Calibration
of Polarimeter (Frequency: Quarterly)
Dextrorotatory Substances:
- Ensure that instrument is clean and free from dust.
- Switch ON the main supply.
- Sodium lamp will glow, wait for 15 – 20 minutes till lamp glow fully to bright yellow.
- Maintain the temperature of solution at 25°C ± 2°C for taking reading on Polarimeter.
- Set the alignment of the sodium lamp compartment to the optical bench.
- Set the angle of rotation zero position of Polarimeter scale.
- Open the Polarimeter tube compartment and place the Polarimeter tube, which is filled with water as blank in such a way as to avoid air-bubbles.
- Observing through telescope when the darkened and light portions of a circle are in equilibrium.
- These all portions will match with the help of knob rotating in clockwise or anti-clockwise direction.
- Repeat the procedure five times for blank & note down the average value of the Blank reading.
- Dry approx. 110 g of sucrose at 105 Degree C for 3 hrs using hot air oven. (Operate the instrument as per related operational SOP.)
- 10% w/v solution of sucrose: Take 10
g of sucrose in 100 ml volumetric flask add 50 ml of water, and mix properly.
Makeup 100 ml with purified water and mix well until clear solution.
- 20% w/v solution of sucrose: Take 20
g of sucrose in 100 ml volumetric flask add 50 ml of water, and mix properly.
Makeup 100 ml with purified water and mix well until clear solution.
- 30% w/v solution of sucrose: Take 30
g of sucrose in 100 ml volumetric flask add 50 ml of water, and mix properly.
Makeup 100 ml with purified water and mix well until clear solution.
- 40% w/v solution of sucrose: Take 40
g of sucrose in 100 ml volumetric flask add 50 ml of water, and mix properly.
Makeup 100 ml with purified water and mix well until clear solution.
- 50% w/v solution of sucrose: Take 50
g of sucrose in 100 ml volumetric flask add 30 ml of water, and mix properly.
Makeup 100 ml with purified water and mix well until clear solution.
- Now fill the polarimeter tube with 10% w/v solution of sucrose within 30 min from the time of preparation and during this time interval maintain the solution at 25°C ± 2°C record the temperature before observation.
- Take reading in same manner for 20%, 30%, 40% & 50% solutions.
- The table containing concentration and corresponding angle of rotation in a 2-dm tube at 25°C ± 2°C are indicated below:
- Concentration gm/100ml Angle of rotation (+) at 25°C
|
Concentration gm/100ml
|
Angle of rotation (+) at 25°C
|
|
10.0
20.0
30.0
40.0
50.0
|
+13.33o
+26.61o
+39.86o
+53.06o
+66.23o
|
Levorotatory
Substances
- Ensure that all the settings are done in the zero position.
- Open the Polarimeter tube compartment and place the Polarimeter tube, which is filled with Blank solution prepared by diluting 0.2 ml of 5M ammonia to 100 ml with water, and allowed to stand for 30 minutes, in such a way as to avoid air-bubbles.
- Observing through telescope when the darkened and light portions of a circle are in equilibrium.
- These all portions will match with the help of knob rotating in clockwise or anti-clockwise direction.
- Repeat the procedure five times for blank & note down the average value of the Blank reading in calibration Record
- Now fill the Polarimeter tube with reference solution prepared by dissolving 10.0 g Fructose in 80 ml water, adding 0.2 ml of 5M ammonia, mixing well, allowing to stand for 30 minutes, and diluting to 100 ml with water. Carry out the determination in the similar manner as blank.
- Repeat the procedure five times for Sample & note down the average value of the Sample reading.
- Perform all the measurement of blank and Sample at 25°C ± 2°C.
- Determine the water content of Fructose with 0.5 g of Fructose by using Karl Fischer Titrator (Operate the instrument as per related SOP), and calculate the SOR on anhydrous basis.
- Report any discrepancy observed during calibration of instrument to Head/Designee QCD for corrective and preventive action.
- Head/Designee QCD informs the defect to Engineering Department service engineer to rectify the defect. Affix ‘Under Maintenance’ label on the instrument.
- Calibration should be required after major maintenance.
