Sample Handling and Pretreatment Using Flow Injection Analysis

Automation of selective assays for on-line bioprocess monitoring by flow-injection analysis

On-line analysis of one component in a complex media used for bioprocesses requires the application of selective tests such as enzymes assays. Because these assays are susceptible to interference by other medium components and have a limited detection range, automatic sample pretreatment is a prerequisite. The progress made with automatic sample pretreatment in flow-injection analysis makes this technique particularly suitable for on-line monitoring of bioprocesses. Moreover, newly developed software control systems may improve the necessary robustness of flow-infection analysis systems.

Near-infrared detection of flow injection analysis by acoustooptic tunable filter-based spectrophotometry

The instrumentation development of a near-infrared (near-IR) spectrophotometer based on an acoustooptic tunable filter (AOTF) and its application as a detector for flow injection analysis (FIA) are reported. In addition to being compact and all solid state, this AOTF-based instrument is very sensitive, has high resolution, and can be rapidly scanned. The latter advantage make it uniquely suited as a detector for FIA, in that it can rapidly record the whole near-IR absorption spectrum of a mixture passing through the FIA flow cell. Subsequent treatment of the recorded spectra with multivariate calibration methods makes it possible to use the FIA, for the first time, for such applications as the simultaneous determination of trace amounts of water and benzene in ethanol. Because all organic compounds absorb light in the near-infrared region, this AOTF-based near-IR detector can serve as a universal detector for FIA; as a consequence, applications of the FIA techniques can be expanded to other areas which are not possible otherwise.

Software FIACRE: bioprocess monitoring on the basis of flow injection analysis using simultaneously a urea optode and a glucose luminescence sensor

Various computer programs for large-scale bioprocess control and optimization have been developed as well as software for simple laboratory routine analysis. In comparison, software can hardly be found that works on laboratory scale and provides the control of complex flow injection analysis (FIA) systems, multisubstrate determination, data evaluation as well as minimal process control abilities. The sensors applied can be of different type (luminometric or other optical as well as electrochemical biosensors). The development of such a software may be very helpful for the transfer of FIA/biosensor systems from the state of development to industrial processes. Hence, each analysing system--even a well established biosensor--has to be individually adapted to the process, a task which is best done under laboratory conditions. Such a flexible, computer-controlled FIA system for research level based on the software FIACRE is presented. Five FIA/(bio)sensor system can be controlled simultaneously. Additionally, common temperature and pH recordings are possible. Determinations of substrate concentrations are performed by means of calibration curves which can be recorded at different times. This allows supervising the activities of the sensors during a cell cultivation and controlling the bioprocess, e.g. by adding substrate to a cell culture. The automated monitoring of the degradation of glucose and urea by two different optical sensing principles during a cell cultivation under the control of one microcomputer is presented for the first time. For this purpose, already well examined biosensors (a urease optode and a luminometric glucose sensor) were employed and their properties discussed under the aspect of working in real cultivation media. It will also be shown that substrates being of interest for bioprocess control can be detected by slight modifications of known reactions. For example, substrates of NADH-dependent enzymatic reactions can be detected by the luminol chemiluminescence system, and optodes can be employed for pH, penicillin and glucose determination.