LaMotte DC1500 Mode D'emploi page 5

6. Insert tube into chamber, close lid and
select Scan Blank.
7. Remove tube from colorimeter. Add one
DPD #1 IG Tablet (6903A). Cap tube and
shake for 10 seconds. Invert slowly 5 times.
Solution will turn pink if free chlorine is
present.
8. Immediately insert tube into chamber.
Close lid. Select Scan Sample. Record
result as Free Chlorine.
PROCEDURE – COMBINED CHLORINE
9. Remove tube from colorimeter. Add one
DPD #3 IG Tablet (6197A). Cap tube and
shake for 10 seconds. Invert slowly 5 times.
An increase in color represents combined
chlorine.
NOTE: For wastewater samples, Standard Methods for the Examination of Water and Wastewater
recommends waiting 2 minutes for full color development when testing total chlorine.
10. Insert tube into chamber, close lid and
select Scan Sample. Record result as Total
Chlorine (Monochloramine, Dichloramine,
and Nitrogen Trichloride) present in the
water sample.
11. Subtract free chlorine reading from total chlorine reading to obtain concentration of
combined chlorine.
12. Press
make another menu selection.
Levels of chlorine about 4 mg/L will cause a bleaching effect on the DPD indicator, and may give
a false indication that no chlorine is present. If if is possible that the chlorine concentration is
greater than 4 mg/L, perform test on a diluted sample and multiply the result by appropriate
dilution factor.
CAUTION: DO NOT leave reacted samples in test tubes. Discard sample and thoroughly rinse tubes. If allowed
to remain, DPD wil stain tubes, signigicantly impairing the operation of the colorimeter. If necessary, acid
wash, and vigorously clean glassware with test tube brush and detergent.
to turn off the colorimeter or press
025 Chlorine T DPD
0.99
Scan Blank
Scan Sample
12:00:00
to exit to a previous menu or
EXIT
5
ppm
001/500