What is TOC Analysis?

TOC stands for total organic carbon and is a measurement used to define the amount of carbon found in an organic compound. Analysis of TOC will measure both the total amount of carbon present in the compound and also the amount of “inorganic carbon”, or IC. IC is comprised of carbon acid salts and dissolved carbon dioxide.

Once the IC is subtracted from the total carbon, the TOC can be found. Alternatively, analysts may choose to artificially remove all of the IC before measuring to ensure that they only gain a figure for the TOC itself. This latter technique actually is more accurately described as determining the amount of non-purgeable organic carbon (NPOC) since the figure is arrived at by purging the acidified sample using nitrogen or carbon-free air.

TOC Analysis and Water Quality Control

The main use of TOC analysis is to determine the quality of drinking water during the purification process to check whether it is safe for humans to imbibe. The TOC found in water can come from two sources: natural organic matter (NOM) and synthetic sources.

TOC has been used an analytical technique for determining water purification levels since the early 70s, but has only really gained widespread popularity in the last decade or so. It has supplanted chemical oxygen demand (COD) analysis and biological oxygen demand (BOD) analysis due to its higher accuracy and efficiency.

Though the technique has been used in waste water treatment for many years, traditionally it has not been compatible with waste water from paper mills, due to frequent instances of machine clogging and the need for cleaning and maintenance. However, an innovative new online TOC analyser has been developed in the Netherlands which has produced improved results in the industry, perhaps heralding a new age for TOC analysis.

Other Uses of TOC Analysis

As well as being an accurate indicator of water cleanliness, TOC levels have also been linked to the growth rates of endotoxins and microbes. As such, TOC analysis has been recommended as a required test for many purification and distribution systems in the biotechnology industry, since the level of biofilms on pipeline walls and within the systems, as well as microbial growth, can apparently be measured using the technique of TOC analysis.

Indeed, many of these systems are integral to the production of medicines for human consumption. Because of this, the US Food and Drug Administration (FDA) use the practice to test for the success of cleaning operations within biotechnological procedures.

Meanwhile, TOC analysis can also be helpful in analysing the amount of organic carbon found in source rock and therefore determining whether or not it is worthwhile to mine it. As a general rule, a minimum of 2% of carbon content is required to sanction a mining operation.