Table of Contents
Advertisement
Chematest 35
Photometry
4.
4.1.
12
Photometry
Basic Rules for Photometric Measurements
The precision and repeatability of a photometric determination
depends greatly on the operator's technique. Please observe the
following rules:
Always use clean utensils
Residues from previous measurements can falsify the results. The
cuvette cap and all utensils such as syringes or cuvettes must be
rinsed with clean water after each measurement. Rinse the cuvette
additionally with the sample 2 to 3 times before each measurement.
Keep the outside of the cuvette clean and dry
Keep the cuvette free of fingerprints and dry the outside of the
cuvette before inserting it into the cuvette adapter.
If condensation occurs on the cuvette (cold sample in a warm
environment), wipe it off and carry out the measurement as quickly
as possible.
Observe proper sampling
Take the water samples about 10 cm below the water surface and
about 50 cm from the edge of the pool. Allow as little time as possi-
ble to elapse between taking the sample and making the measure-
ment.
Observe proper dosing and mixing
Use the 10 ml syringe for exact dosing of the sample. Rinse the sy-
ringe several times with the sample. When filling the syringe, make
sure that there are no air bubbles and that the volume is 10 ml.
The order in which sample and reagents are added to the cuvette
varies from method to method. If the reagents are added to the cu-
vette after the sample, special care must be taken to ensure that
the sample and the reagents mix well.
Observe reaction times
With most methods, the measurement can be carried out immedi-
ately after the reagents have been added and mixed with the sam-
ple. If a reaction time is required, this is indicated on the screen.
A-96.730.121 / 160920
Advertisement
Table of Contents
