Foreword
The cold vapour mercury techniqu'e is designed to improve the atomic absorbance sensitivity of mercury measurements. Mercury is unique in that the ground state atom, the species required for atomic absorption, can be generated chemically at room temperature. In this cold vapour method, mercury atoms are produced in solution by chemical reduction with stannous chloride or sodiu m borohydride. The volatile mercury atoms are driven of from solution by bubbling air or an inert gas (normally nitrogen gas) into the solution. The, mercury vapours are then carried directly or through a drying tube (to remove moisture) into an absorption cell aligned in the optic-al path for the measure- ments of absorbance. The sensitivity of such measurements, however, depends upon the efficiency of the vapour generation system, design of the absorption cell and other factors. A comparison of two different mercury measurement systems, Mercury/Hydride (MHS-lO) kit attached to Perkin-Elmer's (703) Atomic Absorption Spectrophotometer (AAS) and Mercury Analyser (MA 5800 C) of ECIL make is provided in the present report. The calibration details of the latter have also been included.