SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

M7
EVALUATION OF KETAMINE ABUSE USING HAIR ANALYSIS: CONCENTRATION
TRENDS IN A SINGAPORE POPVLA TION
H.S. Leong', N.L. Tan, C.P. Lui, and T.K. Lee: Narcotics II Laboratory, Centre for Forensic Science,
Health Sciences Authority, 11 Outram Road, Singapore 169078.
Ketamine has been used as an anaesthetic since its discovery in 1961. Today, the drug is used primarily in
veterinary medicine, and in some short-term surgical procedures in humans. Ketamine also produces posthypnotic
emergence reactions such as prolonged hallucination and delirium, which has led to its abuse.
Due to the increasing abuse of ketamine in Singapore, ketamine, norketamine and its dehydro derivatives
were listed as Class B Controlled Drugs under the Misuse of Drugs Act (CAP.185) in September 1999. As
a drug of abuse, ketamine can be administered orally, snorted, or injected. In Singapore, the most common
mode of administration is through snorting. The majority of the ketamine abusers consist of teens and
young working adults.
The laboratory has been analyzing ketamine in urine of suspected abusers since September 1999. In the
period of January 2000 to April 2004, there were a total of 17,133 urine samples submitted for ketamine
analysis, out of which 26.6 % were tested positive for ketamine during the period of January 2000 to April
2001. The number of positive samples increased significantly to 51.2 % during the period of May 2003 to
April 2004. Recently, the enforcement agency of Singapore has indicated interest in the detection of
ketamine in hair. This is because many of the abusers have claimed that their drinks were spiked with
ketamine to avoid prosecution. The detection of ketamine in hair would determine whether they were
habitual users or it was an one-off consumption.
This paper presents a method for the detection of ketamine in hair. Hair samples (25 mg) were washed,
pulverized and digested in hydrochloric acid (O.5M) overnight at 45°C. The samples were extracted by an
automated solid-phase extraction procedure and the extracts were subsequently analyzed using gas
chromatography/mass spectrometry (GCIMS) in selected ion monitoring mode (SIM). Good linearity up to
120 ng/mg was obtained for both ketamine and norketamine (r 0.9987 and r2 0.9985, respectively).
Limit of detection (LOD) was found to be at 0.4 ng/mg for both drugs while the limit ofquantitation (LOQ)
was found to be 0.6 and 0.8 ng/mg for ketamine and norketamine, respectively. Other parameters- such as
intra- and inter-day variation were also determined.
About 9 I hair segments from suspected ketamine abusers were analyzed. In most of the hair segments,
ketamine was found to bethe predominant analyte (norketamine to ketamine ratio < 1). This is in contrast
to urine where the metabolite norketamine is usually found to be the predominant analyte. The range of
ketamine detected in hair was found to be from 0.6 ng/mg to 489.0 ng/mg (Mean = 49.0 ng/mg) whereas
the range of norketamine detected was from 0.8 ng/mg to 196.3 ng/mg (Mean = 12.1 ng/mg). At
concentrations higher than 120 ng/mg, about 5 mg of hair is sufficient for the re-analysis of the sample.
Based upon the· voluntary confession of the ketamine abusers, a correlation between the amount of
ketamine detected and the frequency of abuse was observed. For abusers who snort the drug occasionally
(once a week), the concentration ofketamine detected in hair was in the range of 1.1 ng/mg to 42.7 ng/mg
(Mean 9.9 ng/mg). For those who abuse the drug more frequently (twice or thrice a week), the
concentration of ketamine detected was in the range of 13.5 ng/mg to 111.l ng/mg (Mean 37.4 ng/mg).
For those who abuse the drug daily, the concentration of ketamine detected was above 45.1 ng/mg (Mean =
121.3 ng/mg). Based on the results of the analysis, three types of trends for ketamine abuse were observed:
Low (1.0 - 10.0 ng/mg), medium (11.0 50.0 ng/mg), and high (>50.0 ng/mg). Segmental analysis of the
hair samples of the abusers was also performed and its significance is discussed in relation to the history of
drug use.
In conclusion, ketamine in hair can be determined by using acid digestion and subsequent GCIMS analysis.
Based on the amount of ketamine found in hair, certain patterns of consumption among ketamine abusers
can be demonstrated.
Keywords: Ketamine, hair analysis, GC/MS/SIM
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