Mercury laboratory methods

Atmospheric pressure can be measured by any of several methods. The common laboratory method uses a mercury column barometer. The height of the mercury column serves as an indicator of atmospheric pressure. At sea level and at a temperature of 0° Celsius (C), the height of the mercury column is approximately 30 inches, or 76 centimeters. This represents a pressure of approximately 14.7 psia. The 30-inch column is used as a reference standard. 

MDHS 14 General method for the gravimetric determination of respirable and total dust MDHS 15 Carbon disulphide MDHS 16 Mercury vapour in air Laboratory method using hopcalite adsorbent tubes, and acid dissolution with cold vapour atomic absorption spectrometric analysis MDHS 17 Benzene in air Laboratory method using charcoal adsorbent tubes, solvent desorption and gas chromatography MDHS 18 Tetra alkyl lead compounds in air Continuous on-site monitoring method using PAC Check atomic absorption spirometry... 

A convenient method of carrying out such a galvanic test in the laboratory has been described by Wesley in which the vertical circular-path machine is used. Each assembly includes two pairs of dissimilar metals—one pair coupled galvanically while the other pair is left uncoupled in order to determine the normal corrosion rates under the same environmental conditions. The type of motion provided (specimens moving in a vertical circular path) enables electrical connections to be made without mercury cup or commutator and the leads can be connected to a calibrated resistance for current measurements attached to the specimen carrier. 

Gill and Fitzgerald [481] determined picomolar quantities of mercury in seawater using stannous chloride reduction and two-stage amalgamation with gas-phase detection. The gas flow system used two gold-coated bead columns (the collection and the analytical columns) to transfer mercury into the gas cell of an atomic absorption spectrometer. By careful control and estimation of the blank, a detection limit of 0.21 pM was achieved using 21 of seawater. The accuracy and precision of this method were checked by comparison with aqueous laboratory and National Bureau of Standards (NBS) reference materials spiked into acidified natural water samples at picomolar levels. Further studies showed that at least 88% of mercury in open ocean and coastal seawater consisted of labile species which could be reduced by stannous chloride under acidic conditions. 

A convenient method for the laboratory preparation of sulphuryl chloride consists in boiling chlorosulphonic acid with about one per cent, of mercury or mercuric sulphate under a reflux condenser kept at a temperature of 70° C. in order to return to the flask any unchanged chlorosulphonic acid ... 

O Gorman et al. (19) used radiochemical NAA as a referee method in evaluating the determination of mercury by atomic absorption techniques. A commercial testing laboratory did the neutron activation analyses. 

In the round-robin analysis, a minimum of five samples each of coal, fly ash, gasoline, and fuel oil were analyzed. The NBS Probable Certified Value for certain elements are shown in Table IX along with PBR values. Since no data were reported on gasoline, there are no comparisons. The most inconsistent comparison was for mercury. Only four laboratories reported mercury by INAA in coal, three by INAA in fly ash, and two by INAA for fuel oil. Most other laboratory results reported were based on atomic absorption spectrometry. With one exception, all mercury values reported by INAA (a nondestructive method) were higher than... 

This method was developed to replace the hazardous mercury catalyst required in the original mercuric oxide Kjeldahl method. It has been evaluated through an interlaboratory comparison of catalysts and has been adopted as the official replacement for the mercuric-oxide catalyzed Kjeldahl method. An inter-laboratory evaluation (Berner, 1990) indicated that this method (which uses the copper/titanium catalyst mixture) produces results more closely in agreement with the mercuric oxide catalyst method than methods using a copper sulfate catalyst. As a result of this study, mercuric... 

The Apparatus and General Methods section has been increased by the addition of an outline of the mercury vapour lamp and its uses in polari-metry and in catalytic reactions. A laboratory-scale apparatus, devised by us, for the distillation of solids is included. The section on the use of the library has been extended, and attention has been drawn to the changes which have taken place in the German reference literature. 

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