Ken A. Terry

Quantitative high-resolution gas chromatography and mass spectrometry of toxaphene residues in fish samples

This report describes an analytical method which permits the determination of ppb (1 microgram/kg) level of toxaphene in fish tissues. Interferences both from biogenic and from xenobiotic substances are reduced even with low-resolution mass spectrometry. The methodology has a low susceptibility to false positive determinations, which could result from the presence of a wide variety of co-contaminants. The method is based on the measurement of a signal representative of the toxaphene residue (m/z 158.9) relative to a known amount of an internal standard 37Cl-labelled compound. A modular approach to toxaphene enrichment has permitted a moderately simple procedure, significantly reducing analytical time requirements and the number of sample manipulations, and making the procedure amenable to automation. The reliability and accuracy of the procedure are demonstrated by the results of intra- and interlaboratory studies. The methodology has been validated and the presented data indicate that the detection limit is 1 microgra/kg of total toxaphene. Toxaphene recovery from fish at concentration levels between 0.1 and 10 micrograms/g is 84 +/- 12%.

Identification and determination of polychlorinated biphenyls by high-resolution gas chromatography

Abstract We have developed an integrated analytical procedure for polychlorinated biphenyl (PCB) multiresidues in sediment samples that enables quantitation of PCB residues at levels as low as 0.1 μg/kg in sediments. PCB residues are characterized and quantified by wall-coated open-tubular column gas chromatography with electron-capture detection. An automated data system, based on a Spectra Physics SP-4100 computing integrator, is used to select and quantitate peaks of individual isomers and homologous groups of PCBs. This procedure consistently yields results with a reproducibility within 3%.

GAS CHROMATOGRAPHIC SEPARATION OF PCB ATROPISOMERS ON CYCLODEXTRIN STATIONARY PHASES

Gas chromatographic study on chiral separation of PCBs was performed in a series of capillary columns coated with 0.1-μm film of modified cyclodextrin (CD) stationary phases. The preparation of columns included the investigation into the effect of the content of cyclodextrin derivative in polysiloxane, the type of polysiloxane and temperature of analysis on the quality of separation and retention of atropisomers of 15 selected PCB congeners. The separation properties towards PCBs of stationary phase heptakis(2,3-di-O-methyl-6-O-tert-butyl-dimethylsilyl)-β-CD dissolved in SE-30, SE-54, and OV-1701, were compared with those of 6-monokis-octamethylene-permethyl-β-CD anchored to polydimethylsiloxane polymer (ChirasilDex column, Chrompack, Middelburg, The Netherlands) and octakis(2,6-di-O-methyl-3-O-pentyl)-γ-CD in OV-1701 (MEGA, Legnano (MI), Italy). The correctness of quantitative enantiomer ratio determination was assesed by splitless analysis of PCBs reference solutions in concentration of 1.25–125 ng/ml (PCBs 45 and 91) and 2.5–250 ng/ml (PCB 95) (the PCB congeners are numbered according to IUPAC). Chirality 10:540–547, 1998.

Determination of toxaphene in soil by electron-capture negative-ion mass spectrometry and capillary column gas chromatography

Abstract Although toxaphene is now limited in use, interest in its analysis continues because of its persistence and widespread atmospheric transport in the environment and its presence in many dump-sites all over the world. Top soil samples collected from a dump site were analyzed for toxaphene residues. Analyses were performed by wall-coated open tubular column gas chromatography in tandem with electron-capture negative-ion mass spectrometry. Since the concentrations of toxaphene residues were at mg/kg levels, the application of a mass spectrometer as a substance-selective detector has been applied. Advantages of this mode of real-time acquisition in continuous repetitive scanning of mass spectra has significant advantages in comparison to the selected-ion monitoring technique. An average R.S.D. of 10% and recoveries of 90 to 109% were obtained. Levels down to 50 μg/kg are obtainable.