Colorimetric detectors indicate the presence of a
target chemical through a chemical reaction that results in a color change.
Colorimetric test kits are available for a wide variety of CBRNE targets and
includes M8 paper for CWA detection to the SPX 300 for trace explosives
detection. The tests are usually analyte
and/or class specific and are well suited for presumptive testing of compounds
with suspected identity. Results are
typically examined by comparison of the resulting color to a key in the test
kit. However, a few vendors offer
electronic readers that provide more objective results than visual comparison
and can store the results of a test.
Detection limits are typically in the part-per-million to
part-per-thousand range (ppm-ppth), depending on the analyte.
Typically colorimetric detection has a small form
factor and can be easily transported by hand.
As the tests are based on chemical reactions, they generally require
little or no additional power to conduct.
There are a large number of colorimetric test kits available. Kit cost varies depending on the analyte and
the number of reagent packets in the kit.
They typically require one-time use consumables such as cartridges,
reagents, papers or swabs for each target chemical.