Determination of polychlorinated biphenyls in biota samples using simultaneous pressurized liquid extraction and purification

Removing Disturbing Matrix Constituents from Biota Extracts from Total Extraction and Silicone-Based Passive Sampling

Contaminant analysis in biota extracts can be hampered by matrix interferences caused by, for example, co-extracted lipids that compromise the quality of the analytical data and require frequent maintenance of the analytical instruments. In the present study, using gas chromatography coupled to high resolution mass spectrometry (GC-HRMS), we aimed to develop and validate a straightforward, robust, and reproducible cleanup method with acceptable recoveries for diverse compound classes with a wide range of physicochemical properties representative of pollutant screening in biota extracts. We compared Oasis PRiME HLB cartridges, Agilent Captiva EMR-Lipid cartridges, and "Freeze-Out" with salmon lipids spiked with 113 target chemicals. The EMR-Lipid cartridges provided extracts with low matrix effects at reproducible recoveries of the multi-class target analytes (93 ± 9% and 95 ± 7% for low and high lipid amounts, respectively). The EMR-Lipid cartridges were further tested with spiked pork lipids submitted to total extraction or silicone-based passive sampling. Reproducible recoveries were achieved and matrix residuals were largely removed as demonstrated gravimetrically for both types of extracts. Ion suppression of halogenated compounds was not as efficiently removed by the cleanup of total and silicone-based extracts of pork lipids as for the salmon lipids. However, the samples with clean up provided better instrument robustness than those without cleanup. Hence, EMR-Lipid cartridges were shown to be efficient as a cleanup method in multi-class monitoring of biota samples and open up new possibilities as a suitable cleanup method for silicone extracts in biota passive sampling studies using GC-HRMS analysis. Environ Toxicol Chem 2021;40:2693-2704. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

A multiresidue method for the analysis of pesticides, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls in snails used as environmental biomonitors

This paper reports an optimized multiresidue extraction strategy based on the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction procedure and on solid-phase microextraction (SPME) for the simultaneous screening of 120 pesticides, 16 polycyclic aromatic hydrocarbons, and 22 polychlorinated biphenyls from the terrestrial snail Helix aspersa. The optimized extraction method was based on QuEChERS using acetonitrile, followed by dispersive-Solid-phase extraction clean-up using primary secondary amine and octadecyl (C18) sorbents. The obtained extracts were analyzed by liquid chromatography coupled with tandem mass spectrometry and gas chromatography coupled with tandem mass spectrometry. This latest technique was preceded by a pre-concentration step using SPME with appropriate fibers. Afterwards, the method was validated for its linearity, sensitivity, recovery, and precision. Results showed high sensitivity, accuracy, and precision, with limits of detection and quantification lower than 20 ng g ^- 1 for most considered pollutants. Both inter and intra-day analyses revealed low relative standard deviation (%), which was lower than 20% for most targeted compounds. Moreover, the obtained regression coefficient (R²) was higher than 0.98 and the recoveries were higher than 60% for the majority of the assessed pollutants.

Determination of organochlorine priority substances in fish tissue: Optimisation of the clean-up step balancing removal of lipids with analytes' recovery

Quality-assessed analytical methods are required to determine organic priority substances (PS) in biota for the monitoring of the water status according to the EU Water Framework Directive. Although the literature describes several analytical methods to determine these substances in fish, discussion about the efficiency of the clean-up procedures to remove the lipids in the final organic extract (and decrease the disturbance of co-extractives at the detection step) is scarce. This work highlights the results of the development of an analytical method for organochlorines in fish tissue focused on the optimisation of the clean-up step in order to obtain a final extract with the lowest amount of lipids. The efficiency of the purification of the final extract was assessed by quantifying the removal of co-extractives gravimetrically, by considering the sensitivity of the gas chromatography-mass spectrometry (GC-MS) method for the analytes and by assessing the analytes' recovery. An analytical method based on accelerated solvent extraction followed by gel permeation chromatography and dual solid phase extraction (as clean-up steps) and quantification via isotope dilution GC-MS was applied to the analysis of seven PS [α-, β-, γ- and δ-hexachlorocyclohexane (HCH) isomers, pentachlorobenzene (PeCB), hexachlorobenzene (HCB) and hexachlorobutadiene (HCBD)]. A preliminary validation of the method was carried out with satisfactory results for all analytes in terms of intermediate precision (2.9-9.4%, except 11.8% for β-HCH). Repeatability values were satisfactory for α-, γ-HCH, PeCB and HCB (4.3-6.9%), while the obtained results for β-, δ-HCH and HBCD showed the need for further optimisation. Trueness was within the target performance (recovery range: 96.0-107.5%) for all analytes except β- and δ-HCH. Limits of quantification between 0.5 and 3.3 ng/g wet weight were achieved, depending on the analytes. The proposed method can be employed to determine the mentioned PS in fish tissue with up to approximately 6% lipid content. The presented results show the challenges in establishing an analytical method which aims at balancing the required accuracy with the routine applicability (and a minimised impact on the detection system) as needed in the context of environmental monitoring.

