Hach DR2400 - Page 381

Mercury
Mercury
Mercury_PP_Other_CVM_Eng_Ody.fm Page 9 of 12
3. Prepare a 0.1-mg/L mercury standard solution by serially diluting a
1000-mg/L Mercury Standard Solution:
a. To make a 10.0 mg/L standard, add 1.0 mL of concentrated nitric acid to
a 500-mL volumetric flask. Dilute 5.00 mL of a 1000-mg/L standard to
500 mL with deionized water. Mix well.
b. To make a 1.0-mg/L standard solution, add 0.2 mL of concentrated nitric
acid to a 100-mL volumetric flask. Dilute 10.0 mL of the 10.0-mg/L
standard to 100 mL with deionized water. Mix well.
c. To make a 0.1-mg/L standard solution, add 0.2 mL of concentrated nitric
acid to a 100-mL volumetric flask. Dilute 10.00 mL of the 1.0-mg/L
solution to 100 mL with deionized water. Mix well.
4. Pipet 10.0 mL of the 0.1-mg/L mercury standard solution into the Gas
Washing Bottle. Swirl to mix.
5. Begin at step 2 of Phase 2. Follow the procedure steps.
6. Test the eluate as described in Phase 3. The displayed concentration should be
0.9–1.1 µg/L Hg.
System Start Up
Hach recommends that the analyst perform a few analyses on mercury
standards and blanks for system equilibration before beginning sample testing.
This allows the system to stabilize before processing samples.
Startup Standard
Test a mercury standard solution by following the procedure under Accuracy
Check using the Standard Solution Method. Continue with step 1 (below) if the
value is not within specified limits.
1. Pipet 10.0 mL of the 0.1-mg/L mercury standard solution into the purged
solution in the Gas Washing Bottle. Immediately stopper the Gas
Washing Bottle.
2. Begin at step 3 of Phase 2. Follow the procedure steps.
3. Test the eluate as described in Phase 3. The displayed concentration should be
0.9–1.1 µg/L Hg. Repeat steps 1–3 if the value is not within these limits.
Startup Blank
Run a system blank by using the purged solution in the Gas Washing Bottle after
a satisfactory test of the Startup Standard has been completed.
1. Leave the purged solution in the Gas Washing Bottle. Do not add an aliquot
of mercury standard.
2. Begin at step 3 of Phase 2. Follow the procedure steps.
3. Test the eluate as described in Phase 3. The displayed concentration should be
≤ 0.2 µg/L Hg. Repeat the Startup Blank procedure until a reproducible value
is obtained.