Development of an automated on-line analysis system using flow injection, ultrasound filtration and CCD detection

The design and construction of an automated on-line analysis system is described with reference to applications in bioprocess control, clinical, and environmental analysis. The new system is built around three main elements: ultrasound filtration, a micro flow injection analysis (FIA) system, and direct readout spectrophotometry. The advantages of three on-line ultrasound filtration devices, developed for clarification of water, human blood and mammalian cell culture samples, are described. The filters avoid off-line centrifugation and do not suffer from the blockage problems associated with conventional filters. The separation efficiency of the ultrasound filters is also discussed. The delivery system is based on a gas driven FIA technique, using helium to avoid bubble formation, with the carrier and reagent flow being controlled by computer switched solenoid valves. Direct readout spectrometers are used, based on charge coupled devices (CCDs) covering the wavelength range 200–900 nm. These detectors provide near instantaneous capture of full spectra, allowing several analytes to be monitored simultaneously, and are much smaller than conventional spectrophotometers. Optical fibres are used to link the light source to the detector via a flow cell in the FIA system. Software to run the entire system was developed using the LabVIEW™ graphical programming environment, enabling rapid development of the control system and user interface. The integration of these components has shown significant improvement in the application of FIA techniques to on-line analysis.