Top of the TOCs
Total Organic Carbon (TOC) is a key parameter in ultrapure water for trace organic analysis and life science applications, such as molecular biology, PCR and DNA sequencing. Among the effects that trace organics can cause are:
• poor detection limits;
• poor reproducibility;
• coating of reactive surfaces;
• chemical interference and;
• cell toxicity;
For this reason TOC concentrations in laboratory water are often specified at very low levels: typically less than 5mg/l or even less than 2mg/l depending on use. The Elga LabWater Purelab Ultra meets these specifications, and registers that the target has been met.
To meet the specified limits the TOC monitor must be able to provide a good indication of the organic carbon level in the water being dispensed and ensure that any breakthrough of organics is detected before the water is used. For this reason, the Purelab Ultra Analytic and Genetic models come equipped with a full flow real-time in-line TOC analyser.
ELGA LabWater's r&d manager, Dr Paul Whitehead, has produced a guide to TOC measurement called: 'Why Monitor TOC in Ultrapure Water for Laboratories?', in which he explores the meaning of TOC and the value of its measurement.
Burkert Fluid Control Systems has supplied high purity control valves for the latest Purelab purification system. Burkert sensors and solenoid valves are used to control all the automated sequences in the water purification system, including water flow and recirculation, auto rinsing procedures, sanitisation operations and isolation from the feedwater. They also control the dispensing of purified water into a wide range of containers.
Because ultra-pure water is a very aggressive solvent, the selection of materials is crucial. 'Our specification included valve bodies made from inert materials and dry armatures designed with minimum hide-out areas where bacteria can grow,' said Alan Mortimer, Elga's r&d director.
'To ensure the precision control of the flow rate and recirculation, we needed a multi-valve manifold system, which Burkert manufactured specifically for the Purelab Ultra.'