Nail Analysis for Drugs: A Role in Workplace Testing?

Analysis of nail clippings may be a useful back-up for hair analysis when hair is unavailable. One aspect of using nails or hair is the ability to analyze whether drug present is from ingestion or from contamination. A common method of three 15-s rinses in methanol failed to remove drug from nails that had been soaked in either 5 or 50 μg/mL cocaine, methamphetamine or morphine for 1 h. While methanol rinsing did not remove contaminating drug, washing the nails soaked with 5 and 50 μg/mL of these drugs with an extended wash, a method developed for hair analysis and consisting of a 15-min isopropanol wash, and three 30-min and two 60-min phosphate buffer-0.1% albumin washes, when applied to nails did remove most of the contaminating drug. The drug left in the nails after extended washing could be interpreted as contamination by applying a wash criterion that is routinely applied in hair analysis. Successful decontamination of the soaked contaminated nail model was followed by applying this extended wash method to presumptive positive nail samples identified in workplace testing. While the extended buffer wash and wash criterion distinguish contamination from ingestion with hair, we failed to demonstrate that the method effectively differentiates contamination from ingestion with nails.