Cloud point extraction and concentration of carbaryl from natural waters

Abstract

An improved procedure is proposed for determination of the pesticide carbaryl in natural waters based on double cloud point extraction. The clean up step was carried out only with Triton X-114 in alkaline medium in order to avoid the use of toxic organic solvents as well as to minimise waste generation. Cloud point preconcentration of the product of the reaction of the analyte with p-aminophenol and cetyltrimethylammonium bromide was explored to increase sensitivity and improve the detection limit. Linear response was achieved within 10 and 500 µg L⁻¹ and the apparent molar absorptivity was estimated as 4.6 × 10⁵ L mol⁻¹ cm⁻¹. The detection limit was estimated as 7 µg L⁻¹ at the 99.7% confidence level and the coefficient of variation was 3.4% (n = 8). Recoveries within 91 and 99% were estimated for carbaryl spiked water samples. The results obtained for natural water samples were in agreement with those achieved by the batch of spectrophotometric procedure at the 95% confidence level. The proposed procedure is then a simple, fast, inexpensive and greener alternative for carbaryl determination.

Keywords:

• cloud point
• spectrophotometry
• carbaryl
• pesticide analysis
• waters
• Triton X-114

Acknowledgements

The authors acknowledge the fellowships and financial support from the Brazilian agencies Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP).