Magnetic stirring-assisted dispersive liquid–liquid microextraction in narrow neck glass tube for determination of cadmium in water, fruit and vegetable samples using response surface methodology

Abstract

Narrow neck glass tube-magnetic stirring-assisted dispersive liquid–liquid microextraction for extraction and preconcentration of trace amounts of cadmium ions as ammonium pyrrolidine dithiocarbamate complex was developed. In this method, a cloudy state is formed in a homemade glass syringe by magnetic stirring. Afterward the organic phase on top of the solution was transferred into narrow neck by moving the piston upwards, and withdrawn by the syringe for conventional injection to flame atomic absorption spectrometry. The experimental conditions were optimized by Plackett–Burman and Box–Behnken design methods. Under the optimum conditions (pH 5.5, chelating agent = 1 × 10⁻⁵ mol L⁻¹, sodium chloride (0.04% w/v), extraction solvent volume = 250.0 μL, stirrer rate = 1,200 rpm, and extraction time = 10 min), the calibration graph was linear over the range 10–1,000 μg L⁻¹ and the limits of detection was 1.4 μg mL⁻¹. The relative standard deviation was 1.15% (n = 10, C = 100 μg L⁻¹) and the enrichment factor was about 280. The developed method was successfully applied to the extraction and determination of cadmium in wastewater, fruit, and vegetable samples.

Keywords:

• Narrow neck glass tube-magnetic stirring-assisted dispersive liquid–liquid microextraction (NNGT-MSA-DLLME)
• Cadmium
• Water
• Fruit and vegetable samples
• Flame atomic absorption spectrometry