Supercritical fluid extraction and clean-up of organochlorine pesticides and polychlorinated biphenyls in mussels

The simultaneous extraction and clean-up of mussel samples followed by gas chromatography with electron-capture detection and mass spectrometric confirmation of 15 organochlorine pesticides (OCPs) and 11 polychlorinated biphenyls (PCBs) is developed using Florisil sorbent in the supercritical fluid extraction cell. The method detection limits vary from 1 to 10 ng/g for OCPs and from 2 to 15 ng/g for PCBs. Mean reproducibilities of 11% and 10% and mean recoveries of 80% and 53%, respectively, for OCPs and PCBs are obtained. The feasibility of the proposed supercritical fluid extraction method was confirmed by analyzing a certified reference material and mussels collected from Taiwan region. The method is simple, rapid and requires only small amounts of samples and solvents. It may serve as a screening protocol for the determination of OCPs and PCBs in mussels on a routine basis.     

Pressurized liquid extraction in determination of polychlorinated biphenyls and organochlorine pesticides in fish samples

Pressurized liquid extraction (PLE) is a relatively new technique applicable for the extraction of persistent organic pollutants from various matrices. The main advantages of this method are short time and low consumption of extraction solvent. The effects of various operational parameters (i.e. temperature of extraction, number of static cycles and extraction solvent mixtures) on the PLE efficiency were investigated in this study. Fish muscle tissue containing 3.2% (w/w) lipids and native polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and other related compounds was used for testing. Purification of crude extracts was carried out by gel permeation chromatography employing Bio-Beads S-X3. Identification and quantitation of target indicator PCBs and OCPs was performed by high-resolution gas chromatography (HRGC) with two parallel electron-capture detectors (ECDs). Results obtained by the optimized PLE procedure were compared with conventional Soxhlet extraction (the same extraction solvent mixtures hexane–dichloromethane (1:1 v/v) and hexane–acetone (4:1 v/v) were used). The recoveries obtained by PLE operated at 90–120 °C were either comparable to “classic” Soxhlet extraction (for higher-chlorinated PCB congeners and DDT group) or even better (for lower chlorinated analytes). The highest recoveries were obtained for three static 5 min extraction cycles.     

Multiresidue-matrix solid-phase dispersion method for determining 16 organochlorine pesticides and polychlorinated biphenyls in fish

Summary An effective, multiresidue-matrix, solid-phase dispersion — extraction (MSPD) and GC-MS method for the determination of 16 organochlorine pesticides (OCPs), as well as polychlorinated biphenyls (PCBs) from the level chlorination in fish is described. The method uses an octadecylsilyl-derivatized silica and Florisil-based MSPD co-column for direct, on-line clean-up. Recoveries calculated from five different fortification levels are >85% in all cases for OCPs, except for heptachlor and 4,4-DDT where recoveries of 78% and 81% are ob-tained, and >95% for PCBs. Detection limits determined for the OCPs vary from 19.6–91.1 ng g^–1, and from 71.4–111.2 ng g^–1 for the two to five chlorine-containing PCBs. The method has been applied to the analysis of fish grown in Er-Jen river (Taiwan) and method may serve as a screening protocol for the determination of OCPs and PCBs in fish.     

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%.     

Sediment certified reference materials for the determination of polychlorinated biphenyls and organochlorine pesticides from the National Metrology Institute of Japan (NMIJ)

