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2-4 TTi
®
Colorimeter User’s Manual
Part 2 Testing Primer
SAMPLING
• Use dedicated sample bottles. These bottles should be labeled as such and not used for another purpose.
• Use a sample bottle of sufficient size. If too small, you will not have enough water to perform multiple
tests.
• Rinse the sample bottle and cap well (we recommend three times) with deionized water, distilled water, or
sample water.
• Take a sample that is representative of conditions in the whole system:
Closed Systems - Let the sample stream flow at a constant velocity for at least five minutes before begin-
ning the collection process. If you blow out the line with a higher-than-normal flow, subsequently be sure
to reduce the flow to the normal rate for five minutes before proceeding with sampling.
Open Systems - Chemistry at the surface is atypical as the water is interacting with the air above and
oils and debris may be present. Samples taken near return lines, makeup water inlets, chemical feeders,
or in corners also can be different than in the body-at-large since the water may not have experienced the
same mixing action as in open areas. A sample taken downstream from a tributary or pollution source
will be different from a sample taken upstream. With these considerations in mind, select a representative
location, immerse the sample container bottomside up to about elbow depth, and then turn the container
upright to fill.
• Fill the sample bottle to overflowing. Do not leave any room for air in the bottle.
• Avoid contaminating the sample once collected. Immediately cap the bottle tightly to avoid contamination.
• Do not put any probe into a bottle of sample water that will be used for multiple tests.
• Do not let the sample sit before testing, or it may change its character. Boiler water samples that should be
at room temperature when beginning the test should be promptly cooled in a cold water bath to between
80°F– 90°F (27°C–32°C).
• Dispense sample water into the sample cell until the lowest point of the meniscus sits on the correct fill
mark when viewed at eye level.
• After a sample cell has been filled and capped, hold it by the cap and then wipe off any moisture or
fingerprints on the glass using a clean, lint-free cloth.
FILTERING SAMPLES
Unless otherwise specified, test methods are designed to determine dissolved substances in water samples.
If samples are turbid they may contain suspended solids, algae, or other substances that may interfere in the
test procedure. We recommend using a 0.45 µm membrane filter disc in a syringe-type filter to remove these
substances prior to testing.
DILUTING SAMPLES
Some test procedures specify diluting a sample to adjust the concentration of the analyte to fit the range of
the test. In such cases, the instruction will provide all details for performing the procedure with the dilution
vial supplied with the kit. When a test sample is diluted, the result displayed must be multiplied by a factor
to obtain the concentration of the undiluted analyte. This multiplication factor will be specified in the test
instruction.
Sample dilution also may be required even if a this procedure is not specified in the test instruction. When the
test result is above RANGE, the sample must be diluted using high-purity water and the dilution vial supplied
with the kit. See example display, following.