Analytical Sciences

Determination of Glyphosate in Water Samples by Multi-pumping Flow System Coupled to a Liquid Waveguide Capillary Cell

Aline S. SILVA,* Ildikó V. TÓTH,** Leonardo PEZZA,* Helena R. PEZZA,* and José L. F. C. LIMA**

*Instituto de Química, Universidade Estadual Paulista (UNESP), P. O. Box 355, Araraquara CEP 14801-970, SP, Brazil
**REQUIMTE, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha 164, Porto 4099-030, Portugal

A simple screening method was developed for the determination of glyphosate in water samples using a multi-pumping flow system. The proposed method is based on the reaction between glyphosate and p-dimethylaminocinnamaldehyde (p-DAC), in an acid medium where the reaction product can be measured spectrophotometrically at λ_max = 495 nm. An experimental design methodology was used to optimize the measurement conditions. The proposed method was applied to the determination of glyphosate in water samples in a concentration range from 0.5 to 10 μg mL⁻¹. The limit of detection and quantification were 0.17 and 0.53 μg mL⁻¹, respectively. The results obtained (88.5 to 104.5%) in recovery studies for the determination of glyphosate in different water samples indicated good accuracy and no matrix effect for the developed method. Samples were also analyzed by a confirmatory HPLC method, and agreement within the two set of results was found.

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