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MEASUREMENT
Keep the sample tube containing distilled water or any other blank solvent into the sample
chamber and close the cover. Press ZERO key to display reading equal to '0'.
Make sure that there are no air bubbles in the sample tube by tilting the tube to make the air
bubbles float on the protruded tube neck. The vapour drops on both the ends of sample tube
should be wiped dry. The screw nuts on both ends of the sample tube should not be tightened
too much to avoid stress on the end pieces or else the readings may get affected because of the
stress.
If there is any marking of position and direction in the tube care should be taken while placing
the tube.
Remove the sample tube, inject the solution to be measured into the tube and place it in the
chamber and close the cover. Instrument will read the optical rotation.
The instrument will repeat the measurement for N number of times automatically & all
readings are displayed along with average value and standard deviation f readings.
If the optical rotation of the sample exceeds +45 the motor oscillates at +45 the sample has
to be diluted and tried again.
After the measurement, light source switch and power supply switch should be turned OFF
in the same sequence.
MEASUREMENT CALCULATIONS
Specific Rotation [ ] = 100 x / LC
Where is the measured optical rotation, L is the length of the tube in dm and C is the
concentration of solution in gms/100ml.
Purity = Measured specific rotation as per instrument / theoretical specific rotation as per the
above formula.
Measurement of International sugar concentration : While 26g of pure sugar is made upto
100ml of solution by adding distilled water and a 200mm test tube is used in a polarimeter
using sodium light source of 589.44 nm wavelength at 20 C, the optical rotation should be
+34.626 and international sugar scale should be 100 Z.
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