Enrichment of trace Hg(II) ions from food and water samples after solid phase extraction combined with ICP-OES determination

Abstract

Environmental water and food contamination with inorganic mercury ions is a chronic issue with major public health consequences across the globe. Due to sample complexity or spectral interferences, existing methodologies for analyzing Hg(II) ions at trace level concentrations are challenging. We used electrochemical anodization of aluminium substrate to create a unique extremely porous and hydrophilic membrane. To improve the chelating activity of Hg(II) ions, the produced aluminium oxide (AO) membrane was chemically grafted with poly-aminophosphonic acid brushes. Scanning electron microscopy, elemental analysis and X-ray photoelectron spectroscopy were used to evaluate the functionalized AO membrane. The functionalized AO membrane was used in column-based approach to enrich trace level concentrations of Hg(II) ions prior to ICP-OES analysis. Because of the high hydrophilicity and large number of chelating sites, Hg(II) ions are extracted quickly in actual samples. Before instrumental determination, the suggested technique reduces spectral interferents and enhances the analyte ion concentration. Under optimal experimental circumstances, the detection limit for the examined ion was 0.02 ng mL−1. With coefficients of variation of 3.22%, a good accuracy was attained. The proposed method shows good enrichment limit of 0.35 µg L−1 with preconcentration factor of 933. The presence of other co-ions had no significant effect on the measurement of Hg(II) ions upto a certain level. The method's accuracy was tested by spiking actual samples and evaluating Standard Reference Materials (NIST SRM 1641d). At 95% confidence level, the Student’s t test results were determined to be less than the crucial Student's t value of 4.303. The proposed method has good precision, with coefficients of variation of less than 5% for five repeated measurements.