Refractometer
Operation, Calibration & Maintenance
PURPOSE:
To provide the procedure for operation,
calibration and maintenance of Refractometer Mettler
Refracto 30 PX. This instrument operating procedure also provides precautions to be
taken and preliminary checks to be performed during operation.
SCOPE:
Applicable to Refractometer
Mettler Refracto 30 PX of Quality Control department.
DEFINITIONS:
°C Degree
Centigrade
min Minutes
RESPONSIBILITY :
Quality Control Chemists is responsible for
the implementation of this Instrument Operating Procedures.
ACCOUNTABILITY:
Manager Quality control is accountable for implementation and
compliance of this Instrument Operating procedure.
PROCEDURE:
1.0 PRELIMINARY CHECK :
1.1 Check
and ensure that :
1.1.1 The instrument is clean and
free from dust.
1.1.2 There should not be any
deposition of the surface of the prism of the instrument if it is there clean
with the soft cloth provided along with the instrument.
1.1.3 Before analysis, perform the
adjustment of the measuring cell with purified water, it should come
<0.0005.
2.0 BASIC
OPERATION:
2.1 Measurement
(Measure)
2.1.1 Procedure
for proper measurement – Ensure
that the prism and the measuring cell are clean before each measurement.
Insufficient cleaning leads to remains on the prism and, therefore, incorrect
results.
2.1.1
Check the sample for chemical resistance of the following materials :
·
Prism : Glass
(Refracto 30 GS : gold )
·
Measuring cell : Stainless steel SUS
316 (Refracto 30 GS : gold)
·
Housing : PBT (
Polyester )
2.1.2
Ensure that the samples to be measured
·
Have reached more or less
ambient temperature
·
Are homogeneous. Viscous and
highly concentrated liquids have to be mixed thoroughly before a sample is taken or
a measurement is carried out.
·
Can be dissolved with a
solvent suitable for cleaning the measuring cell
2.1.3 Adjust the instrument with water
before performing the analysis.
3.0
Pipetting the sample onto the measuring cell.
3.1
Pipette the sample onto the measuring cell. The measuring cell has to be filled
up to inner circle of the cell.
4.0
Dipping the measuring cell into the sample
4.1
Immerse the measuring cell completely in the sample.
Caution
: Never immerse the instrument deeper into the sample than the indicated line
(about 1.8 inch). The instrument is only resistant to splashed water.
5.0
Measurements
The
procedure is dependent upon the setting in the menu
Measurements
without temperature – compensation coefficient (α).
Configuration
of sample identification and method of data storage.
Sample Name Sample
identification
A
letter ( A… Z or space ) can be set for the identification of samples)
Mode
Method
of data storage.
Labo By
pressing the ok/measure key the result is saved and transferred ( pinter, PC).
Filed By pressing the ok/measure key
the result is saved Customer
User-defined setting.
Memory
in Save results.
Auto Save result automatically
Manu
result saved by pressing ok/measure
key.
Memory
out Transfer result to PC or printer.
Auto Save result automatically
Manu
result saved by pressing → key.
Measurements
with temperature – compensation coefficient (α).
( nDT or conc. on the
display ).
- Press ↑ key
until a previously saved temperature – compensation coefficient appears in
the display, eg. a0= 0.091 - Select the desired
coefficient using the ↓ and ↑ keys.
- Confirm the selected
coefficient with the ok/measure key.
- Press the ok/measure
key to start the measurement.
6.0
Saving the results
instrument can save up to 1100 results internally. Each time a results is
saved, the sample number increase by one.
instrument saves all results
automatically, After the measurement, as soon as the results are is saved,
Ready appears on the display.
Down symbol does not appear in the display
: savings selected result manually
the measurement, the result appears in reverse display Save
the result :
Press the ok/measure key.
not save the result :
Press the esc key.
appears on the display and the instrument is ready for the next measurement.
7.0 Displaying
and marking saved result
Display
saved result
– Press the ← key.
The sample number flashes and the symbol appears.
–
Scroll through the saved result using the ↑ and ↓ key.
Marking results
For the identification of invalid or
incorrect results or for marking a sample change.
– Select the desired sample
number using the ↑ and ↓ keys.
– Press the ok/measure key.
