YSI 9300 Photometer - Manual (Page 36)

Reagents and Equipment
YSI DPD No 1 Clear Tablets
YSI DPD Nitrite Tablets
YSI 9300 or 9500 Photometer
Round Test Tubes, 10 ml glass (PT 595)
Separation of Bromine Residuals
The photometer is programmed for both total and free bromine. Use program
Phot 5 Total Bromine, then select the ‘Follow On’ option on screen to continue
test for program Phot 6 Free Bromine. The Free Bromine residual is calculated
automatically.
Test Procedure
1 Rinse test tube with sample leaving two to three drops of sample in the tube.
2 Add one DPD No 1 tablet, crush tablet and then fill the test tube with sample
to the 10 ml mark.
3 Select Phot 5 on the photometer.
4 Take photometer reading (%T) in usual manner (see photometer instructions).
5 Result displayed is Total Bromine as mg/l Br.
For most purposes the test can be terminated at this stage. If it is desired to
measure free and combined bromine, select ‘Follow On’ from screen options and
proceed as indicated in the following section.
Test Procedure - Free and Combined Bromine
1 Fill test tube with sample to the 10 ml mark. Add one DPD Nitrite tablet,
crush and mix to dissolve.
2 Take a second clean test tube and add two to three drops of solution from
the first tube. Add one DPD No 1 tablet, crush and then add the remainder of
the solution to make up to the 10 ml mark. Mix to dissolve tablet.
3 Take photometer reading in usual manner.
4 The photometer carries out the necessary calculation and displays the Free
Bromine residual as mg/l Br.
Note
In systems containing both chlorine and bromine it is possible to differentiate
between the chlorine and bromine residuals using a supplementary procedure
involving YSI DPD Glycine tablets. Details of this procedure are given on a
separate instruction sheet.