Preconcentration and Determination of Carbamate Pesticide Residues in Vegetable Samples by Electrokinetic Flow Analysis with On-Line Hollow Fiber Liquid–Liquid–Liquid Microextraction and Spectrophotometry

ABSTRACT

A simple, convenient, sensitive, and environmentally friendly analysis method for carbamate pesticide residues in vegetable samples was proposed by using electrokinetic flow analysis (EFA) with on-line hollow fiber liquid–liquid–liquid microextraction (LLLME) and ultraviolet spectrophotometry (UV). On-line LLLME conditions were investigated, including organic solvents, flow rate of sample loading, extraction times and sample volume, and so on. With dodecanol phase immobilized on the hollow fiber, the on-line LLLME unit could be operated for 150 hr. In each regeneration of dodecanol phase on the hollow fiber, the consumption of dodecanol was 50 µL, namely., the consumption rate was 0.33 µL h⁻¹. By introducing 5.0 mL sample solution, the analytical time was 22 min and the enrichment factor of carbaryl achieved 300. The linear calibration range was from 0.0033 to 1.0 µg mL⁻¹ carbaryl, which was used as a converted concentration for total carbamate pesticides. The relative standard deviation (R.S.D.) of peak height was 2.7% (n = 5) and the limit of detection (LOD) was 1 ng mL⁻¹ carbaryl (K = 3, n = 11).

KEYWORDS:

• carbamate pesticide
• electrokinetic flow analysis
• green analysis method
• hollow fiber
• on-line liquid–liquid–liquid microextraction
• spectrophotometry
• vegetable

ACKNOWLEDGMENTS

The authors thank the Natural Science Foundation of China (Nos. 20675075 and 20275035) for financial support to carry out this work.

Notes

An invited paper submitted to a special issue on Green Spectroscopy and Analytical Techniques, organized by Professor Miguel de la Guardia, of the Department of Chemistry, University of Valencia, Spain, and Professor Arabinda Kumar Das, of the Department of Chemistry, University of Burdwan, West Bengal, India.