Application of PLS and PARAFAC in simultaneous spectrophotometric determination of oxytetracycline, tetracycline and doxycycline in honey samples

A simple, sensitive, rapid and precise spectrophotometric method has been developed and validated for simultaneous determination oxytetracycline (OTC), tetracycline (TC) and doxycycline (DXC) in honey samples. Chemometrics methods suitable for overlapping spectra and have resolved successfully the overlapping bands. Two chemometrics techniques parallel factor analysis (PARAFAC) and partial least square (PLS) were applied to the determination of TCs in their ternary mixture and the proposed calibration techniques were validated by analyzing synthetic mixtures consisting of these drugs. The calibration and validation sets were constructed with solutions in the concentration ranges from (0.1-16) µgmL-1 for TC, (0.1-30) µgmL-1 and (0.1-20) µgmL-1 for DXC and OTC. The procedure was repeated at different pH values. Partial least squares (PLS) models were built at each pH and used to determinate a set of synthetic mixtures. The best model was obtained at pH =8.0. The PARAFAC model was applied to a three-way array constructed using all the pH data sets and enable better results. The RMSEP for DXC, OTC and TC with PLS and PARAFAC were 0.123, 0.236, 0.167 and 0.0196, 0.0480, 0.0316 respectively.