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How to calibrate micropippete?


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#1 teddytariku

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Posted 02 May 2010 - 10:29 PM

HI Friends,

I am thinking to calibrate micropippetes, but I don't have the basic knowledge to do it. Is any one can tell me what materials do I need and How I can do it OR suggest a website?

Any help is appreciated!

Thanks

Edited by teddytariku, 03 May 2010 - 02:40 AM.


#2 Prep!

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Posted 02 May 2010 - 10:35 PM

HI Friends,

I am always thinking t calibrate our my micropippetes, but I don't have the basic knowledge to do it. Is any one tell me what materials do I need and How I can do it OR suggest website?

Any help is appreciated!

Thanks


The best way to do it is by weighing water!!
more accurate measurements require to monitor the air pressure and all... but the basic validation of the pipette can be done by weighing water on the weighing balance considering the density of water to be 1. make sure u use pure water (Type I) or else the salts present in it will make the readings faulty. The main thing to take care is that the balance shud be too sensitive. Normally people use dmetler balances for calibration prupose!!
hope this helps... and if i remember right thermo site has a calibration page where the details are given!!
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#3 gebirgsziege

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Posted 02 May 2010 - 10:52 PM

If you want to "permanently" calibrate the pippetts, you should have a look at the manual (which you should be able to find online as well) as the procedure differs depending on the brand of pippetts. Often there are special tools to calibrate which make things much easier.

For the calibration process itself I agree with Prep, use pure water, the most precise balance you can find and weight the volume until you have the correct volume for at least 3 times in a row. Best would be to let somebody else try as well BEFORE you calibrate! You would not belive how different the volumes pippetted can be depending on the person working!
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#4 Prep!

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Posted 02 May 2010 - 10:56 PM

If you want to "permanently" calibrate the pippetts, you should have a look at the manual (which you should be able to find online as well) as the procedure differs depending on the brand of pippetts. Often there are special tools to calibrate which make things much easier.

For the calibration process itself I agree with Prep, use pure water, the most precise balance you can find and weight the volume until you have the correct volume for at least 3 times in a row. Best would be to let somebody else try as well BEFORE you calibrate! You would not belive how different the volumes pippetted can be depending on the person working!


actually yes... a calibrated pipette according to one user can be completely out of sorts wen another one tries!!!! and make sure there is no air trap during the measurement. that will give wrong readings as well.. so use a hollow vessel rather than a wide one to aliquot the liquid!!
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#5 almost a doctor

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Posted 03 May 2010 - 12:35 AM

This is what we do in my lab (copied from the SOP). Hope it helps! :)

1. Record the temperature of the lab, using the thermometer situated next to the balance.
2. For volumes less than 200無 use a 1.5mL eppendorf as the receptacle for weighing, with a starting volume of 500無.
For volumes equal to and greater than 1000無 a 10mL falcon tube must be used, with a starting volume of 4mL.
For volume less than 30無 a 200無 PCR reaction vial should be used, with a starting volume of 50無.
3. Pipette the starting volume as listed above and seal the receptacle.
4. Place the sealed receptacle on the balance and tare the balance.
5. Remove the receptacle from the balance, pipette the test volume into the receptacle, then read and record the weight.
6. Repeat steps 3 and 4 above until 5 individual measurements are obtained.
7. The % accuracy can be worked out by the following:
(Mean value obtained/volume measured *100)-100 = X%.
For example: using a P1000 pipette at the bottom range of 200痞.
Mean value of (200.8/200 *100)-100 = 0.4%
8. The percentage precision can be calculated as follows:
(Standard deviation of measurements/mean value obtained)*100 = Y%
For example: using a P1000 pipette at the bottom range of 200痞.
Mean value of (21/200.8 *100) = 10.45%

#6 Prep!

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Posted 03 May 2010 - 01:19 AM

This is what we do in my lab (copied from the SOP). Hope it helps! :)

1. Record the temperature of the lab, using the thermometer situated next to the balance.
2. For volumes less than 200無 use a 1.5mL eppendorf as the receptacle for weighing, with a starting volume of 500無.
For volumes equal to and greater than 1000無 a 10mL falcon tube must be used, with a starting volume of 4mL.
For volume less than 30無 a 200無 PCR reaction vial should be used, with a starting volume of 50無.
3. Pipette the starting volume as listed above and seal the receptacle.
4. Place the sealed receptacle on the balance and tare the balance.
5. Remove the receptacle from the balance, pipette the test volume into the receptacle, then read and record the weight.
6. Repeat steps 3 and 4 above until 5 individual measurements are obtained.
7. The % accuracy can be worked out by the following:
(Mean value obtained/volume measured *100)-100 = X%.
For example: using a P1000 pipette at the bottom range of 200痞.
Mean value of (200.8/200 *100)-100 = 0.4%
8. The percentage precision can be calculated as follows:
(Standard deviation of measurements/mean value obtained)*100 = Y%
For example: using a P1000 pipette at the bottom range of 200痞.
Mean value of (21/200.8 *100) = 10.45%


this is exactly what we do in our lab too!!!
just one correction that % accuracy shud be (Mean value obtained/volume measured *100) as
(Mean value obtained/volume measured *100)-100 will give inaccuracy or error % in other words. Please correct me if i m wrong!!
I say that as 0.4% cannot be the accuracy. It shud either be the innacuracy or the error % :(
Support bacteria - They are the only culture some people have!!!
Cheers!!!




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