A Rapid Gas Chromatographic Method Quantitating Clozapine in Human Plasma or Serum for the Purpose of Therapeutic Monitoring

Author: Jennison Thomas A.   Brown Paul   Crossett Jonathan   Kushnir Mark   Urry Francis M.  

Publisher: Oxford University Press

ISSN: 0146-4760

Source: Journal of Analytical Toxicology, Vol.19, Iss.7, 1995-11, pp. : 537-541

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Abstract

A gas chromatographic method using nitrogen-phosphorus detection was developed to quantitate clozapine in plasma or serum. Methyl clonazepam was used as an internal standard. Sample preparation included a single-step extraction with ethyl acetate, which was injected directly onto a wide-bore capillary column. Within-run and total precision, measured as percent coefficient of variation, were determined at low, therapeutic, and high clozapine plasma concentrations. The within-run precision for the low, therapeutic, and high clozapine plasma samples was 5.2, 2.7, and 2.4%, respectively. The total precision for the low, therapeutic, and high clozapine plasma samples was 10.0, 2.6, and 2.0%, respectively. Analytical accuracy was evaluated by comparing quantitative results with those obtained from a reference laboratory. Those samples containing therapeutic or high concentrations agreed within 3%; the sample containing a subtherapeutic concentration differed by 11.9%. The limit of quantitation was determined to be 35 ng/mL, and the upper limit of linearity was 3000 ng/mL. No significant interferences were detected after testing more than two dozen drugs and metabolites.