Fingerprinting of the development of aerobic processes of agricultural wastes by on-line combination of liquid chromatography and mass spectrometry

Liquid chromatography (LC) was employed in conjunction to mass spectrometry (MS) to develop a straightforward LC-MS procedure for monitoring the variation of functionalized nonpolar organic compounds during the development of an aerobic composting process of agricultural wastes. The LC separation was performed by a reversed-phase microbore HPLC octadecyl-silica column, which was eluted by a linear acetonitrile gradient in water. The reversed-phase HPLC column was connected online to a triploquadrupole mass spectrometer by an atmospheric pressure ionization interface. Weighed amounts of agricultural wastes sampled at different time intervals during the aerobic composting process were extracted by dichloromethane and analyzed by LC-MS. The resulting fingerprinting offered a means to monitor the variations of functionalized nonpolar compounds during the aerobic process and indicate the presence of compounds that are not degraded by the biotranformation, such as ursolic acid and ?-sitosterol.