Screening for drugs of abuse in hair with ion spray LC–MS–MS

Abstract

Analyzing hair for many substances can be tedious and expensive, and a rapid screening method should prove helpful. Generally, screening has been performed using immunological tests, mainly in workplace drug testing, where the number of samples has been high. The aim of this study was to develop an LC–MS–MS method for the simultaneous analysis of several drugs of abuse in human hair as an alternative to immunological screening tests. In 75 randomly selected autopsy cases, hair was analyzed in addition to the usual specimens of blood and urine. The method included nicotine, cotinine, morphine, codeine, 6-acetylmorphine, ethylmorphine, amphetamine, methamphetamine, MDA, MDMA, benzoylecgonine, cocaine, 7-aminoflunitrazepam and diazepam. The LC–MS–MS analysis was performed on a SCIEX API 2000 MS–MS instrument equipped with an electrospray interface. To 20–50 mg of hair, 0.5 ml of mobile phase A (acetonitril:methanol:20 mM formate buffer, pH 3.0 (10:10:80)) and 25 μl of internal standard were added and the sample was incubated in a water bath at 37 °C during 18 h. Using a threshold of 20 ng/sample, equivalent to 1 ng/mg if 20 mg hair is used, 26 positive results were found in 16 cases. Three of the 26 positive detections could not be confirmed by GC–MS. Two of the cases were not previously known as drug users. Of the 59 negative cases, only one case had a positive blood sample showing 0.01 and 0.07 μg/g femoral blood of 6-acetylmorphine and morphine, respectively. This might indicate drug abstinence resulting in decreased tolerance or even a “first time” use of heroin resulting in death. We conclude that the use of hair analysis in postmortem cases can reveal both unknown drug use, as well as confirm a period of drug abstinence prior to an acute fatal overdose. The proposed LC–MS–MS method showed high sensitivity, was very easy to perform and seemed appropriate for screening purposes.