Karel Janák

Hexabromocyclododecane in marine species from the western scheldt estuary : Diastereoisomer- and enantiomer-specific accumulation

Hexabromocyclododecane (HBCD) is a widely used brominated flame retardant, which is increasingly reported in the environment. Here, we report on the diastereomeric and, for the first time, on the enantiomeric composition of HBCD in muscle and liver of several fish species caught in the Western Scheldt Estuary (The Netherlands). The total HBCD content (sum of alpha-, beta-, and gamma-diastereoisomers), as well as the distribution of diastereoisomers and enantiomers, varied between the species. The levels of total HBCD (9-1110 ng/g lipid weight) found in fish tissues were higher than those measured in fish from European rivers with no known point sources of HBCD but lower than in fish samples collected near factories producing or using HBCD. The concentrations of total HBCD expressed on a lipid weight basis were higher in liver than in muscle for bib and whiting, while in sole, HBCD had no preferential distribution between the tissues. A similar pattern for liver and muscle distribution was already observed for polybrominated diphenyl ethers (PBDEs) in these species. The alpha-HBCD diastereoisomer was most abundant in all fish samples with a higher contribution to the total HBCD levels in liver compared to muscle for bib and whiting. The gamma-HBCD diastereoisomer accumulated less in liver than in muscle of sole, bib, and whiting. For the first time, enantiomer fractions were determined for HBCD diastereoisomers in liver of three fish species and in muscle of two fish species. A significant enrichment of the (+) alpha-HBCD enantiomer was found in whiting and bib liver samples. A high enantioselectivity has also been seen for the gamma-HBCD diastereoisomer in whiting liver.

Determination of phenolic flame-retardants in human plasma using solid-phase extraction and gas chromatography–electron-capture mass spectrometry

A method for determination of phenolic flame-retardants in human plasma utilizing solid-phase extraction (SPE) and gas chromatography with electron-capture mass spectrometric detection (GC-ECMS), has been developed. The plasma lipids were decomposed by application of concentrated sulphuric acid directly on the polystyrene-divinylbenzene SPE column. The method has been validated for 2,4,6-tribromophenol (TriBP), pentabromophenol (PeBP), tetrachlorobisphenol-A (TCBP-A) and tetrabromobisphenol-A (TBBP-A) in the concentration range 1.2-25, 0.4-40, 4-200 and 4-200 pg g(-1) plasma, respectively. The average absolute recovery of the analytes ranged from 51 to 85%. Tetrabromo-o-cresol and chlorotribromobisphenol-A were found suitable as internal standards, and the average recovery of the analytes relative to the internal standards was in the range 93-107%. The repeatability of the method was in the range 4-30% relative standard deviation. The estimated detection limits of TriBP, PeBP, TCBP-A and TBBP-A were 0.3, 0.4, 3.0 and 0.8 pg g(-1) plasma, respectively. The method has been used for analysis of plasma samples from potentially occupationally exposed human individuals.

Determination of polychlorinated biphenyls in human blood by solid-phase extraction including on-column lipid decomposition

A method for the isolation of polychlorinated biphenyls (PCBs) from human blood using solid-phase extraction (SPE) has been developed. The procedure incorporates decomposition of lipids by concentrated sulphuric acid directly on the SPE column. Conditions for transferring PCBs onto the SPE column and washing the decomposed blood components from the SPE column were optimised. After clean-up the extracts were analysed using gas chromatography with electron capture detection. An average recovery of PCBs from spiked blood samples was about 78+/-8% and an average precision was about 109+/-7%. Quantitation has been done using four internal standards and calibration curves based on five concentration levels. Low procedural blanks made it possible to determine PCBs in blood quantitatively at a level down to 2-10 pg g(-1). The integrated method for blood is fast, less laborious than methods using liquid-liquid extraction and has a low consumption of organic solvents.

Mass transfer in open-tubular supercritical fluid chromatography

Solute band broadening in 50 μm I.D. open tubular columns coated with PS-264 stationary phase has been evaluated in supercritical fluid chromatography. An improved method for on-column measurements of stationary phase swelling was used. For the conditions evaluated, a significant contribution to the total solute band broadening originating from stationary phase interactions was found. Possible sources of solute band broadening in the stationary phase are discussed.