The selected sample number is marked with
asterisk.
Note :The
marking is removed if the sample has already been marked.
8.0
Printing and transferring results
Check the interface and
peripheral device are configured properly
For PRN and RS
interface, the infrared adapter must be connected to the printer / PC.
The
procedure for printing and transferring result is dependent upon the setting in
the menu as specified in the section measurements.
To
transfer or print result, hold the instrument in the direction of the infrared
adapter at a maximum distance of approx. 20 cm.
The Up symbol appears in the display : printing or transferring results automatically
Every display result is transferred automatically.
9.0 Adjustment
9.1 Adjusting the measuring cell with water
– Ensure that the measuring cell and surface of the prism are clean.
– Transfer pure distilled water onto the measuring cell by means of the pipette which comes with the instrument. The measuring cell has to be filled up to the mark.
– Wait until the water has reached more or less ambient temperature .
– Press and hold the ↓ key, until CALIB (water) appears in the display
.– The instrument adjust automatically ( duration : several seconds ). After adjustment is completed, the measured deviation from the theoretical value and Execute ? (No) appears.
Measured deviation < 0.0005
– Press the
↓ or ↑ key.
– Execute ? (Yes) appears .
– Press the ok/measure key.
The adjustment is confirmed.
Measured deviation > 0.0005
– Check whether the measuring
cell and the surface of the prism are clean.
– Measuring cell and the surface of the prism
are clean.
– Press the ↓ or ↑ key.
– Execute ? (Yes) appear.
– Press the ok/measure key.
– Measuring
cell and / or the surface of the prism are dirty.
– Confirm
Execute ? (No) by pressing the ok/
measure key.
– Clean
the cell and the surface of the prism and repeat the adjustment.
9.2 Adjusting the measuring cell with air
The
Refractometer measures with specified accuracy if the measuring cell is
correctly adjusted with distilled water. An adjustment with air is only
necessary if the error message E-01 appears frequently during measurement or
adjustment.
Preparing
the measuring cell.
–
Clean the
measuring cell and the surface of the prism thoroughly with a cleaning tissue.
Wait until the surface of the prism is completely dry.
Adjusting
– Press the ↓ or ↑ key.
Simultaneously. CALIB (Air) appears in the display. The instrument adjust the measuring cell automatically.
Adjustment is complete when CALIB (Air) disappears.
– Adjust measuring cell with distilled water
If
the error message E-01 appears in the display during the adjustment with air
call inform service engineer.
10.0 CLEANING :
10.1 Before cleaning, disconnect the balance from
the power supply.
10.1.1 Do not use any aggressive cleaning agents or
strong solvents.
10.1.2 Use a piece of cloth, which has been wet with a
mild detergent (Soap) to clean the weighing pan and balance housing.
10.1.3 Make sure that no liquid enters the balance
housing.
10.1.4
After cleaning, wipe down the balance with a soft, dry piece of cloth.
10.1.5
Carefully remove any sample residue / spilled powder by using a brush that is
placed with the balance.
CALIBRATION PROTOCOL
frequency : Once in three months
Perform
the calibration of the instrument by the following solvents:
|
Sr. No. |
Solvents |
Refractive |
Tolerance |
|
1. |
PURIFIED WATER |
1.3330 |
1.3330 |
|
2. |
PURIFIED WATER |
1.3325 |
1.3325 |
|
3. |
CARBON TETRA |
1.4603 |
1.4603 |
|
4. |
TOLUENE |
1.4969 |
1.4969 |
Calibration:
Perform
the temperature calibration using calibrated thermometer at a temperature at
20°C and 25°C using purified water maintained at 20°C and 25°C respectively.
Limits: ±
0.5°C of the specified temperatures.
instrument does not comply with any of the calibration parameters, then follow
the relevant procedure of instrument breakdown.
MAJOR BREAKDOWN: Following are the major breakdown
of the instrument
a)
Change in electronics
REFERENCES:
Manufacturers
Operation Manuals
Indian
Pharmacopoeia (IP).
ANNEXURE:
Instrument
calibration data sheet
Instrument
calibration summary sheet
DISTRIBUTION:
Master Copy : Quality Assurance
Control Copy : 10 : Quality control