Simultaneous Spectrophotometric Determination of Minoxidil and Tretinoin by the H-Point Standard Addition Method and Partial Least Squares

The paper describes two methods, H-point standard addition method (HPSAM) and partial least squares (PLS), for the simultaneous determination of minoxidil and tretinoin using spectrophotometry. The authors tested the accuracy and repeatability of the method using synthetic mixtures of the two drugs and found that they could be accurately determined in a concentration ratio of minoxidil to tretinoin from 33:1 to 1:2. The authors also used partial least squares regression to construct a model for resolving an overlapped spectrum and found that the method was effective in predicting the concentrations of the two drugs. The paper concludes that both methods are rapid, accurate, and simple for resolving minoxidil and tretinoin mixtures.