Evidence for the formation of 2,4-imidazolidinediones and pyrrolidino[1,2 a]-3,6-piperazinediones in human hair pyrolyzate by pyrolysis-gas chromatography-mass spectrometry-mass spectrometry

Abstract

In an earlier report from this Laboratory, the identification of compounds formed during the anaerobic pyrolysis of human hair using both electron impact and chemical ionization capillary gas chromatography-mass spectrometry was described. In addition to compounds formed from simple cleavage of amino acids, the formation of 5-substituted 2,4-imidazolidinediones during protein pyrolysis by lactam ring formation was proposed. In this report, the formation of 5-substituted pyrrolidino[1,2 a]-3,6-piperazinediones by a similar mechanism is proposed. Due to the complexity of the hair pyrolyzate, even with separation by capillary gas chromatography, few single-component peaks were obtained with pyrolysis-gas chromatography-mass spectrometry. The use of capillary pyrolysis-gas chromatography-tandem mass spectrometry overcame this problem. Electron impact and chemical ionization collisionally activated dissociation experiments provided data which support the proposed formation of 5-substituted 2,4-imidazolidinediones and 5-substituted pyrrolidino[1,2 a]-3,6-piperazinediones during the anaerobic pyrolysis of human hair. None of the results to date, however, show potential usefulness for the forensic examination of hair.