Distribution pattern of common drugs of abuse, ethyl glucuronide, and benzodiazepines in hair across the scalp

Abstract

While hair analysis is important and accepted in forensic applications, fundamental knowledge gaps still exist, exacerbated by a lack of knowledge of the incorporation mechanisms of substances into hair. The influence of the hair sampling location on the head on ethyl glucuronide (EtG) and cocaine concentrations was investigated by measuring the complete scalp hair of 14 (2 EtG, 4 cocaine, 8 both EtG and cocaine) study participants in a grid pattern for EtG, drugs of abuse, and benzodiazepines. Head skin perfusion and sweating rates were investigated to rationalize the concentration differences. For EtG, ratios between maximum and minimum concentrations on the scalp ranged from 2.5 to 7.1 (mean 4.4). For cocaine, the ratios ranged from 2.8 to 105 (mean 17.6). EtG concentrations were often highest at the vertex, but the distribution was strongly participant dependent. Cocaine and its metabolites showed the lowest concentrations at the vertex and the highest on the periphery, especially at the forehead. These differences led to hair from some head parts being clearly above conventional cut‐offs and others clearly below. In addition to EtG and cocaine, the distributions of 24 other drugs of abuse and benzodiazepines/z‐substances and metabolites are described. No clear pattern was observed for the head skin perfusion. Sweating rate measurements revealed higher sweating rates on the periphery of the haircut. Therefore, sweat could be a main incorporation route for cocaine. Concentration differences can lead to different interpretations depending on the sampling site. Therefore, the results are highly relevant for routine forensic hair analysis.

Development, validation, and application of an LC–MS/MS method for mitragynine and 7‐hydroxymitragynine analysis in hair

“…The distribution showed a narrow concentration range with no clear distribution pattern. The results contrast with the distribution found by Meier et al for most DoA, as most show higher concentrations on the periphery of the hairline . 7‐Hy‐Mitra was not detected in any of the hair samples, likely due to the lower abundance of 7‐Hy‐Mitra in the plant material compared with mitragynine, in combination with the higher LOD of 7‐Hy‐Mitra.…”

“…Sample preparation was done using a published method for the combined sample preparation of EtG, DoA, and BZD‐Z . Hair strands were briefly (1–2 min) washed with 3 mL each of water, 2‐propanol, and acetone.…”

“…The method was integrated into a published method for the analysis of BZD‐Z . Analysis was done using an Ultimate 3000 high performance liquid chromatograph (Thermo Fisher Scientific, Reinach, Switzerland) coupled to a 5500 QTrap triple quadrupole mass spectrometer (Sciex, Brugg, Switzerland).…”

“…During a recently published study, the entire scalp hair of a self‐reported cocaine and Kratom consumer was collected. The participant reported regular consumption of a moderate amount of ca.…”

“…These alkaloids were chosen as they are considered the most important psychoactive compounds in Kratom. The method was applied to gain insight into the concentration distribution across the scalp, as the sampling site could have a strong impact on the test results as previously demonstrated (Meier et al, 2019) . Additionally, the method was established as a routine analysis method, which allowed the study of the prevalence in our routine population.…”