Shimadzu TOC-L

General Information

The Shimadzu TOC-L with autosampler is capable of five different measurements on filtered samples in solution: Total Carbon (TC), Inorganic Carbon (IC), Total Organic Carbon (TOC) , Non-Purgeable Organic Carbon (NPOC), and Total Nitrogen (TN). 
 

Theory of Operation

Total Carbon (TC): The sample is combusted to CO2 in a column filled with a platinum-based oxidation catalyst within a furnace heated to 680C.  The CO2 is entrained in a carrier gas which flows to a non-dispersive infrared gas analyzer. The detector outputs an analog signal in the form of a peak (signal vs. time).  The area of the peak is proportional to the carbon content of the sample and the concentration can be calculated by comparing to a standard solution.

Inorganic Carbon (IC): The sample is introduced into the IC reactor vessel containing phosphoric acid. The IC is converted to CO2 and sparged from the solution. The CO2 is then entrained in a carrier gas which flows to the infrared detector and the signal is detected and analyzed by the same process as for TC.

Total Organic Carbon (TOC): TOC concentration is determined by subtracting the IC concentration from the TC concentration.

Non-Purgeable Organic Carbon (NPOC):  The sample is acidified and sparged with high purity air to eliminating the IC component. The sample, now containing only residual organic carbon, is then analyzed by the same process as for TC.

Total Nitrogen (TN): Total nitrogen is analyzed in conjunction with TC or NPOC. After thermal decomposition in the oxidation column, nitrogen is determined with a chemiluminescence detector.