title: Fluorescence quantification of tetracycline in the presence of quenching matrix effect by means of a four-way model.
abstract: In this work, a four-way tensor is used to model the quenching effect in fluorescent measurements. By means of the analysis of excitation-emission matrices obtained in the determination of tetracycline in tea, which acts as quencher, it is shown as the impossibility to use a calibration, or an addition standard based on a three-way model. It is analysed the quencher multiplicative effect made on the tetracycline signal by means of an ANOVA. However, by arranging the experimental data in a four-way tensor, it is viable to perform a calibration based on the parallel factor analysis, PARAFAC, decomposition and a four-way partial least squares, 4-PLS, regression to quantify the tetracycline in the presence of the matrix quencher effect. 4-PLS calibration provides better results. In the range from 40 to 220 microg L(-1) gives an average of relative errors in absolute value equal to 8.02% in prediction (3.40% in calibration). The repeatability as standard deviation in this range is 5.08 microg L(-1) and the method is accurate, slope and intercept being statistically equal to 1 and 0, respectively when a regression calculated versus true concentration is performed. Moreover, it has a decision limit (CCalpha) of 13.87 microg L(-1) for a probability of false positive, alpha, equal to 0.05 and a capability of detection (CCbeta) of 26.63 microg L(-1) (for probabilities of false positive, alpha, false negative, beta, equals to 0.05).
authors.affiliation: Department of Chemistry, Faculty of Science, University of Burgos, Burgos, Spain.
authors.forename: N
authors.initials: N
authors.lastname: Rodríguez
authors.forename: M C
authors.initials: MC
authors.lastname: Ortiz
authors.forename: L A
authors.initials: LA
authors.lastname: Sarabia