Total Organic Carbon TOC is a Rapid method that assesses for organic carbon and expresses the result as the amount of carbon discovered. It is a non-prescription method not able to differentiate between different organic species and only suggesting that organic carbon substances are found. Organic carbon analyzers function by the determination of the amount of total carbon present in a sample aliquot. Total carbon contains organic and inorganic carbon. The carbon dioxide, present as carbonate or bicarbonate ions, must be eliminated or quantified before the analysis of organic carbon. When the inorganic carbon is removed, following analysis of the sample aliquot supposes that all carbon staying is organic.
Methodology used to remove Inorganic carbon is based on acidification that converts all bicarbonate and carbonate ions into carbon dioxide that is then purged from the sample having an inert gas. If quantification of inorganic carbon is wanted it is purged to a sensor, otherwise, it is vented to atmosphere. When the inorganic carbon is removed the remaining organic carbon is oxidized to carbon dioxide that is purged from the inert gas to the sensor.
Carbon Measurement Techniques
In about 1630 a Flemish Scientist, Jan Baptista van Helmont identified a gas given off from the burning of wood as carbon dioxide. He also noted that air is a mix of gases. In 1756, Joseph Black, demonstrated that carbon dioxide happened in natural air and may be created from different compounds. In his study on magnesium carbonates Black devised the analytical balance and used it to measure carbon dioxide by Loss on Ignition LOI. The LOI evaluation, where samples are heated and decrease in mass is measured, is the first quantitative test for carbon.
Organic matter in soil has been traditionally measured by LOI or chemical oxidation using dichromate solution. The dichromate, present as Paper Chromatography chromium, reacts with decreasing organic carbon in acid solution to form trivalent chromium. Titration of the unused hexavalent chromium with ferrous iron yields a method capable of estimating the organic carbon present in a sample.
A coal or steel sample can be Put in a furnace, or heated tube, and in the presence of oxygen that the carbon melts into carbon dioxide. The carbon dioxide can be collected and measured, or it may be set by means of a carbon dioxide specific sensor. In 1924, T. D. Yenson of the Westinghouse Electric and Manufacturing Company patented a measuring apparatus that put steel samples in a horizontal 1000C furnace which combusted carbon within an aviation gas and accumulated the CO2 cryogenically.
