Hach Portable Spectrophotometer DR 2800 - Manual (Page 83)

83
Advanced Operations
e. Does the test require the sample to be at a certain
temperature?
f. Was the pH of the sample in the correct range?
g. Is the pipette volume correct?
2. Check the used reagents by repeating the standard addition
procedure with freshly prepared reagents.
If none of these measures resolves the problem, please contact the
manufacturer or a sales representative.
6.3.1 Complete a standard addition
Carry out the standard addition in accordance with the
corresponding procedure.
There are two different methods:
Peak volume (Standard addition):
Defined volumes of a standard solution are added step by step to
an already analyzed sample. The sample is measured again after
each addition.
Sample volume:
A defined volume of a standard solution of known concentration is
added to the volume of sample specified in the procedure and the
sample is measured after each addition. In most cases three
different standard solutions are prepared and the procedure is
repeated for each of them.
Note: The units and chemical forms used for the sample are used for the
standard solutions. Be careful to ensure that to use the correct units for
subsequent entries.
Detection rate Conclusion
100%
The originally used reagents were defective.
Check the standard solution:
Repeat the standard addition procedure with a
freshly prepared standard solution.
Detection rate Conclusion
100%
The originally used
standard solution was
defective.