Non-trilinear chromatographic time retention-fluorescence emission data coupled to chemometric algorithms for the simultaneous determination of 10 polycyclic aromatic hydrocarbons in the presence of interferences

Multivariate calibration coupled to high-performance liquid chromatography-fast scanning fluorescence spectroscopy (HPLC-FSFS) was employed for the analysis of 10 selected polycyclic aromatic hydrocarbons (PAHs), six of which correspond to heavy PAHs. The goal of the present study was the successful resolution of a system even in the presence of real interferences. Second-order HPLC-FSFS data matrices were obtained in a short time with a chromatographic system operating in isocratic mode. The difficulties in aligning chromatographic bands in complex systems, such as the ones presented here, are discussed. Two second-order calibration algorithms which do not require chromatographic alignment were selected for data processing, namely, multivariate curve resolution-alternating least-squares (MCR-ALS) and parallel factor analysis 2 (PARAFAC2). These algorithms did also achieve the second-order advantage, and therefore they were able to overcome the problem of the presence of unexpected interferences. The study was employed for the discussion of the scopes of the applied second-order chemometric tools, demonstrating the superiority of MCRALS to successfully resolve this complex system. The quality of the proposed techniques was assessed on the basis of the analytical recoveries from different types of water and olive oil samples after solid-phase extraction. The studied concentration ranges in water samples were 5.6 × 10-3-0.20 ng mL-1 for heavy PAHs and 0.036-0.80 ng mL-1 for light PAHs, while in oil samples the PAHs concentrations were 0.13-9.6 and 2.3-49.5 ng mL-1 for heavy and light PAHS, respectively. All real samples were analyzed in the presence of the studied interferences.Fil: Bortolato, Santiago Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Arancibia, Juan Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin

Determination of ochratoxin A in coffee and tea samples by coupling second-order multivariate calibration and fluorescence spectroscopy

A new method to quantify the mycotoxin ochratoxin A (OTA) in coffee and tea samples is proposed based on second-order multivariate calibration and excitation-emission fluorescence matrix (EEFM) data. Experimental conditions were optimized by studying the effect of pH and various organized media on the fluorescence signal of OTA. For each analysed matrix (coffee grains and tea leaves), several sample pretreatments and calibration methods (external or standard addition) and data processing by chemometric models (e.g., parallel factor analysis/PARAFAC and multivariate curve resolution-alternating least squares/MCR-ALS) were evaluated and discussed. The MCR-ALS algorithm provided an adequate fit to the data for both samples, while PARAFAC was satisfactory only for the tea samples. Regarding the figures of merit, the limits of detection were in the range of 0.2–0.3 ng mL−1; furthermore, low relative prediction errors, between 2% and 4%, were achieved in both the fortified and real samples. Accordingly, the proposed methodology was applied to analyse fortified roasted and green coffee and real tea leaf samples. Satisfactory recoveries were achieved (ranging from 92 to 110%), and the obtained concentrations were in agreement with the values obtained by the reference method (based on high-performance liquid chromatography with fluorescence detection/HPLC-FLD). In addition, all samples contained OTA levels lower than the maximum permissible levels. Finally, the proposed strategy allows the use of green analytical chemistry principles; for instance, the use of organic solvents and the generation of waste products were significantly lower than for similar analytical methods reported in the literature.Fil: Gonzalez, Albani L.. Pontificia Universidad Católica de Valparaíso; ChileFil: Lozano, Valeria Antonella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Bravo, Manuel A.. Pontificia Universidad Católica de Valparaíso; Chil

Determination of fungicide residues in environmental samples

The current state of analytical methods devoted to the determination of common fungicide residues is reviewed, based on the concern of worldwide government agencies about their potential risk for human health. The review covers relevant analytical methods applied to samples of environmental interest, highlighting the analysis of natural waters and foodstuff for human consumption.Fil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin

Spectrofluorimetric study of the herbicide bentazone in organized media: Analytical applications

The present work is devoted to the study of the spectrofluorimetric behavior of the herbicide bentazone in the presence of selected organized assemblies, with the purpose of optimizing the working conditions for its determination in environmental samples. Bentazone is one of the most applied herbicides in countries of profuse agriculture, and belongs to the group of relevant persistent pollutants. Among the studied media, methyl-b-cyclodextrin produced the largest fluorescence signals for bentazone, and was selected as auxiliary reagent for the quantitative analyses. The selectivity of the method, i.e., its capability to measure accurately an analyte in the presence of interferents that may be present in the sample matrix, was improved through second-order multivariate calibration, measuring excitation- emission fluorescence matrices for both artificial and real samples, and processing them with the algorithm parallel-factor analysis (PARAFAC). A detection limit of 3 ng mL-1 and a relative error of prediction of 5.6% for bentazone were obtained in samples without interferents. In samples containing seven additional agrochemicals acting as interferences, the limit of detection and the relative error of prediction were 5 ng Ml-1 and 9.9%, respectively. The method was successfully applied to spiked natural water samples, with statistical parameters in these cases which were similar to those calculated in samples with interferences. In this study, the advantages of coupling fluorescence measurements in organized media and second-order chemometric analysis are exploited in order to rapidly quantify a frequent pollutant at low concentrations in a very interfering medium and using green chemicals.Fil: Porini, Javier A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin

