Bert van Bavel

Pressurised liquid extraction of polycyclic aromatic hydrocarbons from contaminated soils

The reliability and efficiency of the pressurised liquid extraction technique (PLE) for extracting polycyclic aromatic hydrocarbons (PAHs) from contaminated soil has been investigated. Experimental design was used to study the influence of seven extraction variables (sample load, solvents used, solvent ratios, pressure, temperature, extraction time, and rinse volume). The results show that large sample loads in combination with small solvent volumes may result in low extraction efficiency. They also indicate that the recovery of low-molecular-mass PAHs is reduced by low extraction temperatures. The exact settings of the other variables are, however, less significant for the extraction efficiency. Repeated extractions at optimised settings of the tested variables show that PLE is an exhaustive extraction technique that generally results in high yields. In addition, extraction of a certified reference material (CRM 103-100) revealed that the method is both accurate and precise. Another finding was that adding the internal standard on top of the soil in the extraction cell causes considerable over-estimation of the concentrations when large samples are extracted with small solvent volumes. This is because the PLE-cell resembles a chromatographic column, so compounds added to the top of the soil layer have a longer distance to travel through the soil compared to the average distance of the native compounds, which are distributed evenly throughout the column. We therefore recommend that the internal standard should be added to the extract immediately after the extraction or, alternatively, carefully mixed with the sample prior to extraction.

Polybrominated diphenyl ethers detected in human adipose tissue from Spain.

Polybrominated diphenyl ethers (PBDEs) were detected in 13 human adipose tissue samples from Spain, 3 women and 10 men. Tetra-, penta- and hexabrominated diphenyl ethers were determined at ng/g lipid (ppb) level in all the samples. The average TeBDE level was 1.36 ng/g, the average PeBDE was 0.93 ng/g and the HxBDE 1.83 ng/g. Human adipose tissue levels of PBDE obtained in the current samples from Spain are comparable with the tissue levels reported in recent Swedish investigations.

Levels of PCBs in the aquatic environment of the Gulf of Bothnia : Benthic species and sediments

Levels of PCBs in the aquatic environment of the Gulf of Bothnia: Benthic species and sediments

Organochlorine compounds in the Gulf of Bothnia: sediment and benthic species

Surface sediment, amphipods (Monoporeia affinis), isopods (Saduria entomon) and fourhorn sculpins (Oncocottus quadricornis) were collected at two coastal stations in the Gulf of Bothnia, one in the Bothnian Bay and the other in the Bothnian Sea. The objective was to study the concentrations, composition profiles, bioaccumulation features and spatial differences of organochlorine compounds such as hexachlorocyclohexanes (HCHs), DDTs, hexachlorobenzene (HCBz), chlordanes (CHLs), dieldrin, Mirex and polychlorinated biphenyls (PCBs). All groups of compounds were found in every sample investigated, with the exception of Mirex that was not detected in the sediment samples. The concentrations for e.g. PCBs and CHLs ranged from 700 to 2400 and 70 to 400 ng/g lipid in the specimens. For the corresponding sediments the results were 9.0-9.3 ng/g dw for PCBs and 0.54-0.57 ng/g dw for CHLs, respectively. Bioaccumulation differences between the species with regard to both degree of and type of compound were observed. The highest accumulation potential was found for the cyclodiene compounds including CHLs and Mirex in isopod. Finally, there were only small concentration and bioaccumulation differences between the two stations.

Supercritical fluid extraction of PCBs from human adipose tissue for HRGC/LRMS analysis

Supercritical fluid extraction (SFE) of 36 PCBs from human adipose is presented. Selective extraction of the PCBs is achieved using supercritical CO2 with a density of 0.9 g/ml (281 bar) at 40 degrees C and with AlOx as a fat retainer. Compared to the traditional liquid extraction method followed by further sample clean up, SFE is not only faster (2 hours compared to three days) but also utilises lower amounts of organic solvents (4 ml compared to over 500 ml). The recoveries of 7 added 13C labelled PCBs are 83-106%. The repeatability in the analysis of 36 PCBs in 6 identical samples is excellent, with an average R.S.D. of less than 10%.

