Mercury DOC316.53.

01059

Cold Vapor Mercury Concentration Method Method 10065

0.1 to 2.5 µg/L Hg
Scope and application: For water, wastewater and seawater.

Test preparation

Instrument-specific information
Table 1 shows all of the instruments that have the program for this test. The table also
shows sample cell and orientation requirements for specific instruments.
To use the table, select an instrument, then read across to find the applicable information
for this test.
Table 1 Instrument-specific information
Instrument Sample cell orientation Sample cell
DR 6000 The fill line is to the right. 2495402
DR 3800
DR 2800
DR 2700
DR 1900
DR 5000 The fill line is toward the user.
DR 3900

Before starting
The test can release toxic chlorine or other gases. Do the test procedure in a fume hood.
Use dedicated digestion glassware and sample cells for this procedure.
Determine a reagent blank for each new lot of reagent: complete the procedure, including the digestion, with 1 liter of
deionized water instead of sample; add the same amount of potassium permanganate as required by the sample; subtract
the reagent blank value from the final results or complete a reagent blank adjust.
Review the Safety Data Sheets (MSDS/SDS) for the chemicals that are used. Use the recommended personal protective
equipment.
Dispose of reacted solutions according to local, state and federal regulations. Refer to the Safety Data Sheets for disposal
information for unused reagents. Refer to the environmental, health and safety staff for your facility and/or local regulatory
agencies for further disposal information.

Items to collect
Description Quantity

Refer to Consumables and replacement items on page 11 for a complete list of required
–
apparatus
Cold Vapor Mercury Apparatus Set 1
Cold Vapor Mercury Reagent Set (refer to Consumables and replacement items on page 10) 1
Digestion Reagents and Apparatus (refer to Consumables and replacement items
varies
on page 12)
Sample cells (For information about sample cells, adapters or light shields, refer to Instrument-
2
specific information on page 1.)

1
Refer to Consumables and replacement items on page 10 for order information.

Sample collection
• Collect 1000 mL of sample in an analytically clean, glass or polyethylene
terephthalate (PET) container.
• To preserve samples for later analysis, add 10 mL of concentrated hydrochloric acid
to the sample container before collection.
Note: Close the glass container with a ground glass stopper. Close a PET container with a
PET cap or a polypropylene cap (no liner).
• Fill the bottle completely full, then tighten the cap on the bottle.
• Keep the preserved samples at 2–6 °C (35.6–43 °F) for a maximum of 6 months.
• Correct the test result for the dilution caused by the volume additions.

System start-up
For more accurate results and system equilibration, complete several analyses on
mercury standards and blanks before the sample testing. This allows the system to
stabilize before processing samples.

Standard start-up

1. Follow the procedure Standard solution method on page 9. If the value is not
within the specified limits, continue to the next step.
2. Use a pipet to add 10.0 mL of the 0.1-mg/L mercury standard solution into the purged
solution in the Gas Washing Bottle. Immediately put the stopper in the Gas Washing
Bottle.
3. Use the test procedure to measure the concentration of the standard. Start at step 3
of phase 2.
4. Test the eluate as described in phase 3. The concentration must be 0.9–1.1 µg/L Hg.
Do steps 1 to 3 again if the value is not within these limits.

Blank start-up
After a satisfactory Standard start-up is complete, use the purged solution in the Gas
Washing Bottle to do a system Blank start-up.

1. Keep the purged solution in the Gas Washing Bottle. Do not add an aliquot of
mercury standard.
2. Use the test procedure to measure the concentration of the sample. Start at step 3 of
phase 2.
3. Test the eluate as described in phase 3. The concentration must be ≤ 0.2 µg/L Hg.
Do the Blank start-up procedure again until a reproducible value is shown.

2 Mercury, Cold Vapor Extraction Method (2.5 µg/L)

Phase 1: Sample digestion

WARNING
Gas inhalation hazard. Operate the instrument in a fume hood to prevent exposure to
hazardous gas.

CAUTION
Chemical exposure hazard. Obey laboratory safety procedures and wear all of the
personal protective equipment appropriate to the chemicals that are handled. Refer to the
current safety data sheets (MSDS/SDS) for safety protocols.

1. Measure 1 liter of the 2. Put the flask on a 3. Add 50 mL of 4. Add 25 mL of

sample into a 2000-mL magnetic stirring hot plate. concentrated sulfuric acid to concentrated nitric acid to
Erlenmeyer flask. Add a 50-mm magnetic stir the sample. the sample.
bar to the sample. Set the
stirrer power to on.

