Modification of the gas-liquid chromatography procedure and evaluation of a new column packing material for the identification of anaerobic bacteria.

Gas-liquid chromatography has become a useful aid for the identification of anaerobic bacteria in the clinical laboratory. When many extracted samples are to be analyzed, time is of prime importance. By altering the operating conditions of the chromatograph, we have decreased the total elution time of the volatile fatty acids examined to approximately 12 min. There is, however, a decrease in the ability to resolve propionic and isobutyric acids. A new column packing material, SP-1220 (Supelco), was found to give excellent separation of propionic and isobutyric acids as well as demonstrating the presence of formic acid which was not seen with the previously used Resoflex. Extracts of clinical isolates of anaerobic organisms were processed using the altered conditions and new column packing material with excellent resolution of all acids. The use of SP-1220 in the clinical laboratory will facilitate the identification of anaerobic bacteria.