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1673862 
Journal Article 
Portable system for near-real time measurement of gaseous formaldehyde by means of parallel scrubber stopped-flow absorptiometry 
Toda, K; Yoshioka, KI; Mori, K; Hirata, S 
2005 
Yes 
Analytica Chimica Acta
ISSN: 0003-2670
EISSN: 1873-4324 
531 
1 
41-49 
WOS:000227532200006 
Formaldehyde, HCHO, is one of the important causal agents of sick-building syndrome. It is also an important product of ambient air photochemistry. We report here a portable instrument capable of a 0.08 ppbv limit of detection (LOD) and a time resolution of 5 min that is useful for both indoor and ambient air applications. The detection is based on efficient gas collection and chromogenic reaction with 3methyl-2-benzothiazolone hydrazone (MBTH) through a pair of alternately sampling small-bore porous-membrane tube diffusion scrubbers (DS). The chemistry is well established, requires no special reagent preparation or elevated reaction temperatures and permits the use of inexpensive light emitting diode (LED)-based detectors without need for long path cells. Stopped flow alternate sampling allows an HCHO collection performance, an order of magnitude better than any previous system with high throughput and high sensitivity. Results for indoor and ambient air analyses are presented. (c) 2004 Elsevier B.V. All rights reserved. 
flow analysis; formaldehyde; diffusion scrubber; spectrophotometry; stopped-flow; portable instrument