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4120116 
Journal Article 
Instability of Ozone Samples Collected in Alkaline Potassium Iodide Solution 
Hekmat, M; Fung, P; Smith, R 
1992 
Yes 
American Industrial Hygiene Association Journal
ISSN: 0002-8894 
NIOSH/00210612 
53 
10 
The stability of ozone (10028156) samples collected according to NIOSH method S-8 was investigated. The NIOSH method was based on drawing air samples through a midget impinger containing 10 milliliters 1% potassium-iodide in 1 normal sodium-hydroxide. Ozone in the samples reacted with the potassium-iodide to form a product that was supposed to be stable for several days. Addition of phosphoric-acid/sulfamic-acid reagent resulted in iodine being liberated from the samples. The iodine was quantitated spectrophotometrically and was found to be proportional to the concentration of ozone in the samples. Standard atmospheric samples prepared by the United States National Institute for Standards and Technology were collected according to the NIOSH method. Each sample was split into two parts. One part was analyzed immediately and the other part was stored in a clean vial at 4 degrees-C before being analyzed 24 hours later. The average recovery of the samples stored for 24 hours was 26%. The average recovery of the samples analyzed immediately after collection was 98%. The authors conclude that when analyzing ozone containing samples according to NIOSH method S-8, a delay between sampling and completion of the analysis is unacceptable. The samples should be analyzed shortly or within 1 hour after collection to obtain reliable results.