Two marine sediment certified reference materials, NMIJ CRM 7304-a and 7305-a, have been issued by the National Metrology Institute of Japan in the National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) for the determination of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). The raw materials of the CRMs were collected from a bay near industrial activity in Japan. Characterization of these CRMs was conducted by NMIJ, where the sediments were analyzed using multiple analytical methods such as pressurized liquid extraction (PLE), microwave-assisted extraction (MAE), saponification, Soxhlet extraction, supercritical fluid extraction (SFE), and ultrasonic extraction; the target compounds were determined by one of the primary methods of measurements, isotope dilution–mass spectrometry (ID-MS). Certified values have been provided for 14 PCB congeners (PCB numbers 3, 15, 28, 31, 70, 101, 105, 138, 153, 170, 180, 194, 206, 209) and 4 OCPs (γ-HCH, 4,4′-DDT, 4,4′-DDE, 4,4′-DDD) in both CRMs. NMIJ CRM 7304-a has concentrations of the contaminants that are a factor of 2–15 greater than in CRM 7305-a. Both CRMs have information values for PCB homolog concentrations determined by collaborative analysis using a Japanese official method for determination of PCBs. The total PCB concentrations in the CRMs are approximately 920 and 86 μg kg⁻¹ dry mass respectively. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Evaluation of lipid removal from animal fats for the determination of organochlorine, pesticides, and polychlorinated biphenyl indicators by gas chromatography with electron capture detector

For cleanup of animal fat before GC analysis of organochlorine pesticides and polychlorinated biphenyls, freezing-lipid filtration with solid-phase extraction and matrix solid-phase dispersion were evaluated to replace the official Brazilian methodology that uses preparative alumina column chromatography. General drawbacks associated with this last technique, such as the use of large amounts of solvent, laborious and time-consuming procedure could be avoided by using these alternative approaches. Experiments were carried out to study the performance by using different combinations of sorbents and elution solvents. Efficiency of alternative extraction methods in terms of fat removal and recovery capability was monitored by gravimetry, TLC, and GC with electron capture detection. Freezing-lipid filtration with solid-phase extraction afforded better clean up efficiency with recoveries in a range of 54.5 to 103.6% with the relative standard deviation of less than 10% for all compounds under investigation.     

Application of C-labelled polychlorinated biphenyl congener 153 as internal standard in the gas chromatographic-mass spectrometric analysis of polychlorinated biphenyls

We developed a method of qualitative and quantitative GC-MS analysis of polychlorinated biphenyls (PCBs) in soil samples, to be able to determine the biodegradation efficiency for individual PCBs. ¹³C₁₂-Substituted PCB 153 was used as internal standard. The analyses were performed on a DB-5 capillary column. The identification procedure was based on the correlation analysis of the measured and published relative retention r₁₂ data using [¹³C₁₂]PCB 153 instead of octachloronaphthalene (OCN). [¹³C]PCB 153 was also used for quantification of individual PCBs in soil samples.     

Ultrasonic solvent extraction of organochlorine pesticides from soil

Ultrasonic solvent extraction of the organochlorine pesticides (OCP) including α-, β-, γ- and Δ-hexachlorocyclohexane (HCH), heptachlor, aldrin, o,p′-DDE, dieldrin, p,p′-DDE, p,p′-DDT, methoxychlor, mirex from soil is reported. The extraction procedure was optimized with regard to the solvent type, amount of solvent, duration of sonication and number of extraction steps. Determination of pesticides was carried out by gas chromatography (GC) equipped with electron capture detection (ECD). Twice ultrasonic extraction using 25 mL of a mixture of petroleum ether and acetone (1/1 v/v) for 20 min of sonication showed satisfactory extraction efficiency. Recoveries of pesticides from fortified soil samples are over 88% for three different fortification levels between 15 and 200 μg kg⁻¹, and relative standard deviations of the recoveries are generally below 6%. Real soil samples were analyzed for OCP residues by optimized ultrasonic solvent extraction and shake-flask as well as soxhlet extraction technique. Investigated all extraction methods showed comparable extraction efficiencies. Optimized ultrasonic solvent extraction is the most rapid procedure because the use of time in ultrasonic extraction was considerably reduced compared to shake-flask and soxhlet extraction.     

