The trace analysis of musk xylene in biological samples: problems associated with its ubiquitous occurrence.

Musk xylene (1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene) (MX), a synthetic musk often used in fragrances has previously been described to occur in human tissue. In this article a specific and sensitive method for the determination of MX in blood is described. It includes a simple clean-up by silica gel adsorption chromatography followed by GC/MS detection with negative chemical ionisation (NCI) and multiple ion detection of the molecular ion and M-30. The absolute detection limit in the MID-mode was 50 fg of MX. 11 human blood samples of 3 individuals were analysed to elucidate the suitability of this method. The MX concentrations ranged from 66 to 270 pg/g plasma or 12 to 49 ng/g blood lipids, respectively. In the course of the method evaluation the hazard of sample contamination during the clean-up procedure was investigated and MX was found to be present in several materials in the laboratory. Some of these contamination sources could be eliminated.