Abstract: An example method for determining a partial density of a compound in a downhole fluid may comprise exposing the downhole fluid to an electromagnetic radiation, and measuring a spectrum of radiation absorption by the downhole fluid. An absorption peak of the compound may be identified in the measured spectrum. A first parameter indicative of radiation absorption by the downhole fluid may be determined in the identified absorption peak. Second and third parameters indicative of radiation absorptions by the downhole fluid may be determined essentially out of the identified absorption peak. A weighted combination of the second and third parameters may be computed, and the partial density of the compound may be determined from a difference between the weighted combination and the first parameter.