Determination of Antidepressants in Hair via UHPLC-MS/MS as a Complementary Informative Tool for Clinical and Forensic Toxicological Assessments

Background: Hair analysis is a complementary approach for the detection of antidepressants (ADs) in clinical and forensic schemes because it yields a picture of long-term exposure over a time window depending on the length of the hair. Methods: A fast and sensitive ultra-high performance liquid chromatography tandem mass spectrometry method using a BEH C18 column with a mobile phase consisting of ammonium acetate/acetonitrile was developed and validated according to international guidelines for the simultaneous analysis of 24 ADs in hair. Methanol/acetonitrile/ammonium formate buffer 1 mmol/L (25: 25: 50, vol/vol/vol) was used to extract the drugs from the hair matrix before a solid-phase extraction using cation exchange cartridges was applied. Hair samples (n = 18) obtained from a US workplace drug testing center were analyzed to demonstrate the method applicability. Results: The limit of quantification values ranged from 0.006 to 0.05 ng/mg hair, and the calibration curves ranged from the LOQ up to 10 ng/mg hair. The bias and imprecision were,15% for all the compounds except maprotiline (17%). This was evaluated with 2 "in-house" QCs and 1 authentic hair sample from an amitriptyline user. No significant matrix effects for most of the compounds were observed, and the extraction efficiency of the sample cleanup procedure ranged from 40% to 80% (relative standard deviation,15%) [except for demethylcitalopram, didemethylcitalopram, and trazodone (relative standard deviation,33%)]. The method was then successfully applied to the analysis of hair samples from workplace drug testing. The samples were analyzed in 1-cm segments to determine the medication history of the patient. When a sample was reported positive, information concerning the prescription was obtained anonymously for several samples. Concentrations of (minimum-maximum value in ng/mg) citalopram (0.01-132: extrapolated), trazodone (0.01-5.3), sertraline (0.05-0.1), paroxetine (0.02-1.0), bupropion (0.05-0.6), fluoxetine (0.5-8), and amitriptyline (0.2-4.8), including metabolites, are reported. Conclusions: This study may be of interest to clinical and forensic laboratories for interpretation because it demonstrates the AD concentration windows in hair and the link to the prescribed drugs.