Measuring method of mercury meter

Mercury and its compounds are highly toxic substances, especially organic mercury compounds. The mercury content in natural water is very small, generally not exceeding 0. 1ug/l, and the standard limit of drinking water in China is 0.00 1mg/L/L, so most universities and scientific research units choose mercury meter for measurement. The following are several measuring methods of mercury meter:

(1) cold atomic absorption spectrometry is suitable for the determination of mercury in various water bodies, and its minimum detection concentration is 0. 1-0.5ug/L mercury (depending on instrument sensitivity and gas production volume). The principle is that mercury vapor selectively absorbs 253.7nm ultraviolet light, and within a certain concentration range, the absorbed light is directly proportional to the mercury concentration. After the water sample is digested, various forms of mercury are converted into bivalent mercury, and then the bivalent mercury is reduced to elemental mercury by stannous chloride. The generated mercury vapor is brought into the absorption pool of mercury meter with carrier gas, and the absorbance is measured and compared with that of mercury standard solution. Determination points: A, pretreatment of water sample B, drawing standard curve C, determination of water sample

(2) Cold atomic fluorescence spectrometry, in which mercury ions in water samples are reduced to ground-state mercury vapor, and after absorbing 253.7nm ultraviolet light, excited to generate characteristic * * * vibration fluorescence. Under some measuring conditions and low concentration range, the fluorescence intensity is directly proportional to the mercury concentration. The minimum detection concentration of this method is 0.05ug/L, and the upper limit can reach 65438 0 ug/L. Because there are few interference factors, this method is suitable for the determination of surface water, domestic sewage and industrial wastewater.