Simultaneous determination of amoxicillin and doxycycline with partial least-square regression.

The existence of colinear and overlapping phenomena in the ultraviolet absorption spectra of amoxicillin and doxycycline makes it difficult to use ultraviolet spectrophotometry to determine the respective contents in a mixture of both components.L16(45) orthogonal experimental design was applied in this study and absorption data from of 200 to 250 nm of their mixture were obtained with UV scan procedure.Then a data normalization was made and a PLS(partial least square regression) predicting model was developed by using DPS 8.01 software.It was shown that this method was accurate and reliable,with the RPE% for both amoxicillin and doxycycline were 3.13% and 6.42%,respectively,and the average recovery rate were 100.34% and 100.71%,respectively.It was also simple and rapid without the necessity of separating the samples beforehand.