Proficiency test sample media for single and mixed pure cultures of water pollution indicator bacteria.

Two transport media, NYSDH-1 and NYSDH-2, were developed for use in a split bacteriological water sample program. The media maintained 88% viability of inoculated organisms for at least 48 h, and the samples do not require special handling or reconstitution. Procedures for preparing and shipping the samples to participating laboratories were developed. A reference set of samples was analyzed in laboratories certified by either New York State or the Environmental Protection Agency. A statistical analysis was performed, and the results indicate that the media are suitable for integration into a laboratory quality control program.