Fluorescence and Phosphorescence Chemical Sensors Applied to Water Samples

Due to the outstanding characteristics of both fluorescence andphosphorescence signals, they are widely applied to the construction of chemicalsensors. The development of these sensors for the detection and quantification ofcompounds of environmental concern is an active research topic, daily enriched withthe contribution of new works in the area. This chapter provides fundamentals andpractical aspects of this type of sensors, focusing in those works devoted to quantifyboth organic and inorganic pollutants in environmental waters. The chapter isorganized upon the basic functional units of a chemical sensor. A few examples ofstrategies of evaluation involving multivariate chemometric analysis are alsodiscussed.Fil: Ibañez, Gabriela Alejandra. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Analítica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Analítica; Argentin

Solid-surface fluorescent properties of estrogens: Green analytical applications

For the first time, the fluorescent signals produced by 17β-estradiol (E2), estradiol valerate (E2V) and 17α-ethinylestradiol (EE2) were investigated after being retained in selected solid surfaces. Among different studied supports, both C18 and nylon membranes demonstrated to have been able to induce intense signals over their surface, after aqueous solutions of the analytes were retained via a solid-phase extraction procedure. Physicochemical variables which affect the quality of the fluorescence signals were optimized, and the results obtained in the studied solid supports were compared and discussed. While nylon successfully faced the trouble of spectrofluorimetrically quantifying estrogens in pharmaceuticals with unbalanced estrogen/progestagen ratios, C18 membranes showed very good qualities for second-order spectrofluorimeric measurements, allowing the determination of E2 (the most active estrogen) in potentially contaminated fish and chicken samples. The fluorescence excitation–emission matrices, directly measured on a C18 surface, were processed using appropriate chemometric algorithms in order to efficiently quantify E2 in the presence of natural matrix constituents. The present strategy avoids the elution step, considerably decreasing the use of organic solvents, the analysis time and the experimental errors. In addition, the instrumental involved is nonsophisticated and, therefore, the experiments could be carried out in routine laboratories.Fil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Pérez, Rocío Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; Argentin

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

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.Fil: Piccirilli, Gisela Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin

Flow injection analysis with on-line nylon powder extraction for room-temperature phosphorescence determination of thiabendazole

A fast and very selective flow-through phosphorescence optosensor was designed and characterized for the determination of the fungicide thiabendazole in water samples. For the first time, thiabendazole was determined using a flow-through optosensor based on the phosphorescence signals obtained when it is retained in a solid support. While thiabendazole does not phosphoresce in packing materials commonly used to fill the flow-cell, significant emission signals are observed when it is retained on nylon powder in the presence of iodide and sulfite. The experimental set-up was based on a flow-injection manifold coupled to an on-line phosphorescence detector containing nylon powder packed in a conventional flow-cell. Potassium iodide and sodium sulfite were added to sample aliquots to improve the thiabendazole phosphorescence and injected in the flow manifold using water as carrier. After the phosphorescence emission was registered, the analyte was eluted from the packed nylon with a 65% (v/v) methanol-water mixture. Optimal instrumentation, experimental and flow conditions were evaluated. Using a sample volume of 2000 μL, the analytical signal showed a very good linearity in the range 12.9-110 ng mL-1, with a detection limit of 4.5 ng mL-1, and a sample throughput of about 14 samples per hour. The effects of the presence of concomitant species in the thiabendazole phosphorescence signal were studied, and a comparison with the fluorescence nylon-powder optosensor was carried out and discussed. Finally, the applicability of the proposed optosensor was tested in water samples, and satisfactory recoveries ranging between 97% and 105% were obtained.Fil: Piccirilli, Gisela Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin

Multi-way chromatographic calibration: A review

This review discusses recent advances in both theory and experiment regarding multi-way chromatographic calibration. The focus is directed towards the chemometric processing of multi-way data arrays in which one or more instrumental modes describe the elution time behavior across liquid or gas chromatographic columns, and the remaining ones are of spectroscopic nature, e.g. UV?vis absorption, fluorescence emission (either as vectors or matrices) or mass spectrometry. Successful multi-way data decomposition into profiles for the contributing components allows one to perform quantitative analysis of complex samples. Quantitative applications usually make appropriate use of the second-order advantage which is inherent to multi-way data processing, and reduce the complexity of the data to a virtual univariate calibration which is typical of classical analytical chemistry. A number of recent experimental works will be discussed to illustrate the above concepts.Fil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Olivieri, Alejandro Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin

A novel flow-through fluorescence optosensor for the determination of thiabendazole

This paper presents the development of a new flow-injection system combined with solid-surface fluorescence detection for the determination of the widely used fungicide thiabendazole. Nylon powder was probed as a novel solid support for building the optosensor. The method is based on the on-line immobilization of thiabendazole onto nylon in a continuous flow system, followed by the measurement of its native fluorescence. Aqueous samples are directly injected in a water carrier, resulting in a very simple and economical method. The analytical figures of merit obtained using 1500 μL of sample and 75% methanol (v/v) as eluting solution were: linear calibration range from 8 to 120 ng mL-1 (the lowest value corresponds to the quantitation limit), relative standard deviation, 0.9% (n = 5) at a level of 64 ng mL-1, limit of detection calculated according to 1995 IUPAC recommendations is to 2.8 ng mL-1, and sampling rate of 14 samples h-1. The potential interference from other agrochemicals, metal ions and common anions, and the viability of determining thiabendazole in real water samples were also evaluated.Fil: Piccirilli, Gisela Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin