Novel pipette-tip graphene/poly (vinyl alcohol) cryogel composite extractor for the analysis of carbofuran and carbaryl in water

Abstract

A novel pipette-tip extractor of a graphene/poly (vinyl alcohol) cryogel (graphene/PVA) composite sorbent was prepared to preconcentrate carbamate pesticides in environmental water samples before analysis with a gas chromatograph-flame ionization detector (GC-FID). This novel pipette-tip extractor with the graphene/PVA sorbent exhibited a high porosity when observed through a scanning electron micrograph (SEM). Under optimal conditions, using only 1.0 mL of sample and 0.75 mL of eluting solvent, the developed method provided a wide linear range of 10–700 ng mL⁻¹ and 10–500 ng mL⁻¹ with limit of detection (LOD) of 6.40 ± 0.18 and 9.17 ± 0.34 ng mL⁻¹ for carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) and carbaryl (1-naphthyl methylcarbamate), respectively. The pipette-tip extractor provided high extraction efficiency with high accuracy indicated, by good recoveries in the range of 74.5 ± 4.8% to 119.7 ± 1.6% and 76 ± 15% to 114 ± 19% for carbofuran and carbaryl, respectively. In addition, the fabrication procedure showed a good pipette-tip extractor-to-pipette-tip extractor reproducibility with a relative standard deviation of 1.3–9.8% (n = 5). When the developed pipette-tip extractor was applied for the extraction of carbofuran and carbaryl in surface water samples near vegetable plantation areas, 25.9 ± 8.2 ng mL⁻¹ of carbofuran was found, and carbaryl was also detected in concentrations that ranged from 45.0 ± 4.0 to 191 ± 13 ng mL⁻¹.

Keywords:

• Carbamate pesticides
• cryogel
• graphene
• pipette-tip extractor

Acknowledgments

The authors thank Dr. Brian Hodgson for assistance with the language editing of this manuscript.

Funding

This project was supported by the Higher Education Research Promotion and National Research University Project of Thailand (NRU); Office of higher Education Commission; the Center of Excellence for Innovation in Chemistry (PERCH-CIC), Commission on Higher Education, Ministry of Education, Thailand; Trace analysis and Biosensor Research Center (TAB-RC); Department of Chemistry, Faculty of Science and Graduate School Prince of Songkla University, Hat Yai, Songkhla, Thailand.

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