Efficacy of a detector tube method in formaldehyde measurement

In order to determine the efficacy of a detector tube method in formaldehyde (HCHO) measurement, we performed a chamber experiment and a field study. The experiment clearly showed that the value obtained by the detector tube method was significantly correlated to that obtained using an active-DNPH method, and was not influenced by the coexistence of toluene, xylene or carbon monoxide, but was by acetaldehyde. In the field study, we investigated 171 rooms in 81 houses. Indoor air was simultaneously sampled for 30 minutes by both an active-DNPH method and the detector tube method. The mean HCHO concentration in the 171 rooms was 0.110 +/- 0.089 ppm determined by the active-DNPH method and 0.12 +/- 0.10 ppm by the detector tube method. Regression analysis showed that the two measures closely correlated with a regression equation Y=1.057 X + 0.002 (r=0.912, p<0.0001), where X is the HCHO concentration determined by the active-DNPH method and Y is that determined by the detector tube method. The mean acetaldehyde concentration in the 171 rooms was 0.024 +/- 0.018 ppm using the active-DNPH method, and no correlation was found between acetaldehyde concentrations using the active-DNPH method and the values obtained by the detector tube method. Therefore, this study clearly showed that the detector tube method is not only simple and fast but also precise in measuring HCHO in indoor air.