A selective and sensitive mercury sensor for drinking water based on fluorescence quenching of pure rhodamine B

The escalating threat of industrial pollutants, particularly heavy metals, in water sources poses a significant risk to global populations. Among these heavy metals, mercury stands out as a severe contaminant with detrimental health implications. This paper introduces a novel and efficient method for the selective detection of mercury ions in drinking water, employing laser-induced fluorescence with pure rhodamine B as the sensing probe. The method achieves a low detection limit of 7 ppb, closely approaching the World Health Organization's maximum permissible limit. The simplicity of the procedure, coupled with the use of pure rhodamine B, distinguishes this approach from others relying on complex chemical procedures and derivatives of rhodamine B. The sensing mechanism involves the fluorescence quenching of rhodamine B due to complex formation with tetraiodomercurate. Noteworthy is the method's selectivity, demonstrated by its resistance to interference from common ions present in water (e.g. Magnesium, calcium, sodium, and potassium), ensuring accurate detection of mercury ions. Extensive testing with tap water samples, considering potential interference, validates the robustness of the sensor, with recovery percentages of 99.25% and 109.2%. In summary, this study contributes a practical solution to the critical challenge of mercury detection in drinking water, addressing issues of sensitivity, selectivity, and on-site applicability. The proposed method holds promise for widespread implementation, enhancing efforts to safeguard public health and ensure the safety of water resources.