ANALYSIS OF LANTHANIDE-SENSITIZED EXCITATION-TIME DECAY LUMINESCENCE DATA MATRICES FOR THE DETERMINATION OF FLUOROQUINOLONES IN HUMAN SERUM. STANDARD ADDITION METHOD AND ACHIEVEMENT OF THE SECOND-ORDER ADVANTAGE

ALEJANDRO CESAR OLIVIERI; VALERIA LOZANO,; A. IBANEZ, GABRIELA; ROMA TAULER,

Bolonia

Congreso; XIII Simposio Internacional de Espectroscopía de Luminiscencia; 2008

Lanthanide-sensitized excitation-time decay luminescence produces a new type of second-order data which allows obtaining the second-order advantage when coupled to appropriate second-order multivariate calibration methods (1). When the analyte forms a complex with lanthanide ions, usually in the presence of synergistic ligands, surfactants and/or sodium sulphite, a data matrix consists of the time decay curves measured for the lanthanide luminescence emission at several different excitation wavelengths. We have determined the anbitiotic ciprofloxacin (CIP) in deproteinized human sera in the presence of terbium, sodium dodecyl sulphate and sodium sulphite. The deproteinized serum matrix is shown to affect the luminescence signal in such a way that the standard addition method is required for analyte quantitation. Potentially interfering therapeutic drugs, such as salycilate, produce a signal after complexation with terbium, which severely overlaps with that from the fluoroquinolone-terbium complex. Processing of the second-order excitation-time decay data allows: a) modelling the presence of the salycilate interferent signal, b) achieving the second-order advantage, and c) accurately estimating the analyte concentration. Several chemometric procedures have been  applied to process the data, and the most suitable one was multivariate curve resolution-alternating least-squares (MCR-ALS) (3,4), employing a novel procedure which combines the test sample data matrix and several matrices obtained by digital subtraction of test data matrix from the standard addition matrices. The results indicated adequate accuracy and precision for the determination of CIP in a range from 0.0 to 5.0 ppm in serum, well within the therapeutic range for the studied drug.