Derivative spectrophotometric and colorimetric methods for the determination of guanoxan sulphate in tablets, urine and serum.

Three simple and rapid methods for the determination of guanoxan sulphate in tablets, urine and serum are presented. The first method is based on the direct measurement of the first (D-1) and second (D-2) (peak-trough) derivative values at 274-250 nm and 276-260 nm respectively. The other two methods depend on the formation of a charge-transfer chromogen with either tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The absorbance of the color developed at 416 and 840 nm respectively. The first and second derivative (D-1 & D-2) values for the charge-transfer products were also measured. The methods were proved to be accurate and reproducible as indicated by relative standard deviation of less than 2%. The proposed methods have been applied to the determination of guanoxan sulphate in tablets, and spiked human urine and serum.