[Isotopic fractionation of iproniazid and isopropylhydrazine from their deuterated analogues and application for isotope dilution analysis by capillary gas chromatography].

Quantitative analyses of iproniazid (IPN) and deuterated analogue (IPN-d6) and of isopropylhydrazine (IP-Hy) and deuterated analogue (IP-Hy-d6) after conversion to pyrazole derivatives (IDP) were carried out by gas chromatography. The complete separation of protio- from deutero-forms of IPN and IDP was achieved by using a fused-silica CBP1 capillary column (50 m). The resolution coefficients between two isotopic molecules were 1.10 for IPN and 1.62 for IDP, respectively. The present isotopic fractionation procedure was applied to the isotope dilution analyses of IPN and IP-Hy. By the measurement of the samples prepared by the addition of known amounts of IPN and IPN-d6 to the control plasma and urine of rat, a linear relationship between peak height ratio and added amount ratio was observed. The correlation coefficients obtained by regression analysis were 0.9990 for the plasma and 0.9999 for the urine, respectively. In the case of IP-Hy, a linear relationship was also observed, and the correlation coefficients were 0.9998 for the plasma and 0.9997 for the urine, respectively. The present method was compared with the gas chromatography-mass spectrometry method in urinary samples from rats treated with IPN. The results of these parallel determinations were comparable.