微波萃取/气相色谱-质谱测定土壤中的多氯联苯

分别对多氯联苯的微波萃取条件进行了优化。优化后的分析条件为微波功率1200 W,萃取温度115℃,萃取时间20 min,萃取溶剂为V(正己烷)∶V(丙酮)=1∶1。方法的检出限为20~30 ng/g,线性范围40~4000 ng/mL(多氯联苯总量),相关系数均大于0.9990,样品基体加标回收率为92.2%~115%,相对标准偏差为9.4%(n=6)。     

Simultaneous microwave-assisted extraction of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phthalate esters and nonylphenols in sediments

A new method was developed for the simultaneous extraction of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), phthalate esters (PEs), nonylphenols (NPs) and nonylphenol mono- and diethoxylates (NP1EOs and NP2EOs, respectively) in sediment samples by means of a closed microwave system. The extractions were carried out at 21 psi and 80% of microwave power and 15 ml of acetone were used as the common extraction solvent. The filtered extract was further fractionated in two groups using Florisil cartridges: PAHs and PCBs were eluted with n-hexane:toluene (4:1) and the PEs, NPs and ethoxylates were eluted with ethyl acetate. All the compounds were analysed by gas chromatography-mass spectrometry (GC-MS). In case of PAHs and PCBs, the developed method was validated by comparison of the results obtained for the certified reference material NIST 1944 with the certified values. In the absence of a reference material for phthalate esters and nonylphenols, one sediment sample was extracted twice under the optimal conditions in order to check than an exhaustive extraction of the analytes occurred. This method is currently used in the study of the distribution of those organic contaminants in the estuaries of the Bay of Biscay (Spain).     

Comparison of five extraction methods for measuring PCBs,PBDEs, organochlorine pesticides,and lipid content in serum

An increasing number of studies use blood obtained noninvasively to monitor organohalogen contaminants; however, blood can be difficult to analyze because of its aqueous nature and high protein content. We compared five methods for extracting polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides, and lipids from serum using National Institute of Standards and Technology Standard Reference Material 1589a PCBs, Pesticides, PBDEs, and Dioxins/Furans in Human Serum. Liquid:liquid (LLE), cavity-dispersed microwave-assisted (MAE), focused microwave-assisted (FME), solid-phase (SPE), and pressurized fluid (PFE) extraction techniques were compared. FME extraction yielded the optimal recovery of internal standards (IS). All methods resulted in similar contaminant concentrations that also agreed with the certified values for SRM 1589a, except for only a few compounds measured by methods other than FME. Based on these findings, the FME method was determined to be the best overall extraction method. One procedural factor was found to affect contaminant concentrations; use of IS carrier solvents that were immiscible with serum (or when the serum was not directly physically mixed with IS) resulted in a 30% underestimation of organohalogen concentrations. This study offers valid, novel extraction alternatives beyond traditional methods (e.g., LLE) for blood contaminant measurements. Figure       

Separation of polychlorinated biphenyls from chlorinated pesticides using aminopropyl bonded-phase cartridge and determination by GC-ECD

Summary Gas chromatography of polychlorinated biphenyls and chlorinated pesticides in water samples is carried out after adsorption from a 25–500 mL sample, on a cartridge containing 100 mg aminopropyl-bonded porous silica. The clean-up step in which the PCBs and chlorinated pesticides are separated in different eluates is achieved by passing 25 mL of 40% aqueous methanol through the NH₂ Sep-Pak cartridge. The PCBs are desorbed with 500 μL ethylacetate, which is concentrated and analysis by GC-ECD. The average recovery, at 1 ppb is >97% with a standard deviation <2. The limits of detection are 0.1 ng μL⁻¹ and 5 pg μL⁻¹ respectively for Cl₃-PCB and Cl₈-PCB congeners. In the separation of PCBs from the chlorinated pesticides tested in this work, only the Aldrin is adsorbed for 60% with the PCBs by the NH₂ Sep-Pak cartridge. The method described is rapid, simple and reproducible.     

