PROPOSALS FOR A STANDARDIZED SAMPLE HANDLING PROCEDURE FOR THE DETERMINATION OF ELEMENTAL COMPOSITION AND ENTHALPY OF COMBUSTION OF BIOLOGICAL-MATERIAL

A procedure has been developed for the preparation of microbial biomass of standard, defined quality suitable for the determination of elemental composition and enthalpy of combustion. Furthermore methods for the determination of residual moisture and ash content of biomass samples have been established. The results indicate that samples should be prepared in a freeze-dried (lyophilized) state and that residual moisture content should be determined immediately prior to sample preparation for combustion calorimetry and elemental analysis. Results from such analysis should then be related to material which is first freeze- dried and subsequently oven dried (100°C for 24 hours) as reference state. The method outlined here for microbial biomass should prove suitable for biological samples from a wide variety of sources including both pure proteins, fats etc. as well as cells and tissues. © 1990.