5. Add 4.0 g of potassium 6. Add 7.5 g of potassium 7. Use a watch glass as the 8. Continue to stir and keep
persulfate to the sample. permanganate to the flask cover. After the the sample temperature at
Alternatively, add one sample. reagents dissolve, increase 90 °C for 2 hours.
5 gram measuring scoop of Alternatively, add a 10 gram the temperature of the The solution must stay dark
potassium persulfate to the measuring scoop of sample to 90 °C (194 °F). purple during the entire
sample. potassium permanganate to Do not boil. digestion. Some samples
the sample. Note: It is not necessary to (e.g., seawater, industrial
Stir until dissolved.
increase the temperature for effluents or samples that are
Stir until dissolved.
a mercury standard or high in organic matter or
reagent blank in distilled chloride) require additional
water. permanganate. It can be
difficult to see a dark purple
color if the sample contains
black/brown manganese
dioxide precipitate. Add
more potassium
permanganate if the solution
is not dark purple.

Mercury, Cold Vapor Extraction Method (2.5 µg/L) 3

9. Set the hot plate power 10. Put the cool digested 11. Add hydroxylamine- 12. Remove the stir bar.
to off. Let the temperature of sample on the cool stirring hydrochloride until all The digested sample is now
the digested sample hot plate. Set the stirrer manganese dioxide is ready for the cold vapor
decrease to room power to on. dissolved. Use a 0.5-g separation and
temperature. measuring spoon to add preconcentration procedure.
A brown/black precipitate of 0.5 g additions of Go to Phase 2: Cold vapor
manganese dioxide can hydroxylamine- separation and
form during this step. If the hydrochloride until the preconcentration of mercury
digested sample does not purple color is gone. Wait on page 4.
have a purple color, the 30 seconds after each
digestion is not complete. addition and look for the
Add more potassium color change.
permanganate. Put the
sample back on the stirring
hot plate and continue the
digestion until the sample
has a purple color.

Phase 2: Cold vapor separation and preconcentration of mercury

WARNING
Gas inhalation hazard. Operate the instrument in a fume hood to prevent exposure to
hazardous gas.

1. Pour the digested 2. Set the Gas Washing 3. Connect the 100-mL 4. Pipet 8 mL of HgEx
sample into the Cold Vapor Bottle in the support ring. Erlenmeyer flask to the Reagent B into the Mercury
Gas Washing Bottle. Place the top on the Gas mercury absorber column. Absorber column.
Note: The volume of the Washing Bottle. Wait until
digested sample must step 9 to connect the
contain 0.1 to 2.5 µg Hg. mercury absorber column to
the Gas Washing Bottle.

4 Mercury, Cold Vapor Extraction Method (2.5 µg/L)

5. Apply a vacuum to the 6. Use the quick disconnect 7. Remove the 100-mL 8. Pipet 2 mL of HgEx
Mercury Absorber Column. to disconnect the vacuum Erlenmeyer flask from the Reagent C into the Mercury
Pull most of the HgEx pump when HgEx Reagent Mercury Absorber Column. Absorber Column.
Reagent B into the B starts to drip from the Replace it with the 10-mL
Erlenmeyer flask. inner delivery tube on the Distilling Receiver.
Mercury Absorber Column
(approximately 10 seconds
after starting the vacuum).
Make sure to not pull too
much air through the
Mercury Absorber Column,
to prevent drying the
packing.

9. Use the glass elbow to 10. Shake an ampule of 11. Put the stopper on the 12. Use the quick
connect the Mercury HgEx Reagent A to suspend side neck of the Glass disconnect to connect the
Absorber column to the Gas undissolved reagent. Washing Bottle. vacuum pump to the
Washing Bottle. Open the ampule and Mercury Absorber Column
carefully pour the contents again. Apply the vacuum to
into the Gas Washing Bottle pull HgEx Reagent C
through the side neck. through the Mercury
Absorber Column packing
and into the 10-mL receiver.
Air bubbles should be
produced at the gas
dispersion tube in the Gas
Washing Bottle. Complete
the next two steps
immediately.

Mercury, Cold Vapor Extraction Method (2.5 µg/L) 5

 Start

13. Start program 14. Start the instrument 15. After the timer expires, 16. Pipet 8 mL of HgEx
312 Mercury, Cold Vap. timer. A 5-minute reaction remove the glass elbow Reagent B into the Mercury
For information about time starts. Let the solution from the top of the Mercury Absorber Column to elute
sample cells, adapters or bubble for this period. Absorber Column. Keep the the captured mercury.
light shields, refer to The air flow rate through the vacuum pump power on. Continue to apply the
Instrument-specific Gas Washing Bottle should vacuum to pull the HgEx
information on page 1. be between 1-5 L/min. Let Reagent B into the Distilling
Note: Although the program the solution bubble for more Receiver.
name can be different time when the air flow rate is
between instruments, the low. For example, if the air
program number does not flow rate is 1 L/min., let the
change. solution bubble for
10 minutes.

