SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

M2
DRUG ANALYSIS IN HAIR: COMPARISON OF CRYOGENIC GRINDING AND CUTTING
FOR SAMPLE PREPARATION.
Yvonne Cruickshank i *, Fiona M. Wylie 2 and Robert A. Anderson 2 .: iForensic Science Unit, University of
Strathclyde, Glasgow Gl lXW, United Kingdom' ; 2Forensic Medicine and Science, University of
Glasgow, Glasgow G12 8QQ, United Kingdom.
Sample preparation is potentially the most important step in an analytical procedure. The forensic
toxicology laboratory at Glasgow University has established methods for the extraction of drugs from
keratinous matrices by cryogenic grinding (nail) and by cutting with scissors (hair) (1,2). To date, only one
report has compared drug extracts obtained from cut and ground hair. Eser et al. found that both the
qualitative and quantitative results from ground hair were better than from cut hair (3). In this report, two
methods of sample preparation for the analysis of drugs of abuse in hair are compared, namely cutting and
cryogenic grinding of hair. The drugs analysed were morphine, 6-monoacetylmorphine, codeine,
dihydrocodeine, methadone, EDDP, diazepam, cocaine and ecgonine methyl ester.
Samples of hair from 20 drug-related deaths were used for the evaluation. These were collected at autopsy
by plucking from the occipital region of the scalp and the root balls were removed prior to analysis. Drugfree
hair was obtained from laboratory personnel for use as a control and for preparation of standards. Each
sample was washed with SDS (0.1 % w/v), DI water and dichloromethane before being dried at room
temperature overnight. Each sample was weighed and separated into two portions of equal size that were
subsequently minced with scissors or ground, respectively. Mincing was carried out in screw-cap tubes
with long-blade scissors for 1 minute. Grinding was carried out in liquid nitrogen using a Glen Creston
Model 6750 freezer mill equipped with micro-inserts. The optimum grinding cycle was established as 2 x
2 min by SEM examination of the powders obtained following various grinding periods. The ground hair
was recovered from the grinding tube and reweighed.
Hair standards were prepared by adding solutions containing known amounts of drugs to drug-free hair and
allowing it to dry. After addition of deuterated internal standards, hair standards and the case hair samples
(up to 20 mg) from both series were suspended in methanol (1 ml), sonicated (15 min) and left for 12 hours
at 45°C. The methanol was removed from the samples to clean vials and evaporated under a flow of
nitrogen at room temperature. The mixture was redissolved in 4 ml phosphate buffer for SPE with Bond
Elut Certify LRC cartridges. Extracts were derivatised at 70°C for 20 min using 50 Jll BSTFA containing
1 % TMCS and analysed by GC-MS using a Thermo-Finnigan Trace instrument fitted with a 30 m x 0.25
mm x 0.25 Jlm HP-l column.
The cryogenic grinding device worked effectively and produced small hair particles (19-57 Jl). However
specimen losses (up to 50%) during the procedure were significant. The grinding method was time
consuming and, coupled with the use of liquid nitrogen, made grinding a less cost-effective procedure.
Comparison of the extracts from cut and ground hair by GC-MS indicated that grinding resulted in more
matrix interferences and also that ground hair was more likely to produce a false negative result. For
example in the case of methadone five samples were identified as containing methadone using cut hair but
only one of these samples was identified as containing methadone using ground hair. However, ground
hair gave higher recoveries of drugs than cut hair, after correction for sample losses, in many cases up to
twice the amount of drug was extracted from ground hair.
The results confirmed the findings of Eser et al. that the ground hair was best in terms of quantitative
analysis but the findings in terms of the qualitative analysis showed clearly that cut hair is the best
preparation technique. Further work will indicate if grinding will permit the use of a shorter extraction
period than cut hair.
Keywords: Hair Analysis, Cryogenic Grinding, Drugs of Abuse
(1 ) K. Takaichi, N. P. Lemos, R. Anderson, Analysis of Opiates in Nail Clippings from Chronic Heroin
Abusers, Presented at the 39 th Annual TIAFT Meeting, Prague, 2001.
(2) F.M Wylie, Personal Communication.
(3) H.P. Eser, L. Potsch, G. Skopp and M.R. Moeller, Influence of sample preparation on analytical
results: drug analysis (GC/MS) on hair powder using various extraction techniques. For. Sci. Int.,
84,271-279 (1997).
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