Extractive spectrophotometric determination of trace amounts of sulfur dioxide in air

Journal Article · Sun Nov 01 04:00:00 EST 1992 · Journal of AOAC International

OSTI ID:443625

Kumar, B S.M.; Balasubramanian, N ^[1]

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1. Indian Institute of Technology, Department of Chemistry, Madras (India)

A sensitive spectrophotometric method was developed for the determination of trace amounts of sulfur dioxide (SO{sub 2}) in air after SO{sub 2} has been fixed in a buffered formaldehyde solution. The reaction of iodate with the fixed SO{sub 2} in the presence of an acid an an excess of chloride leads to the formation of ICI{sub 2} ions. The resulting ICI{sub 2} species forms an ion-pair with pararosaniline cation; the product is extracted into isopentyl alcohol and measured spectrophotometrically at 560 nm. The color system obeys Beer`s law over the range 0-40 {mu}g SO{sub 2}. The color is stable for 72 h from the time of extraction. The molar absorption coefficient of the color system is 4.5 {times} 10{sup 3}Lmol{sup {minus}1}cm{sup {minus}1}. The coefficient of variation is 3.6% for 10 determinations at 20 {mu}g SO{sub 2}. The effect of interfering gases on the determination is discussed. The method was applied to the determination of SO{sub 2} at low concentrations, and the results obtained were compared with the widely used West and Gaeke method. The method can be used to determine as low as 2 {mu}g SO{sub 2}. 12 refs., 2 figs., 2 tabs.

• OSTI ID: 443625
• Journal Information: Journal of AOAC International, Journal Name: Journal of AOAC International Journal Issue: 6 Vol. 75; ISSN JAINEE; ISSN 1060-3271
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AIR
AIR POLLUTION
ECOLOGICAL CONCENTRATION
SPECTROPHOTOMETRY
SULFUR DIOXIDE
TECHNOLOGY ASSESSMENT