Determination of hippuric-, methylhippuric-, mandelic and phenylglyocylic acid

Excessive exposure to toluene in the industrial environment leads to an increased presence of hippuric acid in the body. The analysis of hippuric acid in urine of exposed persons is suitable to monitor increased toluene-exposure. Likewise, the finding of excessive amounts of methylhippuric acid can be used to monitor xylene exposure, mandelic acid to monitor ethylbenzene exposure and phenylglyoxylic acid to monitor styrene exposure. Using this method, the mentioned substances in urine can be analysed quantitatively without prior extraction. The limit of quantification is determined to be at 0.05 g/L, which correlates with the concentration in the urine of a non-exposed person.