Given that hair testing for drugs of abuse needs matrix-matched control materials to help ensure the laboratory’s process and authenticity of its results, this project developed and produced four reference materials of hair fortified with controlled substances for use as controls and/or calibrators.
The four reference materials are THCA (11-Nor-delta-9-delta-9-tetrahydrocannabinol [THC]-9carboxylic acid); morphine (MOR); cocaine (COC); and amphetamine (AMP), including methamphetamine (MAMP) and methylenedioxymethamphetamine (MDMA, Ecstasy). All analytes of interest were successfully incorporated into hair at or above targeted concentrations. Determined reference ranges for the THCA and MOR reference materials were comparable to the targeted fortification concentrations. The THCA reference range was 0.25 plus or minus 0.17 pg/mg, and the individual laboratory average percentage coefficient of variation (CV) was 23 percent Intra-laboratory percentage CVs ranged from 12.0 percent to 12.7 percent. MORs range was 627 plus or minus 320 pg/mg, and its intra-laboratory and inter-laboratory percentage CVs were 8.7 to 13.8 percent and 23.8 percent, respectively. Amphetamine analytes were similar, but all were twice the targeted concentration of 750 pg/mg. The higher-than-expected amphetamine concentration is not unusual, based on previous experience with hair fortification studies, in which amphetamines tended to be sensitive to variations in hair structure. The current study found that unspecified characteristics of the donor hair were responsible for the increased AMPs. Statistical evaluations were determined on 98 THCA measurements, 102 MOR measurements, 98 COC measurements, and 89 AMP measurements. Eighty control samples were submitted to the reference laboratory as randomized samples for analysis, and the laboratory was unaware that it was receiving positive and negative controls. Controls were analyzed at an 18-percent frequency rate in comparison to other samples within the study. All controls were correctly identified as positive or negative. Extensive tables and 39 references
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