Published: Journal of Analytical Toxicology, ISSN 0146-4760, Volume 31, Number 4, May 2007, pp. 224-226

Quantification of Lorazepam and Lormetazepam in Human Breast Milk Using GC–MS in the Negative Chemical Ionization Mode
Patrick Lemmer[1], Serge Schneider[1], Annette Mühe[2], and Robert Wennig[1]
[1]Laboratoire National de Santé, Division de Toxicologie, Université de Luxembourg, 162a, avenue de la Faïencerie, L-1511 Luxembourg and
[2]Services de Psychiatrie Adulte et de Psychiatrie de l’Enfant, Centre Hospitalier de Luxembourg, 4, rue Barblé, L-1210 Luxembourg

Lormetazepam (Loramet®) is a benzodiazepine mainly used as an hypnotic to treat insomnia. Lorazepam (Temesta®) is used as an anxiolytic, tranquilizer, sedative, and anticonvulsant, and it is the major metabolite of lormetazepam. In this study, we designed a method to simultaneously detect and quantify these substances in human breast milk. Solid-phase extraction of 2 mL of milk was followed by derivatization with a trimethylsilyl reagent. Separation and detection was performed using gas chromatography coupled to mass spectrometry in the negative chemical ionization mode. Calibration curves were linear in the ranges of 10–200 and 1–20 ng/mL for lorazepam and lormetazepam, respectively. Limits of detection were estimated at 0.016 ng/mL for lormetazepam and 0.100 ng/mL for lorazepam. Our method was applied to real case samples from a woman receiving both benzodiazepines. Lorazepam concentrations varied from 55.3 to 123.1 ng/mL, and lormetazepam concentrations varied from 1.7 to 7.3 ng/mL.

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