Highly collinear three-way photoinduced spectrofluorimetric data arrays modelled with bilinear least-squares: Determination of tetracyclines in surface water samples

A new sensitive method for the determination of three tetracyclines in surface water samples (tetracycline, chlortetracycline and oxytetracycline) using highly collinear data corresponding to photochemical-induced fluorescence excitation emission matrices, modelled with three-way data arrays chemometric tools has been developed. The method involves irradiation of aqueous basic solution of antibiotics with UV light and fluorescence determination of the generated photoproducts after solid phase preconcentration (SPE) with Oasis hydrophilic lipophilic balance (HLB) cartridges. The chemometric models were built by using an eight samples calibration set and samples corresponding to both a validation set and a test set. The latter set containing unsuspected interferents. Considering this latter samples, recoveries of 101.5, 97.9 and 102.2 were obtained for the three analytes. Evaluation of constant and proportional bias and precision were made by using the elliptical joint confidence region (EJCR) test for the estimated intercept and slope.