Rapid determination of ketamine in urine by liquid chromatography-tandem mass spectrometry for a high throughput laboratory

In recent years, the abuse of ketamine had gained popularity in rave parties in Hong Kong. The Urinalysis Unit of the Government Laboratory of Hong Kong faced a tremendous increase in workload for ketamine analysis. The number of tests performed rose from 10 in 1999 to 15,000 in 2002. As a fully validated immunoassay test for ketamine was not available in the market, most laboratories analyzed ketamine by chromatographic techniques after liquid-liquid extraction. However, these methods reported in the literature are not suitable for high throughput laboratories. Hence, a rapid screening/confirmation method for ketamine by liquid chromatography-tandem mass spectrometry (LC-MS-MS) with a detection limit of 5 ng/ml was developed. After automated solid-phase extraction (SPE), the urine extract was analyzed for ketamine by a 2.5-min chromatographic run, the estimated recovery was 89% and the precision was 11% R.S.D. at 20 ng/ml. With the aid of an in-house developed computer program, the results were presented in spreadsheet format for easy checking. The method has been applied to our laboratory for routine ketamine analysis and a maximum of 200 samples per day can be achieved.