Determination of atropine in blood by gas chromatography/mass spectrometry

A gas chromatographic/mass spectrometric (GC/MS) method for the rapid quantitation of atropine (AT) in blood is presented. A 2.0-mL blood specimen containing deuterated N-methyl-atropine as the internal standard was alkaline-hydrolyzed to convert atropine to tropine. The tropine was extracted by organic solvent which was evaporated to dryness. Tropine in the residue was derivatized with pentafluoropropionic anhydride (PFPA) to the PFPA-tropine ester which was chromatographed on a 25-m cross-linked methyl silicone capillary column with temperature programming at 100 degrees C initially and increased by 20 degrees C/min. The retention time of atropine was 1.7 min. The GC/MS was operated in the SIM mode and the mass fragments monitored were 124 and 287 for AT and 127 and 290 for the internal standard. The assay was linear from 10-300 ng/mL. Replicate analysis of blood specimens containing 200 ng/mL gave a CV = 6.5% (n = 10). Recovery of AT at 75 and 150 ng/mL was 69% (n = 10). The limit of quantitation of AT was 10 ng/mL. Scopolamine may be simultaneously extracted and identified; the retention time was 1.8 min with mass ions 81 and 138.