In recent decades, urine drug testing in the workplace has become common in many countries in the world. There have been several studies concerning the use of the urine specimen validity test (SVT) for drug abuse testing administered in the workplace. However, very little data exists concerning the urine SVT on drug abuse tests from court specimens, including dilute, substituted, adulterated, and invalid tests. We investigated 21,696 submitted urine drug test samples for SVT from workplace and court settings in southern Taiwan over 5 years. All immunoassay screen-positive urine specimen drug tests were confirmed by gas chromatography/mass spectrometry. We found that the mean 5-year prevalence of tampering (dilute, substituted, or invalid tests) in urine specimens from the workplace and court settings were 1.09% and 3.81%, respectively. The mean 5-year percentage of dilute, substituted, and invalid urine specimens from the workplace were 89.2%, 6.8%, and 4.1%, respectively. The mean 5-year percentage of dilute, substituted, and invalid urine specimens from the court were 94.8%, 1.4%, and 3.8%, respectively. No adulterated cases were found among the workplace or court samples. The most common drug identified from the workplace specimens was amphetamine, followed by opiates. The most common drug identified from the court specimens was ketamine, followed by amphetamine. We suggest that all urine specimens taken for drug testing from both the workplace and court settings need to be tested for validity.

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To facilitate the analysis of targeted drugs under high sample volume testing environment, an extraction, derivatization and gas chromatographic-mass spectrometric analysis method was developed for simultaneously determination of amphetamine (AMP), methamphetamine (MAMP), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyethylamphetamine (MDEA), ketamine, and norketamine in urine. This method utilized solid-phase extraction in conjunction with derivatization using heptafluorobutyric anhydride (HFBA) as the derivatization reagent. Using a 1-mL sample, the limits of quantitation achieved for the analysis of AMP, MAMP, MDA, MDMA, MDEA, ketamine, and norketamine were 25, 15, 60, 60, 70, 25, and 30 ng/mL, respectively. Upper limits of quantitation were 8000 ng/mL for all amphetamines and 6000 ng/mL for ketamine and norketamine. Except for dehydronorketamine (DHNK), within-day and between-day precisions (as expressed in CV%) for quality control samples were ≤ 3.1% and ≤ 4.95%, respectively. Except DHNK, the within-day accuracy ranged between 96.0% and 110.7% and the between-day accuracy ranged between 96.9% and 108.7%. A group of 107 urine samples previously determined to contain the target analytes were analyzed by this new approach. Quantitative data produced by both methods agreed well. With this new approach, we were able to use a single analytical protocol to conduct the confirmation test for samples that preliminarily tested positive (by immunoassay) for amphetamines, ketamine, or both.