Ultrasound assisted-dispersive-ionic liquid-micro-solid phase extraction based on carboxyl-functionalized nanoporous graphene for speciation and determination of trace inorganic and organic mercury species in water and caprine blood samples

Abstract

The carboxyl-functionalized nanoporous graphene (NG-COOH) as solid phase sorbent was prepared and investigated in a new and simple ultrasound assisted-dispersive-ionic liquid-micro-solid phase extraction (US-D-IL-μ-SPE) procedure for rapid preconcentration and speciation of trace Hg (II) and R-Hg (CH3Hg+ and C2H5Hg+) in water and caprine blood samples. Both of inorganic and organic mercury were extracted by NG-COOH at pH8. Hydrophobic ionic liquid (IL) was used to fast trap of the mercury loaded sorbent from the sample solution. The loaded NG-COOH/IL phase was then eluted by 500μL of HNO3 (0.3molL−1) and finally Hg (II) concentration of the eluent phase was determined with flow injection-cold vapor-atomic absorption spectrometry (FI-CV-AAS) after dilution with deionized water up to 1mL. By microwave assisted-UV system, organic mercury (R-Hg) species of the eluent were converted to Hg (II) and total Hg amount was also measured. Finally, R-Hg content was determined by mathematically subtracting the Hg (II) content from the total Hg. Under the optimal conditions, the linear range, limit of detection and preconcentration factor were obtained 0.03–6.3μgL−1, 0.0098μgL−1 and 10.4 for caprine blood samples, respectively (RSD<3%). The developed method was successfully applied to natural water and human/caprine blood samples. The Validation of methodology was confirmed by two standard reference materials (SRM).