Partial least-squares method in analysis by differential pulse polarography. Simultaneous determination of amiloride and hydrochlorothiazide in pharmaceutical preparations

A method is proposed for the simultaneous determination of amiloride and hy drochlorothiazide in pharmaceutical preparations using differential pulse p olarography in the presence of oxygen and partial least-squares (PLS) for c alibration. The experimental variables that influence the system (pulse hei ght, pulse delay and pH) are optimized by using response surface methodolog y to relate the variables to be optimized to the mean relative square error of prediction (RSEP), which is minimized. The proposed method was used to determine the two drugs in synthetic mixtures and pharmaceutical preparatio ns. The results were validated by comparison with HPLC, with errors less th an 10% in all instances. (C) 1999 Elsevier Science B.V. All rights reserved .