1.0 Objective:
The objective of this standard
operating procedure is to lay down the procedure for
Operation and Calibration
of Refractometer. (Model: RSR-2)
2.0 Scope:
This SOP covers
operating procedure for Operation and Calibration of Refractometer.
3.0 Responsibility
Jr. Research Officer, Research Officer:
Responsible for operation, calibration and
maintenance of the
instrument as per procedure.
Head of Department:
Responsible for calibration and maintenance, timely as per schedule.
QA officer/QA Manager:
Review the records and governing the document.
4.0 Procedure:
4.1 Ensure that the instrument is visibly clean
and free from dust.
4.2 Set up the instrument on a plain platform
and clean the optical elements with methanol.
4.3 Align the light source properly with
respect to optical mirror.
4.4 Adjust the mirror provided on the left
side so as to clearly read the scale viewed through
the top eyepiece.
4.5 condition the instrument to the desired
temperature as mentioned in the individual
monograph,by passing or circulating
water from the arrangement provided in the prism
box at required temperature and
maintain the temperature throughout the analysis since the
refractive index varies
significantly with temperature.
4.6 Thermometer is provided at the right side
of the instrument for reading the temperature.
4.7 Turn on the illumination, using the switch
provided on the illumination assembly box.
4.8 To check liquid sample, simply open the
prism box, now place few drops of the sample on
the lower prism and gently close the
prism box so that a thin layer of sample is squeezed
between the prisms.
4.9 Now looking in the eyepiece focus simply
by rotating the eyepiece in either direction.
4.10
After the sample is placed in the prism box the refraction creates a
shade in the cross wire
box. The shade is to be brought in
the center of the cross wire using the scale knob located
on the left side of the
instrument.
4.11
Rotating the dispersion scale located on the right side in either
direction eliminate the
colour bands visible on the edge of
the shade to attain sharp borderline.
4.12
By looking in the eyepiece read the refractive index or the sugar
contents percentage of the
sample on the scale.
4.13
Report the result as n = t/d
Where, n = temperature
at which the determination is done.
d =
refractive index value for D line of sodium light.
Note: for
examining plastic bodies such as resin detach the lower prism and soften the
material by
heat and smear a little on the
exposed surface of the upper prism. To examine crystals or
glasses a specimen must be prepared
similar to the standard test piece.
5.0 Calibration procedure:
5.1 Calibrate the instrument using the following liquids as given
in table.
Reference Liquid
|
Temperature
|
Limits ± 0.015
|
Carbon Tetrachloride
|
20°C
|
1.4453 to 1.4753
|
Toluene
|
20°C
|
1.4819 to 1.5119
|
Water
|
25°C
|
1.3175 to 1.3475
|
6.0 Range of measuring
scale:
1. Refractive index from 1.300 to 1.700
2. Contents of sugar in water
solution from 0 to 95%
7.0 Frequency: Once in a three month and after each maintenance job
8.0 Routine maintenance:
Clean instrument with
dry cloth.
9.0 Documentation:
9.1 Annexure – 1 - Refractometer usage log book. XXX/FRM/000
9.2 Annexure – 2 -
Refractometer Calibration record format XXX/FRM/000
10.0 History of Revision:
Revision No.
|
Effective Date
|
Revision details
|
Reason for revision
|
Annexure – 1
|
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Date
|
Name of Sample
|
A. R. No.
|
Batch No.
|
Used by
|
Remark
|
SOP No. : XXX/SOP/000 Format No. : XXX/FRM/000-00
|
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Calibrated by : Checked by :
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SOP No. : XXX/SOP/000 -00 Format No. : XXX/FRM/000-00
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