SOP Title: Operation, Cleaning and Calibration of Automatic Refractometer
- Objective:
To lay down the procedure for Operation, Cleaning and Calibration of Refractometer.
- Scope:
This SOP is applicable for Operation, Cleaning and Calibration of Refractometer located in Quality Control Laboratory.
- Responsibility:
- Quality Control: To prepare and review the SOP. To follow the procedures laid down for Operation, Cleaning and Calibration of Refractometer as per this SOP.
- Quality Assurance Department: To review and approve the SOP and Annexures.
- Accountability:
Head Quality Control Department, Head Quality Assurance Department.
- Procedure
| 5.1 | Safety Precautions/Instructions: | |||||
| 5.1.1 | Ensure all the electrical connections are properly earthed. Ensure the power plug of the automatic Refractometer is fixed in the socket properly. | |||||
| 5.1.2 | Wear personal protective equipments such as safety glasses, hand gloves during operation of instrument. | |||||
| 5.1.3 | Ensure that the ON/OFF switch is working properly by switching “ON” the Refractometer. | |||||
| 5.1.4 | Clean the Automatic Refractometer with dry lint free duster. | |||||
| 5.1.5 | Do not move the automatic Refractometer during cleaning | |||||
| 5.1.6 | Do not attempt to do any repairs unless trained. | |||||
| 5.1.7 | Keep measuring surface clean. Clean the measuring surface with a wet (with water or isopropyl alcohol), soft, clean cloth or paper towel. For most accurate reading, keep the measuring surface clean and free of residual at all times. | |||||
| 5.1.8 | Use only one or two drops of sample. Use a disposable plastic pipette to place the sample on the measuring surface and use the same pipette to suck back up and dispose of it. | |||||
| 5.1.9 | Inspect the measuring surface to make sure it is clean and dry with IPA before putting sample on measuring surface. | |||||
| 5.1.10 | Do not keep instrument to temperature above 50°C | |||||
| 5.1.11 | Keep instrument away from vibration. | |||||
| 5.2 | Operation Procedure: | |||||
| 5.2.1 | Check the validity of calibration before starting any operations. | |||||
| 5.2.2 | The instrument should be cleaned before operation. | |||||
| 5.2.3 |
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| Introduction to Key: | ||||||
| 5.2.4 |
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| 5.2.5 | Click on “MENU” key on main screen, The system will ask for password. Enter Password , Then screen will show parameters as :
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| 5.2.6 | Click on “SCALE” option from menu key, the screen will display parameters as :
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| Note: Brix and Honey are scale used generally in food industry. | ||||||
| 5.2.7 | Click on “Refractive index” parameter, then press “Exit” key. | |||||
| 5.2.8 |
Click on “TEMPERATURE” parameter, the screen will display sub-parameter |
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| 5.2.9 | Click on “TEMPERATURE CONTROL” option, the screen will display options as
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| 5.2.10 | Select “Temperature control “20ºC or 25ºC” as per standard test procedure and click on “back” option | |||||
| 5.2.11 | Click on “TEMPERATURE CORRECTION” from temperature parameter , and press “back” key. | |||||
| 5.2.12 | Click on “SETUP” menu from main screen “menu” key . The Screen will display setup parameters as
1.User calibration 2.Operational parameters 3.Measurement Parameters 4.Communication setting 5.system information 6.Service calibration |
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| Introduction to key: | ||||||
| 5.2.13 |
This setup menu is used by outside service engineer during annual maintenance. |
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It contains the instrument information. |
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It shows setting to print the results. |
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| 5.2.14 |
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| 5.2.15 |
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| 5.2.16 | Select “Celsius” temperature scale and press “Exit” key. | |||||
| 5.2.17 |
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| 5.2.18 |
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| Introduction to Key : | ||||||
| 5.2.19 |
“Single measure” Mode is used in routine analysis. |
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| 5.2.20 | Click on “Single Measure” mode. Press on “Done” key. | |||||
| 5.2.21 | Click “zero” key on main screen to auto zero the instrument without blank sample i.e. Air Zero. Then the system will display a message “Place pure water on sample dish. Then press zero again.” | |||||
| 5.2.22 | Place approximately 1-2 drop of water as blank on measuring surface, such that black circle of measuring surface will cover. Put the lid of Refractometer on sample. Click on “ZERO” Key on main screen to auto zero. | |||||
| 5.2.23 | After pressing “ZERO” key, the system will show the message of “Water Zero successful” | |||||
| 5.2.24 | Click on “Continue” option. Then system will start to measure Refractive index of water. The measured reading will display on main screen. | |||||
