Determination of glyphosate in soil samples using CdTe/CdS quantum dots in capillary electrophoresis

In this work, CdTe/CdS quantum dots were incorporated in a capillary electrophoresis system for the determination of glyphosate in soil samples. Fluorescence spectroscopic evaluation indicates there is an interaction between CdTe/CdS quantum dots and glyphosate, which produces an enhancement of the emission signal as a result of the formation of quantum dots-glyphosate complex. A capillary electrophoresis system for the separation of the complex from the remaining CdTe/CdS quantum dots is described herein. The variables involved in the separation were evaluated and optimized using a central composite design. Signals are elucidated under optimal conditions by calculating the difference in their electrophoretic mobility. The methodology selectivity allows the determination of glyphosate in complex matrices such as soil samples. The proposed method exhibits a linear range from 77.1 to 700?mg?kg?1 with a limit of detection of 25.7?mg?kg?1 and adequate repeatability and reproducibility (%RSD <5.0%). The described methodology was applied to 7 soil samples collected from crop fields in Hidalgo, Mexico, found concentrations varied from 320.6 to 607.7?mg?kg?1.