A multivariate calibration method for the analysis of two hypotensive binary mixtures is
described. The mixtures are composed of reserpine in combination either with
hydrochlorothiazide or hydrofluomethiazide respectively. The components of the two mixtures
show a considerable degree of spectral overlapping (83.5-88.5%). Resolution of the binary
mixtures under investigation has been accomplished mainly by using classical least squares
(CLS) analysis. The mixtures are simultaneously determined in three laboratory prepared tablet
forms with high accuracy without interference from the commonly added excipients. Good
recoveries were obtained with both synthetic mixtures and prepared tablets. The obtained
results were compared with those obtained from official methods and found in good agreement
with them. A comparison of the obtained results from CLS were performed with those obtained
from principle component regression (PCR).