Metsulfuron-methyl determination in environmental samples by solid surface fluorescence

A new environmental friendly methodology for metsulfuron-methyl quantification based on the fluorescent signal enhancement of rhodamine B dye has been developed. A cationic surfactant (cetyltrimethylammonium bromide, CTAB) and an anionic one (sodium dodecylsulfate) were employed to preconcentrate the herbicide using a coacervation phenomenon, in sodium borate buffer medium (pH 9.2). The coacervate phase was collected on a nylon membrane (0.45 μm) and the solid surface fluorescence signal was determined (λexc = 515 nm, λem = 565 nm). Experimental variables that influence on preconcentration step and fluorimetric sensitivity have been studied and optimized using response surface methodology. Under optimal working conditions, a LOD of 0.17 μg L−1 and a LOQ 0.53 μg L−1 was obtained. The zeroth order regression calibration was linear from 0.53 to 5.00 μg L−1. The method showed adequate sensitivity and selectivity, and was applied to the determination of trace amounts of metsulfuron-methyl in environmental water samples. The proposed methodology implies an alternative to traditional techniques for metsulfuron-methyl monitoring using an accessible instrument in control laboratories, representing a contribution in the toxicological and environmental areas for the monitoring of MSM in environmental samples, in agreement with the Green Chemistry.