the mesoporous porphyrinic zirconium metal-organic framework for pipette-tip solid-phase extraction of mercury from fish samples followed by cold vapor atomic absorption spectrometric determination

In this study, the highly stable mesoporous porphyrinic zirconium metal-organic framework, namely pcn-222/mof-545 (zr-mof), was prepared and used for pipette-tip solid-phase extraction of hg(ii). as a high-capacity sorbent, 4 mg of the zr-mof was placed into a conventional pipette tip and used, for the first time, for the fast extraction and preconcentration of mercury ions. for desorption, 50 μl of 10% hcl was used by 15 repeated aspirating/dispensing cycles, and hg ions in elusion were measured by a cold vapor atomic absorption spectrometer. affecting parameters on extraction efficiency were studied, and optimum conditions were established as amount of sorbent 2 mg, ph was adjusted to 5.0, the eluting volume was 15 μl, and extraction was performed on 1.8 ml of the sample. the optimal number of aspirating/dispensing cycles for extraction and desorption of analytes was found to be 10 and 15 cycles, respectively. the limit of detection of the method was found to be 20 ng l−1 with a relative standard deviation of ≤3.1% (for seven replicate analyses of 20 μg l−1 of mercury). adsorption capacity and enrichment factor were 35.5 mg g−1 and 120-fold, respectively. the proposed method was successfully applied for the determination of hg(ii) ions in fish samples.