Jan Sollenberg

Isotachophoretic analysis of mandelic acid, phenylglyoxylic acid, hippuric acid and methylhippuric acid in urine after occupational exposure to styrene, toluene and/or xylene

A simple, rapid and sensitive analytical method has been developed for the determination of phenylglyoxylic acid, mandelic acid, hippuric acid and methylhippuric acid; 0-, m- and p-methylhippuric acids are partly separated. These compounds are found as metabolites after occupational exposure to styrene, toluene and xylene. The method has been applied successfully to samples extracted from human urine by diethyl ether. The method can be used to accurately and simultaneously determine as little as 0.5 nmole of all of these acids in less than 20 min.

Biological exposure limits estimated from relations between occupational styrene exposure during a workweek and excretion of mandelic and phenylglyoxylic acids in urine

SummaryStyrene exposure of 18 workers in fiber-glass reinforced plastic industries was measured for 30-min periods throughout each workday for a week. The styrene uptake was estimated using pulmonary ventilation measurements. All urine voidings were collected separately and the styrene metabolites, mandelic acid (MA) and phenylglyoxylic acid (PGA) were determined. The relationship between both exposure and uptake versus excretion of these metabolites was studied. Styrene metabolite concentrations and excretion rates (with 95% tolerance limits) were calculated to correspond to a constant 8-h exposure at the Swedish exposure limit level (25 ppm) or an uptake of an exposure limit related styrene dose (6.3 mmol). The tightest tolerance limits were obtained for excretion rate of MA + PGA per 24 h. The calculated biological exposure limit was 3.4 (± 0.7) mmol MA + PGA/24 h for a dose of 6.3 mmol styrene.

Urinary excretion of hippuric acid and o-cresol after laboratory exposure of humans to toluene

SummaryThe urinary excretion of hippuric acid and o-cresol was studied after respiratory exposure of human volunteers to approximately 80 ppm (306 mg/m3 ± SD 13) of toluene for 2 h under different work loads (0, 50,100, 150 W, respectively, during 30-min periods). The diet before and after exposure varied. An isotachophoresis method for the determination of hippuric acid is described. The correlation between the total urinary excretion, excretion rate and concentration of hippuric acid, and the respiratory uptake of toluene was poor or non-existing. The same was true for the excretion of o-cresol, which 4 h after exposure was concluded amounted to 0.03–0.26% of the toluene uptake. Thus, after a short-time exposure neither metabolite proved to be a reliable measure of individual toluene uptake at varying workloads or food intake in combination with low exposure levels.

Isotachophoretic determination of amines from workroom air

Eight different isotachophoretic systems for the analysis of 27 aliphatic amines are described. Complete methods including sampling and analysis procedures for the determination of eight amines in workroom air are also given. Different systems for the generation of gaseous amine standards in air are discussed, as well as sampling with washing bottles, adsorption tubes and liquid dosimeters. The methods were used in industrial environments. The isotachophoretic method is compared with gas and high-performance liquid chromatography.

Analytical isotachophoresis in biological monitoring of exposure to industrial chemicals

Isotachophoretic methods for the determination of compounds of interest in biological monitoring are reviewed. The analytes are charged biotransformation products such as acids or amines. Comparisons are made between isotachophoretic methods and other techniques regarding sensitivity, need for preseparation or derivatization and similar technical aspects.

High-performance liquid chromatographic analysis of hippuric acid in human blood plasma

A method has been developed for the isocratic high-performance liquid chromatographic analysis of hippuric acid in human blood plasma. After the addition of an internal standard (3-methoxysalicylic acid), plasma samples (1 ml) were made alkaline and extracted stepwise with methylene chloride and ethyl acetate. The detection limit was 50 pmol of hippuric acid per ml of plasma. The concentrations of hippuric acid in plasma from house painters (n = 8), with long-term exposure to solvent vapours from alkyd paints, were in the range 1-21 nmol/mol (median 11 nmol/ml). These values were statistically significantly higher than those for controls (n = 9): 2-8 nmol/ml (median 3 nmol/ml).

Application of a single-compartment model for estimation of styrene uptake from measurements of urinary excretion of mandelic and phenylglyoxylic acids after occupational exposure

In biological monitoring of styrene, the exposure is usually related to the urinary concentration of mandelic (MA) and/or phenylglyoxylic (PGA) acids in a urine sample taken after the workshift or on following morning. To study this relationship further, a single-compartment mathematical model was developed by which measured occupational repetitive uptake of styrene during a working day was related to measured excretion rates of the urinary metabolites. The model was used in practice to calculate the unknown uptake (dose) from MA and PGA excretion analyzed in urine samples. For comparison, a styrene limit dose was calculated from the exposure limit. Analytical results of samples from plastic boat builders were compared with the limit values.