Isotopic fractionation of isopropylantipyrine and its deuterated analogues by capillary gas chromatography.

Isotopic fractionation of isopropylantipyrine (IPA) and its deuterated analogues was examined by gas chromatography (GC) using capillary column. The separation of IPA and seven kinds of deuterated IPAs were proportional to the number of labeled deuterium atoms and inversely to the temperature of the column oven. The resolution coefficient between IPA and IPA-3-C2H3-4-(C2H3)2 (IPA-2H-7) was 1.46 at 200 degrees C for column temperature. The present isotopic fractionation procedure was applied to the isotope dilution analysis of IPA. Measurement of the sample prepared by the addition of a known amount of IPA and IPA-2H-7 to the control plasma of rabbit allowed observation of a linear relationship between peak area ratio and added amount ratio. The correlation coefficient obtained by regression analysis was 1.000. The present method was also applied to determine the plasma level of IPA in rabbit after oral administration.