2 calculation questions

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2 calculation questions

Postby newbie17425 » Dec 11 2017 8:34 pm


In the protocol that I am using it says, make a working concentration of 25 mM and while adding it to my solution of 10 ml, it says add 50 mg.
Can someone please explain how can I do this? i.e. after dissolving the powder to achieve a concentration of 25 mM, how can I use it at 50 mg? The molar mass is 185 g/mol
My antibody data sheet tells me that the concentration is 1.05 µg/µl. And I want to use the antibody at 1:750 concentration. Can you please tell me how can I convert the ratio to µg/ml or vice versa.

Thank you :)
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Re: 2 calculation questions

Postby relaxin » Dec 13 2017 12:25 pm

A 25 mM solution of a substance with MW of 185 will be 25 x 185 mg/liter. Since you have only 10 ml, you need to add 46.25 mg. The change in volume will be minimal. The addition of 50 mg instead of 46.25 mg will be close enough.

If you take 1 ul of the antibody and dilute to 750 ul (1:750 dilution), then the concentration will be 1.05 ug/750 ul = 0.0014 ug/ul or 1.4 ug/ml.
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