Determination of polychlorinated biphenyls in sediment by on-line narrow-bore column liquid chromatography/capillary gas chromatography

Narrow-bore column liquid chromatography coupled on-line with capillary gas chromatography (LC/GC) is used for the determination of polychlorinated biphenyls (PCBs) in sediment via a heart-cutting technique. This method is compared with a method in which two off-line column clean-up steps are used with subsequent analysis by capillary gas chromatography. For the LC/GC analysis the recovery of PCBs was 90–100%. For two sediment samples from the river Meuse the LC/GC and the other, more laborious method showed good agreement.     

微波辅助萃取-气相色谱测定土壤中多氯联苯

建立了微波辅助萃取-气相色谱-微电子捕获检测土壤样品中6种多氯联苯(pcb28, pcb52, pcb101, pcb138, pcb153和pcb180)的方法. 确定了以V(20 mL丙酮):V(正己烷)＝1:1混合溶剂作萃取剂, 萃取温度110 ℃, 仪器功率800 W, 微波萃取5 min的样品前处理条件, 并用柱温程序优化了GC-μECD分析条件. 方法的检出限为0.027～0.087 ng/g; 相对标准偏差为3.4%～7.6% (n=6); 加标平均回收率79.8%～91.1%. 可用于土壤环境中多氯联苯的监测分析.     

Determination of traces of polychlorinated biphenyls in pigments

PCB patterns in a new pigment brand are characterized using GC-MS in the single ion monitoring (SIM) mode. Specific PCBs are then used as external standards for GC-ECD quantification. The following PCB isomers or groups of isomers have to be determined (CB = chlorobiphenyl): total diCBs, 3,3′ diCB, 2,4,5-triCB, 2,2′,4,4′-tetraCB, 2,2′,5,5′-tetraCB, total pentaCB, total hexaCB. Capillary gas chromatography is performed on preseparated solutions (LC) of pigment. An electron caputure detector (ECD) is used for PCB detection and quantification. Calibration is based on the peak areas of external standards and the PCB isomers in the samples, all normalized for internal standard peak areas. Total concentrations of diCB, hexaCB, or pentaCB in a sample are calculated by summing the individual PCB isomer concentrations within the correcsponding elution ranges. Determination limits lie in the range of 1 mg/PCB-isomer/kg pigment.     

Radiation degradation of polychlorinated biphenyls

Gradual dechlorination of the polychlorinated biphenyls (PCBs) in alkaline solutions in 2-propanol under the effect of high energy electrons (4.5 MeV) produced by electron accelerator has been studied using a flow-through apparatus of the volume of about 50 L. The dependence of both relative radiation chemical yield and the dechlorination degree on the initial concentration of OH⁻ ions or PCBs, absorbed dose as well as on dose rate has been investigated.     

Gas chromatographic enantiomer separation of agrochemicals and polychlorinated biphenyls (PCBs) using modified cyclodextrins

The enantiomers of the polychlorinated polycyclic xenobiotics heptachlor, cis- and trans-chlordane, cis- and trans-heptachlorepoxide, oxychlordane, and bromocyclen have been resolved by gas chromatography with selectively substituted cyclodextrins. The order of elution of these compounds and of α-hexachlorocyclohexane (α-HCH) was determined by comparison with enantiomerically enriched reference compounds obtained by preparative enantioselective gas chromatography. A separation of the eight stereoisomers of the pyrethroid insecticide allethrin into seven peaks was achieved. Both trans-diastereomers were separated into their enantiomers and the order of elution could be determined by comparison with commercially available (S)-bioallethrin and trans-bioallethrin. Also one cis-diastereomer was separated, wheras the other cis-isomer could not be resolved. In addition 15 out of 19 stable atropisomeric polychlorinated biphenyls with 5, 6 and 7 chlorine substituents, some chiral organophosphorus pesticides, including acephate and malaoxon and the herbicide bromoacil were separated.     