Distribution and transfer pattern of Polychlorinated Biphenyls (PCBs) among the selected environmental media of Ny-Ålesund, the Arctic: As a case study

Polychlorinated Biphenyls (PCBs) were analyzed in multi-environmental samples collected from Ny-Ålesund, the Arctic to explore their legacy and transfer patterns. PCBs were ubiquitously in the environmental media, within the ranges of 1.73-6.27 and 9.18-141.1 pg m(-3) in vapor and aerosol, 2.76-10.8, 3.09-8.32, 22.5-56.3, 35.4-51.4 and 31.8-39.6 ng g(-1) (dry weight) in soil, sediment, plant, bird guano and reindeer faeces, respectively. The spatial distribution patterns exhibited a general southward decline in soil and sediment from the bay entrance to the inner bay. The concentration ratios of plants to soil inferred that no distinguished selective adsorption of PCBs congeners by plants existed and PCBs were mainly attributed to the air deposition on plant surface. The fugacity ratios among vapor, aerosol and soil indicted that the equilibrium status has not been reached and the net transferring direction was air-soil.

Development and application of a novel method for high-throughput determination of PCDD/Fs and PCBs in sediments

A selective pressurized liquid extraction technique was developed for the simultaneous extraction of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) from contaminated sediments. The final method incorporated cleanup adsorbents (Florisil, alumina, and silica) into the extraction cell in a 1:1 ratio of matrix to individual adsorbent (w/w). Sulfur, a common interference found in sediments, was successfully removed by placing activated copper in the extraction bottle prior to extraction. No additional postextraction cleanup was required, and sample throughput was reduced to 2.5 h per sample. Target analytes were quantified using high-resolution gas chromatography/electron-capture negative ionization mass spectrometry and verified by high-resolution gas chromatography/high-resolution mass spectrometry. Though mean analyte recoveries (n = 3) of PCDD/Fs and dl-PCBs were 84 ± 5.8% and 70 ± 8.4%, respectively, mean surrogate recoveries for all PCDD/Fs using this novel method were greatly improved compared with US Environmental Protection Agency (USEPA) method 1613 (∼25-155%) and USEPA method 8290a (40-135%). After development, the method was used to examine surficial sediment samples from the San Jacinto River waste pits, a Superfund site in Houston, Texas, USA. In all samples, PCDD/Fs and dl-PCBs were detected, and the contaminant concentrations ranged over 5 orders of magnitude.

Accelerated solvent extraction for natural products isolation

Accelerated solvent extraction (ASE(®)), first introduced in 1995, is an automated rapid extraction technique that utilizes common solvents at elevated temperature and pressure, and thereby increases the efficiency of extraction of organic compounds from solid and semisolid matrices. ASE(®) allows extractions for sample sizes 1-100 g in minutes, reduces solvent uses dramatically, and can be applied to a wide range of matrices, including natural products.

Simultaneous determination of benzotriazoles and ultraviolet filters in ground water, effluent and biosolid samples using gas chromatography-tandem mass spectrometry

A new method using gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed for the determination of four benzotriazoles, i.e. benzotriazole (BT), 5-methylbenzotriazole (5-TTri), 5-chlorobenzotriazole (CBT), 5,6-dimethylbenzotriazole (XTri), and six UV filters, i.e. benzophenone-3 (BP-3), 3-(4-methylbenzylidene)camphor (4-MBC), octyl 4-methoxycinnamate (OMC), 2-(3-t-butyl-2-hydroxy-5-methylphenyl)-5-chloro benzotriazole (UV-326), 2-(2'-hydroxy-5'-octylphenyl)-benzotriazole (UV-329), and octocrylene (OC) in ground water, effluent and biosolid samples. Solid phase extraction (SPE) and pressurized liquid extraction (PLE) were applied as the preconcentration method for water samples (ground water and effluent) and biosolid samples, respectively. The optimized method allowed us to quantify all target compounds with the method detection limits ranging from 0.29 to 11.02 ng/L, 0.5 to 14.1 ng/L and 0.33 to 8.23 ng/g in tap water, effluent and biosolid samples, respectively. The recoveries of the target analytes in tap water, effluent and biosolid samples were 70-150%, 82-127% and 81-133%, respectively. The developed analytical method was applied in the determination of these target compounds in ground water, effluent and biosolid samples collected from Bolivar sewage treatment plants in South Australia. In effluent samples, the target compounds BT, 5-TTri, CBT, XTri and BP-3 tested were detected with the maximum concentration up to 2.2 μg/L for BT. In biosolid samples, eight out of ten compounds tested were found to be present at the concentrations ranging between 18.7 ng/g (5-TTri) and 250 ng/g (4-MBC).

