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Chlorine, Total
Sample Collection, Storage, and Preservation
Treating Analysis Labware
Cleaning the Pour-Thru Cell
Accuracy Check
Chlorine, Total
Page 6 of 8
Analyze samples for chlorine immediately after collection. Many factors,
including reactant concentrations, sunlight, pH, temperature and salinity
influence decomposition of chlorine in water.
Avoid plastic containers since these may have a large chlorine demand. Pretreat
glass sample containers to remove any chlorine demand by soaking in a dilute
bleach solution (0.5 mL commercial bleach to l liter of deionized water) for at
least 1 hour. Rinse thoroughly with deionized or distilled water. If sample
containers are rinsed thoroughly with deionized or distilled water after use, only
occasional pre-treatment is necessary.
A common error in testing for chlorine is obtaining a representative sample. If
sampling from a tap, let the water flow for at least 5 minutes to ensure a
representative sample. Let the container overflow with the sample several times,
then cap the sample containers so there is no headspace (air) above the sample.
Perform the chlorine analysis immediately.
Glassware used in this test must be chlorine demand-free. Treat all glassware
with a dilute solution of chlorine bleach prepared by adding 0.5 mL of
commercial bleach to 1 liter of water. Soak glassware in this solution at least on
hour. After soaking, rinse the glassware with copious amounts of deionized
water and allow to dry before use.
Treat the Pour-Thru Cell similarly with dilute bleach and let stand for several
minutes and then rinse several times with deionized water.
The Pour-Thru Cell may accumulate a buildup of colored reaction products,
especially if the reacted solutions are allowed to remain in the cell for long
periods after measurement. Remove the buildup by rinsing the cell with
5.25 N Sulfuric Acid (Cat. No. 2449-53) followed by several rinsings with
deionized water.
Standard Additions Method (Sample Spike)
1. After reading test results, leave the sample cell (unspiked sample) in the
instrument. Verify that the units displayed are in mg/L.
2. Touch
. Touch
Options
average chlorine concentration shown on the certificate enclosed with the
®
Chlorine Voluette
3. A summary of the Standard Additions procedure will appear. Touch
accept the values for standard concentration, sample volume, and spike
volumes as shown. Touch
accepted, the unspiked sample reading will appear in the top row. See
Standard Additions in the instrument manual for more information.
4. Snap the neck off a LR Chlorine Voluette Ampule Standard,
20–30 mg/L Cl
.
2
. A keypad will appear. Enter the
Standard Additions
Ampules. Touch
.
OK
to change these values. After values are
Edit
to
OK
ChlorineTot_PT_ULow_DPD_Eng_Ody.fm
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