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Carbon - Total Organic (TOC)

Category Environmental Chemistry Lab Services
Test Carbon - Total Organic (TOC)
Description

SCOPE AND APPLICATION

Method 9060 is used to determine the concentration of organic carbon in ground water, surface and saline waters, and domestic and industrial wastes. Some restrictions are noted in Sections 2.0 and 3.0.

Method 9060 is most applicable to measurement of organic carbon above 1 mg/L.

SUMMARY OF METHOD

Organic carbon is measured using a carbonaceous analyzer. This instrument converts the organic carbon in a sample to carbon dioxide (CO2) by either catalytic combustion or wet chemical oxidation. The CO2 formed is then either measured directly by an infrared detector or converted to methane (CH4) and measured by a flame ionization detector. The amount of CO2 or CH 4 in a sample is directly proportional to the concentration of carbonaceous material in the sample.

Carbonaceous analyzers are capable of measuring all forms of carbon in a sample. However, because of various properties of carbon-containing compounds in liquid samples, the manner of preliminary sample treatment as well as the instrument settings will determine which forms of carbon are actually measured. The forms of carbon that can be measured by Method 9060 are:

Soluble, nonvolatile organic carbon: e.g., natural sugars.

Soluble, volatile organic carbon: e.g., mercaptans, alkanes, low molecular weight alcohols.

Insoluble, partially volatile carbon: e.g., low molecular weight oils.

Insoluble, particulate carbonaceous materials: e.g., cellulose fibers.

Soluble or insoluble carbonaceous materials adsorbed or entrapped on insoluble inorganic suspended matter: e.g., oily matter adsorbed on silt particles.

Carbonate and bicarbonate are inorganic forms of carbon and must be separated from the total organic carbon value. Depending on the instrument manufacturer's instructions, this separation can be accomplished by either a simple mathematical subtraction, or by removing the carbonate and bicarbonate by converting them to CO2 with degassing prior to analysis.