Hans-Rudolf Buser

Analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans in chlorinated phenols by mass fragmentography.

A rapid, highly specific method for the analysis of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in pentachlorophenol and other chlorinated phenols is described. The rapid sample preparation procedure includes an alkaline extraction of phenolic compounds and chromatography of the neutral substances on an alumina micro-column. After gas chromatographic separation, individual polychlorinated dibenzo-p-dioxins and dibenzofurans are detected and quantified by mass fragmentography. The sample purification procedure removes polychlorinated diphenyl ethers, polychlorinated biphenyls and benzenes, phthalates and polychlorinated phenoxyphenols (predioxins), which might otherwise severely interfere in the analysis. Significant levels of hexa-, hepta- and octachlorodibenzo-p-dioxin and of hexa-, hepta- and octachlorodibenzofuran were found in two commercial products.

Polychlorinated dibenzo-p-dioxins : Separation and identification of isomers by gas chromatography-mass spectrometry

Abstract Attempts were made to synthesize all polychlorinated dibenzo-p-dioxin isomers containing six to eight chlorine atoms by micro-scale pyrolysis of different polychlorophenates. Eight of the ten possible hexachlorodibenzo-p-dioxins, the two hepta- and the octachlorodibenzo-p-dioxin were observed and separated by gas chromatography using glass capillary columns. Without actual isolation of these toxic materials, isomers were characterized by gas chromatography and mass spectrometry. Commercial chlorinated phenols were analyzed for the presence of these isomers. The major hexachlorodibenzo-p-dioxin observed in two commercial products was the unexpected 1,2,3,7,8,9-substituted isomer, which was not formed as the main dioxin component in any of the pyrolysis experiments. The same isomer was reported to be isolated from toxic fat and identified by X-ray crystallography.

Preparation of qualitative standard mixtures of polychlorinated dibenzo-p-dioxins and dibenzofurans by ultraviolet and γ-irradiation of the octachloro compounds

High-resolution gas chromatography using an OV-17 glass capillary column and mass spectrometry were used to analyze uv-and psi-irradiated octachlorodibenzo-rho-dioxin and octachlorodibenzofuran. Under the conditions investigated, dechlorination of these compounds to lower chlorinated dibenzo-rho-dioxins and dibenzofurans appears to be the major reaction pathway. The resulting mixtures of penta-, hexa-and heptachloro compounds can be used as easily and safely prepared qualitative reference samples to determine gas chromatographic, mass spectrometric and other properties of individual components for which pure standards are not available.

Determination of 2,3,7,8-tetrachlorodibenzo-1,4-dioxin at parts per billion levels in technical-grade 2,4,5-trichlorophenoxyacetic acid, in 2,4,5-T alkyl ester and 2,4,5-T amine salt herbicide formulations by quadrupole mass fragmentography☆

Abstract A fast, higly selective gas chromatographic method was developed for the determination of 2,3,7,8-tetrachlorodibenzo-1,4-dioxin (TCDD) in technical 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and also in 2,4,5-T alkyl ester and amine salt herbicide formulations using quadrupole mass fragmentography. The method is faster, more sensitive and has a higher specificity than previously reported methods using conventional gas chromatography. It requires minimal or no sample clean-up. The content of TCDD found in batches of 2,4,5-T produced from 1967 to 1973 by one manufacturer showed a sharp decrease after 1970 from 500 to 50 ppb.

Sex pheromone blends of three tortricid pests in European vineyards

Abstract The sex pheromone glands of the three most important tortricids of European vineyards, Eupoecilia ambiguella Hbn., Sparganothis pilleriana Den. and Schiff. and Lobesia botrana Den. and Schiff., have been chemically investigated and found to contain up to 15 different straight-chain acetates and alcohols. Behavioural observations in the wind tunnel and field trapping demonstrate that in each species at least three female-produced components are involved in male attraction.

Analysis of insect pheromones by quadrupole mass fragmentography and high-resolution gas chromatography

A sensitive technique is described for the analysis of insect pheromones. Insect extracts are separated into fractions by column chromatography and are analyzed directly by quadrupole mass fragmentography on high-resolution glass capillary columns and by mass spectrometry. Applications are illustrated with two important pests. In the codling moth, trans-8, trans-10-dodecadien-1-ol was found to be present at a level of 3.5 ng per female, and in the European grapevine moth trans-7, cis-9-dodecadienyl acetate at a level of 1.6 ng. Both compounds appear to be present in high isomeric purity in the female insect and are absent in the corresponding males.