LaMotte DC1100 Colorimeter - Manual (Page 5)

5. For best results, use the same tube that was used to adjust the blank for all
measurements. If the test you are performing requires a wait of more than
thirty seconds, turning the meter off will extend battery life.
6. Follow individual test instructions to add reagents to the tube.
7. Cap the treated sample tube, making sure the tube is clean and dry, then
insert the tube into the chamber.
8. Press the “ON/OFF” button if the meter has been turned off. Record
reading directly from the display.
TEST SAMPLE DILUTIONS AND VOLUMETRIC MEASUREMENTS
If the indicated reading is higher than the maximum concentration specified on
the reagent specifications, a dilution should be done to ensure accuracy. In rare
cases of extremely high concentrations, the display may indicate an over-range
condition: the left digit will be a “1,” the other digits will remain blank. The
sample must then be diluted with demineralized water and the test repeated to
bring the concentration within a range that can be accurately measured by the
meter. The reading is then multiplied by the appropriate dilution factor to
obtain the test result.
EXAMPLE:
Measure 5 mL of the original sample into a graduated cylinder. Dilute to 10 mL
with distilled or demineralized water. The sample has now been diluted by half,
and the test results are multiplied by 2.
The following dilution table shows the amount of original sample to be diluted,
the amount of distilled or demineralized water required, and the dilution factor.
Since the tests are based on a 10 mL sample, the dilutions must be measured
accurately to assure reliable results.
Size of Sample
Distilled Water to Bring
Volume to 10 mL
Multiplication Factor
10 mL 0 mL 1
5 mL 5 mL 2
2.5 mL 7.5 mL 4
1 mL 9 mL 10
0.5 mL 9.5 mL 20
NOTE: When measuring small sample sizes, use graduated cylinders or pipets,
and measure the final dilution in a graduated cylinder. Pipet the
sample water into the graduated cylinder, then fill the cylinder to the
10 mL line with distilled or demineralized water.
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