| 5.2.25 | Clean measuring surface with paper towel or cloth. | |||||
| 5.2.26 | Place sample on measuring surface and put the lid of Refractometer. | |||||
| NOTE: Place approximately 1-2 drop of sample or blank such that it should cover black circle of measuring surface. If sample is not sufficient on measuring surface, the system will display a message “Waiting for Sample” | ||||||
| 5.2.27 | Click on “START” Key on main screen. The measurement reading will display on main screen. | |||||
| 5.2.28 | Click on “PRINT” key on main screen. The print taken via RS 232 Port cable which is connected to printer OR via PC connected to Printer. | |||||
| 5.2.29 | After measurement clean the measuring surface with wet cloth or paper towel of water or isopropyl alcohol to remove residue particle. | |||||
| 5.3 | Calibration procedure : | |||||
| 5.3.1 | Update the “Instrument/Equipment Usage Log Book” as per SOP “Calibration of Instruments and Equipments”. | |||||
| Frequency: Quarterly or after carrying out any major maintenance work. | ||||||
| 5.3.2 | Generate the A. R. No. on the “Instrument/Equipment Calibration Register” as per SOP and give requisition to QA department for calibration formats of instruments on the due date of calibration. | |||||
| 5.3.3 | For issuance of calibration report refer SOP “Control of documents, Preparation, Approval, Issuance and Maintenance. | |||||
| 5.3.4 | Perform the calibration of instrument as per Annexure and procedure mentioned below. | |||||
| 5.3.5 | Determine the refractive index of the following standard materials:
1) Purified Water at 20°C 2) Carbon tetrachloride 3) Toluene |
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| User Calibration: (Two Point Calibration) | ||||||
| 5.3.6 | Click on “User Calibration” setup parameter from “Setup” option. The screen will show sentence
“Prism must be cleaned and covered” then click on “Continue” key. |
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| 5.3.7 | After clicking on “continue” option
Wait for air zero as shown in figure. |
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| 5.3.8 | After completion of air zero, the screen will display parameter as
1. Refractive index 2. Brix |
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| 5.3.9 | Click on “Refractive index” option. The screen will
Display message as “ Place sample 1 on prism” “Water” is used as sample 1 |
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| 5.3.10 | Click on “Done” key. The screen prompt enter Standard value of Sample 1
E.g. Water – 1.33299 |
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| 5.3.11 | Press “Enter” hence system will start measuring sample-1. | |||||
| 5.3.12 | After completion measurement of sample-1 The system will then proceed sampe-2 Remove sample -1 from measuring surface.
Clean it wet cloth or paper towel so that no any Residue obtained. |
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| 5.3.13 | Place “sample-2” on measuring surface . | |||||
| 5.3.14 | Press “Enter” hence system will start measuring sample-2
After measuring sample-2 the system will return to main screen. |
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| 5.3.15 | Enter the details in calibration report. Ensure that the results obtained, comply with the acceptance criteria. If instrument fails to meet to acceptance criteria then file an incident and investigate the cause of failure. | |||||
| 5.3.16 | Update the “Instrument/Equipment Usage Log Book”, “Annual Calibration Schedule” and “Quarterly Calibration Schedule” as per SOP “Calibration of Instruments and Equipments”. | |||||
| 5.3.17 | Affix the “Calibration Status Label” on the Instrument as per SOP “Calibration of Instruments and Equipments”. | |||||
| 5.3.18 | If calibration activity is outsourced, the values are to be transcribed in the Annexure , and external party certificate to be attached. | |||||
- Definitions / Abbreviations:
Definitions:
- Calibration: Tests performed to ensure that the instrument is functioning as per set parameters. These tests are performed as per predefined frequency and also after any major repair or replacement of parts.
- Refractometer: Automatic Refractometer automatically measure the refractive index of a sample. The automatic measurement of the refractive index of the sample is based on the determination of the critical angle of total reflection.
Abbreviations:
| Abbreviation | Expansion |
| SOP | Standard Operating Procedure |
| QC | Quality Control |
| QA | Quality Assurance |
| 0C | Degree Celsius |
| No. | Number |
Calibration Report
| Sr. No. | Standards | Acceptance Criteria | Observed Values |
| 1. | Purified Water at 20°C | Water at 20°C ±0.5°C
1.33299 (±0.0001) (1.3329 to 1.3331) |
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| 2. | Carbon Tetrachloride at 20°C | Carbon Tetrachloride at 20°C±0.5°C
1.4603 (±0.0003) (1.4600 to 1.4606 ) |
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| 3. | Toluene at 20°C | Toluene at 20°C ±0.5°C
1.4969 (±0.0003) (1.4966 to 1.4972) |
Remark: The result Complies/Does not complies as per acceptance criteria.
Performed By: ________________ Date:________________ Checked By: ______________ Date: ______________
*Note – Ready to use SOP available in “DOWNLOAD” Section.