What is spectrophotometry

Dr. sonal singh 1

Spectrophotometry can be an extension of any of the foregoing types of spectroscopy. It is a term that refers to the quantitative analysis of spectra to compare the relative absorption or emission of different wavelengths of light. Photometry is used to determine either the absolute amount or the relative amounts of two or more compounds or elements in a sample or set of samples. In either case, SP requires the careful calibration and validation of the spectroscopy system and detector. SP is an essential element of many forensic comparisons of spectra, especially those involving mixtures of light absorbing materials such as dyes and pigments. Fabrics and carpets are an example of materials that are often colored with a mixture of dyes and the relative proportion of dyes absorbed by a fabric may vary from dye lot to dye lot. It is necessary to establish not only that the dyes in two items are similar but also that they are present in the same amounts if the two items are to be associated. Environmental and occupational laws, regulations, and penalties are often based not only on the presence of dangerous materials but also on the amounts of those materials that are present, making SP and essential part of an analysis. The techniques like spectrophotometry, based on color intensity measurements, are most widely used to determine the concentration of the unknown substances for quantitative- and qualitative-specific determinations of recently sophisticated instruments like pH meter, atomic absorption spectrophotometer (AAS), flame photometer, gas chromatography, and electrodes, which are useful to analyze color, pH, EC, fluoride, sulfate, phosphate, sodium, and heavy metals (Cu, Pb, Mn, and Cd).