Analytical method of volatile aromatic compounds in meconium by headspace-solid-phase microextraction gas chromatography coupled to mass spectrometry
Résumé
Meconium is the earliest stools of newborn. It starts forming from the 13th week of gestation in intestinal contents and accumulates until birth. Usually, it is expelled by the newborn between 24 first hours after birth. This complex matrix has the advantage to integrate a large period of exposure of the foetus to xenobiotics compare to infantile urine or blood. This matrix was used in the PENEW[1] project to determine a correlation between congenital malformations and foetus exposure. This work presents the analytical consideration for the quantification of volatile organic compounds (VOCs): BTEX (benzene, toluene, ethylbenzene and xylenes) and chlorinated solvents (trichloroethylene and tetrachloroethylene) in meconium. This biological matrix is very viscous and sticky, difficult to manipulate and to homogenize. Analyzes were then carried out by HeadSpace Solid Phase MicroExtraction (HSSPME) with Gas Chromatography coupled to Mass Spectrometry (GC/MS). Several extraction parameters were optimized (fiber type, incubation time and temperature of fiber, use of salt). Internal calibrations performed in water and in matrix were compared to determine if quantification in water was possible with the correction of isotopic labelled internal standards. Importance of internal standard for each target molecules was particularly verified with a comparison between calibrations performed with specific internal standards and calibrations carried out with a single internal standard for all compounds. It was determined that analyzes of meconium should be carried out with an internal calibration in matrix for BTEX and chlorinated solvents with specific internal standards. The limits of quantification were established between 80 pg/g and 120 pg/g of meconium. The method was applied to 40 meconium samples in which all target compounds were determined.