Used primarily in analytical chemistry for calibration and quantification of mercury in environmental, industrial, and biological samples. Commonly applied in techniques such as atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) to ensure accurate measurement of mercury levels. Essential in monitoring pollution in water, soil, and air, especially in regulatory compliance testing. Also used in research settings to validate methods for mercury detection and to prepare working standards from stock solutions. Due to its toxicity, handled with strict safety protocols in controlled environments.