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Total organic carbon analyser

21st February 2013


Total organic carbon analysis (TOC) is vitally important in applications ranging from power generation, wastewater, drinking water, surface water and ultrapure water, to agricultural soils, contaminated land and food.

A typical analysis for TOC measures both the total carbon present as well as the inorganic carbon. This method has traditionally been the preferred analytical technique to measure water quality during the purification process.

COD (Chemical Oxygen Demand) is the total measurement of all chemicals in the water that can be oxidised. BOD (Biochemical Oxygen Demand) is a longer method designed to measure the amount of material (or organic carbons) that bacteria can oxidise.

Although closely related to both BOD and COD analysis, TOC is important in its own right because it is the sole analytical method able to quantify only those species that contain carbon. For this reason TOC is a parameter that is required by regulations in many industries, for example, as a waste acceptance criterion of hazardous waste TOC analysis is now compulsory. It also provides a number of key benefits over BOD and COD including a significantly improved analysis speed and higher accuracy.

The Hache-Lange IL550 can also be used for the determination of dissolved organic carbon (DOC) as well as total organic carbon (TOC) in sewage, river, landfill leachates, effluents and groundwater samples. Subsequently, it has proved to be an important addition for HACH LANGE customers including the Environment Agency’s National Laboratory Services (NLS), South West Water and laboratory testing services company Chemtest.

At the NLS, much of the analytical work is for regulatory purposes, so it is vitally important that fast, accurate, reliable results are produced. Richard Yates, Inorganic Analysis Team Leader at the NLS, said: “The high calibration range of the IL550 reduces the number of over-range repeat analyses we have to perform, thereby saving valuable lab time and improving the sampling process. In addition, the instrument is very easy to use and meets our required limit of detection.”

Tracy Churchill, Senior Assistant Scientist for South West Water, also praised the benefits of the IL500. She explained: “The IL 550 software is very user-friendly, making it easy to train analysts. Additionally, and most importantly, because the analyser has a ‘stand-by’ mode we are able to leave the instrument on at a reduced temperature, which prolongs the life of the catalyst. As a result of these features we have significantly reduced downtime and maintenance costs, because previously we had to replace the catalyst on a fairly regular basis. We are delighted with the TOC-TN analyser and the results it is producing.”

The IL550 has also helped Chemtest save significant time and costs over the past year. Laboratory manager Darrell Hall said: “We have found the IL550 more reliable than the previous methods we used for TOC analysis on water and leachates samples and in general it has made the lab analysis process much more efficient.”

A key feature of the IL550 is particle tolerance in liquids. The autosampler needle has a large internal diameter and the sample is injected directly via the pneumatic port into the furnace – this eliminates blockages, cross-contamination or leaks because there is no septum or valve.  This also removes the need to filter waste water samples because the IL550 measures the TOC of both liquid and solid particulates in a sample. Samples are also stirred prior to injection to ensure homogeneity.

With the IL550, digestion takes place at up to 950 Deg C and the solids module is able to increase the temperature to an unrivalled 1300 Deg C. The UV version is equipped with a high-energy UV lamp, which offers the advantage of direct contact with the sample.

For more information, www.hach-lange.co.uk








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