To lay down a procedure for Operation & Calibration of refractometer
This procedure is applicable for procedure for Operation & Calibration of refractometer.
QC Officer/ QC Executive
- Operating Procedure
- Ensure that instrument is clean and free from dust.
- Switch ON the mains.
- Open the prism box for measurement of refractive index of the sample.
- Place 2-3 drops of sample on the ground surface of lower prism.
- Close and fit the prism box.
- Focus the cross wires of eyepiece by adjusting screw.
- Adjust the mirror till good illumination is obtained.
- Gently turn the prism box by means of milled head screw clockwise or anticlockwise till a colored band appears in the field of view.
- Turn the milled ring at the base of telescope clockwise or anticlockwise where colored band is illuminated and a sharp dividing line is seen. Which divides a field of view in half illuminated and a half dark position.
- By means of milled head screw, adjust the dividing line exactly at the intersection of the cross wire.
- Read the refractive index on the divided arc by means of magnifier to the third decimal point and fourth decimal on the milled ring at the base of telescope.
- Note down the reading, which is the refractive index of the sample.
- Open the prism box. Wipe off the sample with moistened tissue paper 2-3 times and dry the prism with dry tissue paper. Close the prism box and keep instrument in its cabinet securely.
- The cleanliness of the instrument should be checked before use by determining the refractive index of distilled water which at 25°C is 1.3320 – 1.3330.
- Operate the instrument as mention in the operation procedure.
- The instrument should be checked by determining the Refractive Index of distilled water at 25oC.
- If the refractive index of distilled water at 25oC is not between 1.3320 – 1.3330, adjust the small square screw and at the back of telescope with the key provided with instrument. Bring the reading setting to 1.3325 and adjust the diving line exactly at the intersection of the cross wire by turning the key clockwise or anticlockwise, remove the key.
- The instrument shall be further checked by determining the refractive index of the reference liquids. (Carbon Tetrachloride, Toluene, Distilled Water) & record.
- Operating Procedure
|Name of Reagents||Specification|
|Carbon Tetrachloride at 20°C||1.4600 to 1.4610|
|Toluene at 20oC||1.4940 to 1.4970|
|Distilled Water at 25oC||1.3320 to 1.3330|
- Calibration Frequency – once in month.
- Fill the calibration status on metallic calibration label of the instrument; record the calibration result.
- If instrument is out of calibration, affix “UNDER MAINTENANCE “or “DO NOT USE” label on the instrument and immediately inform to maintenance & call service engineer.
Trainer : Manager – Quality Control
Trainees : Staff of the QC departments
Master Copy : QA Department
Controlled Copy : QC Department
Display Copy : QC Department (If Required)
|SOP||Standard Operating Procedure|
|Sr. No.||Serial Number|
- REVISION HISTORY OF CHANGE:
|Sr. No.||Date||Revision Details||Revision No.|