YSI 9300 Photometer - Manual (Page 46)

Reagents and Equipment
YSI DPD No 1 Tablets
YSI DPD No 2 Tablets
YSI DPD No 3 Tablets
YSI 9300 or 9500 Photometer
Round Test Tubes, 10 ml glass (PT 595)
Separation of Chlorine Residuals
The photometer is programmed for free chlorine and for the chloramine stages. Use
program Phot 71 Free Chlorine then select ‘Follow On’ from screen options to continue
test for program 72 Monochloramine and again for program 73 Dichloramine.
Test Procedure
1 Rinse test tube with sample leaving two or three drops of sample in the tube.
2 Add one DPD No 1 tablet, crush tablet and then fill test tube with sample to
the 10 ml mark. Mix to dissolve tablet.
3 Select Phot 71 on photometer.
4 Take photometer reading immediately (as result may drift on standing), in
usual manner - see photometer instructions. The result represents the free
chlorine residual as mg/l Cl
2
.
5 To measure monochloramine, continue the test on the same test portion.
Select ‘Follow On’ from screen options to continue the test program.
6 Add one DPD No 2 tablet, crush and mix to dissolve.
7 Take the photometer reading immediately. The result displayed is the mono-
chloramine concentration as mg/l Cl
2
.
8 To measure dichloramine, continue the test on the same test portion. Select
‘Follow On’ option from screen options to continue the test program.
9 Add one DPD No 3 tablet, crush and mix to dissolve. Stand for two minutes
to allow full color development.
10 Take the photometer reading. The photometer displays the dichloramine
concentration as mg/l Cl
2
.
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