Dilution Procedures; Testing Tips - LaMotte 2020 Instruction Manual

DILUTION PROCEDURES

If a sample is encountered that is higher than 1100 NTU, a careful dilution will
bring the sample into the acceptable range. However, there is no guarantee that
halving the concentration will exactly halve the NTU values. The particulates
often react in an unpredictable manner when diluted.

TESTING TIPS

1. Samples should be collected in a clean glass or polyethylene container.
2. Samples should be analyzed as soon as possible after collection.
3. Discard tubes that are badly scratched.
4. Gently mix sample by inverting before taking a reading but avoid
introducing air bubbles.
5. Turbidity readings will be affected by electric fields around motors.
6. Carbon in the sample will absorb light and cause low readings.
7. Observe shelf life recommendations for turbidity standards.
8. The turbidimeter should be placed on a surface free from vibration.
Vibrations can cause high readings.
9. Excessive color in a sample will absorb light and cause high readings. The
user should verify if a certain level of color will cause a significant error at
the level of turbidity being tested.
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