Analysis of Some Organosilicon Compounds in Biological Materal

Summary

The analytical chemical experience gained in the analysis in biological material of the compound 2,6-cis-diphenylhexamethyl-cyclotetrasiloxane (KABI 1774, Cisobitan^R) and the products formed following its biotransformation is discussed. Quantitative analysis was performed with the highly selective technique of gas chromatography- mass spectrometry (GC-MS), enabling the determination of concentrations down to 0.1 µg/ml of serum. The extraction of this rather lipophilic compound from serum samples into organic solvents was very slow, and to achieve quantitative extraction a homogeneous extraction technique using heptane containing methanol followed by the addition of water was developed. Contamination problems due to the volatility of the organosilicon compound are discussed. Mass fragmentography and mass chromatography were used to unequivocally identify five products formed following the biotransformation of 2,6-cis (in rat, monkey and man), i.e., dimethylsilanediol, methylphenylsilanediol, trimethylphenylsiloxanediol and phenol, all identified as their trimethylsilyl derivatives. The M.S. data were compared to those obtained from similarly derivatized authentic samples. In these studies radioactively labelled substrate was used as an aid for coarse separation of the metabolites and stable isotope labelling was an aid in confirming the source of dimethyl-silanediol as various amounts of this compound appeared in the blanks. Possible metabolic and chemical routes leading to the formation of the breakdown products are briefly discussed.