Colorimetric qualitative detectors

Colorimetric qualitative detectors should not be used as the sole means for the detection of toxic vapors. However, these devices are suitable for use in low-risk settings where they can be worn on the exterior of PPE. Military M9 and M256 kits are examples of kits that wiU detect gases. The military M8 kit is an example of a kit that will detect chemical liquids. 

Keen visual observation is the most important task during a site reconnaissance. Flowever, some basic in-held chemical testing equipment is useful. Commercial kits are available, mainly based on colorimetric reactions. These kits can be used to check for the presence or absence of common contaminants and to measure soil pH. However, the results obtained using these test kits should only be regarded as qualitative, not least because samples taken at the surface may not represent the bulk of materials on the site. For site reconnaissance, the use of in-held instrumental testing is not justihed. An exception is hand-held equipment to test for the presence of gaseous and volatile contamination—photo-ionisation and other detectors are useful where such contaminants are anticipated. While a Phase la study does not normally include intrusive investigation, a small number of samples may be taken for laboratory analysis. These can be important when waste and other potentially contaminated materials of unknown composition have been spread, deposited or are stored on the site. 

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