September 24, 2021, 08:37:18 AM
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Topic: Question about dilutions  (Read 346 times)

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Offline Vodkaz

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Question about dilutions
« on: May 19, 2021, 06:45:47 AM »
Hello, I have to prepare a stock solution of 10 mg caffeine and 1 ml acetonitrile, from that stock I need to make some standards with concentrations: 1; 05; 0.1... and so on (mg/ml). It's clear that I have to calculate the concentration of stock but I'm not sure how to; it's important to say that density of caffeine is not given just volume of the vessel (2ml Eppendorf tube). What other calculations should I do in order to obtain the volume of the standards?.

Online Babcock_Hall

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Re: Question about dilutions
« Reply #1 on: May 19, 2021, 09:30:10 AM »
One does not need the density of caffeine in order to perform this calculation.  The standard formula for dilutions (C1V1 = C2V2) can be used, but in my experience students sometimes plug in wrong values.  My usual suggestion is to draw a picture, to avoid errors of this kind.
« Last Edit: May 19, 2021, 10:25:03 AM by Babcock_Hall »

Offline jeffmoonchop

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Re: Question about dilutions
« Reply #2 on: May 19, 2021, 01:26:04 PM »
The concentration of the stock is 10mg/ml, due to you dissolving 10mg into 1ml.

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