Colorimetry is a method used to estimate substances in biological materials by developing and comparing colors with known standards, while spectrophotometry extends this capability to measure light absorption beyond visible colors, making it suitable for colorless compounds. The key differences between colorimeters and spectrophotometers include sensitivity, light sources, measurement ranges, and types of cuvettes used. Spectrophotometers are more advanced, allowing for greater sensitivity and accuracy across UV, visible, and IR wavelengths.

2. Colorimetry: The colorimetry is a technique by which
substance to be analysed in biological material is estimated by
developing colour with suitable reagent, which is compared
with known concentration of substance or standard.
Spectrophotometry – is similar to colorimetry but in this
technique, it extends the range of possible measurements
beyond those that can be determined by the eye alone i.e.,
quantification of colourless compounds by using UV or visible
light.

3. Spectrophotometry
Spectrophotometer - an instrument that measures the amount
of light absorbed, or the intensity of color at a given
wavelength.
The intensity of color can be given a numerical value by
comparing the amount of light prior to passing it through
the sample and after passing through the sample.
These quantitative measurements of light absorbed are the
Transmittance and the Absorbance.

4. Differences b/n colorimeter and
spectrophotometer
Features COLORIMETER SPECTROPHOTOMETER
1.Sensitivity Low 1000 times more
2.Source Tungsten lamp Dueterium or hydrogen lamp
3.EMS Visible range(400-700) UV.IR,VR
4.Chromatic
devices
Filters are used Diffraction gratings/Prisms
5.Absorbance Measures conc. only
colored solutions
Measures conc. Even in
colorless solutions.
6.Cuvettes Glass/quartz Only quartz(as glass
absorbs UV rays).
7.cost low 100 times more

5. Advantages of
spectrophotometer
1. Useful for the measurement of
absorbance of coloured as well as
colourless solutions.
2. Works in UV, visible and IR (260- 800nm)
3. Prism or diffraction gratings used instead
of filters.
4. More sensitive,accurate and
sophosticated.