Simultaneous determination of flufenamic and meclofenamic acids in human urine samples by second-order multivariate parallel factor analysis (PARAFAC) calibration of micellar-enhanced excitation–emission fluorescence data

A new spectrofluorimetric method has been developed for the quantitative determination of the anti-inflammatory flufenamic and meclofenamic acids in urine samples. The method is based on second-order multivariate calibration applying parallel factor analysis (PARAFAC). The fluorescence excitation–emission matrices (EEMs) of these compounds are highly overlapped, precluding analyte direct determination without performing a previous separation procedure. The use of a micellar medium allowed for both fluorescence enhancement and analyte discrimination from the biological background. The calibration solutions were prepared in water, with concentrations in the ranges from 0.15 to 4.00 μg ml−1 for flufenamic acid and from 0.25 to 6.00 μg ml−1 for meclofenamic acid. The use of the second-order calibration method, in the standard addition mode, was required to avoid internal filter interference effects from the urine background. The measured EEMs of the two analytes as analytical signals allowed their simultaneous determination in human urine samples, in the therapeutic ranges from ca. 40 to 150 mg l−1. The proposed procedure was validated by comparing the obtained results with a capillary electrophoresis method, with satisfactory results for the assayed method.