Determination of hydroxylated polychlorinated biphenyls by ion trap gas chromatography–tandem mass spectrometry

Hydroxylated polychlorinated biphenyls also known as biphenylols, are suspected estrogen mimics found in the environment. Various derivatization schemes were evaluated and a gas chromatography–ion trap mass spectrometry method was developed for the trifluoroacetyl derivative using MS–MS techniques for the analysis of eleven biphenylols. A time-segmented chromatographic method was developed using the respective MS–MS parameters to analyze all the eleven biphenylols in a single chromatographic run. Isomers were differentiated based on the MS–MS data of the trofluoroacetyl-biphenylol derivatives. The method was applied to detect 40 pg on-column of these compounds in a spiked egg sample which simulates a real world sample.     

Congener profile and toxicity assessment of polychlorinated biphenyls in human adipose tissue of Italians and Chileans

Human exposure to polychlorobiphenyls (PCBs) in humans was determined by analyzing adipose tissue samples collected in 1996–1997 from two different localities: Siena (Italy) and Concepción (Chile). ΣPCBs was higher in Italian samples than that from Chile (493 and 53 ng/g wet wt., respectively). Thirty-seven different PCB congeners were identified in all samples. The prevailing PCB congeners in both groups were 22′44′5 pentachlorobiphenyl (IUPAC no. PCB 118), 22′344′5′ (PCB-138) and 22′44′55′ (PCB-153) hexachlorobiphenyls and 22′33′44′5 (PCB-170), 22′344′55′ (PCB-180) and 22′34′55′6 (PCB-187) heptachlorobiphenyls. PCB-153 accounted for more than 20% of the total PCB residue in both groups, while the remaining six congeners accounted for approximately 70%. Hexachlorobiphenyls were the most abundant congeners in all samples, with 42% of total residue in those from Italy and 43% in the Chilean samples, followed by heptachlorobiphenyls with 41 and 36% in Italian and Chilean samples, respectively. Average concentrations of non-ortho substituted coplanar congeners were below 1 pg/g wet wt. In the samples from Siena no noticeable differences were observed between the three average coplanar concentrations, while in those from Concepción 33′44′tetrachlorobiphenyl (PCB-77) was much higher than 33′44′pentachlorobiphenyl (PCB-126) and 33′44′55′hexachlorobiphenyl (PCB-169). For each sample the contribution to the total toxic equivalent values (ΣTEQs) of each non-ortho, mono-ortho and di-ortho substituted PCB congeners was assessed. The overall TEQs calculated for the monitored PCBs, were 10.16 pg/g wet wt. in Italian samples and 1.09 pg/g wet wt. in Chileans ones. In both groups the main contribution to ΣTEQs were the di-ortho substituted PCB congeners (Siena: 6.17 pg/g wet wt.; Concepción: 0.56 pg/g wet wt.) and the mono-ortho substituted PCB congeners (Siena: 3.97 pg/g wet wt.; Concepción: 0.50 pg/g wet wt.).     

Determination of selected polychlorinated biphenyls in soil by miniaturised ultrasonic solvent extraction and gas chromatography-mass-selective detection

Miniaturised ultrasonic solvent extraction procedure was developed for the determination of selected polychlorinated biphenyls (PCBs) in soil samples by gas chromatography-mass-selective detection by using 2³ factorial experimental design. Recoveries of PCBs from fortified soil samples are over 90% for three different fortification levels between 40 and 120 μg kg⁻¹, and relative standard deviations of the recoveries are below 7%. The limits of detection (LODs) ranged from 0.003 to 0.006 μg kg⁻¹. The performance of the proposed method was compared to traditional shake flask extraction method on the spiked real soil sample and extraction methods showed comparable efficiencies. Proposed miniaturised ultrasonic solvent extraction offers several advantages, i.e., reducing sample requirement for measurement of target compound, less solvent consumption and reducing the costs associated with solvent purchase and waste disposal.