An investigation into the occurrence and distribution of polycyclic aromatic hydrocarbons in two soil size fractions at a former industrial site in NE England, UK using in situ PFE-GC-MS

Polycyclic aromatic hydrocarbon (PAH) concentrations were determined in 16 topsoils (0-10 cm) collected across the site of a former tar works in NE England. The soils were prepared in the laboratory to two different particle size fractions: <250 μm (fraction A) and >250 μm to <2 mm (fraction B). Sixteen priority PAHs were analysed in the soils using in situ pressurised fluid extraction (PFE) followed by gas chromatography-mass spectrometry (GC-MS). The average total PAH concentration in the soils ranged from 9.0 to 1,404 mg/kg (soil fraction A) and from 6.6 to 872 mg/kg (soil fraction B). These concentrations are high compared with other industrially contaminated soils reported in the international literature, indicating that the tar works warrants further investigation/remediation. A predominance of higher-molecular-weight compounds was determined in the samples, suggesting that the PAHs were of pyrogenic (anthropogenic) origin. Statistical comparison (t-test) of the mean total PAH concentrations in soil fractions A and B indicated that there was a significant difference (95% confidence interval) between the fractions in all but two of the soil samples. Additionally, comparisons of the distributions of individual PAHs (i.e. 16 PAHs × 16 soil samples) in soil fractions A and B demonstrated generally higher PAH concentrations in fraction A (i.e. 65.8% of all individual PAH concentrations were higher in soil fraction A). This is important because fraction A corresponds to the particle size thought to be most important in terms of human contact with soils and potential threats to human health.

Determination of pharmaceuticals in environmental and biological matrices using pressurised liquid extraction--are we developing sound extraction methods?

Pressurised liquid extraction (PLE) is now a well established and extensively applied extraction technique in environmental analysis for pollutants such as persistent organic pollutants (POPs). During the past decade, an emerging group of environmentally interesting analytes are pharmaceuticals that are continuingly released into the environment. This class is comprised with compounds of various properties. As the field of the analysis of these compounds grows, an increasing number of PLE methods for pharmaceuticals of varying quality are developed and published. This review summarises the critical PLE parameters during PLE method development and highlight them with examples from recently published papers utilising pressurised liquid extraction for the determination of pharmaceuticals in environmental and biological matrices. These recent methods are summarised and critically discussed with the aim to provide important reflections to alleviate in future PLE development for pharmaceuticals in environmental matrices.

Optimization of the matrix solid phase dispersion extraction procedure for the analysis of polybrominated diphenyl ethers in human placenta

Characterization of prenatal exposure to hazardous chemicals most often relies upon the analysis of cord blood. However, human placenta is an appropriate tissue alternative with noteworthy advantages. Owing to analytical challenges, reports on placental levels of toxic chemicals are limited. The purpose of this study was to establish a reliable, cost-effective, and relatively fast and simple method to extract polybrominated diphenyl ethers (PBDEs) from human placenta for analysis using gas chromatography coupled with mass spectrometry (GC/MS). The matrix solid phase dispersion (MSPD) method was optimized for the extraction and analysis of 43 PBDEs (including BDE209) from human placenta samples. Different sorbents, sample conditions, grinding methods, elution solvents, and single and repeated extractions were compared for their effects on the extraction efficiency. The performance of the optimized method was validated by analyzing spiked placenta samples and a standard reference material of fish tissue. Congener specific PBDE recovery ranged from 91% to 114% for the spiked samples and 89% to 115% for a standard reference material (SRM) of fish tissue. The optimized MSPD procedure was compared with two conventional extraction methods. The extraction efficiency of MSPD was found to be comparable with that of the traditional Soxhlet method and superior to that using a liquid extraction method. Twenty two PBDEs were detected in all of the five samples collected in Chicago in 2008. This is the first description of PBDEs detected in human placentas in the U.S.

Simultaneous extraction and cleanup method based on pressurized solvent extraction for multiresidue analysis of pesticides in complex feed samples

The development of a multiresidue method based on pressurized solvent extraction (PSE) to determine a large number of pesticides (mostly pyrethroids and organochlorines) in cattle feed is described. As far as we know, this is the first work dedicated to the PSE of many of the target pesticides from animal feed. A mixed level fraction design was performed to investigate the influence of several operational variables on the PSE procedure; integrated cleanup strategies were also assessed allowing the direct chromatographic analysis of the extracts. Method accuracy was evaluated by the analysis of a certified reference material (BCR-115) and different fortified cattle feed samples. Most analytes were recovered in the range of 70-110%, with relative standard deviations generally lower than 15%. Limits of detection (LODs) were below the maximum residue levels (MRLs) set by the European Union for animal feed and main crops used in the preparation of feedingstuffs. The applicability of the proposed method was demonstrated by the analysis of real cattle feed samples collected from 23 dairy farms located in Galicia (NW Spain).

