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4.4 Sample Vials.
Before being use the vials should always be washed with with detergent to remove any dirt
or fingerprints.
Dry the outside of the tubes with a clean, lint-free cloth. Let the tubes dry in the air, in an
inverted position to prevent dust from entering the vials.
The handling of the vials has great importance. Scratch, fingerprints and water droplets in the vial or
inside the light chamber can cause interference, leading to inaccurate results.
It is very important that vials and light chamber are clean and dry constantly.
The variability in the glass geometry is the predominant cause of the variability of the results. The
position variation of the vial in the light chamber will greatly affect the results. To obtain accurate results,
the vials must be positioned exactly,
The "I" mark in the vial must be aligned with the arrow (▲) in the instrument sample chamber.
Sample Vials calibration
The turbidimeter AP 2000 vials are factory selected for optimal precision, however in low turbidity
conditions, small changes in the glass can cause different readings on the same sample.
To measure samples in the lower range, below 1NTU, for greater accuracy, a vial calibration is
recommended.
1.
Fill each vials with dilution
water *.
2.
Complete a reading of all the vials, take
note of each reading.
3.
Mark the vials with the lowest
reading with an "R", Those will
be your reference vials.
This tag should be near the
top, close to the lid, and with
permanent marker.
4.
The difference between the value of the
reference vials "R" with the other vials is the
correction factor for each of the vials.
This value may be used when
comparing the readings with different vials.
* dilution water
- prepared according to Standard Methods - Method 2130 (latest edition) with membrane
filtration for retention of particles ≥ 0.1 μm - generating a nominal value of 0.02 or below 0.1 NTU.
