Cocaine contamination in pubic hair: Analysis of the decontamination method

Abstract

Even if pubic hair represents a reliable and widely accepted alternative hair matrix to identify drug abusers, it might produce false positive results due to external contamination. The aim of this study was to verify whether the external contamination of pubic hair with cocaine could influence the discrimination between active users and false positive subjects. The analysis was performed on in vivo and in vitro samples; the contamination was carried out by rubbing pubic hair with cocaine hydrochloride contaminated hands for three consecutive days. Five days after the beginning of the contamination, the pubic hair was collected and analysed at different times for two months. Data from our studies show that all in vivo samples yielded false positives; the in vitro samples were negative only for 10 days and then yielded false positives. ª 2014 Hosting by Elsevier B.V. on behalf of The International Association of Law and Forensic Sciences (IALFS).

A systematic investigation of forensic hair decontamination procedures and their limitations

“…BZE and EME are hydrolytic metabolites frequently detected in contaminated hair and illicit seizures of COC. 24,27 NCOC is produced by the N-demethylation of COC but can also be found as a contaminant. 53 Cocaethylene was not detected in COC-contaminated hair in the present study.…”

“…25 However, two reports that this extended aqueous wash removed COC contamination to less than the SoHT cut-offs could not be replicated by independent groups. 9,[25][26][27] The initial drug concentration of the soaking solution is also important, as soaking hair in a highly concentrated solution will maintain hair concentrations above the SoHT cut-offs after washing. 26 The soaking of hair in an aqueous drug solution model has been criticized as being unrealistic, although it may have some relevance to the external contamination of hair attributable to biofluids.…”

“…Following this procedure, COC concentrations in hair extracts remained above the SoHT cut-off, demonstrating an incomplete removal of the illicit drug. 9,24,[27][28][29] Furthermore, external surface exposure may possibly lead to internal hair contamination via sweat acting as a carrier solvent for the diffusion of ionizable drugs into the hair fibermaking it more challenging to remove using decontamination procedures. 30 The solvents used in hair decontamination procedures can vary greatly between laboratories, and the impact of washing protocols on drug concentrations in hair has not been fully elucidated.…”

“…The extended aqueous wash is also a frequently cited decontamination procedure, which involves an initial 15minute wash with isopropanol, followed by three 30minute and two 60minute washes with 0.01 M phosphate buffer (pH 6) containing 0.1% w/v bovine serum albumin at 37°C . However, two reports that this extended aqueous wash removed COC contamination to less than the SoHT cut‐offs could not be replicated by independent groups . The initial drug concentration of the soaking solution is also important, as soaking hair in a highly concentrated solution will maintain hair concentrations above the SoHT cut‐offs after washing …”

Desenvolvimento de método de triagem de substâncias psicoativas em amostras de cabelo através de técnicas imunológicas

“…O mesmo feito não foi possível para os métodos desenvolvidos neste trabalho, havendo assim a necessidade de alíquotas de 50 mg para se realizar os ensaios confirmatórios. Essa quantidade de amostra também foi observada em outros trabalhos que utilizam GC-MS (MUSSHOFF et al, 2009;PANTALEÃO et al, 2012;MIGUEL-FRAMIL et al, 2013;LOPEZ-GUARNIDO et al, 2013;ROMANO et al, 2014).…”