Abstract

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. © 2017, Springer Science+Business Media New York.