Total Organic Carbon Analyzer (Combustion)
Shimadzu TOC-L Analyzer with Autosampler
This is 680 oC Combustion Catalytic Oxidation system with NDIR Detection Method, equipped with combustion tube for High Salt Samples.
- Measured Items: TC, IC, TOC=TC-IC, NPOC (TOC measurement via acidification and sparging).
- Concentration range: TC: 0-30,000 mg/L, IC: 0-35,000 mg/L
DEFINITIONS/ABBREVIATIONS
TC - Total Carbon
Defined as all carbon in a sample, including inorganic, organic, and volatile carbon, as
they may be present. TC is reported in terms of total mass of carbon per unit of sample
(mg C/L, etc.).
TC = TOC + IC
IC - Inorganic Carbon
Defined as that carbon in a sample, which is converted to carbon dioxide after
acidification of the sample. IC includes all dissolved carbon dioxide, bicarbonate, and
carbonate species and is reported in terms of total mass of carbon per unit of sample (mg
C/L, etc.).
IC = TC - TOC
TOC - Total Organic Carbon
Generally defined as that carbon in organic compounds which is converted to carbon
dioxide by oxidation, after inorganic carbon has been removed or subtracted. Although
TOC in water samples should ideally include carbon in volatile materials, most
laboratories report TOC analyses of samples in which volatiles have been previously
removed.
TOC = TC – IC (difference)
TOC = NPOC + POC (sum)
POC - Purgeable Organic Carbon
Defined as that organic carbon (volatile and semivolatile materials) which is purged from
solution by a stream of gas under a specific set of purging conditions. Specific conditions
have not yet been standardized in the scientific literature. POC is generally less than 1%
of TC in a sample.
NPOC - Non-Purgeable Organic Carbon
Defined as that organic carbon, which remains in solution after a sample has been purged
by a stream of gas under a specific set of purging conditions. NPOC is often reported as
TOC due to popular methods, which require acidification and purging of TIC prior to
oxidation of organics. This substitution is valid for samples containing negligible volatile
or purgeable organic compounds.
DOC - Dissolved Organic Carbon
Defined as that organic carbon which is determined by analysis of aqueous samples,
which have been filtered through 0.45-micron filters. DOC is reported in terms of total
mass of carbon per unit of sample (mg C/L, etc.).
SOC - Suspended Organic Carbon
Defined as that organic carbon which is determined by analysis of particles captured by
filtration of aqueous samples through 0.45 micron filters. SOC is sometimes called
Particulate Organic Carbon (POC) especially in the marine chemistry literature. It is
reported in terms of total mass of carbon and referred to as SOC.
ppm C - parts per million Carbon
Defined as mass units of carbon per million sample mass units (μg C/g). In aqueous
samples this is generally taken to be the same as mg C/L.
ppb C – parts per billion Carbon
Defined as mass units of carbon per billion sample mass units (ng/g). In aqueous samples
this is generally taken to be the same as μg C/L.
Standard
Defined as any sample to which a known amount of carbon has been added.
SUMMARY OF METHOD
Analyzing TC
The TC of a sample is burned in the combustion tube containing oxidation catalyst
(680oC) to form carbon dioxide. Formed carbon dioxide detected by non-dispersive
infrared (NDIR) gas analyzer.
Analyzing IC
The first step in analyzing IC in liquid samples is acidification with HCl to pH 3 or lower.
The acidification converts carbonates and bicarbonates to carbon dioxide, which is then
removed along with dissolved CO2 by the gas stream and measured to provide an IC
value.
Carrier gas, acid