Talk:Total organic carbon

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Untitled

How can a molecule (CO2) be measured if it has been atomised?Piyrwq 22:16, 16 August 2005 (UTC)[reply]

No current mention of CO2 being atomised Rich257 21:17, 14 September 2006 (UTC)[reply]

Previous See Also Section

'See Also' used to contain the text: "Standard Method 5310, Disinfection by-Product Rule (DBR), US Pharmacopiea Chapter 643, ASTM D5997, ASTM D5904, ASTM D6317" that I have removed as they are not Wikipedia topics and I don't have the domain knowledge to find suitable references.Rich257 21:17, 14 September 2006 (UTC)[reply]

Online or in-process TOC measurement

Measuring TOC in a process environment is more difficult and complex then a laboratory situation. The big amount of salts, unknown components, solid parts, and waste create a situation that will need an awsome lot of maintenance and care. Using the regular ways of measuring TOC f.e. combusting the liquid with high temperature catalyst will cause you a lot of energy in a weekly base.

The only way you can measure the in process waters/ solutions in a proper way is by using a wet chemical reaction more agressive in a solid controlled system. The Biotector system provided by a company named Ankersmid-M&C products is a unique system that uses a robust and controlled system that needs only a refill every 1/2year!

The standard procedure for TOC measurement has as its first step the removal of all inorganic carbons (IC), leaving only the organic carbons (OC) in the sample. This is normally achieved by lowering the pH in the sample and using a stripper gas to remove the carbon dioxide (CO2) that is formed.

Normally, the BioTector uses sulphuric acid (H2SO4) to remove the IC. Sulphuric acid, however, reacts with calcium to form gypsum (CaSO4), which builds up into a stone hard sediment within the analyzer. To avoid this, for the Shell application the BioTector uses hydrochloric acid (HCl).

High concentrations of salts and the use of hydrochloric acid combine to create a highly agressive environment. To avoid corrosion of the stainless steel reactor standard in the BioTector, a new reactor made of teflon® PFA (per fluor alkoxy) was specially developed for Shell and is now commercially available as an optional feature of the BioTector.

The BioTector was further fitted with an air purge system and certified for EExp Zone 2 use as it was to be installed in a hazardous area.

More information of flowpath, principle and reaction can be provided by Ankersmid-M&C products.

http://www.mc-products.com/AF/application.biotector.On.Line.TOC.analysis/ —Preceding unsigned comment added by 217.136.59.50 (talk) 10:21, 27 March 2009 (UTC)[reply]

Elemental Carbon (EC)

This article needs to be improved to address the role of EC in TOC analysis. Depending on POV, TOC (soil and sediments) either excludes EC (charcoal, soot) content, tallying it as equivalent to inorganic C (Lal 2007), or TOC includes EC (Schmidt 2001). The issue is important because the EC pool in soil and sediments ranges from 5-50% of the OC pool. I will continue to delve into this area, with the intent of editing this article once I have come up with the best sources. Here is my current progress

In soils and sediments, there are three basic forms of carbon that may be present. They are: (1) elemental C, (2) inorganic C, and (3) organic C. (page 1 of Schumacher, 2002) NCEA-C- 1282 EMASC-001 April 2002 Methods for the Determination of Total Organic Carbon (TOC) in Soils and Sediments Brian A. Schumacher, Ph.D. United States Environmental Protection Agency Environmental Sciences Division National Exposure Research Laboratory P.O. Box 93478 Las Vegas. Found it here

The EC pool is either 1) outside the OC pool as implied by Lal 2007 or 2) inside the OC pool as implied by folks citing Schmidt 2001. The Schmidt-attributed phrasing Biomass-derived black C comprises a substantial component (5–50%) of organic C in some soils has been widely distributed. Examples in chronological order Laird 2010 powerpoint, no cite,Dungait 2012,2013,2015. I need to reconcile these opposing perspectives before I engage in editing the article.

---The SIC pool includes elemental C and carbonate minerals, page 4, Lal, R. 2007. C management in agricultural soils. Mitigation and Adaption Strategies for Global Change. 12:303-322. here (Note added 1/16/16: Lal says elsewhere in this reference that TOC includes charcoal. I can add that early wet chemistry approaches when I was young

---(added later: Schmidt 2001 doesn't specifies EC as within OC, nor does it specify the 5-50% amount. however this appears to be the consensus interpretation of the data by those citing it as their source.) Schmidt, M.W.I., Skjemstad, J.O., Czimczik, C.I., Glaser, B., Prentice, K.M., Gelinas, Y., Kuhlbusch, T.A.J. 2001. Comparative analysis of black C in soils. Global Biogeochemical Cycles. 15:163-168. here I will admit to being confused by the disconnect, not sure I can reconcile this very quickly. any thoughts? -- Paleorthid (talk) 17:36, 15 January 2016 (UTC)[reply]

Done. I posted "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" under "Measurement" which is currently under Total_organic_carbon#Pharmaceutical. Supporting the either/or view, Lal 2007 indicates that TOC includes charcoal, at the same time as Lal 2007 indicates EC is part of TIC. This makes sense in my experience. I observed the use of the Walkley-Black Method, an early wet chemistry TOC approach that did not use heated digestion, and did not pick up the soil charcoal fraction. I was given to understand that there was value in excluding EC from TOC in terms of comparative evaluation and in soil types based on organic carbon levels. The concern was that fire history would introduce anomalous variation into the data. This was in the early 1970s. I have not researched yet how that attitude relates to current soil map unit characterization in the USA, but my curiosity is piqued. -- Paleorthid (talk) 21:17, 16 January 2016 (UTC)[reply]

Suggested Split into Total Organic Carbon and Total Carbon

A content split is suggested to avoid confusion. Some of the discussion in the middle of the article appear relevant to a discussion of total carbon.

Total Carbon is different from Carbon because Total Carbon is an analytical measurement. Carbon is an element.

Relation between TOC and Conductivity

since the TOC analyser is under maintenance, conductivity measurement con be used with limit NMT 1.3 µS/cm for 500 ppb TOC as substitute method of analysis and limit for Purified water. — Preceding unsigned comment added by 103.59.213.2 (talk) 10:23, 30 May 2019 (UTC)[reply]