Advantages of Spectrophotometer | disadvantages of Spectrophotometer

This page covers advantages and disadvantages of Spectrophotometer. It mentions Spectrophotometer advantages or benefits and Spectrophotometer disadvantages or drawbacks.

It is an instrument which measures amount of light absorbed by sample as a function of wavelength. It does by diffracting light beam into spectrum of wavelengths and detecting their intensities with CCD and displaying results on the detector and later on display device in the form of graph. The figure-1 depicts working of Spectrophotometer.

spectrophotometer or spectrometer working

• It measures concentration of the solution.
• It is used for color determination in the range from 380 to 700 nm.
• It is used to identify organic compounds by determining their absorption maxima.

Following are the types of spectrophotometers.
• Single beam spectrophotometer: In this type, all light passes through sample. In this type, in order to measure incident light intensity, the sample needs to be removed so that all the light can pass through.
• Double beam spectrophotometer: It measures blank and sample virtually simultaneously. In this type, in order to measure spectrum, two cuvettes both containing solvent are placed in sample and reference positions and balanc measurement is also made.
• Split beam spectrophotometer: It is similar to double beam type but uses beam splitter instead of chopper to transmit light along the blank and sample paths at the same time towards two separate but identical detectors.

Each of these types have their respective advantages and disadvantages as outlined below.

Benefits or advantages of Spectrophotometer

Following are the benefits or advantages of Spectrophotometer:
Advantages of single beam type: cheaper due to less parts, high throughput, high sensitivity, less complicated
Advantages of Double beam type: High stability due to simultaneous measurements of reference and sample.
Advantages of Split beam type: Good stability, Good noise

Drawbacks or disadvantages of Spectrophotometer

Following are the disadvantages of Spectrophotometer:
Disadvantages of single beam type: There is significant amount of time needed between two events (taking the reference and making sample measurement) and hence drift problems arises. With modern electronics and design, this problem is not seen any more in most of the applications.
Disadvantages of Double beam type: High cost, low sensitivity due to poor light throughput, low reliability due to more complexity.
Disadvantages of Split beam type: stability poorer than double beam type as two detectors can drift independently, noise not as good as single beam type as light is splitted and hence less than 100% passes through the sample.

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