A procedure has been developed for the prepn. of microbial biomass of std., defined quality suitable for the detn. of elemental compn. and enthalpy of combustion. Furthermore methods for the detn. of residual moisture and ash content of biomass samples have been established. The results indicate that samples should be prepd. in a freeze-dried (lyophilized) state and that residual moisture content should be detd. immediately prior to sample prepn. for combustion calorimetry and elemental anal. Results from such anal. should then be related to material which is first freeze-dried and subsequently oven dried (100 Deg for 24 h) as ref. state. The method outlined here for microbial biomass should prove suitable for biol. samples from a wide variety of sources including both pure proteins, fats, etc. as well as cells and tissues. [on SciFinder (R)]