Dear Suliman

There are huge texts that you can refer to their for your answer.

I included some of them:

Measurement of DOC Concentration

Before DOC analysis the samples need filtration. The most commonly used pore

size is 0.45 pm, but 0.2 pm and 0.7 pm are also common. Membrane filters are most

commonly used, but syringe filters may be more convenient if small amounts of

water are being filtered. Different kinds of filters are used, but cellulose acetate filters

are probably most common. Most important is that the filters do not release any

DOC during filtration. Samples from the mineral soil collected with tension lysimeters

and samples from stream water may not always need filtering, but this needs

to be evaluated for each site.

174 R. Kolka et al.

Numerous analyzers exist on the market, most of which are termed TOC analyzers.

Measurement of DOC entails removing inorganic carbon with acid, sparging the

resultant CO, and oxidizing the remaining C (presumably all OC) and measuring

the CO, generated by the oxidation process. Oxidation of DOC can be accomplished

by combustion, UV persulfate oxidation, ozone, or through UV fluorescence.

Good reviews of the analytical methods can be found in Bolan et al. (1996) and

Doyle et al. (2004).

http://www.nrs.fs.fed.us/pubs/jrnl/2008/nrs_2008_kolka_001.pdf

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Dissolved organic carbon (DOC) and dissolved

nitrogen (DNt) concentrations were measured in

solutions obtained after extraction with borate

buffer (pH = 7). The extraction was done using

the soil sample to extractant ratio of 1:10 over

1 h. DOC and DNt content were assayed with

the TOCN Formacs autoanalyser (Skalar, Breda,

Holland).

http://www.agriculturejournals.cz/publicFiles/50518.pdf

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How Is DOC Measured?

Dissolved organic carbon can be measured via several different techniques. High temperature combustion and UV/persulfate oxidation methods are discussed in detail below, but both methods share the same sample preparation protocol:

The sample is collected in a glass container that has been baked in the laboratory at 550° C for 2-4 hours (the baking process removes any residual carbon in or on the collection vessel that may cause contamination).

The sample is then filtered with a glass filtration device. Commonly used filters include glass fiber filters (GF/F), silver membrane filters, or a nitrocellulose/polypro filters and range between 0.7-0.25 um in pore size. The nitrocellulose/polypro filters are the least expensive of these filters, but may leach DOC, so they should be cleaned by passing deionized water through them before collection.

Once collected, samples should be stored cold (e.g. in the refrigerator or on ice) until they can be processed. They should be processes as soon as possible to prevent post-filtering sample alteration.

Measuring DOC By High Temperature Combustion:

The high temperature combustion method for measuring DOC involves conversion of inorganic carbon to dissolved CO2, and purging this from the sample. The remaining (organic) carbon is then oxidized at a high temperature to CO2 which can be detected by the instrument's nondispersive infrared (NDIR) sensor and directly correlated to total organic carbon (TOC) content.

Measuring DOC By UV/Persulfate Oxidation:

This method combines the sample with an acid, lowering the sample pH to 2.0. This process converts inorganic carbon to dissolved CO2, which is then purged from the sample. A persulfate reagent is then added to the sample and the remaining carbon is oxidized by UV radiation to form CO2, which can be detected by the NDIR sensor and directly correlated to total organic carbon (TOC) content.

http://serc.carleton.edu/microbelife/research_methods/biogeochemical/organic_carbon.html

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PDF IconView Actual EPA Method 415.3 (PDF File)

EPA Method 415.3:

Dissolved and Total Organic Carbon and UV Absorbance at 254 nm in Source Water and Drinking Water. Official Name: Determination of Total Organic Carbon and Specific UV Absorbance at 254 nm in Source Water and Drinking Water

Summary:

TOC is determined by removing inorganic carbon, oxidizing the remaining carbon to carbon dioxide using combustion or chemical oxidation with persulfate, and measuring the carbon dioxide produced using a conductivity detector or nondispersive infrared detector. DOC is determined similarly to TOC, but the sample is filtered through a 0.45 um filter prior to oxidation.UVA is measured by filtering a sample with a 0.45 um filter and measuring absorbance at 254 nm. SUVA is calculated by dividing UVA by DOC and multiplying by an appropriate unit correction factor as described in Section 12.2 of the method.

