LaMotte SMART Colorimeter, Operator'S Manual

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CHEMICAL TESTING
WATER SAMPLING FOR CHEMICAL ANALYSIS
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Taking Representative Samples
The underlying factor to be considered for any type of water sampling
is whether or not the sample is truly representative of the source.
To properly collect a representative sample:
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Sample as frequently as possible.
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Collect a large sample or at least enough to conduct whatever tests are
necessary.
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Make a composite sample for the same sampling area.
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Handle the sample in such a way as to prevent deterioration or
contamination before the analysis is performed.
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Perform analysis for dissolved gases such as dissolved oxygen, carbon
dioxide, and hydrogen sulfide immediately at the site of sampling.
These factors, as well as samples for pH, cannot be stored for later
examination.
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Make a list of conditions or observations which may affect the sample.
Other considerations for taking representative samples are dependent
upon the source of the sample. Taking samples from surface waters
involves different considerations than taking samples from impounded
and sub-surface waters.
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Sampling of Open Water Systems
Surface waters, such as those found in streams and rivers, are usually well
mixed. The sample should be taken downstream from any tributary,
industrial or sewage pollution source. For comparison purposes samples
may be taken upstream and at the source of the pollution before mixing.
NOTE: For waterwater samples,
Standard Methods for the Examination
of Water and Wastewater recommends waitings for full color
development.
In ponds, lakes, and reservoirs with restricted flow, it is necessary to
collect a number of samples in a cross section of the body of water, and
where possible composite samples should be made to ensure
representative samples.
To collect samples from surface waters, select a suitable plastic container
with a tight fitting screw cap. Rinse the container several times with the
sample to be tested, then immerse the container below the surface until it
is filled to overflowing and replace the cap. If the sample is not to be
tested immediately, pour a small part of the sample out and reseal. This
6 SMART COLORIMETER