Trace determination of heavy metals in farmed trout fish using dispersive liquid–liquid microextraction based on solidification of floating organic drop and graphite furnace atomic absorption spectrometry

Abstract

A dispersive liquid–liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) method followed by graphite furnace atomic absorption spectrometry (GFAAS) was developed for the extraction, preconcentration and determination of ultra-trace amounts of heavy metals in farmed trout fish samples. The influences of analytical parameters, including pH, extraction solvent type and its volume, disperser solvent type and its volume, concentration of the chelating agent, salt effect and extraction time on the quantitative recoveries of cadmium, lead and mercury ions were investigated. Under the best experimental conditions (extraction solvent: 40 μL of 1-undecanol; disperser solvent: 1000 μL of methanol; ligand concentration: 0.15% (v/v); pH: ∼2.4 and without salt added), the enhancement factor ranged from 68 to 93. The calibration graphs were linear in the range of 0.5–50 μg kg⁻¹ for Hg, 0.1–100 μg kg⁻¹ for Cd and Pb with a correlation coefficient (r²) better than 0.990. The detection limits were between 0.04 and 0.1 μg kg⁻¹. The application of the proposed method to the analysis of the fish certified reference material produced results that were in good agreement with the certified values. The results obtained for heavy metal ions in analyzed trout fishes were below the established values by various authorities. The results showed that DLLME-SFO is a very simple, rapid, environmentally friendly, sensitive and efficient analytical method for the determination of metal ions in fish samples and suitable results were obtained.