Sop of Polarimeter.

This Document describes (Standard Operating procedure) Sop for Operation and Calibration of Polarimeter. Which is used to measures the angle of rotation by passing polarized light through an optically active (chiral) substance using polarized light. To measure optical rotation, a Light Emitting Diode (LED) produces a beam of ordinary light.

Sop for Operation and Calibration of Polarimeter.

I. Purpose & Scope:

• The Purpose of this SOP is to lay down the procedure for Operation, Cleaning and Calibration of Polarimeter.
• This procedure is applicable to all Quality Control Department for operation, cleaning and calibration of Polarimeter

II. Responsibilities:

• All Quality Control, Quality Assurance personnel’s shall be responsible to follow and implement this SOP.

III : Introduction and Procedural Part :

General Cleaning :

• Ensure that the power supply to the instrument is switched OFF before Cleaning.
• Clean the instrument with a clean and dry lint free cloth before and after analysis.
• Occasionally clean with wet cloth dipped in dilute soap solution.
• A precaution has to be taken to clean the instrument immediately with dry cloth to remove the moisture.

General Instruction :

• Connect the instrument to power supply and turn ON the switch of main supply.
• The Sodium lamp will glow on. Allow it to warm up for about 5 minutes till it changes the colour from pink to bright yellow.
• Check the cleanliness of tube & fill it with distilled water.
• See the alignment of lamp & two lenses of polarimeter
• Clean tube after every analysis to remove sample residues and switch off the instrument.

Method for Liquids :

• Determine the zero reading with the polarimeter tube empty and closed.
• The zero reading is obtained by taking several readings rotating the tube through 45° between each reading through 45° between each reading.
• Angle of Rotation- Unless otherwise specified, adjust the temperature of the substance being examined to 25°C and transfer it to  the  polarimeter  tube   ensuring that no  bubbles which would interfere with the passage of the beam of light are present Rotate the scale setting knob ultimately left and right with decreasing amplitude until the colour and intensity of both sections of the field are equal  and  record  the reading.Take four more readings while rotating the tube through 45° between each reading.

Method for solids :

• Zero reading- Fill the polarimeter tube with the same solvent used for sample dilution. Adjust the temperature of the solvent to 25°C or specified in the monograph. Take 5 readings rotating the tube through 45° between each reading.
• Angle of Rotation- Weigh accurately a suitable quantity of the substance being examined to obtain the solution of the strength specified in the individual monograph and transfer to a volumetric flask by means of water or other solvent, if specified unless otherwise specified, adjust the contents of the flask to 25°C by suspending the flask   in a constant temperature bath. Make up to volume with the solvent at 25°C and mix well.  Transfer the solution to the polarimeter tube ensuring that no air bubbles are which would interfere with passage of the beam of light.
• Rotate the scale setting knob ultimately left and right with decreasing amplitude until the colour and intensity of both sections of the field are equal and record the reading. Take four more readings while rotating the tube through 45° between each reading.

Calculation

• Calculate the specific optical rotation using the following formulae, Dextro-rotation & laevorotation being designated by (+) and (-) respectively.
• For liquids [a]^{25 D} = a/ld ²⁵
• For solids [a] D = 100a/lc

Where

a    = Corrected observed rotation, in degrees, at 25°C

D   = D line of Sodium light (wavelength = 589.3 nm)

l     = Length of the polarimeter tube in dm.

d²⁵ = Specific gravity of the liquid or solution at 25°C

c    = Concentration of the substance in % w/w         

Calibration of Polarimeter :

• Preparation of sucrose solution.
• Dry the sucrose at 105°C for 3 hours before use. Prepare the sucrose solution in Purified water of five concentrations stated in the table. Adjust the temperature to 25°C and measure the angle of

Sucrose Solutions (gm/100 ml)	Angle of Rotation at 25°C
10	13.33° ± 0.05°
20	26.61° ± 0.05°
30	39.86° ± 0.1°
40	53.06° ± 0.1°
50	66.23° ± 0.1°

• Record the observations in the calibration record.(Refer Annexure I)
• Enter the calibration details on “CALIBRATION LABEL” affixed on the instrument.

