Abstract
An improved method for estimation of the tolbutamide and chlorpropamide levels in the plasma by GLC is described.
After adding 10 μg of N-methyl-para-toluene sulfonamide as an internal standard, 0.5 ml of plasma was extracted into chloroform, back-extracted into alkali, and finally re-extracted into the chloroform layer. The chloroform layer was then evaporated under N2 stream and subjected to GLC. The GLC apparatus was equipped with a flame ionizing detector including a 2 m dual glass column packed with 3% XE 60 on acid-washed DMCS chromosorb W (100-120 mesh). The temperatures at the injection port, column and detector were 280, 230 and 280°C respectively. To ensure complete pyrolysis of the tolbutamide and chlorpropamide, a small amount of glass wool was inserted at the inlet part of the column which was surrounded by the inlet heating block according to the method of Simmons et al.
The mean coefficients of variation at 5, 10, 20, 40, 80 and 160 μg/ml were approximately 3.3% and 4.8% in the case of tolbutamide and chlorpropamide, respectively. The recovery rates were 90-98% and 96-110 in the case of tolbutamide and chlorpropamide, respectively.
