SENSITIVE MICROANALYSIS OF IMIPRAMINE AND DESIPRAMINE IN SINGLE-RAT THYROIDS BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

A new sensitive method for the quantitative determination of imipramin e and desipramine in single rat thyroids using gas chromatography-mass spectrometry with selected ion monitoring, after enzymatic hydrolysis and liquid-liquid extraction has been developed. The technique was de emed suitable for microanalysis of single rat thyroids and for other s olid tissues, using smaller sample sizes than usually required for tra ditional determination methods. The quantification was linear from 10 to 200 nmol/l (i.e., from 0.25 to 5 mu g/g) for imipramine and from 10 0 nmol/l to 2000 nmol/l (i.e., from 2.4 to 47 mu g/g) for desipramine, and the limits of detection (less than 25 ng/g tissue for both compou nds) were better than those previously reported. Recoveries, repeatabi lity and reproducibility of this technique were satisfactory. It has b een successfully applied in a preliminary study of the concentration-t ime profiles of imipramine and desipramine in the thyroid of rats trea ted with either of these drugs.