calibrated pipettes

Discussion in 'Alternative Processes' started by jbrodkey, Dec 2, 2003.

  1. jbrodkey

    jbrodkey Member

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    I got tired of measuring out drops of Pt and Pd so I ordered some 2cc calibrated pipettes from B & S. When I tried to use them today I found that 0 was at the top end and 2 cc near the pointy end with extra room to spare beyond that to the tip. I expected to have the calibration so that as I drew up the liquid It would tell me how much was in the pipette. I was wondering what other people use? I would need calibrations in 0.1cc. Thanks

    Jerry
     
  2. lee

    lee Member

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    why not just the pipettes to transfer the small amounts to a calibrated vessel? I have a very accurate vial and I just poke the pipette into the container and transfer the liquid to the other vial.

    lee\c
     
  3. Jorge

    Jorge Inactive

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    Pipettes are always like this, since you need to know how much you have put into the solution, not how much you have drawn into the pipette. If you want to know how much you have drawn use a syringe. In the US are a bit hard to get but those used for diabetic shots are great for measuring how much you have drawn and are calibrated in 0.1 ml.
     
  4. Donald Miller

    Donald Miller Member

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    I found a medicine dispensor at a local drug store. It is made of plastic and calibrated to 1/2 ml. Cost was something on the order of 3-4 dollars.
     
  5. Kerik

    Kerik Member

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    I've been using Pipettes like this for years - 1 ml, 2 ml, 5 ml, 10 ml. Once you get used to reading them 'backwards', they're a snap. Don't worry about the 'extra room' at the tip. Precision is more important than accuracy. Or do I have that backwards? At any rate, it doesn't matter if it's off as long as it's always off by the same amount, which it is.

    Kerik
    www.kerik.com
     
  6. jbrodkey

    jbrodkey Member

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    Thanks all. Jorge is right - One just puts 2cc into the pipette and then empties the amount that is needed. I was thinking backwards - putting the amount needed into the pipette and then emptying it - but pipettes aren't built that way....
     
  7. Michael Mutmansky

    Michael Mutmansky Member

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    Some pipettes are built "to deliver", by filling to the line, and then clearing out the pipette with a small puff of air.

    Others are not built TD, and you need to be clear which type you have if you want to be both precise and accurate!

    Regardless, develop a standard way to measure, and then be consistant, and it won't matter if you are not actually measuring an exact amount when you fill the pipette.

    Oh, if you're like me, you won't like the glass pipettes, and will eventually find plastic ones, so you never have to worry about breakage.

    ---Michael