Table 11. Recovery of Mercury from Various Sources
Mercury source
1. HgClz 2. Methyl mercuric
Concentration, ppb H g
10 5 10
Media
HzO H?O
Relative responsea
Hz0
1.00 1.00 0.97
HZO
1.06
HzO; samples stored sealed for 3 days before autoclaving HzO; samples stored sealed for 3 days before autoclaving HeO; samples stored for 3 weeks after autoclaving H,O; samples stored for 3 weeks after autoclaving H,O; samples stored for 4 weeks after autoclaving H 2 0 ; samples stored for 4 weeks after autoclaving HzO; 50 ppm carbon as dextrose HZO; 35 ppt Nosas NaN03 H,O; 35 ppt S01’as Na2SOi H?O; 20 ppm C1as NaCl Natural pond water
1.00
acetate 3. HgClz
5 10 5
4. HgClz
10 5
5. HgClz
10 5
6 . HgClz
10
7. HgC12
10
8. HgClz
10
9. HgClz
10
10. HgClz
10
0.98
1.02 0.95 0.91 0.84 1.00
0.94 0.97 0.98 0.98
Defined as relative to mercuric chloride in distilled water.
chlorine gas was noticed escaping from the open end of the reflux condenser. It appears that the persulfate oxidation causes chloride to be converted to chlorine gas which is trapped in the ampoules, This gas occupies the head space of the ampoules and is released into the flow system when the ampoule is broken for analysis. The entrained chlorine then oxidizes the elemental mercury which is swept out of the ampoule after addition of stannous chloride. The oxidized mercury is no longer volatile and settles out on the walls of the tubing. Any mercury in higher oxidation states
which may reach the absorption cell will not be read since the instrument is set to detect absorption of the 253.7-nm elemental mercury line. To see if the head gas could be eliminated, samples of 10 ppb mercury with concentrations of chloride >50 ppm were placed in the ampoule breaker and shaken vigorously just prior to opening in an attempt to supersaturate the liquid phase with chlorine. This treatment restored the mercury peak height to the expected level for concentrations of chloride to 200 ppm. A further attempt to reduce the gas before reducing the oxidized mercury in the sample involved injection of 0.5 ml, 10% SnCl2 above the unbroken ampoule in the ampoule breaker. This treatment, followed by vigorous shaking, allowed extension of the determination to 500 ppm C1. However, above this level, further attempts a t eliminating the excess chlorine by means of SnCl2 saturated glass, wool, and SnC12 liquid traps placed downstream of the ampoule failed to prevent the reduction in peak height with increase in concentration of dissolved chloride. The mercury signal was eventually totally eliminated at 5 ppt C1. Since fresh water chloride concentrations are usually below 12 ppm C1 ( 9 ) , the method will have significant interferences in estuarine and oceanic waters. The procedure described represents a simple and rapid (between 30 and 40 samples at the 10-ppb level may be run in an hour) technique of determining mercury in natural waters. It also alleviates the problems of storage and sample handling attendant with other methods of mercury analysis. It should be emphasized that the procedure has been investigated only in aqueous samples. Unpublished data from these laboratories indicate that samples containing solid-liquid phase boundaries-i. e., sediment and tissue-undergo only partial oxidation of the organic carbon under these experimental conditions. Therefore, these latter samples may be more profitably analyzed with other existing methods. Received for review April 11, 1973. Accepted October 4, 1973. This project has been financed in part with Federal funds from the Environmental Protection Agency under grant No. R-800427. The contents do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. (9) D. A. Livingston, U.S.Geol. Sur. Prof. Paper 440-G (1963).
Direct X-Ray Spectrometric Determination of Bromine in Water Yoetz Deutsch Geochemistry Department, Geological Survey of Israel, 30 Malkhei lsrael St., Jerusalem, lsrael
A rapid X-ray spectrometric method for the routine determination of bromine in water was investigated. Once calibrated, the procedure developed requires no standards and is simple, rapid. precise, and at least as accurate as the conventional “wet chemical” method (