Scope:

This method provides procedures for the determination of total organic carbon (TOC), dissolved organic carbon (DOC), and UV absorption at 254 nm (UVA), and Specific UV Absorbance (SUVA) in source waters and drinking waters.

Citation:

EPA Web site for Analytical Methods for Drinking Water

http://www.caslab.com/EPA-Method-415_3/

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METHOD 415.3 - MEASUREMENT OF TOTAL ORGANIC CARBON, DISSOLVED ORGANIC CARBON AND SPECIFIC UV ABSORBANCE AT 254 NM IN SOURCE WATER AND DRINKING WATER

Contact

NERLScience

email: [email protected]

Citation:

Potter, B B. AND J. C. Wimsatt. METHOD 415.3 - MEASUREMENT OF TOTAL ORGANIC CARBON, DISSOLVED ORGANIC CARBON AND SPECIFIC UV ABSORBANCE AT 254 NM IN SOURCE WATER AND DRINKING WATER. U.S. Environmental Protection Agency, Washington, DC, 2005.

Description:

2.0 SUMMARY OF METHOD

2.1 In both TOC and DOC determinations, organic carbon in the water sample is oxidized to form carbon dioxide (CO2), which is then measured by a detection system. There are two different approaches for the oxidation of organic carbon in water samples to carbon dioxide gas: (a) combustion in an oxidizing gas and (b) UV promoted or heat catalized chemical oxidation with a persulfate solution. Carbon dioxide, which is released from the oxidized sample, is detected by a conductivity detector or by a nondispersive infrared (NDIR) detector. Instruments using any combination of the above technologies may be used in this method.

2.2. Setteable solids and floating matter may cause plugging of valves, tubing, and the injection needle port. The TOC procedure allows the removal of settleable solids and floating matter. The suspended matter is considered part of the sample. The resulting water sample is then considered a close approximation of the original whole water sample for the purpose of TOC measurement.

2.3. The DOC procedure requires that the sample be passed through a 0.45 um filter prior to analysis.

2.4. The TOC and DOC procedures require that all inorganic carbon be removed from the sample before the sample is analyzed for organic carbon content. If the inorganic carbon (IC) is not completely removed, significant error will occur. The inorganic carbon interference is removed by converting the mineralized IC to CO2 by acidification and sparging with an inert gas to remove the generated CO2. The sample, which is now free from IC interference, is then injected into a TOC instrument system. The orgnaic carbon is oxidized to CO2 which is released from the sample, detected, and repoted as mg/L or ppm TOC or DOC.

2.5. The UVA procedure requires that the sample be passed through a 0.45 um filter and transferred to quartz cell. It is then placed in a spectrophotometer to measure the UV absorbance at 254 nm and reported in cm -1.

2.6. The SUVA procedure requires both the DOC and UVA measurement. The SUVA is then calculated by dividing the UV absorbance of the sample (in cm -1) by the DOC of the sample (in mg/L) and then multiplying by 100 cm/M. SUVA is reported in units of L/mg-M. The formula for the SUVA may be found in Section 12.2.

....

http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=103917

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Background paper

Dissolved organic carbon methods: a critical review

Peter J. Wangersky

Department of Oceanography, Dalhousie University, Halifax, N.S. B3H 4J1, Canada

Received 8 July 1991, Accepted 4 January 1992, Available online 15 April 2003

in:

http://dx.doi.org/10.1016/0304-4203(93)90106-X

http://www.sciencedirect.com/science/article/pii/030442039390106X

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Thank you All

Dear Suliman

I have added one link for DOC analysis of amended soils may also help for some extent

Dowson et al, 2007. Application of biological indicators to assess recovery of hydrocarbon impacted soils. Soil Biology & Biochemistry, 39, 164–177

Also go through Steenberger et al., 2005. environmental science and technology 39 (15), 5694-5702) will be helpful. Thanks

quivk way, extract it based on the extract ratiom filter it thorugh 0.45 micron, run it under TOC

Thanks

thank you all for your valuable suggestions, 

let me study thses papers .