According to Wikipedia the principle of Polarimeter is “The ratio, the purity, and the concentration of two enantiomers can be measured via polarimetry. Enantiomers are characterized by their property to rotate the plane of linear polarized light. “
Therefore, those compounds are called optically active and their property is referred to as optical rotation. Light sources such as a light bulb, a light-emitting diode (LED), or the sun emit electromagnetic waves at the frequency of visible light. Their electric field oscillates in all possible planes relative to their direction of propagation.
In contrast to that, the waves of linear-polarized light oscillate in parallel planes. The ratio, purity, and concentration of two enantiomers can be measured via polarimetry. Enantiomers are characterized by their property to rotate the plane of linear polarized light. Therefore, those compounds are called optically active and their property is called optical rotation.
Also Read: FDA guidelines for high purity system in pharma
Light sources such as a light bulb, a light-emitting diode (LED), or the sun emit electromagnetic waves at the frequency of visible light. Their electric field oscillates in all possible planes relative to their direction of propagation. In contrast to that, the waves of linear-polarized light oscillate in parallel planes.
SOP for Polarimeter
Objective
To lay down a procedure for the operation and Calibration of Polarimeter.
Scope
This procedure is applicable to the Quality Control Department of XYZ Pharma company.
Responsibility
Quality control officer
Quality control Manager.
Accountability
QA Head
Procedure
Operation:
1 Turn on the Power supply switch (in the right).
2 LCD operates and displays “wait”.
3 After 6 Seconds, the LCD displays: MODE→model,C→concentration,L→tube length, n→time of measurement.
4 Put the test tube containing the Blank solution specified in STP into the sample chamber.
5 Press the “clear” Button, Display shall show “0.000”
6 Take out the test tube and inject the sample to be measured into the test tube. (According to the same position and direction as Blank).
7 Put the test tube into the sample chamber and then close the cover.
8 Now the instrument shall indicate the reading of the sample.
9 Note down the reading and calculate as per requirement.
10 Turn off the light source switch, and power supply switch step by step when the measurement process is over.
Also read: MHRA guidelines for manufacturers of pharmaceutical formulations
Calibration:
Prepare Concentrations 1,2,3,4 and 5 of 10%, 20%, 30%,40%, and 50% of Sucrose into the water and note down the observation.
Preparation of Dilution:
1.) Weigh Accurately 50.00 g of Sucrose (LR grade) into a 100 ml volumetric flask and dissolve it with purified water and make the volume up to mark volume. (Solution A)p
2.) 10% Solution: Pipette out 5 ml of Solution A into a 25 ml volumetric flask and dilute with water up to the mark volume.
3.) 20% Solution: Pipette out 10 ml of Solution A into a 25 ml volumetric flask and dilute with water up to the mark volume.
4.) 30% Solution: Pipette out 15 ml of Solution A into a 25 ml volumetric flask and dilute with water up to the mark volume.
5.) 40% Solution: Pipette out 20 ml of Solution A into a 25 ml volumetric flask and dilute with water up to the mark volume.
6.) 50% Solution: Use 100% of Solution A.
7.) Angle of Rotation and Acceptance Criteria: At Different Concentration, Levels are as follows:
S.No Concentration (In %) Angle of Rotation (At 25°C)
1 1013.33 ±0.50
2 2026.61±0.50
3 3039.86±0.50
4 4053.06±0.50
5 5066.23±0.50
Frequency of Calibration.
Every three months.
References:
User manuals of Polarimeter.
Safety Precautions:
Handle the test tube without any breakage.
Summary
We here tried to summarize both the principle of polarimeter and SOP for polarimeter because both topics are connected to each other. SOP is described in the GMP version for any pharmaceutical company’s laboratory to meet any audit.
References
- Jenkins, F. A., & White, H. E. (1976). Fundamentals of Optics. McGraw-Hill.
- Collett, E. (2003). Polarized Light: Fundamentals and Applications. Marcel Dekker.
- Ghatak, A. K. (2005). Optics. Tata McGraw-Hill Education. Book
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