Time scales spectrophotometry method

Figure 5. Time scale III. Spectrophotometry method. Comparison between asymptotic...

The uses of micelles in chemical analysis are rapidly increasing (Hinze, 1979). Analytical reactions are carried out typically on a small scale and are based on spectrophotometry. At the same time, undesired side reactions can cause major problems, especially when the analytical procedure depends on reactions which are relatively slow and require high temperatures, exotic solvents or high reagent concentrations for completion. Micelles can suppress undesired reactions as well as speed desired ones and they also solubilize reagents which are sparingly soluble in water. In addition it is often possible to make phosphorescence measurements at room temperature in the presence of surfactants which enormously increases the utility of this very sensitive method of detection. 

There are a bewildering variety of methods and instruments available to the food technologist in the field of colorrr measurement. When one is approaching the subject for the first time or when attempting to devise a method for a material outside the normal experience, the wealth of possibilities available sometimes makes the choice difficrrlt. It is the purpose of this chapter to attempt to identify a systematic approach in order to ease the task. The approach is concerned primarily with the use of tristimulus colorimetry and reflectance spectrophotometry. These two techniques will be discussed in detail along with colour scales and formulae commonly in use. The key points which may influence measured results will also be described followed by advice on the selection, preparation and presentation of samples. Finally, detailed references to work carried out in the field of food colour measirrement and where to access further information will be provided. 

D5. Delves, H. T., A micro-sampling method for the rapid determination of lead in blood by atomic absorption spectrophotometry. Andyst 95, 431-438 (1970). D6. Delves, H. T., and Reeson, R. B., A simple time-delay accessory for use with micro-scale sampling atomic absorption techniques. Analyst 98, 343-346... 

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