Computerized capillary gas chromatographic analysis of hydrocarbon mixtures in workplace air.

The quantitative composition of white spirit vapours in workplace air may differ considerably from the solvent being used, although all components are the same. By calculating the hygienic effect from the threshold limit value (NGV) of each component, a more reliable estimate is obtained of the occupational hazard than by using the NGV for white spirit. In this method the analyses were performed by on-column injection onto a temperature-programmed capillary column. Retention indices based on n-paraffins and isooctane were calculated using spline functions. Index tables were established for different hydrocarbon mixtures. The validity of the retention indices was found to be satisfactory, depending on the stability of the column and the possibility of optimizing the indices when replacing one column by another of the same type and dimensions. Comparisons were made with alternative methods for determining the concentration of white spirit vapours in air samples. A polar column was used to check the total content of aromatics.

Trichloroacetic acid accumulates in murine amniotic fluid after tri- and tetrachloroethylene inhalation.

The distribution of trichloroethylene (Tri) and tetrachloroethylene (Tetra) and their metabolites have been studied in pregnant mice by means of whole-body autoradiography (14C-labelled Tri and Tetra) and gas chromatography, with special emphasis on possible uptake and retention in the foetoplacental unit. Volatile (non-metabolized) activity appeared at short intervals after a 10 min. or 1 hr inhalation period in foetus and amniotic fluid. Most notable, however, was a strong accumulation and retention (peak at 4 hrs) in amniotic fluid of the metabolite trichloroacetic acid (TCA) after inhalation of either of the solvents. The main metabolite of Tri, trichloroethanol (TCE) (or conjugates), did not accumulate specifically as compared to maternal plasma. TCA infused intravenously in the maternal plasma was accumulated in amniotic fluid, but less pronounced than after Tri and Tetra inhalation, indicating that some metabolism of Tri and Tetra to TCA may occur in the foetoplacental unit. The results suggest that TCA may be transported to the foetus partly paraplacentally through foetal membranes and amniotic fluid, with the possibility of foetal swallowing or absorption through the skin. Foetal urinary activity also suggests that circulation between foetus and amniotic fluid may contribute to the long-term retention in the foetoplacental unit. In the mother, after inhalation exposures, and in intraperitoneally injected newborn mice, non-extractable radioactivity was found in the respiratory tract, liver, and kidney, indicating binding to these organs through metabolism.

Exposure to trichloroethylene II. Metabolites in blood and urine.

Fifteen men were exposed to trichloroethylene (TRI) in three different ways with regard to the concentration of TRI in the air as well as exercise on a bicycle ergometer. The total amount of TRI supplied and taken up by each person was measured. The concentrations of trichloroethanol (TCE) and trichloroacetic acid (TCA) were determined in blood and urine. In spite of large differences in uptake, there were only small differences in the concentration of TCA in blood during the day of exposure. There was a large scatter for the values of TCA in urine within each group. The concentration of TCE in arterial blood increased during exposure. Thereafter the concentrations were almost constant for 2 h and differed among the groups. These results can be interpreted as being due to balanced rates of the formation and elimination of TCE. The levels mentioned were related to the uptake of TRI. The same was found for the rate of excretion of TCE in urine when calculations were made from the morning sample obtained the day after exposure.

Methods for measuring trichloroethanol and trichloroacetic acid in blood and urine after exposure to trichloroethylene.

A description is given of procedures for the analysis of trichloroethanol, conjugated trichloroethanol, and trichloroacetic acid (TCA) in blood and urine. The determination of TCA is effected by measuring its decarboxylation product chloroform. The methods depend on extraction with isooctane and subsequent analysis by gas chromatography.