Four-way calibration applied to the processing of pH-modulated fluorescence excitation-emission matrices. Analysis of fluoroquinolones in the presence of significant spectral overlapping

Abstract

A new methodology involving four-way multivariate calibration with a balanced number of data points in all modes is presented. The method is based on fluorescence excitation-emission matrices modulated by a double pH gradient obtained in a flow injection system. This data array was employed for the quantitation of ciprofloxacin, ofloxacin and norfloxacin in unprocessed urine samples. Due to the presence of potential interfering compounds with overlapping profiles in the analyzed samples, it is required to achieve the second-order advantage. The four-way arrays obtained were processed by parallel factor analysis (PARAFAC), attaining satisfactory results with relative errors of prediction (REP%) between 3% and 7.5% in the analyzed samples for all analytes. The average limit of detection (mg L− 1) was 0.035 for norfloxacin and ofloxacin and 0.028 for ciprofloxacin.