Abstract
In the high-temperature method for the determination of sulfur in petroleum products, sodium azide added to the titration cell solution eliminates nitrogen and/or chlorine interferences with the iodometric finish. In a laboratory in which sodium azide is used routinely for this purpose, some laboratory personnel working adjacent to the sulfur analyzer reported irritations such as nasal stuffiness. It was suspected that hydrazoic acid was being released from the titration cell, although the reportedly pungent odor of hydrazoic acid was not evident. Subsequent analysis showed hydrazoic acid being released from the titration cell at the rate of approximately 12 mg/min under the conditions for the automated titration of sulfur dioxide. It was estimated that hydrazoic acid vapors at a concentration as low as 0.5 ppm can cause some discomfort to laboratory personnel. The titration cell was subsequently placed within an exhaust hood.