Currently samples for reaction chambers or vessels might be sent off to a centralised lab for chemical analyses using HPLC or GC-MS. Another option could be to use surface enhanced Raman scattering, or SERS, a trace analytical technique that can detect small organic molecules to parts-per-billion levels.
“SERS is extremely sensitive. You could swab the inside of a reactor, extract from the swab, and read it directly in a hand-held Raman spectrometer in real time,” says David Eustace, business development manager at Renishaw Diagnostics, part of the FP7 project, PHOTOSENS.
In Raman spectroscopy, laser light is directed onto the sample. The scattered light is collected and processed to produce a Raman spectrum, a unique 'fingerprint', consisting of sharp peaks attributed to the specific molecular vibrations within the target. The sensitivity can be greatly enhanced by placing the sample on a roughened metal surface, usually gold or silver, to give SERS. Current SERS substrates typically consist of patterned silicon chips coated with silver or gold functional layers.
UK company Renishaw Diagnostics took part in the FP7 PHOTOSENS project with the aim of developing a more sensitive SERS substrate and replacing this use of silicon technology with much cheaper nanoimprinting on plastic base layers. “By using roll-to-roll nanoimprinting, hundreds of metres or even kilometres of patterned material can be produced extremely quickly, reducing manufacturing time and massively decreasing cost,” Eustace explains.
The consortium is now seeking industrial partners in the pharmaceutical cleaning verification field, as well as instrumentation partners. “We would really benefit from an established industrial partner who understands intimately the industry’s cleaning verification requirements,” Eustace tells in-Pharmatechnologist. They would help define the requirements of the technique such as sensitivity and specificity and the solvent type that is used.
“Introducing a new analytical technique to a highly regulated industry is challenging given that the current technology is deeply entrenched and approved by notified bodies,” Eustace explains. “That is why the consortium requires an industrial partner who acknowledges the unique advantages of the technique and is prepared to become an early adopter and to help its passage through the regulatory landscape.”
For now, SERS is mainly used in academia for detecting all sorts of material, from cells to explosives to food materials. SERS has also show promise in the detection of markers in fuel to prevent fuel fraud and uncover fuel smuggling. In this use, it has been lauded for its high specificity and sensitivity for fuel markers and a quick, clear and decisive analysis.
The PHOTOSENS project also investigated the use of photonic crystals for environmental sensing.