Investigation of heroin profiling using trace organic impurities.

The acidic and neutral impurities in heroin samples (46 Purified South-East Asian (PSEA) and 8 non-PSEA samples) were analysed using gas chromatography. Mass spectral detection allowed the construction of a comprehensive library of over 649 impurities. A variety of statistical procedures were used to select 70 viable profiling parameters. Cluster analyses were used to investigate the similarities between samples using organic parameters. A blended PSEA profile was constructed for comparison with samples of unknown origins. Resolution between samples of PSEA/non-PSEA origins was demonstrated with a selection of 25 (18 continuous and 7 dichotomised) discriminating factors. Several predictive logistic models were created using up to 18 parameters, explaining 85-100% of the variation in the experimental data.

The recovery of selenious acid aerosols on glass fiber filters.

Previous workers have shown that selenium is only partially trapped on a filter during air sampling. In some cases, these losses have been attributed to volatilization of selenium dioxide. Our results demonstrate that selenium dioxide, in the presence of moist air, is completely recovered (apparently as selenious acid aerosols) and that the previous shortfalls must be due to other selenium species as yet unidentified. Selenious acid aerosols in our study were formed by volatilizing selenium dioxide (approximately 3 mg) into a stream of moist ambient air (relative humidity, greater than 50%), and trapped on glass fiber filters using a high-volume air sampler. Selenium(IV) was ultrasonically extracted from the filter with water and analyzed by atomic absorption spectrometry. Selenious acid aerosols were trapped on the filters with high efficiency (105 +/- 5 percent) using a 50 minute sampling period. With an extended sampling period (24 hours) the recovery was 103 +/- 6 percent.

Toxic and genotoxic action of electric-arc welding fumes on cultured mammalian cells.

Welding fumes generated by manual metal arc welding (MMAW) with an automatic welding machine were extracted with water and both the soluble and insoluble fractions were investigated for mitotic delay and for sister chromatid exchange (SCE) induction in cultured Chinese hamster lung (Don) cells. Five flux-coated electrodes of varying composition were chosen as representative of those available. In general, water-soluble and water-insoluble fractions induced SCE in proportion to their chromium(VI) content, and any contribution from chromium(III), fluorides, nickel, manganese or other fume constituents was minor. However, mitotic delay could not be explained in terms of the chromium(VI) concentration alone. This indicated that other components of both the soluble and insoluble fractions of the fumes were capable of inducing mitotic delay. The activity of insoluble fume fractions, either in mitotic delay- or in SCE-induction, was markedly less than that of soluble fractions. This was presumably because of the lower, though still significant, bioavailability of 'insoluble' components of the fume particles.

Mutagenicity of metal ions in bacteria.

The mutagenicity of 24 metal salts was investigated in plate incorporation and fluctuation assays with Salmonella TA strains or Escherichia coli WP2 uvrA pKm 101. Chromate(VI) and selenate(VI) ions were found to be mutagenic in plate incorporation assays employing conventional media. On the other hand, cadmium(II), beryllium(II), chromate(VI), and metavanadate(V) ions were detected in conventional fluctuation assays, indicating the importance of this technique in detection of metal mutagens. Modified culture media, with trimetaphosphate ions in place of orthophosphate as the sole phosphate source for bacterial growth, were also used in this study. The media modifications prevented precipitation of metals such as nickel and cadmium as their insoluble phosphates, and allowed detection of the mutagenicity of metavanadate ions in plate incorporation assays. However, the fluctuation technique using standard media was shown to detect a wider range of mutagenic metal ions than tests with modified media. It is notable that metaarsenite(III), arsenate(V), and nickel(II) ions were not found to be mutagenic in any of the assays although they are known to be carcinogenic and are mutagenic in other test systems. Their lack of mutagenicity in the modified media indicates that precipitation of these ions as orthophosphates is not the reason for their lack of activity in standard bacterial assays.

Chromium(VI) and apparent phenotypic reversion in Salmonella TA100.

After treatment with potassium chromate at concentrations causing ultramicroscopic cellular lesions, a significant proportion (up to 75%) of TA100 colonies fail to replicate on fresh minimal plates containing biotin. This suggests that chromium(VI) may not always induce his- reversion to his+ in Salmonella TA100. The terms 'false' or phenotypic reversion have been used to distinguish such instances from 'true' or genotypic reversion, where progeny his+ cells readily grow on biotin replica plates. Results of the present study indicate that the majority of chromate-exposed colonies, initially scored as his-, are identifiable as his+ after 24 h culture on nutrient agar. Moreover, chromate exerts a cytostatic effect on TA100 since early colony development is suppressed at high chromate concentrations. A gradual chemical reduction of chromium(VI) ions by normal media compounds is probably responsible for the re-emergence of colony growth during prolonged incubation of test plates. Thus, temporary growth inhibition at high chromate concentration appears to be responsible for most of the non-replicating colonies detected in mutagenicity assays of chromium(VI).

Effect of pH on chromium(VI) species in solution.

Published values of equilibrium constants were used to calculate the percentage of each chromium(VI) species (CrO(4)(2-), Cr(2)O(7)(2-), HCrO(4)(-) and H(2)CrO(4)) present in aqueous solution at total chromium(VI) concentrations of 10(-2)-10(-6)M in the pH range 1-8.