17. Set the vacuum pump 18. Remove the distilling 19. Use a pipette to add
to off when the volume in Receiver from the Mercury 3 mL of HgEx Reagent B
the Distilling Receiver is at Absorber Column. Connect into the Mercury Absorber
the 10-mL mark. the 100-mL Erlenmeyer Column without applying
If necessary, adjust the flask to the column again. vacuum. This keeps the
volume in the Distilling absorber packing wet
Receiver a maximum of between tests.
10 mL with HgEx Reagent The Mercury Absorber
B. Column eluate in the
To prevent low volumes in Distilling Receiver is ready
the future, disconnect the for analysis.
vacuum sooner in step 6. Go to Phase 3: Colorimetric
This leaves more HgEx analysis on page 7.
Reagent B in the packing of
the Mercury Absorber
Column.

6 Mercury, Cold Vapor Extraction Method (2.5 µg/L)

Phase 3: Colorimetric analysis

WARNING
Gas inhalation hazard. Operate the instrument in a fume hood to prevent exposure to
hazardous gas.

1. Use the supplied funnel 2. Put the stopper on the 3. Use the supplied funnel 4. Put the stopper on the
to add the contents of one receiver. Invert to dissolve to add the contents of one receiver. Invert to dissolve
HgEx Reagent 3 foil pillow the reagent. HgEx Reagent 4 foil pillow the reagent.
to the eluate in the Distilling to the Distilling Receiver.
Receiver.

5. Add 8 drops of HgEx 6. Put the stopper on the 7. Start the instrument 8. During the reaction
Reagent 5 to the Distilling receiver. Invert to mix the timer. A 2–minute reaction period, pour the solution into
Receiver. reagent. time starts. a sample cell.

Zero

9. Clean the prepared 10. Insert the sample cell 11. Push ZERO. The 12. Remove the cell from
sample cell. into the cell holder. display shows 0.1 µg/L Hg the cell holder. Add the
(this program uses a non- contents of one HgEx
zero intercept). Reagent 6 foil pillow to the
solution.
Note: Do not use the funnel
to add HgEx Reagent 6 to
the sample cell. HgEx
Reagent 6 contamination
from the funnel will make it
impossible to find mercury in
subsequent tests.

Mercury, Cold Vapor Extraction Method (2.5 µg/L) 7

 Read

13. Swirl the cell until the 14. Clean the prepared 15. Insert the prepared 16. Push READ. Results
reagent is completely sample cell. sample into the cell holder. show in µg/L Hg. This is the
dissolved. Immediately concentration in the original
continue with next step . sample.

Interferences
Standards were used to prepare a single test solution with substances at the
concentrations shown in Table 2. A second test solution containing only mercury at the
same concentration was prepared as the control. The two solutions were digested, then
analyzed concurrently. There was no interference from the matrix of the test solution at
the concentrations listed.
In addition, no interference occurred with a test solution containing 1000 mg/L Na+,
1000 mg/L K+, 1000 mg/L Mg2+ and 400 mg/L Ca2+.
Table 2 Interfering substances
Interfering substance Interference level
Ag+ 7 mg/L
Al3+ 10 mg/L
Au3+ 500 µg/L
Cd2+ 10 mg/L
Co2+ 10 mg/L
Cr6+ 10 mg/L
Cu2+ 10 mg/L
F– 1.0 mg/L
Fe2+ 100 mg/L
Mo6+ 10 mg/L
Ni2+ 10 mg/L
NO3––N 50 mg/L
Pb2+ 10 mg/L
SiO2 100 mg/L
Zn2+ 10 mg/L

Accuracy check
Standard additions method
Use the standard additions method (for applicable instruments) to validate the test
procedure, reagents and instrument and to find if there is an interference in the sample.
Items to collect:
• 1000-mg/L Mercury Standard Solution

8 Mercury, Cold Vapor Extraction Method (2.5 µg/L)

 • 500-mL volumetric flask
• 10-mL volumetric pipet and pipet bulb
• Pipet, TenSette®, 0.1–1.0 mL and tips
• Deionized water

1. Prepare a 10.0-mg/L mercury standard as follows:

a. Use a pipet to add 5.00 mL of a 1000-mg/L Mercury Standard Solution into a
500-mL volumetric flask.
b. Use a pipet to add 1.0 mL of concentrated nitric acid to the flask.
c. Dilute to the mark with deionized water. Mix well.
2. Use a TenSette Pipet to add 0.10 mL of the 10.0-mg/L mercury standard to the
purged solution in the Gas Washing Bottle after an analysis has been completed.
Immediately put the stopper on the Gas Washing Bottle.
3. Use the test procedure to measure the concentration of the sample. Start at step 3 of
Phase 2.
4. Test the eluate as described in Phase 3. The expected result is 0.9–1.1 µg/L Hg.

