Total Organic carbon

TOC (Total Organic Carbon) is the amount of organic carbon found in water, this includes all organic compounds, both dissolved and suspended. These can occur naturally from the flora and fauna living in or beside the water or they can originate from man-made sources such as discharge from factory or a wastewater works.

TOC is normally measured in mg/L or PPM, however in pharma type applications values of PPB are used. 

It is used as an indicator of water quality. It is historically measured using a five-minute combustion test, although other tests do exist. Most TOC techniques measure a combination of both organic and inorganic carbon so additional adjustments have to be made.

See our TOC products

How do you measure Total Organic Carbon

TOC Measurement

TOC (Total Organic Carbon) can be measured in multiple ways  the two most common are a reagent based test or a combustion test.

Reagent based test for TOC

A TOC reagent such as Method 10129
turns the sample a different colour depending on the organic content as the pigmented reagent reacts with the carbon.
A test like this costs around £5 per test  and takes over two hours reaction time once the process begins.

Combustion test for TOC

The combustion test is a simple idea. It involves a high-temperature combustion at 700-1000 °C in an oxygen-rich environment. This converts the organic carbon to Carbon dioxide and it is then passed through cleaning paths to remove interferences. The CO2 is then measured using infrared laser absorption.

This method will give you a result every five or six minutes and the machine cost in the region of £100,000 along with consumables

What is UV254 and how does it save me time and money?

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Ultraviolet transmittance refers to the amount of light that passes through a sample at the wavelength of 254 nm. UV254 absorption can be used as a surrogate measurement of TOC (Total Organic Carbon).  UV254 is absorbed and scattered by the organics, colloids, and suspended solids. UV Absorbance often expressed as A254 or ABS is the light absorbed by a sample giving a TOC value.

The use of UV254 results in reduced capital spend for a TOC analyzer, no consumable chemicals such as Acids or reagents. UV254 is a simple device with no moving parts, and hence little opportunity for down time from mechanical failure.

Compared to the flash test uv254 produces 35 times more results in the same time and for the lab reagent test uv254 is 700 times more results. This gives valuable trend data and detects even short spikes or dips.

A UV254 system is portable and can be easily relocated as needed, giving at a tiny cost per location compared to the flash test systems.

UV254 can act as a complimentary measurement to fill in the six minute gap between the flash measurements detecting spikes and dips.

UV254 is absorbed and scattered by the organics, colloids, and suspended solids. UV Absorbance often expressed as A254 or ABS is the light absorbed by a sample.

UV254 a proven modern measure of TOC   

Learn more about what we do

• Reagent free

• Results in seconds not minutes

• All data stored in excel compatible format

• 10 hours use without recharging

• Modern icon-driven touch screen

• All results come with time and date stamps

•Devices will store calibration for 16 different locations

• Stores over 10 years of results


Lisburn, BT28 2GN, GB

About us

Photonic Measurements is:
Incorporated in N.Ireland (NI622996) 
VAT registered in UK (GB192976846)
VAT registered in N.Ireland (XI192976846000)

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