METHOD AND INSTRUMENT FOR SIMULTANEOUSLY MEASURING MERCURY AND CADMIUM BY DIRECT SAMPLE INJECTION

摘要

A method and instrument for simultaneously measuring mercury and cadmium by direct sample injection, without the need of sample digestion, comprising the steps of: heating a sample in an oxygen atmosphere, with the temperature being controlled at 120-500°C, so that most of the Hg and decomposition products in the sample are evolved; carrying Hg and evolved substances by an air flow into a catalyst furnace (3) for further decomposition, and amalgamating and absorbing Hg with gold while Cd still exists in the sample; placing the treated sample in a pyrolysis furnace (6) for further thermal decomposition, so that Cd and residual Hg in the sample are evaporated at a high temperature; carrying same by argon gas into a cadmium atom collection trap (5), selectively trapping cadmium using a tungsten wire, and absorbing the residual mercury using a mercury collection trap (4); and in an argon-hydrogen atmosphere, heating the tungsten wire or a molybdenum wire and gold amalgam in turn to release Cd and Hg, and carrying same by argon-hydrogen gas (10) into an atomic fluorescence spectrometer (12) for on-line detection. On the basis of realizing the function of simultaneous measurement of Hg and Cd in a sample, the entire structure of a detection instrument is simplified, realizing the miniaturization, facilitating conventional analysis and urgent demands, being capable of being loaded on a vehicle for field application, and having a prospect of application in on-site detection.