhei samples, in which the selected pesticides were found in eight samples. The results have been further confirmed by solvent extraction methods according to China Pharmacopoeia (2005).     

Comparative study of clean-up and fractionation methods for the determination of organochlorine pesticides in lipids by gas chromatography.

Three of the methods most often used for the clean-up and fractionation of organochlorine pesticides in lipid residue analysis by gas chromatography with electron-capture detection were compared. The overall recoveries of twenty pesticides from spiked samples were higher than 88%, the relative standard deviation being in the range 3-11% (n = 6) at the 36-80 ppb (10(9) level. The three methods were compared by analysis of variance, with no differences in precision at the 0.05 significance level. Differences in recoveries appeared in only two instances. None of the three methods seems to be significantly better than the others for the determination of the pesticides studied.     

同位素稀释高分辨气相色谱-高分辨质谱法测定土壤中痕量有机氯农药残留

建立了同位素稀释高分辨气相色谱-高分辨质谱测定土壤中痕量有机氯农药残留的分析方法。采用加速溶剂法萃取土壤样品,以正己烷/丙酮(体积比为1:1)为提取溶剂,提取液经过Florisil硅土固相萃取小柱净化后,采用高分辨DB-5MS毛细管色谱柱(30 m×0.25 mm×0.25 μm)分离,以保留时间和同位素特征离子丰度比定性,同位素峰面积比定量。实验结果表明,方法的回收率为77.3%～114.5%,相对标准偏差(RSD)≤10.81%（n=5）,检出限均小于0.04 pg/g。应用该方法检测某地区表层土壤中的有机氯农药,结果表明该方法适合测定环境土壤背景中痕量有机氯残留。     

Determination of Organochlorine Pesticides Residue in Ginseng Root by Orthogonal Array Design Soxhlet Extraction and Gas Chromatography

Organochlorine pesticides are known to enter plant products from contamination via spillage and volatilization of the residues from pesticide-treated soils or storage. A method involving four-factor-three-level orthogonal array design including extracting solvent component, particle size, solvent overflow recycle and time needed for the optimization of extracting nine organochlorine pesticides from ginseng root was developed using Soxhlet extraction followed by capillary gas chromatography–electron capture detection and mass spectrometric confirmation. The extraction conditions were optimized from the experimental data. Relationship between the bioaccumulation of benzenehexachloride isomers and their polarity is discussed based on experimental results.     

Improvement of GC-MS analysis of organochlorine pesticides in sediments by use of a computer-optimized temperature program

 A simulation and optimization software program (Pro ezGC^? by Analytical Innovations, Inc., Kettering, OH, USA) for GC temperature programs was applied to the analysis of organochlorine pesticides in sediments. By means of this software, the run time of a conventional temperature program derived from trial and error experiments could be reduced to less than a third, achieving at the same time an increased separation efficiency. Finally, 17 organochlorine pesticides could be baseline-resolved on a capillary column in less than 12 min. In addition, a two-fold sensitivity enhancement was achieved. Received: 31 January 1997/Accepted: 10 April 1997     

Semiautomatic method for the screening and determination of 23 organochlorine pesticides in horticultural samples by gas chromatography with electron-capture detection.

A rapid, simple, efficient device for the extraction-preconcentration of 23 organochlorine pesticides currently applied to vegetables is proposed. Pesticide residues are extracted from chopped samples by using a mixture of distilled water and light petroleum (1:1, v/v). After phase separation, an aliquot of the organic layer is continuously evaporated to dryness under a N2 stream as it is dropped into a glass tube containing distilled water. The aqueous phase, containing the analytes, is then passed through a miniaturized RP-C18 column for preconcentration, clean-up and subsequent elution with 150 microliters of ethyl acetate. A volume of 1 microliter of the extract containing pesticides is injected into the gas chromatograph, fitted with an electron-capture detector, for their selective determination. Limits of detection vary between 0.04 and 10 ng/ml, with linear ranges from 0.2 to 500 ng/ml; the average relative standard deviation at the low nanogram-per-millilitre level is 5.3%. The potential of the proposed method was realized by applying it to the screening/determination of organochlorine pesticides in horticultural commodities.     

Environmental applications of large volume injection in capillary GC using PTV injectors

Temperature programmable (PTV) injectors with packed widebore (ca. 3.5 mm i.d.) liners are used for large volume injection in capillary gas chromatography with the aim to simplify and/or improve off-line sample pretreatment proecdures. A simple procedure for optimization of large volume PTV injection is described. The system performance, i.e. linearity and repeatability, is evaluated for polar nitrogen/phosphorus containing pesticides (PTV-GC-NPD) and organochlorine pesticides (PTV-GC-ECD) in river water extracts as well as for polycyclic aromatic hydrocarbons (PAHs) in river sediment (PTV-GC-MS).     

