Basically we use spectrophotometric techniques to measure the concentration of solutes in solution. If a pollutant acts as solute we can find out its concentration. To do this, we will measure the amount of light that is absorbed by the pollutant in water in a cuvette in the spectrophotometer. We use the dual nature of light. The light has a particle nature which gives rise to the photoelectric effect and then it also has a wave nature this gives rise to the visible spectrum of the light.
A spectrophotometer measures the intensity of a light beam after it is directed through and emerges from the water in cuvette. We can gain greater sensitivity by directing different coloured light through different pollutants. For this, we have to isolate the specific wavelengths in the spectrophotometer. We do this in a spectrophotometer by striking the light source to a prism, which on separating the light into its component wavelengths gives us our specific wavelength light. This incident light represents 100% of the light striking the cuvette filled with pollutant water. The transmitted light is the light, which has not been absorbed by the water in the cuvette. This will strike the phototube in spectrophotometer. The photons of light, which do strike the phototube, will be converted into electrical energy. This current must be amplified to detect by the galvanometer.
A spectrophotometer measures the intensity of a light beam after it is directed through and emerges from the water in cuvette. We can gain greater sensitivity by directing different coloured light through different pollutants. For this, we have to isolate the specific wavelengths in the spectrophotometer. We do this in a spectrophotometer by striking the light source to a prism, which on separating the light into its component wavelengths gives us our specific wavelength light. This incident light represents 100% of the light striking the cuvette filled with pollutant water. The transmitted light is the light, which has not been absorbed by the water in the cuvette. This will strike the phototube in spectrophotometer. The photons of light, which do strike the phototube, will be converted into electrical energy. This current must be amplified to detect by the galvanometer.