Using chemometric tools to investigate the quality of three- and four-way liquid chromatographic data obtained with two different fluorescence detectors and applied to the determination of quinolone antibiotics in animal tissues

Abstract

A comparison of two multi-way methodologies is presented regarding the simultaneous quantitation of several analytes in complex samples. Both protocols are based on liquid chromatography with fluorescence detection, in the following modes: (1) collecting second-order/three-way data by fluorescence emission detection at a fixed excitation wavelength, and (2) measuring third-order/four-way data through excitation-emission fluorescence matrix detection. Ten quinolone antibiotics were simultaneously analyzed in edible animal tissues such as chicken liver and bovine liver and kidney. Multivariate curve resolution - alternating least-squares (MCR-ALS) provided excellent results with the second-order strategy, with average relative prediction errors in the range 4–12% for real samples, at analyte concentrations which are compatible with the corresponding maximum residue levels. For third-order data, however, the overall MCR-ALS analytical results were worse than for second-order data (relative errors were in the range 9–23%), and one analyte was not resolved. As an alternative, unfolded partial least-squares with residual bi- and trilinearization (U-PLS/RBL and U-PLS/RTL) were applied to both second- and third-order data, with relative errors of 7–18% and 5–27% respectively. The latter errors were significantly larger than those for MCR-ALS/second-order data, although the U-PLS/RTL model permitted the detection of all analytes when processing the third-order data. Relative advantages and disadvantages of the applied procedures are discussed on the basis of the analytical performances and the specific details of the instrumental setups.