Detection Tube

Colorimetric methods have led to the development of visual devices for measurement of benzene concentration. These visual detection tubes have been popular since the 1960s and have provided a simple and rehable method for evaluating ambient aromatic vapor contamination. These products are available from anumber of manufacturers such as Drager (Lubeck, Germany), Gastec (Tokyo, Japan), Kitagawa (Kawasaki, Japan), DuPont (Wilmington, Delaware, USA), and 3M (St. Paul, Minnesota, USA) (85). 

Tokunaga R, Takahata S, Onoda M, Ishi-i T, Sato K (1974) Evaluation of the exposure to organic solvent mixture. Comparative studies on detection tube and gas-liquid chromatographic methods, personal and stationary sampling, and urinary metabolite determination. Internationales Archiv Arbeitsmedizin 33 257-267. 

Readers are warned that the literature includes some incident reports originating from the emergency services which are undoubtedly in error. An example is the claimed production of hydrogen cyanide by fuels containing no nitrogen, but much chlorine (the ordinary gas detection tubes for cyanide actually generate and then... 

Figure 2. Detection tubes instruction cards (from Draeger Safety)...

The gas detection tube shows a color change for vapor CWAs with a sensitivity of mg/m concentration level. The... 

TABLE 53.1. Detection performance of Drager gas detection tubes... 

Agent Gas detection tube Limit of detection Response time... 

Takayama, Y., Sekioka, R., Sekiguchi, H., Maruko, H., Ohmori, T., Seto, Y. (2007). Detection performance of Drager Safety gas detection tubes for chemical warfare agents. Bunseki Kagaka 56 355-62. 

Detection tubes, such as civil defense kit, contain special reagents impregnated on inert supports. Air is sucked through the tube with a special pump. Reaction between the reagents in the tube and CWA takes place, and different colors are produced based on the CWA. 

Air samplers using gas detection tubes These tubes are filled with chemicals that change color as air samples are drawn into them. The tubes are calibrated in parts per million (ppm) and give accurate readings down to 1 ppm. The air samplers are manufactured by Mine Safety Co. and the Draeger Corp. Individual tubes cost from 2.00- 4.00 in lots often. (See sources in Appendix). 

Color-Change Chemistry. This technology is based upon chemical reactions that occur when CW agents interact with various solutions and substrates. The most common indicator (for a positive response) is a color change. Detection tubes, papers, or tickets use some form of surface or substrate to which a reagent solution is applied. 

Detection Tubes should be read on the Leader within 60 min of decanting the wash solution. Tubes should be maintained at 20-25 C prior to reading. 

Figure 10.5 A cross section of a detection tube used in Geiger-Muller counters.

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