Development of a high-performance liquid chromatography carbon column based method for the fractionation of dioxin-like polychlorinated biphenyls

A method to separate polychlorinated biphenyls (PCBs) by using high-performance liquid chromatography (HPLC) was developed. The HPLC column was packed with Amoco PX-21 activated carbon dispersed on octadecylsilane (ODS). The separation was carried out by gradient elution with n-hexane-dichloromethane and toluene in the forward direction followed by reversed elution with toluene. The results show that this HPLC method is useful for the separation of PCBs according to the number of substituted ortho chlorine atoms attached to the biphenyl structure. Average recoveries for a number of individual di-ortho PCBs, mono-ortho PCBs, and non-ortho PCBs in three selected elution windows were 97, 92, and 96%, respectively. Clophen A50, a herring sample, and a cod liver oil sample were fractionated on the column and the analytical results are compared with data from the literature. The method presented here is useful for quantitative separations of mono-ortho PCBs as well as non-ortho PCBs which have been assigned toxic equivalency factors by the World Health Organisation.

Potential pathways and exposure to explain the human body burden of organochlorine compounds: a multivariate statistical analysis of human monitoring in Würzburg, Germany.

By means of multivariate statistical analysis of human monitoring in the vicinity of Würzburg it is examined whether the organochlorine levels in blood data of 309 persons can in part be explained by pollution from outdoor and/or indoor air. Although diet is the main source for intake this study concentrated on the remaining sources. Using 12 personal and geographical variables, which describe some aspects or components of indoor or outdoor exposure, the quantities of the different pathways for the intake are calculated and shown. Besides the impact of the indoor air, which can be pointed out for intake at the workplace for some PCB-congeners, also the hypothesis of the existence of an intake from outdoor air for some organochlorine compounds cannot be rejected. Here, the origin is the spatial variation of the pollution, which can be directly traced back to micro-climatic processes, local relief conditions, and the functional set-up of the town.

Results from the second round of the international intercalibration on PCDDs, PCDFs and PCBs in a fly ash extract

The second round of an international intercalibration exercise on the determination of PCDD/DFs and planar PCBs in a fly ash extract took place in 1995/96. Thirty laboratories from around the world were participating, 25 of them were able to produce results before the expiration of the dead line. Six extracts from three batches were sent to the participants who reported the levels of all 2,3,7,8-substituted PCDD/DF congeners, PCB #77, #126 and #169 plus the total of PCDD/DFs at each chlorination level. The results showed good agreement between 21 laboratories with a RSD below 15% for the total TEQ. The results were further evaluated with multivariate statistics. Plots from principal component analyses identified analytical problems for some of the participants, but clustering of the majority of the participants.

Results from an international intercalibration study on PCDDs and PCDFs in a fly ash extract

Abstract Three fly ash extracts, of which two fortified with different PCDFs and PCDFs congeners, were analysed by eight different laboratories. The results show relatively good precision, RSD for levels reported as TEQs are below 25%. Problems with the analysis of 1,2,3,7,8,9-HxCDF was observed. Multivariate data analysis was performed to explore the data and principal component analyses of the data set revealed clustering of different laboratories.

Multivariate structure‐activity relationships for farmacokinetic uptake/elimination curves of polychlorinated dibenzofurans in adipose tissue for four animal species

Adequate multivariate structure‐activity relationships (SARs) were calculated by partial least‐squares (PLS) predicting the complete uptake and elimination curves for 63 PCDFs (tetra to hexa chlorinated congeners) in adipose tissue for guinea pig, hamster, mouse and rat. The SARs for uptake and elimination for these 63 congeners were calculated from a experimental determined data set which contained 16 congeners. The models were tested by selecting a training set (12 congeners) from which predictions were computed for a validation set (4 congeners). This validation set was selected from the 16 congeners by means of a principal component analyses (PCA) of 13 physico‐chemical properties of the PCDFs. Models using only the half‐life (t½) for elimination showed less predictive capability than modelling the complete uptake and elimination curves. Loading plots from the PLS analyses revealed that different physico‐chemical properties were responsible for uptake and elimination. The ionisation potential, the low...