Biological detection principles

Because the aim of the control of residues is to prevent residues in food exerting an undesirable effect on humans, it would be elegant to use this biological effect as the detection principle. Hence, the detection of drug residues in edible animal products has traditionally been performed by microbiological techniques. 

If the combination of a high-resolution separation system with a physicochemical detection principle is specific to properties of many harmful (toxic) chemicals, then a straightforward approach may be possible (27). Electron capture detection (ECD) registers electronegative compounds. Since the early 1960s, Lovelock (28) has pointed at the possible link between the ability of a substance to capture electrons and its biological action. 

There are numerous ways to exploit the calorimetric detection principle in combination with biological materials, not only in metabolite assays, but also for analyses of proteins and other macromolecules as well as for whole cells. These include metabolite determination, bioprocess monitoring, measurements of enzymic activities in separation procedures, determinations in organic solvents, and miniaturized thermal biosensors. 

In recent years, laser-based biosensors have become important tools in many fields such as analytical biochemistry, pharmaceutical research and development, and food/environ-mental monitoring. However, the volumes of the optic components in these biosensors limit their application in portable microdevices. In order to obtain more powerful, miniaturized, and cheaper biosensors using lasers, novel biological sensing principles, detection means, and fabrication methods need to be sought. The integration of biosensors and microfluidic chips will be an important direction for developments in laser-based biosensors. Biosensors can be used as microscale detection tools in lab-on-a-chip for the research and development of miniaturized detection devices, i.e., micro-total analysis systems. 

It may be kept in mind that this detection principles is non-specific and not suitable for complex biological samples giving numerous peaks. Measurements of impurities in substances and in pharmaceutical products are more typical application areas. 

The most attractive feature of calorimetric sensors is the fact that they are based on an almost universal detection principle that is insensitive to the optical or electrochemical properties of the sample. The usefulness of calorimetry as an analytical tool in biology... 

Theory and Equipment. The basic principle behind nuclear medical imaging is that a radiopharmaceutical can be introduced into the body which emits radiation detectable outside of the body. Radiopharmaceuticals are biologically active and have a short half-life (Si/q)- The detectable radiation... 

In principle it is possible to employ physical, microchemical and biological-physio-logical methods for detection in TLC (Fig. 2). 

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