YSI 9300 Photometer - Manual (Page 108)

Reagents and Equipment
YSI Iron MR No 1 Tablets
YSI Iron MR No 2 Tablets
YSI Citrate IR Tablets
YSI 9300 or 9500 Photometer
Round Test Tubes, 10 ml glass (PT 595)
Test Procedure
1 Fill the test tube with sample to the 10 ml mark.
2 Add one Iron MR No 1 tablet, crush and mix to dissolve.
3 Add one Iron MR No 2 tablet, crush and mix to dissolve.
4 Stand for 10 minutes to allow full color development.
5 Select Phot 39 on photometer.
6 Take photometer reading in usual manner (see photometer instructions).
7 The result is displayed as mg/l Fe.
Interferences
Hardness 500 mg/l CaCO
3
, Silica 150 mg/l SiO
2
and Copper 3 mg/l Cu do not
interfere with the test. Chromium 10 mg/l may cause slightly high results.
Nitrite greater than 50 mg/l NO
2
causes low results and molybdate at any
concentration causes precipitation. The pretreatment procedures described below
using Citrate IR tablets remove interference from nitrite up to 500 mg/l NO
2
and
molybdate up to 20 mg/l MoO
4
. This pretreatment does however reduce the
tolerance to chromium and is not recommended therefore for chromium
containing samples.
Pretreatment Procedure using Citrate IR Tablets
Samples Containing Nitrite :-
1 Fill the test tube with sample to the 10 ml mark.
2 Add one Citrate IR tablet, crush and mix to dissolve. Ensure all particles are dissolved.
3 Continue the test as described in the test procedure from Stage 2 above but
allow the tube to stand for 15 minutes to allow full color development before
taking the photometer reading.
Samples Containing Molybdate :-
1 Fill the test tube with sample to the 10 ml mark.
2 Add one Iron MR No 1 tablet, crush and mix to dissolve.
3 Add one Citrate IR tablet, crush and mix to dissolve. Ensure all particles are dissolved.
4 Continue the test as described in the test procedure from Stage 3 but allow
the tube to stand for 15 minutes to allow full color development before taking
the reading.