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GC/MS-determination of THCCOOH in serum: Comparison of different processing methods and the influence of THCCOOHglucuronid

2000; Volume: 37; Issue: 1 Linguagem: Inglês

M Mauden, Gisela Skopp, Rainer Mattern, R. Aderjan,

Forensic Toxicology and Drug Analysis

In the presented study a comparison was made between 4 different methods of sample processing. Drug free serum was spiked with either free or glucuronidated THCCOOH. 20 authentic specimens and 20 spiked samples were subjected to 2 different solid-phase extraction methods as well as to a liquid-liquid extraction prior to and following incubation with (beta)- glucuronidase. For GC/MS analysis the extraction residues were derivatised by silylation. In addition, hydrolysis of THCCOOH glucuronide was studied by the derivatisation reaction and at an elevated temperature. The authentic samples revealed varying amounts of THCCOOH depending on the extraction method used. In spiked samples however, the recovery of free THCOOH did nit depend on the extraction method applied. The glucuronide was eluted from the extraction column by one of the solid phase extraction methods investigated. Although THCOOH glucuronide was not completely cleaved by enzyme hydrolysis, a considerable amount of THCOOH should be present in the blood as the glucuronide conjugate. About 30 % of THCOOH glucuronade ware observed to be hydrolysed by the derivatisation reaction as well as at an elevated temperature. There is evidence from the obtained results that THCOOH glucuronide can impair the GC determination of THCOOH. Should the concentration of THCOOH be used to draw a conclusion on the frequency of cannabis use, a careful validation of the samples processing and the analytical method is necessary.