Total carbon

A variety of different terms are used to identify the different types of carbon present at different levels of detail.

Relationship between carbon types

• Total carbon (TC) – all the carbon in the sample, including both inorganic and organic carbon

• Total inorganic carbon (TIC) – often referred to as inorganic carbon (IC), carbonate, bicarbonate, and dissolved carbon dioxide (CO₂).
• Total organic carbon (TOC) – material derived from decaying vegetation, bacterial growth, and metabolic activities of living organisms or chemicals.

• Volatile organic compounds (VOC) – also referred to as purgeable organic carbon (POC); organic carbon that has been removed from a neutral, or acidified sample by purging with an inert gas. These are usually determined by purge and trap gas chromatography–mass spectrometry.
• Non-purgeable organic carbon (NPOC) – commonly referred to as TOC; organic carbon remaining in an acidified sample after purging the sample with gas.

• Dissolved organic carbon (DOC) – organic carbon remaining in a sample after filtering the sample, typically using a 0.45 micrometer filter.
• Suspended organic carbon – also called particulate organic carbon (POC); the carbon in particulate form that is too large to pass through a filter.

• Elemental carbon (EC) – charcoal, coal, and soot. Resistant to analytical digestion and extraction, EC can be a fraction of either TIC or TOC depending on analytical approach.[1]