Instructions for working with the sampler
Instructions for working with the sampler
Target:
Determining how to use, maintain and secure, quality control and calibration of the sampler
2- Scope of application.
All parts of the laboratory
3- Definitions and terms:
Maintenance refers to activities related to setting up, servicing, and maintaining working conditions.
4- Responsibility and implementation.
Technical staff
5- Related documents:
Executive method of control of equipment and supplies, executive method of calibration, form of maintenance and repair of equipment, form of control, executive method of corrective action
6- Description of actions:
6-1- Generalities:
Carrying out and following up the detailed cases is done under the supervision of the head of the unit. Supervision and how to perform is done by the technical manager.
6-2- How to use:
At the beginning of each working day, before starting to use the desired sampler, turn the chassis up and down at least 20 times. This will help lubricate the components of the device, increasing its useful life. Then do the following to remove the required volume:
A) Samplers> 10 .l
In order to get the most accuracy and precision from the sampler used, you must perform pre-wetting every time you change the head of the sampler. This means filling and emptying the sample or liquid into the sampler head 2-3 times. This is required for all samples above 10 .l.
1- Connect the appropriate sampler head firmly by means of.
2. Perform pre-wetting.
3. Press the sampler chassis down to step 1.
4. At the same time, immerse the sampler chassis vertically to about 3 mm into the sample, liquid or solution without leaving it.
5. Slowly release the chassis so that the liquid enters the sampler head. At this stage, no bubbles should be seen inside the sampler's head. Otherwise, you will have to repeat the liquid operation. Clean the outside of the sampler head with gas.
6- To empty the volume in the sampler head, first stick the sampler head to the inner wall of the test tube.
7. Gently push the chassis down to step 1. Wait 3-1 seconds, then press the chassis to step 2 until the liquid is completely empty.
8- While the chassis is pressed down to the last step, take out the sampler so that the head of the sampler is rubbed against the wall of the tube when it rises.
9- Release the chassis.
10- Discard the head of the sampler and if it is not necessary to use the sampler again, place it in the appropriate base.
Note: 1- Never place the sampler on the desk while the liquid is drawn inside the sampler's head!
2 - If you work with solutions or liquids that have a high viscosity, think more about the steps of suction and discharge.
B) 10 µl or less samplers
The volume removed with such samplers is only required if the sample is rinsed into another solution. In the case of these samplers, pre-wetting should not be applied.
1- After connecting the sampler head, perform the sample aspiration operation as in the above method (steps 5-3).
2- Dip the sampler's sample head into the solution to which the sample is to be added.
3- Fill and empty the sampler head into the solution several times (= washing operation) (when emptying, press the chassis down to step 2).
4- Finally, perform the discharge operation by pressing the chassis up to step 2. Meanwhile, gently pull out the sampler so that the head of the sampler comes in contact with the inner surface of the tube as it rises.
5. Release the chassis.
6- Discard the head of the sampler and if it is not necessary to use the sampler again, place it in the appropriate base.
Attention:
1- Any temperature difference between the sampler head and the sample or liquid can cause a volumetric error.
2- In case of working with volatile liquids, a volumetric error may occur.
6-3- Tips:
1- Ensure that the head of the sampler is firmly connected
2- Keeping the sampler vertical during suction
3- Drain the solution by contacting the tip of the sampler and the vessel wall at an angle of 10-40 degrees
4- Slowly release the button at the time of harvesting and unloading
5- Pull the tip of the sampler to the edge of the container to remove excess drops
6-1-3 seconds of reflection after pressure until the first stop at the time of dissolving the solution (while contacting the wall)
6-4- How to keep the sampler
Periodic maintenance: includes washing and quality control of the sampler, washing twice a year and before the quality control steps are done and is in the form of cleaning the internal parts, which is done according to the method in the sampler guide.
To clean the interior, you should refer to the sampler guide.
Note: After washing, the piston must be lubricated with a small amount of oil along with the sampler.
If necessary, all external parts can be cleaned with a solution of soap and water and dried at room temperature after rinsing.
A 60% solution of isopropanol is recommended to disinfect the sampler.
6-5- Sampler quality control:
It is possible to check the accuracy and precision 4 times a year (every 3 months) by colorimetry (samples less than 1 microliter) or weight measurement (samples larger than 1 microliter).
6-5-1- Precision control ((Precision:
- In routine work, the samplers are divided into two groups of 100-10 microliters and 1000-100 microliters.
- Spectrophtometric or Colorimetric Method is used for the first group.
- Method of colorimetry: For this purpose, we prepare a tangible solution with a concentration of 155 mg / dl (from edible green powder) or edible green dye of chemical abyss. For sampler checks, a 1 to 101 dilution of this color is prepared for each sampler.
Multiplying this difference by 100 is the percentage of bias
Obtained.
Bias = (Expected Value - Observed Value) / Expected Value x 100
- In the weighting method, we multiply the average weights obtained in the correction factor (Correction Factor, which is obtained to convert weight to volume based on the temperature of distilled water and local air pressure).
Then we get the difference between the volume obtained and the volume announced for the sampler and divide it by the volume announced. This value will be the actual value of the deviation and its limit should not exceed 3%.
Note: The points that should be considered in connection with the weight measurement method are:
- Room temperature during the test should be between 20-25 º C with a difference of 0.5 º C and humidity of 90-60%.
- Sunlight should not shine directly on the sampler or water and the temperature of the water and the place should be the same as the tip of the sampler.
- The scale should be in a place free of vibration and temperature controlled.
- The water used must be free of gas, double diphtheria and room temperature.
6-5-2- Qualitative control of variable samplers:
In variable samplers, three volumes of sampler are usually included, including: 50% of the final volume, less than 10% of the final volume, and the final or main volume of the sampler. For example, for a 100-10 sampler check: 100, 50, and 8 microliter volumes are evaluated.
7- Calibration:
If the error is observed, the sampler is adjusted for calibration according to the catalog.
8- Safety:
8-1- Impact on the sampler can take this device out of calibration.
8-2- The liquid should not enter the inner parts of the sampler, always use the appropriate sampler tip with the extraction volume.
8-3- Contact with the tip of the infected sampler is prohibited.
8-4- In case of suction of acidic solutions and other corrosive solutions, the holding part of the sampler head (Tip Holder) should be opened and the piston and plastic ring (O-ring) should be thoroughly washed with water.
8.5 The sampler containing the solution should never be placed sideways
8-6- Variable volumetric samplers should never be used outside their claimed volume range.
9- Records:
Qualitative control results are recorded in the list of samplers and dispensers, and the details of the results are recorded in the quality control results of the samplers.
10- Repairs:
If the device needs to be repaired with the opinion of the technical manager, the work service will be removed and the support company will be notified to repair it. The results of the operation are also recorded and maintained in the equipment repair history form.
Required formulas:
∑ (x– mean) 2
SD = Ö n - 1
CV = SD / mean × 100
% Bias = Expected Value - Observed Value × 100
Expected Value
