چکیده (انگلیسی):

Simple, accurate and precise reversed-phase liquid chromatographic (LC) and spectrophotometric
methods have been developed and validated for the determination of erythromycin
stearate (ERS) and trimethoprim (TMP) in mixture. In LC method, chromatographic separation
was achieved on a Symmetry Waters C18 column (150 · 4.6 mm, 5 lm) based on isocratic elution
using a mobile phase consisting of potassium dihydrogen phosphate buffer pH (9):acetonitrile:water
(25:100:50, v/v/v) at a flow rate of 1.6 ml min1 with UV detection at 210 nm for ERS and 280 nm
for TMP. Besides, two spectrophotometric methods were applied after reaction with perchloric acid
(12 M) which gives a colored product with ERS. Then, the spectral interference between the colored
product of ERS and TMP was resolved by either ratio spectra derivative spectrophotometry in the
first spectrophotometric method or chemometric techniques, namely classical least-squares (CLS),
principal component regression (PCR) and partial least-squares regression (PLS) in the second
spectrophotometric method. The results were statistically compared using one-way analysis of
variance (ANOVA). The methods developed were satisfactorily applied to the analysis of the pharmaceutical preparation containing the two drugs and proved to be specific and accurate for the
quality control of the cited drugs in pharmaceutical dosage forms.