A Fast GC-MS Screening Procedure for Ketamine and Its Metabolites in Urine Samples
HUEI-RU LIN1 AND AHAI-CHANG LUA2*
1. Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan, R.O.C.
2. Department of Laboratory Medicine and Biotechnology, Tzu Chi University, 701, Sec. 3, Chung Yan Rd., Hualien City 970, Taiwan, R.O.C.
(Received: October 28, 2004; Accepted: January 21, 2005)
ABSTRACT
The rapid increase of ketamine abuse worldwide has created a need for a fast and efficient screening procedure. Currently, there is no commercially available immunoassay. We developed a simple extraction and GC/MS screening procedure to screen out negative samples. Urine samples (1 mL) were spiked with ketamine-d4 as internal standard. After liquid-liquid extraction, samples were screened for ketamine (K) and its two metabolites, norketamine (NK) and dehydronorketamine (DHNK), with GC/MS without derivatization. The total analytical time is 5 min for each sample. The detection limit for K, NK and DHNK was 10 ng/mL, 10 ng/mL and 30 ng/mL, respectively. The within-run precision and accuracy for 80, 160, 400 ng/mL of K, NK and DHNK were all between 12.50% and 8.17%. We collected 163 urine samples from disco-dancing clubs in Taiwan. Samples were screened and confirmed with GC/MS. The total analytical time for GC-MS confirmation is 20 min per sample. The sensitivity is 98.9% and specificity is 100%. This screening method is rapid, sensitive and applicable to forensic and clinical toxicological analyses.
Key words: fast screen, ketamine, GC-MS