Standard solution method

Use the standard solution method to validate the test procedure, the reagents and the
instrument.
Items to collect:
• 1000-mg/L Mercury Standard Solution
• 100-mL and 500-mL volumetric flask
• Concentrated sulfuric and nitric acid
• Pipet, TenSette®, 0.1–1.0 mL and tips
• Deionized water

1. Prepare a 10.0-mg/L mercury standard solution as follows:

a. Use a pipet to add 5.0 mL of a 1000-mg/L Mercury Standard Solution into a 500-
mL volumetric flask.
b. Use a pipet to add 1.0 mL of concentrated nitric acid.
c. Dilute to the mark with deionized water. Mix well.
2. Prepare a 1.0-mg/L mercury standard solution as follows:
a. Use a pipet to add 10.0 mL of the prepared 10.0-mg/L mercury standard solution
into a 100-mL volumetric flask.
b. Use a pipet to add 0.2 mL of concentrated nitric acid.
c. Dilute to the mark with deionized water. Mix well.
3. Prepare a 0.1-mg/L mercury standard solution as follows:
a. Use a pipet to add 10.0 mL of the prepared 1.0-mg/L mercury standard into a
100-mL volumetric flask.
b. Use a pipet to add 0.2 mL of concentrated nitric acid.
c. Dilute to the mark with deionized water. Mix well.
4. Pour 800 mL of deionized water into the Gas Washing Bottle.
5. Add 50 mL of concentrated sulfuric acid and 25 mL of concentrated nitric acid to the
Gas Washing Bottle. Swirl to mix.
6. Use a pipet to add 10.0 mL of the 0.1-mg/L mercury standard solution into the Gas
Washing Bottle. Swirl to mix.
7. Use the test procedure to measure the concentration of the sample. Start at step 2 of
Phase 2.
8. Test the eluate as described in Phase 3. The expected result is 0.9–1.1 µg/L Hg.

Mercury, Cold Vapor Extraction Method (2.5 µg/L) 9

Method performance
The method performance data that follows was derived from laboratory tests that were
measured on a spectrophotometer during ideal test conditions. Users can get different
results under different test conditions.
Program Standard Precision (95% confidence interval) Sensitivity
Concentration change per 0.010 Abs change
312 1.0 µg/L Hg 0.9-1.1 µg/L Hg 0.03 µg/L Hg

Pollution prevention and waste management

The reacted samples and equipment components contain mercury and must be disposed
of as a hazardous waste. Dispose of reacted solutions according to local, state and
federal regulations.
Summary of method
The sample is digested to change all the mercury in the sample to mercuric (Hg2+) ions.
The mercuric ions in the digested sample becomes a gas in a semi-closed system. The
ambient air moves the vapor into a chemically-activated absorber column where the
mercury vapor reacts to form mercuric chloride.
The mercuric chloride is eluted off the column and a sensitive indicator is added. The
instrument is zeroed at the absorbance peak of the unreacted indicator. A complexing
agent is added to break the mercury:indicator complex. The increase in unreacted
indicator causes an increase in absorbance proportional to the amount of mercury in the
original sample. Test results are measured at 412 nm.
Storage and maintenance of the cold mercury apparatus
Storage
For the fastest system stabilization and greatest sensitivity, put the apparatus in storage
as follows:
• Keep the Gas Washing Bottle filled with deionized water and 15 mL of concentrated
sulfuric acid. Seal the bottle with the Gas Washing Bottle stopper and top.
• Keep the Mercury Absorber Column with the packing wetted with HgEx Reagent B.
Keep the Erlenmeyer flask attached below the column. Attach the top of the Mercury
Absorber column to the Gas Washing Bottle with the glass elbow as in the procedure.
Maintenance
• Use dedicated glassware and sample cells.
• Fully clean the glassware and sample cells between tests. Rinse with 1:1 hydrochloric
acid solution, then rinse several times with deionized water.
With correct maintenance, the Mercury Absorber Column can 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 buildup 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 (230 °F).

