DETERMINATION DES METABOLITES MONOESTER DE BUTYLBENZYL-PHTHALATE (BBP) PAR GCMS DANS LES URINES DE PERSONNES EXPOSEES: ANALYSIS OF THE MONOESTER METABOLITES OF BUTYLBENZYL PHTHALATE BY GC-MS IN URINE OF EXPOSED WORKERS

Abstract

A method of analysis was developed to determine free and glucuronated monobutyl phthalate (BuP) and monobenzyl phthalate (BeP) in urine for the assessment of exposure of man to butylbenzyl phthalate (BBP) in the workplace and in the environment. This method has also been applied in pharmacokinetic studies in experimental animals and the determination in urine of exposed workers.

Urine samples are first subjected to enzymatic hydrolysis with ß-glucuronidase to enable the measurement of the total amount of monophthalates excreted. A fraction of the hydrolysate is used for further analysis. Monohexyl phthalate is added as an internal standard and the hydrolysed urine extracted with a n-hexane/ dichloromethane mixture after acidification and saturation with salt. The organic fractions are washed, dehydrated and evaporated. The residue is methylated by means of diazomethane dissolved in diethylether, evaporated and further purified by extraction into n-hexane from an alkaline buffer. The organic fractions are evaporated and the residue redissolved in acetonitrile for analysis by ion trap GC-MS equipped with a 50 m apolar WCOT capillary column. TIC mass chromatograms are recorded from which SIM chromatograms can be derived electronically. The m/z values used are 91, 149, and 163 which provide a sufficient sensitive response and which are specific enough to pick up the methylated monophthalates under investigation.

The quantitative limit of detection (LOQ) is 60 μg/L for BuP and BeP when using the Magnum ion Trap detector and 3 μg/L when using the Polaris Q in the splitless mode. The calibration curve in urine is linear from 120 μg/L to 50,000 μg/L with a coefficient of variation of less than 10 % . In case of the Polaris Q linearity started from 10 μg/L. The recovery of the method is monitored by the response signal of the internal standard in the ion chromatogram. In the event of insufficient recovery the analysis is repeated. Variations in recovery are compensated by the internal standard of which the molecular structure is very similar to the ones of the monophthalates under investigation.

Keywords:

• Butylbenzylphthalate
• monobenzylphthalate
• monobutylphthalate
• GCMS
• urine extraction
• exposure
• workplace.