Determination of mercury using the Jerome m-511 Gold Film Mercury Analyzer
Abstract
The M-511 Gold Film Mercury Analyzer, manufactured by the Jerome Instrument Corporation, uses a thin gold film as a detector which in the presence of Hg vapour undergoes a proportional increase in electrical resistance. In working with the M-511, besides the method and equipment recommended by the manufacturer, some modifications were introduced, which were shown to improve the original method. Different techniques were used for calibration as well as for measurement of samples: the reduction - aeration method and the Hg vapour injection technique, directly or in combination with a preamalgamation step on a Au-absorber.
Good linearity was obtained for both methods in the examined range between 5-40 ng Hg. Precision is dependent on the mass of mercury; it is 6-10% for quantities greater than 20 ng Hg. The sensitivity of the M-511 was observed to vary within the day and from day to day. Also, it was shown that the sensitivity of the whole procedure in the mercury determination depends greatly on the technique applied.
The applicability of the M-511 for measurement of natural samples was tested by using different reference materials. Results obtained showed that positive interferences were often present (probably caused by acidic fumes or some volatile substances which are liberated from the digested solution during the reduction-aeration step. In some cases it can be overcome by using a preamalgamation step, or by introducing a filter trap for volatile substances. On the basis of our results, supposing that the performance of our M-511 is typical, it seems doubtful if conditions can be found in which reliable determination of real samples can be combined with the originally intended simplicity of measurement of the M-511.
