A UHPLC-MS/MS method was developed to separate and measure the two mirror-image forms (enantiomers) of ketamine in human urine and hair. After a deceased person used esketamine before death, only S-ketamine appeared in blood and urine, indicating that ketamine does not switch between its enantiomeric forms in the body. In 45 hair samples from ketamine abusers, the ratio of R-ketamine to S-ketamine ranged from 0.809 to 1.43, showing that illegal-market ketamine is mostly racemic (equal parts both enantiomers). A significant difference in this ratio was found between samples from China and Myanmar, likely due to regional variations in synthetic routes.
A dried urine spot (DUS) method using LC-MS/MS was developed to measure the tryptamine hallucinogen 5-MeO-DIPT, which is unstable in liquid urine. Ten microliters of urine were spotted on a card and extracted with methanol. The method's limit of detection was 0.1 ng/ml and lower limit of quantification was 0.2 ng/ml, with accuracy between 98.2% and 103.9% and precision between 2.7% and 8.5%. 5-MeO-DIPT was more stable in DUS than in urine stored at 25 °C. When applied to urine from known users, concentrations ranged from 0.3 to 2.3 ng/ml, lower than those measured by GC-Orbitrap-MS. The small sample volume and simplicity make this useful for drug screening.