The relationship between postmortem methamphetamine concentrations in urine, blood and vitreous humor

Abstract

Methamphetamine (MA) is the most widespread narcotic in Thailand. Urine samples are used as evidences of MA abuse under the Narcotics Law of Thailand, whereas blood samples are specimens for investigation of MA poisoning. However, both specimens are occasionally not available or contaminated. Vitreous humor is a specimen which is less contaminated and easy to work with analytically. The aim of this study is to examine the relationships between MA concentrations in urine, blood and vitreous humor. Those three specimens were collected from 40 Thai deceased and their MA concentrations were quantitatively analyzed by headspace-solid phase microextraction/gas chromatography-mass spectrometry technique. The results showed that the relationships between MA concentrations in urine vs blood, urine vs vitreous humor, and vitreous humor vs blood were linearly correlated with a correlation coefficient (r) of 0.89, 0.99, and 0.88, respectively. Linear regression equations of those relationships between urine vs blood, urine vs vitreous humor, and vitreous humor vs blood were y = 0.001x + 8.08, y = 0.056x - 262.86, and y = 0.027x + 16.20, respectively. This study suggests vitreous humor as an alternative specimen for MA investigation.