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Marine Nitrate LR
PREPARE THE FILTER HOLDER ASSEMBLY
1. Unscrew the two halves of the reusable filter holder and carefully place one paper filter on the lower piece.
The upper piece is marked ‘TOP’; the lower piece has no marking.
Ensure the filter paper is on top of the clear colorless gasket in the filter holder.
2. Thread the upper piece over the lower piece and tighten securely. Ensure that the paper filter is not
overlapping the threads. The filter holder assembly is now ready for use.
Cleaning
To clean zinc powder residue from the filter holder assembly:
1. Unscrew the filter holder and gently pop the small ridged disk out of the upper half.
If necessary, use a small bristle brush and detergent.
2. Rinse thoroughly with Reverse Osmosis Deionized water (RODI) or tap water.
3. Dry before use.
FILTRATION & DILUTION
Filtering
To prevent the filter from tearing:
• Ensure that the filter and filter holder are dry before use.
• During filtering, keep a constant light pressure on the syringe plunger; it should take about 30 seconds
for full filtration. Do not use excessive force.
Dilution
1. Measure 1 mL of sample using
HI740143
1 mL graduated syringe.
2. Dispense into mixing vial.
3. Add nitrate/nitrite‑free artificial seawater up to the 10 mL mark using
HI740157P
droppers.
4. Cap the vial and mix.
5. Attach the blunt needle to the 10 mL syringe. To attach, screw the covered blunt needle and remove the
cap to expose opening.
6. Draw 7 mL of diluted sample into syringe and discard remaining 3 mL of sample from the mixing vial.
7. Dispense 7 mL of diluted sample back into the empty mixing vial.
Continue with the normal procedure by adding
HI781A‑0
. Multiply results by 10.
Note
: Measurement accuracy will be affected by dilution. Measure dilution volumes carefully!
MEASUREMENT PROCEDURE
Select the
Nitrate Marine LR
method using the procedure described in Method Selection.
Note
: If tutorial mode is disabled, follow the measurement procedure below. If the tutorial
mode is enabled, press
Measure
and follow the messages on the screen.
Note
: For samples containing 5-50 ppm nitrate, follow the dilution procedure.
• Use a 10 mL syringe and measure exactly 7 mL of sample into a mixing cuvette (# 1).
• Use a 5 mL syringe and add exactly 4 mL of
HI781A‑0
Marine Nitrate LR Reagent
into the mixing cuvette.
2
3
4
5
6
7
8
9
10
ml
# 1
4 mL