Assessment of inorganic ion in drinking water using new method based on ultra-performance liquid chromatography-mass spectrometry

Abstract

Sulfite ion play a crucial role in the atmospheric environment, its presence in water system is very unsafe to both the human and food production due to the formation of acid after reaction with water (acid rain). In the current investigation, ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) method was used for the identification and quantification of sulfite ion in drinking water and the process was optimized. In this study, a reversed phase BEH C18 chromatography column was applied for the separation of sulfite ion using binary mobile phase comprising water and methanol (95:5, v/v), separation was attained in less than 1 min. Method validation parameters in terms of linearity (r2), limit of detection (LOD), limit of quantification (LOQ) and precision were established. The linearity (r2 > 0.999) and, LOD and LOQ were obtained 0.003 µg/mL and 0.01 µg/mL respectively. The precision in terms of relative standard deviation (RSD) was found to be < 3.5%. The validated standard methodology was used for the quantitative determination of sulfite ion in water obtained from different sources. The sulfite ion amounts were found between 2.21 µg/mL and 90.11 µg/mL water sample, and the recovery values were obtained between 97.55% and 104.49%. It was observed from the data that the quantified levels of sulfite ion were above the maximum contaminant levels (MCLs, 10 μg/mL) according to US Environmental Protection Agency in all 100% metropolitan water samples and about 82% of the analyzed bottled waters. In addition, the comparison of results obtained in water samples from Saudi Arabia with formerly stated data were carried out. The benefits of applying UPLC-MS as a new method in competition with other techniques are smaller analysis time (<1 min), tremendous accuracy and higher recovery values. Nonetheless, the sulfite was still detected in drinking water samples from Saudi Arabia. Hence, the detecting and decreasing the level of sulfite in water samples needed further apprehensions to meet better needs of strategies for consumer health.