Infrared Spectrophotometric Analysis of Medicinal Gases for Trace Impurities

Abstract

The feasibility of examining medicinal gases for trace impurities, using an infrared spectrophotometer in conjunction with a 10 m gas cell, was investigated. Many of the impurities for which the USP includes limits were detected and measured at concentrations at or below those permitted by the USP; these include sulfur dioxide, carbon dioxide, carbon monoxide, and water. However, others (hydrogen sulfide, nitric oxide, and nitrogen dioxide) were not detected at these levels by this technique. Methane was found at low levels in some samples.

Chemical Data: An Essential Tool in the Regulation of Drugs

“…In order to have a single method to analyze for all important gaseous impurities in medicinal gases, an infrared (IR) spectrophotometric method of analysis for trace impurities was developed. 20 This method, which involves the use of a 10-m gas cell, will detect most organic and inorganic compounds present in trace quantities in medicinal gases where USP specifications require that none be present. Methane was found at low levels in some samples, and four common inorganic gases were detectable below their USP limits.…”

“…The ASTM First-1 Fast IR Search system is used when unknowns are submitted for analysis. 20 This system is currently available throughout the FDA where APL programs21 make it easy to use.…”