title: Second-order advantage with excitation-emission fluorescence spectroscopy and a flow-through optosensing device. Simultaneous determination of thiabendazole and fuberidazole in the presence of uncalibrated interferences.
abstract: This paper presents a novel approach for the simultaneous determination of two widely used fungicides in a very interfering environment, combining the advantage of a spectrofluorimetric optosensor coupled to a flow-injection system and the selectivity of second-order chemometric algorithms. The sensor is based on the simultaneous retention of thiabendazole and fuberidazole on C18-bonded phase placed inside a flow-cell. After the arrival of the analytes to the sensing zone, the flow is stopped and the excitation-emission fluorescence matrix is read in a fast-scanning spectrofluorimeter. Parallel factor analysis (PARAFAC) and unfolded and multidimensional partial least-squares coupled to residual bilinearization (U- and N-PLS/RBL) were selected for data processing. These algorithms achieve the second-order advantage, and are in principle able to overcome the problem of the presence of unexpected interferences. The power of U-PLS/RBL to quantify both fungicides at parts-per-billion levels, even in the presence of high concentrations of spectral interferences such as carbaryl, carbendazim and 1-naphthylacetic acid, is demonstrated. Indeed, U-PLS/RBL allowed us to reach selectivity using a commercial but non-selective sensing support. To the best of our knowledge, this is the first time the potentiality of the 'second-order advantage' is evaluated on a flow-injection system, using an unspecific supporting material and in the presence of three real interferences. Using a sample volume of 2 mL, detection limits of 4 ng mL(-1) and 0.3 ng mL(-1) for thiabendazole and fuberidazol were respectively obtained in samples without interferences. In samples containing interferences, the limits of detection were 17 and 1 ng mL(-1) for thiabendazole and fuberidazol, respectively. The sample frequency, including excitation/emission fluorescence matrix measurements, was 12 samples h(-1). The sensor was satisfactorily applied to the determination of both analytes in real water samples.
authors.affiliation: Instituto de Química Rosario (CONICET-UNR), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina.
authors.forename: Gisela N
authors.initials: GN
authors.lastname: Piccirilli
authors.forename: Graciela M
authors.initials: GM
authors.lastname: Escandar
mesh_terms: D000465:Algorithms; D000935:Antifungal Agents / Q000032:analysis*; D001562:Benzimidazoles / Q000032:analysis*; D017022:Flow Injection Analysis; D013050:Spectrometry, Fluorescence / Q000295:instrumentation / Q000379:methods*; D013827:Thiabendazole / Q000032:analysis*
chemical_list: D000935:Antifungal Agents; D001562:Benzimidazoles; D013827:Thiabendazole; C004198:fuberidazole