| Journal: | Quimica nova |
| Database: | PERIÓDICA |
| System number: | 000197752 |
| ISSN: | 0100-4042 |
| Authors: | Pereira, Elisabete A1 Cardoso, Arnaldo A Dasgupta, Parnendu K |
| Institutions: | 1Universidade Estadual Paulista "Julio de Mesquita Filho", Instituto de Quimica, Araraquara, Sao Paulo. Brasil 2Texas Tech University, Department of Chemistry and Biochemistry, Lubbock, Texas. Estados Unidos de América |
| Year: | 2001 |
| Season: | Jul-Ago |
| Volumen: | 24 |
| Number: | 4 |
| Pages: | 443-448 |
| Country: | Brasil |
| Language: | Portugués |
| Document type: | Artículo |
| Approach: | Experimental, descriptivo |
| English abstract | A sensitive and simple system was proposed for the in situ measurement of total aldehyde in outdoor or indoor ambient. The method is based on the use of a reagent drop as an useful interface to preconcentrate the sample prior to determination of total aldehyde as formaldehyde. The drop is formed at the tip of a cylindrical tube that contains two optical fibers placed on opposite sides and in contact with the reagent solution. One optical fiber carries the red light to the drop form a light emitting diode (LED). The transmitted light is measured by a second optical fiber/photodiode system. The analytical signal is read and converted into absorbance. The reagent solution of 3-methyl-2-benzothiazoline hydrazone (MBTH) forms a blue cation during reaction with formaldehyde that can be measured at 660 nm. Some aspects of kinetics reaction formation of dye were reevaluated. The formaldehyde reacts with MBTH and forms the azine in about 12 min. The oxidation of MBTH by Fe (III) and the formation of dye requires 3 min. The absorbance of the reagent drop is proportional to the sampling time and to the analyte concentration. The absorbance signal increases with increased sample gas flow until a maximum is reached then decreases until it forms a plateau. The proposed method was evaluated using both outdoor and indoor samples, and it was shown to viable provide an accurate measure of total aldehyde |
| Disciplines: | Ingeniería, Química |
| Keyword: | Ingeniería ambiental, Química analítica, Contaminación, Aldehídos, Análisis de aire, Formaldehído, Hidrocarburos, Gota suspendida |
| Keyword: | Engineering, Chemistry, Environmental engineering, Analytical chemistry, Aldehydes, Air analysis, Formaldehyde, Hydrocarbons, Suspended droplet |
| Full text: | Texto completo (Ver HTML) |
