Measurement of the amount of light to the absorbance is called spectrophotometer. Spectrophotometer used to test the sample by passing through the light it’s worked to measure the light that passing through. Biological substances such bromophenol blue and methyl orange, are the common substances to be used in testing of interaction of substance with the light. These solutions called pigments where they usually can absorb the visible of light that passing through it. The cleared compounds or solution also can absorb the light that is not seen through the naked eyes. The wavelength specifically used to test the absorbance level is 400 to 600 those are in nanometer unit, in this experiment the wavelength to used is 470, 500, 530, 560, 620, 650, 680 nanometer. Measures the absorption of light by spectrophotometer with a specific wavelength used to determine the concentration of the pigments or solution.
Figure 1.1 shows the schematic diagram of the spectrophotometer.
The instrument show the content of the light source which is come from the light source of a spectrophotometer. The arrow as in the Figure 1.1 to show the path of light from the light source. A prism refracting a light to the wavelength selector and transmit to the cuvette and the results sent to the recorder or computer.
1. To determine the wavelength of maximum absorption, Amax, of bromophenol blue.
2. To construct a standard concentration curve for bromophonol blue.
3. To determine the concentration of the unknown bromophenol blue solutions.
4. To determine the concentration of two different solutes, bromophenol blue and methyl orange, in a mixture.
1. Distilled water
2. Bromophenol blue,
3. mixture of bromophenol blue and methyl orange solutions,
5. 2 cuvettes.
6. test tubes (Labeled 1-6)
9. Tissue and glove