User Guide

18
Method C: Total Chlorine back titration (PL 101 only)
Instrument setting
1. Fill the bottle of the automatic burette with
0.00188N I
2
solution (HI 70469) and fill
the 10 ml automatic burette to the zero mark.
2. Place the stirbar into a clean 250 mL beaker
and add about 200 mL deionized water.
3. Add 1 mL of pH 4 acetate buffer (HI
70467) and one spoon of potassium io-
dide from the bottle (HI 70468).
4. Turn on the speed controlled stirrer and
place the beaker on the top of the PL 101.
5. Immerse the probe tip into the solution, make
sure the platinum electrodes are submerged.
6. Add 1.5 mL of the iodine solution into the bea-
ker and adjust the potentiometric setting using
the ” ” and “ ” keys on the front panel until the
display reads about 0.50 -0.70. Switch off the
stirring action.
7. Remove the probe from the beaker and rinse the plati-
num electrodes with deionized water. The probe response
slope is adjusted. Don’t change the setting from this point.
Blank Titration
8. Refill the automatic burette to the zero mark.
9. Place the stirbar into a clean 250 mL beaker and add
about 200 mL of deionized water.
10. Add exactly 2.00 mL of the standard 0.00564N PAO
solution (HI 70466) to the beaker and swirl to mix.
11. Add 1 mL of pH 4 acetate buffer solution (HI 70467) and
one spoon of potassium iodide from the bottle (HI 70468)
12. Turn on the speed controlled stirrer and
place the beaker on the top of the PL 101.