Tubes And Chambers; Sample Dilution Techniques - LaMotte DC1500 Mode D'emploi

The display may show the following messages:
Battery Status
More choices are available and can be viewed by scrolling up and/or
down through the display.
Header Identifi es the current menu and information on units and reagent
systems if applicable.
Footer In the data logging mode the number of the data point is displayed
and the total number of data points in the memory will be shown. The
footer also shows current time and battery status
 TUBES AND CHAMBERS
The colorimeter uses one type of tube (Code 0290) for all test factors.
The handling of the tubes is of utmost importance. Tubes must be clean and free
from lint, fi ngerprints, dried spills and signifi cant scratches, especially the central
zone between the bottom and the sample line.
Scratches, fi ngerprints and water droplets on the tube can cause stray light
interference leading to inaccurate results. Tubes that have been scratched in the
light zone through excessive use should be discarded and replaced with new ones.
Tubes should always be washed on the inside and outside with mild detergent prior
to use to remove dirt or fi ngerprints. The tubes should be allowed to air-dry in an
inverted position to prevent dust from entering the tubes. Dry tubes should be
stored with the caps on to prevent contamination.
After a tube has been fi lled and capped, it should be held by the cap and the
outside surface should be wiped with a clean, lint-free absorbent cloth until it
is dry and smudge-free. Handling the tube only by the cap will avoid problems
from fi ngerprints. Always set the clean tube aside on a clean surface that will not
contaminate the tube. It is imperative that the tubes and light chamber be clean
and dry. The outside of the tubes should be dried with a clean, lint-free cloth or
disposable wipe before they are placed in the meter chamber.
Tubes should be emptied and cleaned as soon as possible after reading a sample to
prevent deposition of particulates on the inside of the tubes.
Variability in the geometry of the glassware and technique is the predominate cause
of variability in results. Slight variations in wall thickness and the diameter of the
tubes may lead to slight variations in the test results. To eliminate this error the
tubes should be placed in the chamber with the same orientation each time.
Chambers which have been scratched through excessive use should be discarded
and replaced with a new one.
 SAMPLE DILUTION TECHNIQUES
If a test result is out of the range of the meter, it must be diluted. The test should
then be repeated on the diluted sample. The following table gives quick reference
guidelines for dilutions of various proportions.
20