Sensitive assay of phospholipid glycerol in environmental samples

Measurement of very low levels of microbial biomass was achieved by determining the glycerol content of the phospholipids from environmental samples. Successive application of acid methanolysis and hydrofluoric acid hydrolysis was used to release glycerol from the phospholipids. The glycerol, once released, was acetylated and analyzed by capillary gas-luquid chromatography (GLC). The analysis was sensitive to 10^?11 moles by GLC waith flame ionization detection and GLC/mass spectrometry with selective ion monitoring. Estimation of the microbial biomass by the lipid phosphate correlated with the glycerol phosphate measured by the hydrolytic procedures. In addition, indication of the community composition was gained by analysis of the acid labile glycerol. Application of this methodology to the sparse of the ground water sediments showed agreement with other estimates of microbial biomass.