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Components of a single-beam spectrophotometer
A, exciter lamp; B, entrance slit; C, monochromator; D, exit slit; E, cuvet; F, photodetector; G, LED display.
§ Molecular–absorption method is based on measurement of absorption by molecules (or ions) substances of electromagnetic radiation of an optical range:
§ Colorimetry in which visible light was absorbed by a sample. The concentration of analyte was determined visually by comparing the sample’s color to that of a set of standards using Nessler tubes (as described at the beginning of this chapter), or by using an instrument called a colorimeter.
§ Photocolorimetry - in which polychromatic light was absorbed by a sample
§ Spectrophotometry - in which monochromatic light was absorbed by a sample
§ UV - Spectrum (100-200 to 380-400 nanometers)
§ Visible spectrum (380-400 to 780-800 nanometers)
Instrumentation
Frequently an analyst must select, from several instruments of different design, the one instrument best suited for a particular analysis. In this section we examine some of the different types of instruments used for molecular absorption spectroscopy, emphasizing their advantages and limitations. Methods of sample introduction are also covered in this section.
