![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
R9 Laboratory SOP 550
ANALYSIS OF TOC IN WATER
Summary
This method applies to all water samples, such as drinking water, ground water, reagent water, and waste water. This SOP is based on EPA Method 415.1.
The calibration range is from 2 to 100 mg/L. The range can be extended by diluting the sample prior to analysis. The quantitation limit for total organic carbon is 2 mg/L.
Total carbon (TC) in a sample is oxidized to carbon dioxide (CO2) and water (H2O) by catalytic combustion. The oxygen gas flow that is received in the platinum combustion tube (maintained at 700°C) sweeps the CO2 containing stream through a condenser, into a gas/liquid separator, and through a dehumidifier to remove the H2O completely. The dried CO2 containing gas is then passed through a copper scrubber and to a CO2 specific non-dispersive infrared detector (NDIR) for quantification. Inorganic carbon (IC) in the sample is determined immediately after the TC analysis. The sample is automatically introduced into the IC reactor, which contains an acidic water solution at room temperature. In this acidic environment, all forms of IC are purged out of the solution as CO2 by the continuous flow of the carrier, oxygen gas. The CO2 is dried in the dehumidifier and passes on through the NDIR for quantification. Total organic carbon (TOC) is determined by taking the TC result and subtracting the IC result from it.