Mercury
Mercury
Page 10 of 12
Mercury_PP_Other_CVM_Eng_Ody.fm
Method Performance
Precision
Standard: 1.40 µg/L Hg
See Section 3.4.3 Precision on page 44 for more information, or if the standard
concentration did not fall within the specified range.
Sensitivity
See Section 3.4.5 Sensitivity on page 44 for more information.
Storage and Maintenance of the Cold Vapor Mercury Apparatus
Storage
Store the apparatus as follows for fastest system stabilization and greatest
sensitivity:
• Store the Gas Washing Bottle filled with deionized water containing 15 mL of
concentrated sulfuric acid. Seal the bottle with the Gas Washing Bottle
stopper and top.
• Store the Mercury Absorber Column with the packing wetted with HgEx
Reagent B. The erlenmeyer flask should be kept attached underneath the
column. The top of the Mercury Absorber column should be attached to the
Gas Washing Bottle with the glass elbow as in the procedure.
Glassware Care
Hach recommends using dedicated glassware and sample cells because of the
sensitivity of this procedure. Thoroughly clean the glassware and sample cells
between tests. After washing, rinse with 1:1 hydrochloric acid solution, then
rinse several times with deionized water.
Maintaining the System
• With proper care and storage, the Mercury Absorber Column may be used
an unlimited number of times.
• Replace the Mercury Scrubber in the air trap housing at least once for every
reagent set used.
• Moisture build up on the Gas Washing Bottle side of the Acro 50 Vent Filter
will reduce the purging air flow rate. If this occurs replace the filter or dry it
in an oven at 110 °C.
Summary of Method
The sample is digested to convert all forms of mercury in the sample to mercuric
(Hg
2+
) ions. The mercuric ions in the digested sample are converted to mercury
vapor in a semi-closed system. The vapor is carried into a chemically activated
absorber column by ambient air where the mercury vapor is converted to
mercuric chloride.
Program 95% Confidence Limits
312 1.3–1.5 µg/L Hg
Portion of Curve ∆Abs ∆Concentration
Entire range 0.010 0.03 µg/L Hg
To Next Page
Loading...
