Abstrato

Determination of indoor formaldehyde concentration by portable sol-gel scanometric method.

Zohreh Mehrabadi, Hossein Faghihian, Abdolreza Khajehzadeh

Sol-gel scanometric method has several advantages, such as simplicity, high scanning speed, portability, short response time, limited interference, and easy immobilization of reactants, and has been used for determination of many compounds such as dopamine, hydrazine and bromocresol green. In this work, a simple and cost effective sol-gel scanometric method is developed for monitoring of formaldehyde concentration by a portable visual sampling device. The sol-gel containing entrapped formaldehyde was analyzed with software written in visual basic (VB 6) media to red, green and blue (RGB) values and the R, B and B values were obtained. The measurement is based on diffusion of formaldehyde into a transparent sol-gel and reaction with acetylacetone entrapped on the structure of the sol-gel impregnated with sensitive and selective β-diketones. After diffusion, the reaction between formaldehyde and the entrapped β-diketones produced yellow product, lutidine which was detected directly by scanometric method. The method did not require primary sample preparation and enabled screening by visual detection and quantitative measurement. The measurement system had a linear range of 2-20 mgL-1 with detecting limit of 0.1 mgL-1, lower than the maximum exposure concentrations of formaldehyde recommended by the Occupational Safety and Health Administration. The relative standard deviation at 5 mgL-1 was 4.3, 6.1 and 8.5% respectively for red, green and blue colors.