Simultaneous Determination of Sulfonylureas by Solid-Phase Extraction and Photo-induced Fluorescence Detection using a Flow-Batch Analyzer System and Chemometric approach.

GRÜNHUT MARCOS; LLAMAS NATALIA; ACEBAL CAROLINA; IVANA RÁMKOVÁ; HANA SKLENÁřOVÁ; FERNÁNDEZ BAND BEATRIZ

Mendoza

Congreso; 7º Congreso Argentino de Química Analítica; 2013

AAQA

Sulfonylureas are an important family of herbicides employed in ahía lanca?s agricultural region. Among them, metsulfuron-methyl (MSM), chlorsulfuron (CSF) and nicosulfuron (NSF) are non-fluorescent compounds, but fluorescence signals can be obtained upon UV irradiation. The Argentine legislation establishes a maximum of 100 μg L-1 for total pesticides in drinking water [1]. For this reason, detection at low concentration levels is necessary, and preconcentration procedure is required. On the other hand, Flow-Batch Analysis (FBA) systems draw upon the useful features of batch and multi-commutation approaches [2]. FBA systems constitute an excellent alternative to automate analytical procedures because of their flexibility and versatility (multi-task characteristic). FBA systems make possible to implement different analytical processes just by changing the operational parameters in the control software (i.e. no significant modifications have to be made in the system). Moreover, FB systems has several advantages such as easy implementation, sampling rate, high sensitivity, low cost, and the use of small amounts of reagents. In this work, a new FBA method with on-line solid-phase preconcentration step (C18; 100 mg; 60-80 μm particles) and photochemical induced fluorescence (PIF) detection at pH 12 during 23 s for determination of MSM, CSF and NSF was developed. The physical and chemical variables of the system were exhaustively studied (eluting solvent, volume and flow rates of sample and eluting solvent, irradiation time, pH conditions, instrumental conditions). After irradiation, MSM, CSF and NSF present emission spectra with strong signals between 370 and 500 nm. However, the mixture containing the three analytes shows overlapping. Thus, chemometric tools were required to resolve and quantify these analytes. A central composite experimental design was used in order to perform the calibration and validation sets. Partial Least Squares (PLS) and Multiple Linear Regression (MLR) previous selection of variables were applied to the fluorescence spectra data. The sample does not require any pretreatment, resulting in a simple and economic way to carry out the simultaneous determination of MSM, CFS and NSF in drinking water. The sample throughput was 4 h-1, including the preconcentration step. -1 for total pesticides in drinking water [1]. For this reason, detection at low concentration levels is necessary, and preconcentration procedure is required. On the other hand, Flow-Batch Analysis (FBA) systems draw upon the useful features of batch and multi-commutation approaches [2]. FBA systems constitute an excellent alternative to automate analytical procedures because of their flexibility and versatility (multi-task characteristic). FBA systems make possible to implement different analytical processes just by changing the operational parameters in the control software (i.e. no significant modifications have to be made in the system). Moreover, FB systems has several advantages such as easy implementation, sampling rate, high sensitivity, low cost, and the use of small amounts of reagents. In this work, a new FBA method with on-line solid-phase preconcentration step (C18; 100 mg; 60-80 μm particles) and photochemical induced fluorescence (PIF) detection at pH 12 during 23 s for determination of MSM, CSF and NSF was developed. The physical and chemical variables of the system were exhaustively studied (eluting solvent, volume and flow rates of sample and eluting solvent, irradiation time, pH conditions, instrumental conditions). After irradiation, MSM, CSF and NSF present emission spectra with strong signals between 370 and 500 nm. However, the mixture containing the three analytes shows overlapping. Thus, chemometric tools were required to resolve and quantify these analytes. A central composite experimental design was used in order to perform the calibration and validation sets. Partial Least Squares (PLS) and Multiple Linear Regression (MLR) previous selection of variables were applied to the fluorescence spectra data. The sample does not require any pretreatment, resulting in a simple and economic way to carry out the simultaneous determination of MSM, CFS and NSF in drinking water. The sample throughput was 4 h-1, including the preconcentration step. -1, including the preconcentration step.