Biochemical Techniques and Instrumentation

1.2.1. UV-Vis Spectrophotometer

There are two types of UV-Vis spectrophotometer.

1. Single beam spectrophotometer: The double beam compares the light intensity between two light paths, first path contains the sample and the second path holds the control.They are computer controlled with baseline corrections, so easier and more stable.
2. Double beam spectrophotometer: The single beam measures the relative light intensity of the beam before and after a sample is inserted. They have a larger dynamic range, optically simpler and more compact.

Colorimeter

In a colorimetry, wavelength selection is achieved by using coloured filters that absorb all the wavelengths except certain limited range of wavelengths. For instance, the red filter absorbs almost all other colours except red. This red filter is used to examine blue solutions as these would absorb red light the maximum. The filter used is thus made of a colour complementary to that of test solution.