Teledyne 6750 operating instructions Conclusion

Total Organic Carbon Analyzer Theory of Operation

(sparges) the CO2 converted from the TIC and it is measured by an independent CO2 detector as “TIC”. POC is also stripped from the sample in the sparger as HC, but the HC is undetected by the CO2 detector and does not interfere with the TIC measurement.

A portion of the same sample is also directed to the oxidation

reactor, where inorganic and all organic carbon is converted to CO2 and detected by a second CO2 detector as “Total Carbon”.

A mathematical subtraction of the TIC from the TC measurement yields a complete, Total Organic Carbon analysis performed as a “TOC- True” method.

TOC - True = TC - TIC

The difference between the Model 6750’s TOC-True Method and other simple (TC-TIC) subtraction methods is that most other simple TC-TIC subtraction methods only deal with a TC measurement, then a separate TIC measurement and a simple mathematical difference to derive a “TOC” analysis.

In the TOC-True method used by the Model 6750, the analyzer actually performs both TC and TIC measurements simultaneously and continuously on the same sample. The TOC Measurement Basics and Methods are illustrated in Figures 2-3 and 2-4.

In conclusion:

1.NPOC is the preferred method if no POC/VOC is present in the sample.

2.TOC-True is the preferred method if POC/VOC exists in the sample and a TOC analysis is desired which includes all organic carbon species, for a TOTAL Organic Carbon measurement.

Teledyne Analytical Instruments 7