Accurate and reliable determination of Total Organic Carbon (TOC) concentrations in mineral soils or sediments can be challenging. Established techniques for TOC determination use temperatures above 900 °C with prior acidification in order to remove inorganic carbon containing compounds and to achieve consistent analysis results. This method is not only time-consuming since it requires a lot of manual work, but also exposes the operator and the analyzer to dangerous acids with obvious implications. In addition, the use of acid increases the blank value and impacts detection limits and reproducibility.
Temperature-dependent TOC determination as an alternative method to the pre-acidifaction step has been discussed for some time since most inorganic carbon compounds only need combustion temperatures > 600 °C to be completely decomposed. To validate the application of a temperature ramping method in soil analysis, comparison carbon measurements have been made for five different ground soils
The results (please see Application Note below for details) show that carbon determination by ramping to 600 °C performed with Elementar's soli TOC cube can be considered equivalent to the analysis of acidified soil samples combusted at 900 °C. Without the necessity of prior acidification, the workflow of soil analysis at 600 °C is significantly reduced, allowing unattended overnight operation and therefore an increased number of samples that can be analyzed in a 24-hour period.
For more details, please download our Application Note "TOC determination in soils at 600 °C with the soli TOC cube" by clicking on the link below and learn how to perform fast and reliable TOC analysis without pre-acidification.