Abstract: A method and apparatus for preparing uniform carbon-13 labeled biomass using a water soluble carbon-13 labeled carbon source, such as a [13C]-bicarbonate or [13C]-carbonate salt, is disclosed. The biomass is prepared in one or more sterile carboys filled with growth medium, in which acidity, oxygen, and biomass density are carefully monitored and maintained. By using a solid, water-soluble [13C]-bicarbonate or [13C]-carbonate salt as the sole carbon source, a biomass is provided which is uniformly and efficiently labeled with carbon-13. This method and apparatus is particularly useful for the growth of an edible carbon-13 labeled algal mass, with Spirulina platensis being a specific alga species. The biomass may be prepared in conformance with FDA current good manufacturing practice regulations, and may be harvested and formed into lyophilized bulk drug powder which may be further processed into various drug product forms which are useful for diagnostic tests or in pharmaceutical compositions.

Abstract: A method and apparatus for preparing uniform carbon-13 labeled biomass using a water soluble carbon-13 labeled carbon source, such as a [13C]-bicarbonate or [13C]-carbonate salt, is disclosed. The biomass is prepared in one or more sterile carboys filled with growth medium, in which acidity, oxygen, and biomass density are carefully monitored and maintained. By using a solid, water-soluble [13C]-bicarbonate or [13C]-carbonate salt as the sole carbon source, a biomass is provided which is uniformly and efficiently labeled with carbon-13. This method and apparatus is particularly useful for the growth of an edible carbon-13 labeled algal mass, with Spirulina platensis being a specific alga species.