Methods for determining pesticides and polychlorinated biphenyls in food samples--problems and challenges

Determination of residual amounts of pesticides and polychlorinated biphenyls (PCBs) in food samples requires the use of specific techniques regarding sample preparation as well as instrumental analysis which should be characterized by a very low detection limit. A problem associated with the use of pesticides and PCBs is the need for controlling their residues in the environment, particularly in food, as these chemicals show a propensity to accumulate. The analysis of food samples for the presence of pesticides and PCBs brings on many difficulties because of the specificity of sample preparation consisting of multistep purification procedures of samples that contain trace amounts of an analyte. Concentration determinations of pollutants that easily dissolve in complex matrices, particularly in the presence of a large apportionment of interfering substances, pose a big challenge. Therefore, the basic step in food analysis for the presence of pesticides and PCBs is sample preparation which mainly consists of analyte enrichment and the removal of interfering substances. But all steps of the analytical procedure that include sample collection and preparation, extraction of analytes from matrix, extract purification, and final determination, are very significant; their precision and correct application have a decisive effect on the final result.

An experimental design approach employing artificial neural networks for the determination of potential endocrine disruptors in food using matrix solid-phase dispersion

Matrix solid-phase dispersion (MSPD) as a sample preparation method for the determination of two potential endocrine disruptors, linuron and diuron and their common metabolites, 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU), 1-(3,4-dichlorophenyl) urea (DCPU) and 3,4-dichloroaniline (3,4-DCA) in food commodities has been developed. The influence of the main factors on the extraction process yield was thoroughly evaluated. For that purpose, a 3 fractional factorial design in further combination with artificial neural networks (ANNs) was employed. The optimal networks found were afterwards used to identify the optimum region corresponding to the highest average recovery displaying at the same time the lowest standard deviation for all analytes. Under final optimal conditions, potato samples (0.5 g) were mixed and dispersed on the same amount of Florisil. The blend was transferred on a polypropylene cartridge and analytes were eluted using 10 ml of methanol. The extract was concentrated to 50 microl of acetonitrile/water (50:50) and injected in a high performance liquid chromatography coupled to UV-diode array detector system (HPLC/UV-DAD). Recoveries ranging from 55 to 96% and quantification limits between 5.3 and 15.2 ng/g were achieved. The method was also applied to other selected food commodities such as apple, carrot, cereals/wheat flour and orange juice demonstrating very good overall performance.

Simultaneous extraction and clean-up of polychlorinated biphenyls and their metabolites from small tissue samples using pressurized liquid extraction

A pressurized liquid extraction-based method for the simultaneous extraction and in situ clean-up of polychlorinated biphenyls (PCBs), hydroxylated (OH)-PCBs and methylsulfonyl (MeSO(2))-PCBs from small (<0.5 g) tissue samples was developed and validated. Extraction of a laboratory reference material with hexane-dichloromethane-methanol (48:43:9, v/v) and Florisil as fat retainer allowed an efficient recovery of PCBs (78-112%; RSD: 13-37%), OH-PCBs (46+/-2%; RSD: 4%) and MeSO(2)-PCBs (89+/-21%; RSD: 24%). Comparable results were obtained with an established analysis method for PCBs, OH-PCBs and MeSO(2)-PCBs.

Determination of organochlorine compounds in neuston from the Mediterranean

A reliable analytical procedure was developed to determine trace levels of organochlorine compounds in neuston samples. Freeze-dried samples were extracted by sonication (3 x 15 ml cyclohexane, 15 min) followed by gel permeation chromatography (GPC) and gas chromatography electron capture detection (GC-ECD) determination. Neuston samples may present great differences in their lipid content, which may become a drawback for the analytical determination of hydrophobic pollutants. In this way, GPC fractionation combined with Florisil cleanup was successfully used to avoid potential lipidic interferences in the GC-ECD determination. Organochlorine compounds were determined by GC-ECD and a standard addition method was performed to evaluate the recoveries of 41 PCB individual congeners (80 +/- 20%). The congeners with lower K(ow) (octanal water partition coeeficient) values showed lower recoveries (54 +/- 7%) than the more lipophylic ones (80 +/- 7%). The limits of detection ranged from 0.001 to 0.211 ng g(-1) of wet samples. The reproducibility of the developed analytical methodology for independent replicates (n = 3) at low pg g(-1) levels was quite satisfactory (RSD 18 +/- 10%).