Quantification efficiency of the microbial biomass carbon by spectrophotometry assay as compared to the titrimetric method

Abstract

Among the soil quality parameters, the microbial biomass carbon (C_mic) is one of the most used; however, in contrast to the ecological use of this parameter, the analysis process used for C_mic determination has a negative bias with regard to toxic waste generation. Aiming to reduce waste generation in the analytical process, comparative tests were performed between titrimetry and spectrophotometry for the quantification of microbial
carbon from soil samples collected at 0-10 cm and 10-20 cm deep in three soil types with different chemical, physical and management characteristics. Results showed that the C_mic values found by spectrophometry in the three soil types were similar to the values found by titrimetry. When spectrophotometry was used the potassium dichromate concentration was reduced in 42% for the new formulation of the digesting solution. Also, time execution was reduced in 20%, followed by the reduction in the volume of toxic waste generated. According to these results, the spectrophotometry process showed to be environmentally advantageous, besides, it did not differ statistically from the titrimetry method.