YSI 900 Chlorine Colorimeter - Manual (Page 4)

4
Guidelines for photometric measurements
1. Vials, caps and stirring rods should be cleaned thoroughly after each analysis to prevent
interference. Even minor reagent residues can cause errors in the test result.
2. The outside of the vial must be clean and dry before starting the analysis. Clean the outside of the
vials with a lint-free cloth (L197635) to remove fingerprints or other marks.
3. Zero calibration and test must be carried out with the same vial as there may be slight differences
in optical performance between vials.
4. The vials must be positioned in the sample chamber for zeroing and test with the mark on the
vial aligned with the mark on the instrument.
5. Always perform zeroing and test with the vial cap tightly closed. Only use the cap with a light-
shielding ring.
6. Bubbles on the inside wall of the vial lead to incorrect measurements. To prevent this, remove
the bubbles by gently swirling the vial before performing the test.
7. Avoid spillage of water into the sample chamber because this can lead to incorrect test results.
8. Contamination of the transparent cell chamber can result in incorrect readings. Check at regular
intervals and – if necessary – clean the transparent cell chamber using a moist cloth or cotton
swab.
9. Large temperature differences between the instrument and the environment can lead to errors
e.g. due to the formation of condensation in the cell chamber or on the vial.
10. To avoid errors caused by stray light do not use the instrument in bright sunlight.
11. The reagents must be added in the correct sequence.
Method notes
• Prior to measurement ensure that the sample is suitable for analysis (no major interferences) and
does not require any preparation i.e. pH adjustment, filtration etc.
• Reagents are designed for use in chemical analysis only and should be kept well out of the reach
of children.
• Ensure proper disposal of reagent solutions.
• Material Safety Data Sheets are available on request.
General notes