Green method based on a flow-batch analyzer system for the simultaneous determination of ciprofloxacin and dexamethasone in pharmaceuticals using a chemometric approach. 
A green FBA method with UV detection was developed for simultaneous determination of ciprofloxacin (CIP) and dexamethasone (DEX) in ophthalmic and otic preparations.  A lab-made mixing detection chamber (MDC) was designed and coupled to the spectrophotometer in order to perform the mixing of solutions and the detection in the same receptacle.  Only water was used as solvent and no previous separation of the components was required.  Both analytes have a strong absorption between 190 and 370 nm in aqueous medium, at pH 7.  However, the spectrum of DEX is embedded in the CIP spectrum.  Thus, while CIP was analyzed using univariate calibration, DEX analysis was carried out comparing partial least squares (PLS-1) and multiple linear regression (MLR).  The latest required a previous variable selection step, which was performed using the genetic algorithm (GA) and the successive projections algorithm (SPA).  The FBA system made it possible to automatically prepare the calibration and validation sets.  The statistical parameters, in terms of relative errors of calibration and prediction, were acceptable for the determination of both CIP and DEX.  Also, a comparative study of chemometric models was carried out.  Commercial samples were analyzed and the obtained results are in close agreement with HPLC pharmacopeia methods.  The joint interval test for the slope and the intercept was used to test for the presence of bias.  There were no statistical differences between the proposed method and the reference method (α=0.05).  The sample throughput was 10h(-1).  The combination of automation and chemometric tools allows us to develop an environmental friendly method for the quality control of CIP and DEX in pharmaceuticals.