What is Total Organic Carbon?

Water purity is essential for a number of different industries, including pharmaceutical manufacturers and power generators. Bacteria and other organic compounds could be a sign of filtration failure or a storage problem. If left unfiltered, these compounds could cause significant issues, including damaging expensive equipment, impacting product quality and threatening profitability.

But how can you ensure the cleanliness or water and optimise wastewater treatment? While there are many ways you can check water quality, the most commonly used procedure is to monitor Total Organic Carbon (TOC) levels to help protect consumers, industries and the environment.

Monitoring water quality

TOC is a measure of the total amount of carbon in organic compounds, or contaminants, found in a liquid. Most often, it is used to measure water quality or cleanliness of pharmaceutical manufacturing equipment. By using TOC analysis, companies are able to check that the water they are using is pure enough for their process.

No matter how pure, all water contains some level of carbon material. Whether the contaminants come from the water source, purification systems or production workers, you’ll always find some level of organic carbon in water. TOC analysis helps to reduce risk of impure water being used for processes in which water quality is of high importance.

How does TOC work?

There are three key parts of TOC analysis – sampling, oxidation and detection. In order to determine the level of TOC in a liquid, any organic compounds must first be oxidised. This is done in a number of different ways, the most common being:

• High-temperature combustion – involves mixing water sample with oxidation catalyst in a heated chamber in order to convert organics to carbon dioxide
• Photocatalytic oxidation – uses UV light to convert organics to carbon dioxide
• Chemical oxidation – combines UV light with Persulfate to convert organics to carbon dioxide

While all three methods generate similar results, studies have suggested that chemical oxidation, especially when combined with a heated chamber, produces the most accurate results the quickest.

Once the organic compounds have been oxidised, TOC analysis uses a detection system to generate a result. The two main types of detection system are non-dispersive infrared (NDIR) and conductivity detectors (direct and membrane). Again, both systems can be used to produce similar results, but NDIRs are more popular as conductivity detectors can be susceptible to external interference and are not as stable.