DETERMINATION OF TRAPIDIL IN SERUM AND URINE BY SPE AND DERIVATIVE SPECTROPHOTOMETRY

An analytical method to assay the cardiovascular drug Trapidil in human serum and urine is proposed. The high complexity of the biological samples required a preliminary simplification able also to induce a concentration enrichment of the analyte. For this aim a solid phase SPE extraction procedure was defined by means of the cartridges Strata-X, which demonstrated to be able to retain the drug with elevated affinity and contemporarily to eliminate almost all the impurities. The concentration values carried out by the ordinary UV spectra of the solutions from SPE treatment resulted affected by errors of 5-10%. Such inaccuracy was demonstrated to be caused by background absorbance, due to the interferences and turbidity of the biological samples, not completely eliminated in the sample preparation step. Therefore, an analytical procedure was defined by using the derivative third-order spectra, particularly able to keep negligible the absorbance background. The spectral curves in 3dh derivative order allowed so to select in both matrixes a signal proportional to the drug concentration and not influenced from extraneous interferences. Two relationships were defined by linear regression analysis which correlate the drug concentration as function of the respective analytical signals. . The method was validated through analysis of synthetic samples, showing good accuracy (> 95%) and precision (RSD < 4%); the determination limit resulted to be 0.2 and 0.5 g/ml in serum and urine, respectively.