固相萃取-毛细管气相色谱法测定中草药中13种有机氯农药的残留量

建立了中草药中有机氯类农药残留量的固相萃取-毛细管气相色谱(SPE-CGC)分析方法。对丹参、黄芩、射干、白芍、白芷、天南星、牛蒡子、知母、桔梗共9种中草药中六六六的4种异构体、滴滴涕的4种异构体、七氯、艾氏剂、环氧七氯、狄氏剂、异狄氏剂共13种有机氯农药的残留量进行了测定。以丙酮-正己烷混合物作提取剂,采用超声波提取样品,然后用Florisil固相萃取小柱快速净化提取物。采用SPB-5弹性石英毛细管气相色谱柱分离样品,电化学检测器进行检测。13种农药的峰面积与其质量浓度均有良好的线性关系,相关系数均大于0.998。最小检测量为0.064～0.61 μg/L;样品的加标回收率为87.3%～102.3%(相对标准偏差为1.3%～6.8%)。该法简便快速、灵敏准确,具有广泛的应用前景。     

加速溶剂萃取/凝胶渗透色谱－固相萃取净化、气相色谱－质谱法测定茶叶中残留的33种农药

建立了茶叶中有机磷、有机氯、拟除虫菊酯类共33种农药残留的分析方法。样品以丙酮-二氯甲烷(体积比为1:1)为提取剂经加速溶剂方法萃取,提取液用凝胶渗透色谱净化除去大部分的色素、脂类和蜡质,再用Carb-NH2小柱和Florisil小柱净化。采用气相色谱法分析、外标法定量、气相色谱-质谱法（GC-MS）定性。加标水平为0.05 mg/kg时,大部分农药的回收率为70%~120%,相对标准偏差小于20%。方法的检测限为0.005～0.05 mg/kg (以10倍信噪比计)。该方法的提取效率高,准确灵敏,目前已应用于出口茶叶中农药残留的日常检测。大量实际样品的检测结果表明,此方法适于出口茶叶中农药残留检测实际工作的需要。     

Optimization of conditions for PTV large-volume injection combined with fast GC-MS

Large-volume injection utilizing programmable temperature vaporizer in solvent vent mode is combined with fast capillary gas chromatography and mass spectrometric detection. Optimized injection and chromatographic conditions made possible manual injection of a 20-microL ethyl acetate extract containing 15 organochlorine pesticides and their separation on a short, 0.1-mm-i.d. column in less than 8 min.     

快速溶剂萃取-气相色谱法同时测定含脂羊毛中的28种有机氯拟除虫菊酯杀虫剂的残留量

建立了快速溶剂萃取-气相色谱法同时测定含脂羊毛中28种有机氯、拟除虫菊酯杀虫剂残留量的方法。在80 ℃、10.34 MPa条件下用正己烷饱和的乙腈快速提取样品,提取物经冷冻除脂、浓缩、固相萃取净化处理后直接用气相色谱分析。结果表明:16种有机氯杀虫剂在0.005～1.0 mg/L范围内,9种拟除虫菊酯杀虫剂及三氯杀螨醇、三氯杀螨砜在0.01～2.0 mg/L范围内,氟氯苯菊酯在0.02～4.0 mg/L范围内,其峰面积与质量浓度呈良好的线性关系。28种有机氯、拟除虫菊酯杀虫剂的平均回收率为67.2%～107.7%,相对标准偏差为2.6%～29.0%。结果表明：该方法具有操作简便、快速方便、灵敏度高等特点,完全可满足含脂羊毛中28种有机氯拟除虫菊酯杀虫剂残留量初筛检测的要求。     

亚临界水萃取及气相色谱-串联质谱法检测红茶中多种农药残留

建立了亚临界水萃取及气相色谱-串联质谱(GC-MS/MS)检测红茶中21种有机氯和拟除虫菊酯农药残留的方法。在萃取压力为5 MPa条件下,样品经150 ℃的亚临界水提取15 min后,将目标物转移至丙酮-正己烷(1:1, v/v)中,经ENVI-Carb固相萃取净化小柱净化,DB-5毛细管气相色谱柱分离,在多反应监测(MRM)模式下进行MS/MS检测,基质匹配溶液内标法定量。各目标物在5.0～320.0 μg/L范围内线性关系良好,相关系数均大于0.99,其定量限(信噪比(S/N)＞10)为50 ng/g,检出限(S/N＞3)为10 ng/g。茶叶基质中添加50、100和200 ng/g的标准品时,21种农药的回收率为70.18%～119.98%,相对标准偏差(RSD)为5.01%～11.76%。该方法的灵敏度、准确度和精密度均符合农药残留测定的技术要求,适用于红茶中有机氯和拟除虫菊酯农药残留的检测。