Chlorine, Total
© Hach Company, 2003. All rights reserved. Printed in the U.S.A. 3/04 1ed
Page 4 of 4 ChlorineTot_MP_High_DPD_Eng_2400.fm
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Accuracy Check
Standard Additions Method (Sample Spike)
1. After reading test results, leave the sample cell (unspiked sample) in the
instrument.
2. Touch
Options. Touch Standard Additions. A keypad will appear. Enter the
average chlorine concentration shown on the certificate enclosed with the
chlorine voluette ampules. Touch
OK.
3. A summary of the Standard Additions procedure will appear. Touch
OK to
accept the values for standard concentration, sample volume, and spike
volumes as shown. Touch
Edit to change these values. After values are
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 HR Chlorine PourRite Ampule Standard.
5. Prepare three sample spikes. Fill three mixing cylinders (Cat. No. 1896-40)
with 5-mL of sample. Using the TenSette
®
Pipet, add 0.1 mL, 0.2 mL and
0.3 mL of standard, respectively, to each sample and mix thoroughly.
6. Analyze the standard addition as described in the procedure above. Accept
the standard addition by touching
Read.
See Section 3.2.2 Standard Additions for more information.
Summary of Method
The range of analysis using the DPD method for free chlorine can be extended by
adding more indicator in proportion to sample volume. Thus, a larger fill
powder pillow of DPD Free Chlorine Reagent is added to a 5-mL sample
portion.
The combined chlorine oxidizes iodide in the reagent to iodine. The iodine reacts
with DPD (N, N-diethyl-p-phenylenediamine) along with free chlorine present
in the sample to form a red color which is proportional to the total chlorine
concentration. To determine the concentration of combined chlorine, run free
chlorine and total chlorine tests. Subtract the results of the free chlorine test from
the results of the total chlorine test to obtain combined chlorine.
Required Reagents
Quantity Required
Description Per Test Unit Cat. No.
DPD Total Chlorine Reagent Powder Pillows......................................1 pillow........... 100/pkg.............14064-99
Required Apparatus
Adapter, multi-pathlength cell ...............................................................1 ....................... each....................59466-00
Cell, sample, multi-pathlength ...............................................................2 ....................... 6/pkg.................59405-06
Required Standards
Chlorine Standard Solution, PourRite
®
Ampules, 50–75 mg/L.................................. 20/pkg...............14268-20
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