The novel extraordinary separation and preconcentration approach for Cd2+: “Hydrophobic Immiscible Chelating Fluid” based micro-extraction

Abstract

The novel, extraordinary and highly selective separation and preconcentration approach based on hydrophobic immiscible chelating fluid (HICF) having superior features (simultaneous chelation, extraction and masking) and combined with automatized syringe discharge system by peristaltic pump was established firstly for simultaneous chelation and micro-extraction of Cd2+. Mixture of tetra butyl ammonium iodide, tetra butyl ammonium fluoride, n-pentanol (1:1:10) and dithizone were used to formulate HICF. The parameters including pH, chelator concentration on both characteristic of HICF and extraction of Cd2+, time of vortex mixing, amount of HICF and sample volume were optimized and investigated in detail. The optimized method has permitted to obtain 25 preconcentration factor (PF) and detect the lowest cadmium concentration having 2.1 µg L−1 (LOD) in the aqueous solution. Interference effect of defiant metal cations was investigated in detail. The dynamic range of the method (LDR) was obtained linearly between 7.2 and 1500 µg L−1. Relative standard deviations (% RSD) were below than % 4.2 throughout the experiments. The envisaged possible extraction mechanisms were explained. The proposed novel method was validated with applications of multiple analyte-addition recovery tests in water samples (tap, lake and natural spring water) and analysis of standard reference material (UME EnvCRM 03 Elements in Soil). Quantitative satisfactory recovery values changing between 98 and 106 % were obtained. Validated method was also applied to determine Cd contents of sediment, mushroom and raw tobacco samples. The main advantage of HICF is that it contains masking and chelating agents and extraction solvent in only one liquid. Therefore, possible concentration and volume errors were minimized by single micropipette injection that ensured time saving and simplicity for applicability of the method by the analysts. Moreover, automated syringe discharge system has provided repeatable and precision extraction results.