Determination of airborne formaldehyde by active sampling on 3-methyl-2-benzothiazolinone hydrazone hydrochloride-coated glass fibre filters.
Formaldehyde was sampled with the use of a standard miniature glass fibre filter coated with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH). The formaldehyde hydrazone formed [i.e., the adduct of formaldehyde (HCHO) and MBTH] was desorbed from the filter with water and then oxidised by an iron(III) chloride-sulfamic acid solution to form a blue cationic dye in acidic medium which was subsequently determined by visible absorption at 628 nm. The recovery of HCHO as the cationic dye from MBTH-coated filters is 87-102% in the range 0.065-2.9 micrograms of HCHO. This corresponds to 4.3-193.3 micrograms m-3 in a 15 L air sample. The collection efficiency of the MBTH-coated filter is higher than 90%. When the filter sampling system is used in active mode, air can be sampled at a rate of up to 1 L min-1, affording an overall sensitivity of about 3 micrograms m-3, corresponding to about 2 ppb v/v HCHO at 1 atm and 273 K. The method was successfully applied to the determination of HCHO in samples of indoor and outdoor air with satisfactory results.
Chan
W H
WH
Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China. whchan@hkbu.edu.hk
Shuang
S
S
Choi
M M
MM
D000393:Air Pollutants / Q000032:analysis*; D016902:Air Pollution, Indoor; D052160:Benzothiazoles; D002273:Carcinogens / Q000032:analysis*; D005374:Filtration; D005557:Formaldehyde / Q000032:analysis*; D006835:Hydrazones; D013053:Spectrophotometry; D013844:Thiazoles / Q000032:analysis*
D000393:Air Pollutants; D052160:Benzothiazoles; D002273:Carcinogens; D006835:Hydrazones; D013844:Thiazoles; D005557:Formaldehyde; C002536:3-methyl-2-benzothiazolone hydrazone