Avoiding Errors - Tintometer Lovibond Photometer Mode D'emploi

3.2. Avoiding errors in photometric measurements
1. Cells, stoppers and stirring rods should be cleaned thoroughly after each analysis to
prevent errors being carried over. Even minor reagent residues can cause errors in the test
results. Use the brush provided for cleaning.
2. The outside of the cell must be clean and dry before starting the analysis. Fingerprints or
droplets of water on the sides of the cell can result in errors.
3. Zero calibration and test must be carried out with the same cell as there may be slight dif-
ferences in optical performance between cells.
4. The cells must be positioned in the cell compartment for zero calibration and test with the
graduations facing toward the operator.
5. Zero calibration and test must be carried out with the cell compartment lid closed.
6. Bubbles on the inside of the cell may also lead to errors. In this case, fit the cell with a clean
stopper and remove bubbles by swirling the contents before starting test.
7. Avoid spillage of water in the cell compartment. If water should leak into the photometer
housing, it can damage electronic components and cause corrosion.
8. Contamination of the windows over the light source and photo sensor in the cell compartment
can result in errors. If this is suspected check the condition of the windows.
9. When using reagent tablets, use only tablets in black printed foil. For pH value determination,
the PHENOLRED-tablet foil should also be marked PHOTOMETER.
10. The reagent tablets should be added to the water sample without being handled.
11. Large temperature differentials between the photometer and the operating environment
can lead to incorrect measurement due to, for example, the formation of condensate in the
area of the lens or on the cell.
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