A commercially available ceramic material called boron nitride and a £240,000 grant from investment capital group 3i are enabling Banbury startup company Scientific Detectors to develop a universal, low-cost, highly sensitive instrument that can be used to analyse all kinds of liquids including organic compounds.
Industrial lubricants, drugs, foods, plastics and many other compounds depend on the accurate measurement of their contents for their continuing development.
The most widely used instrument is the liquid chromatography mass spectrometer (LCMS). Based on ultraviolet light, detection is highly accurate with a sensitivity of 10-7 (one part in 10 million). But it is also expensive, costing between £100,000 and £250,000.
At 10-10 sensitivity (one part in 10 billion) or better, the Scott Little Detector being developed by Scientific Detectors is at least 1,000 times more sensitive but costs just £20,000.
A drawback of UV detection is that it is not a universal method because it is limited by the solvent used to carry the test sample. Solvents that can be detected by the UV method ‘confuse’ the instrument and cloud the identity of the sample.
In the new instrument argon gas, not UV light, is used in the detection process. The development is based on the argon ionisation principle in which argon, an inert gas, acts as a carrier for the electrically charged ion particles.
Detection is carried out by measuring the current across an argon stream.
Ions are produced by irradiation of boron nitride a commercially available ceramic.
Sensitivity of the instrument is impaired, however, in those cases where the electrical resistance of the ion source (ceramic) is lower than the electrical resistance of the test sample. In that case, the current will ‘track across’ the ceramic and fail to do its detection job.
Scientific Detectors is working on this. The company, which in 1996 won a £45,000 DTI Smart award for the SLD is looking to develop new materials that can be used as the ion source. That will open up the possibility of a truly universal detector.
For fast routine analysis of, say, sulphur in soil samples, the SLD can be converted into a highly specialised instrument using a head attachment.
The Scott Little Detector takes its name from Dr Chris Little, the company’s technical director, and Professor Raymond Scott, leading figures in gas and liquid chromatography.
The global market for such detectors is around £5bn.