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Follow-on Tests
A number of photometric methods have additional
optional methods that can be applied, known as
Follow-on Tests e.g. Phot 008 Total Chlorine follows
Phot 007 Free Chlorine. Follow-on methods are
usually either based on further reagent addition to
the sample just measured for sequential parameters
or used to correct for potential/known interferences.
Follow-on tests are clearly defined in the Palintest
Phot Book and, if available, are accessed via the
Follow-on option located at the right hand side
of the options.
To access the Follow-on test, highlight Follow-on
and press OK. The next method is automatically
loaded and operated in the usual manner.
NOTE: if no viable result is produced during the first
stage of a sequential test method, the Follow-on
option will be automatically removed.
For correction methods, the data log will store
the corrected result automatically along with all
other results in the sequence.
All Follow-on methods have unique allocated Phot
Numbers but not all can be directly accessed.
Follow-on methods that cannot be directly
accessed are not listed in the Choose a Test list
for Hotkey Entry but will be available following
a viable result in the initial test stage.
Photometer 7500
3.6 7500 Test Methods
Fluoride
Range:
0-1.5mg/l (ppm) F
Colour change: Colourless - Red/Yellow
1 Fill test cuvette with sample to the 10ml mark.
2 Add one Fluoride No 1 tablet,
crush and mix to dissolve.
3 Add one Fluoride No 2 tablet,
crush and mix to dissolve.
4 Stand for 5 minutes.
5 Take photometer reading.
Chlorine-Free
Range:
0-5.00mg/l (ppm) Cl
Colour change: Colourless - Purple/Red
1 Rinse test cuvette with sample leaving
two or three drops in the tube.
2 Add one DPD 1 tablet, crush tablet and then
fill the test tube with sample to the 10ml mark.
Mix to dissolve tablet fully and ensure no
particles remain.
3 Take photometer reading immediately.
The result may drift on standing.
4 Retain test solution if the Total Chlorine
Follow-On Test is required.
Chlorine-Total
Range:
0-5.00mg/l (ppm) Cl
Colour change: Purple/Red from Free Chlorine
Test increases in intensity
Carry out this test on the solution
remaining from the Free Chlorine test.
1 Add one DPD 3 tablet, crush and mix to dissolve.
2 Stand for two minutes to
allow full colour development.
3 Take photometer reading after
two minutes have elapsed.
Note: To obtain Combined Chlorine residual
subtract Free Chlorine result from Total Chlorine result:
Combined Chlorine =
Total Chlorine - Free Chlorine
3
2
2
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