Solid-Phase Extraction and Spectrophotometric Determination of Mercury with 6-Mercaptopurine in Environmental Samples

A highly selective, sensitive and rapid method for the determination of trace amounts of inorganic mercury based on the reaction of Hg (II) with 6-mercaptopurine and the solid phase extraction of the complex on C₁₈ membrane disks was developed. The 6-mercaptopurine selectively reacts with Hg (II) to form a complex in the pH range of 5-8. This complex was preconcentrated by solid phase extraction with C₁₈ disks. An enrichment factor of 100 was achieved. The molar absorptivity of the complex is 0.26 ×10^-6 L. mol^-1. cm^-1 measured at 315 nm. The Beer's law is obeyed in the concentration range of 0.002 – 0.048 μg mL^-1. The relative standard deviation for eleven-replicated measurement of 0.04 μg mL^-1 is 1.5 %. The detection limit is 0.001 μg mL^-1 in the water samples. The advantage of the method is that the determination of Hg (II) is free from interference of almost all the cations and anions found in environment and wastewater samples. The determination of Hg (II) in water samples of different origins and marine sediment were carried out by the present method and cold vapor atomic absorption spectrometry (CVAAS). Also the method's accuracy was investigated by using SRM 2709. The obtained results by the present procedure were in good agreement with those of the CVAAS and certified value, so that the applicability of the proposed method was confirmed for the real samples.