General precautions: 

• Hold tube by non-optical surfaces, such as the matt finish surfaces
• Protect tube from scratches and never permit them to rub against hard
• Always wipe the optical surfaces of tube dry and free of finger marks using a tissue paper.
• Always insert tube into the holder with the same orientation.
• Rinse the tube thoroughly with the same solvent as used for sample and then dry it.
• Note – The requirement of Optical rotation and specific rotation in the pharmacopoeia apply to the dried/anhydrous or solvent free material in all those monograph in which standards for loss on drying, water or solvent content are given. In calculating the result the loss on drying, water or solvent content determine by the method specified in monograph is used.

 

IV: Annexure :

Annexure I: Calibration Record of Polarimeter.

 

 

ANNEXURE –I

Calibration Record of Polarimeter.

 

Name of Instrument	Polarimeter	Model No.	R-S-P-1
Instrument ID No.		Calibration Frequency	Quarterly
Calibration done on		Calibration due on

Sucrose Standard B. No.		Valid up to
Drying Temperature/ Time	105°C for 3 hours	Oven Temperature
Sucrose Drying started at		Sucrose Drying completed at

Procedure:

Preparation of Sucrose standard solution:

1. 10 % Sucrose solution:

Weigh accurately ___________ (10 gm) of Sucrose standard and transfer to _______ (100 ml) volumetric flask. Add sufficient quantity of purified water to dissolve the sucrose. Sonicate the solution if necessary to dissolve the sucrose. Cool the solution to room temperature and dilute up to ___________ (100 ml) with purified water.

1. 20 % Sucrose solution:

Weigh accurately ___________ (20 gm) of Sucrose standard and transfer to _______ (100 ml) volumetric flask. Add sufficient quantity of purified water to dissolve the sucrose. Sonicate the solution if necessary to dissolve the sucrose. Cool the solution to room temperature and dilute up to ___________ (100 ml) with purified water.

1. 30 % Sucrose solution:

Weigh accurately ___________ (30 gm) of Sucrose standard and transfer to _______ (100 ml) volumetric flask. Add sufficient quantity of purified water to dissolve the sucrose. Sonicate the solution if necessary to dissolve the sucrose. Cool the solution to room temperature and dilute up to ___________ (100 ml) with purified water.

1. 40 % Sucrose solution:

Weigh accurately ___________ (40 gm) of Sucrose standard and transfer to _______ (100 ml) volumetric flask. Add sufficient quantity of purified water to dissolve the sucrose. Sonicate the solution if necessary to dissolve the sucrose. Cool the solution to room temperature and dilute up to ___________ (100 ml) with purified water.

1. 50 % Sucrose solution:

Weigh accurately ___________ (50 gm) of Sucrose standard and transfer to _______ (100 ml) volumetric flask. Add sufficient quantity of purified water to dissolve the sucrose. Sonicate the solution if necessary to dissolve the sucrose. Cool the solution to room temperature and dilute up to ___________ (100 ml) with purified water.

Measure the angle of Rotation at 25°C of all sucrose standard solution in five replicates by using purified water as blank and record the observations.

Observations:

Reading Number	Observed Angle of rotation of Sucrose solution at 25°C
	10% w/v	20% w/v	30% w/v	40% w/v	50% w/v
I
II
III
IV
V
Average
Acceptance criteria	13.33° ± 0.05°	26.61° ± 0.05°	39.86° ± 0.1°	53.06° ± 0.1°	66.23° ± 0.1°

 

Remark: The above instrument is calibrated/Not calibrated

 

Calibrated By                                      Checked By                                        Approved By

Sign/Date                                            Sign/Date                                            Sign/Date