Organic carbon analysis

Our services include the analysis of organic carbon in potable water supplies, waste waters, and saline samples.

Dissolved organic carbon (DOC), biodegradable dissolved organic carbon (BDOC), total organic carbon (TOC) and total carbon (TC) can all be analysed by one of our methods depending on sample type.


Natural organic matter (NOM) present in raw waters can cause problems in drinking water if not removed during the treatment process. Biodegradable Dissolved Organic Carbon (BDOC) represents the fraction of dissolved organic carbon (DOC) that can be mineralised by bacteria. The reduction of BDOC in drinking water is an important part of the water treatment process as even low concentrations are sufficient to support bacterial growth in the distribution system.

Organic Carbon has been recognised as an effective way to measure water quality during the drinking water purification process. Levels of organic carbon also become important during the disinfection process as high levels can lead to disinfection by-products being formed (DBPs).

Treatment plant operators can use our testing results to optimise water treatment processes for removal of BDOC, minimise disinfection requirements and reduce disinfection by-products.

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The limit of reporting is 0.2 mg/L.

The BDOC method measures the amount of organic matter that is biodegraded by a bacterial inoculum. The inoculum is biologically active sand (sand colonised by bacteria) originating from a water treatment plant filter. A 900 mL water sample is inoculated with 300 g of sand and aerated for the duration of the experiment. DOC is measured at the beginning and then approximately every second day until a minimum value is reached (approx. 10 days). BDOC concentration is derived from the difference between the initial and minimum DOC values.

Low Level DOC/TOC - Potable waters and waters with low turbidity.

DOC and TOC in samples with this type of matrix is analysed using the persulphate oxidation method . Limit of reporting for this method is 0.3mg/L , with an upper limit of 20mg/L before dilution. Samples with expected higher levels of DOC or TOC can be analysed by the combustion method.

Low Level Saline DOC/TOC - Seawater samples with low turbidity.

DOC and TOC can be measured in seawater samples by using an especially modified persulphate oxidation method. Limit of reporting for this method is 0.5mg/L, again with an upper limit of 20mg/L before dilution. Seawater samples with high turbidity can be analysed by the combustion method.

High Level DOC/TOC - Waste samples typically with high turbidity.

DOC and TOC can be measured in waste samples and samples with high turbidity by a combustion method. This method offers an increased upper limit and can in fact measure organic carbon up to several thousand mg/L. The limit of reporting is 1mg/L and is an excellent choice when measurement to very low levels is not required. This method is also applicable to seawater samples with high turbidity.

TC – Water samples with low or high turbidity.

TC is measured by the combustion method and has reporting limits identical to the high level DOC/TOC method. TC is a useful parameter to measure because if the TOC is also known the inorganic carbon (IC) in a sample can also be calculated.

Sample container
355mL plastic (PT355)

PT355 - none - none - no air gap, ice

Analytes & holding times
All water types
***Dissolved organic carbon, total organic carbon (ASAP)
***Total carbon (ASAP)
***Glyphosate (ASAP)
***Formation potential of THM and HAA (ASAP)

Sampling requirementsNo air gap

Storage and preservation
Iced or chilled to 4°C.
No preservative