Consumables and replacement items

Required reagents

Description Quantity/test Unit Item no.

Cold Vapor Mercury Reagent Set (25 tests), includes: 2658300

HgEx™ Reagent A, Stannous Sulfate Solution, 20-mL ampules 1 25/pkg 2658825
HgEx™ Reagent B, Sulfuric Acid Solution 19 mL 500 mL 2658949

10 Mercury, Cold Vapor Extraction Method (2.5 µg/L)

Consumables and replacement items (continued)
Description Quantity/test Unit Item no.

HgEx™ Reagent C, Sodium Hypochlorite Solution 2 mL 55 mL 2659059

HgEx™ Reagent 3, Alkaline Reagent Powder Pillows 1 pillow 25/pkg 2658448
HgEx™ Reagent 4, Indicator Powder Pillows 1 pillow 25/pkg 2658548
HgEx™ Reagent 5, Sodium Hydroxide Solution 8 drops 10 mL SCDB 2658636
HgEx™ Reagent 6, Complexing Reagent Powder Pillow 1 pillow 25/pkg 2658748
Mercury Scrubber 2/reagent set 2/pkg 2655800

Required apparatus

Description Quantity/test Unit Item no.

Cylinder, graduated, 50-mL 1 each 50841

®
Pipet, TenSette , 0.1–1.0 mL 1 each 1970001
®
Pipet, TenSette , 1.0–10.0 mL 1 each 1970010
®
Pipet Tips, for TenSette Pipet, 0.1–1.0 mL 2 50/pkg 2185696
®
Pipet Tips, for TenSette Pipet, 1.0–10.0 mL varies 50/pkg 2199796
Vacuum Pump, 1.2 CFM 115 V 1 each 2824800
Vacuum Pump, 230 VAC w/ North American Plug 1 each 2824801
Vacuum Pump, 230 V w/ European Plug 1 each 2824802
Cold Vapor Mercury Apparatus Set, includes: 2674400
Acro 50 Vent Filter 1 18/pkg 2683318
Air Trap Holder Assembly 1 each 2663900
Ampule breaker 1 each 2564000
Breaker/Capper Tool for Mercury Scrubber 1 each 2664000
C-flex Tubing, 0.25-inch ID, white 4 ft 25 ft 2327367
Clamp for Mercury Absorber Column 1 each 2656200
Clamp Holder 2 each 32600
Sample cell, 10-mL square, matched pair 2 2/pkg 2495402
Riser Cell, 1" Square DR2000/2010 1 each 4528200
Riser cell, 1", Square DR3000 1 each 4840300
Distilling Receiver, 10-mL 1 each 2655438
Flask, Erlenmeyer, 100-mL 1 each 2655342
Funnel, micro, poly 1 each 2584335
Gas Washing Bottle, 1200-mL 1 each 2662200
Glass Elbow, 90-degree, with hose adapter 1 each 2655200
Mercury Absorber Column 1 each 2655510
Support Ring for Gas Washing Bottle 1 each 2656300
Stopper, for Distilling Receiver 1 each 2655900
Stopper, for Gas Washing Bottle 1 each 2662300
Support, Base and Rod 1 each 32900
Tubing Quick Disconnect, HDPE 1 12/pkg 1481000

Mercury, Cold Vapor Extraction Method (2.5 µg/L) 11

Required digestion reagents and apparatus

Description Quantity/test Unit Item no.

Flask, Erlenmeyer, 2000-mL 1 each 2489454

Hot plate, stirrer, 115 VAC 1 each 2881600
Hot plate, stirrer, 220–240 VAC 1 each 2881602
Hydroxylamine Hydrochloride, ACS varies 113 g 24614
Nitric Acid, ACS 25 mL 500 mL 15249
Potassium Permanganate, ACS varies 454 g 16801H
Potassium Persulfate, ACS 4.0 g 454 g 2617501
Sulfuric Acid, concentrated, ACS 75 mL 2.5 L 97909
Spoon, measuring, 0.5 g 1 each 90700
Stir Bar, Octagonal 50.8 x 7.9 mm 1 each 2095355
Thermometer, -20 to 110 °C 1 each 56601
Watch Glass, Pyrex, 65 mm 1 each 57867

Recommended standards

Description Unit Item no.

Mercury Standard Solution, 1000-mg/L Hg (NIST) 100 mL 1419542

Water, deionized 4L 27256

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© Hach Company/Hach Lange GmbH, 2007, 2010, 2012, 2014. All rights reserved. 03/2014, Edition 8