The Hach Lange COD test follows the ISO 15705 standard method exactly, with all reagents supplied ready-to-use, in precisely the correct amounts in a small cuvette
Alcontrol Laboratories has awarded a major contract to Hach Lange for a five-year supply of COD tests.
Alcontrol's Andrew Timms anticipates that this could represent up to half a million tests over the entire contract, adding: "We receive samples from all over the UK; these are sent by our own staff and from a wide variety of customers including water companies, waste management companies and consultants.
"Highly accurate results must be produced quickly and in our view the Hach Lange products enable us to provide the best possible service to our customers".
COD (chemical oxygen demand) is a measure of organic pollution in wastewater, and is the most frequently mentioned parameter in European legislation.
The Hach Lange COD test follows the ISO 15705 standard method exactly, with all reagents supplied ready-to-use, in precisely the correct amounts in a small cuvette.
To perform a test, users simply add a water sample to a cuvette and leave it in a heater for two hours.
At the end of this period the intensity of colour in the solution is directly related to the COD value in the sample, and can be measured quickly and easily in a spectrophotometer.
Alcontrol operates a number of Xion 500 spectrophotometers from its laboratory in Rotherham.
These instruments offer a number of significant advantages over the company's previous COD analysis equipment.
In the past, samples would be prepared and digested in open tubes and the resultant liquor would undergo a titration in order to determine the COD value.
This process was labour intensive, potentially hazardous and presented opportunity for human error.
However, the Hach Lange cuvettes are delivered containing precise quantities of analytical chemicals.
A wide variety of tests are available but each tube is bar-coded to avoid any potential error.
The spectrophotometer automatically recognises each tube and selects the appropriate wavelength (between 340nm and 900nm) for measurement.
A ten-fold rotational measurement and automatic control of electronic and optical systems ensure high levels of accuracy and repeatability.
Up to 2500 results can be stored onboard each instrument, but in Alcontrol's Rotherham laboratory the spectrophotometers are connected directly to the laboratory's Lims so that Alcontrol's customers are able to receive their results as quickly as possible.
Alcontrol continuously evaluates other COD products, but as Andrew Timms says: " I have tried most of them and in my view nobody does COD as well as Hach Lange".
