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# Treating cells with chemicals and how to dilute into medium

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### #1 kellyly

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Posted 26 March 2009 - 08:41 AM

Hi all,

Im wondering if anyone knows how to make up chemical solutions for treating cells in culture. Im using a compound with mol wgt 254.24g. If i want to add it to my cells at a concentration of 50nm, how would i calculate how much is needed, say for a 6well plate? I need to make it up in DMSO. DO i have to do serial dilutions or something? Sorry, its been a while since I've done these kind of calculations and its not coming easily to me so any help would be great!

Many thanks

### #2 gfischer

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Posted 26 March 2009 - 11:55 AM

Hi all,

Im wondering if anyone knows how to make up chemical solutions for treating cells in culture. Im using a compound with mol wgt 254.24g. If i want to add it to my cells at a concentration of 50nm, how would i calculate how much is needed, say for a 6well plate? I need to make it up in DMSO. DO i have to do serial dilutions or something? Sorry, its been a while since I've done these kind of calculations and its not coming easily to me so any help would be great!

Many thanks

I'd recommend making a high concentration stock solution that you can store in aliquots. Then, when you need to add it to the cells, add in the appropriate amount.
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### #3 bob1

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Posted 26 March 2009 - 03:50 PM

The equations you need are:

c= n/v where "c" is concentration, "n" is number of moles and "v" is volume

n=m/Mr where "n" number of moles, "m" is mass (in grams) and "Mr" is molar mass in grams per mole.

Ci*Vi= Cf*Vf where "i" stands for initial, and "f" stands for final, C and V are concentration and volume.

Remember to keep your units consistent - i.e. if you are working in uM then make all concentrations uM, it won't work if one concentration is in uM and the other in picoM. Use the Merck index or the product manual to tell you the solubility and storage limits for each compound, so that you don't try to dissolve too much at once.

Also, I think you mean that your compound has a mol weight of 254.24 g/mol, which a quick google search tells me is daidzein.

### #4 hjlrobson

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Posted 03 June 2009 - 01:20 AM

Hey, I find this website really useful, follow the link below. Near the bottom of the screen on the right hand side is a dilution and molarity calculator, then you just need to plug in your numbers and............hey presto!

http://www.tocris.com/index.php

Edited by hjlrobson, 03 June 2009 - 01:22 AM.

### #5 kellyly

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Posted 15 June 2009 - 06:11 AM

Hey, I find this website really useful, follow the link below. Near the bottom of the screen on the right hand side is a dilution and molarity calculator, then you just need to plug in your numbers and............hey presto!

http://www.tocris.com/index.php

Thats great thanks, helps a lot. It will be another 2wks or so until I have enough cells to plate and treat so Im just looking back on the calculations now to have them ready.

You never know i might be back! Hate this part of lab work

### #6 bob1

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Posted 15 June 2009 - 04:42 PM

A useful tip - even if you are using a calculator - is to look at the answer and see if you believe it. Working these sorts of things out in long form is often the best way to make sure, as you can check your working. Remember to keep your units consistent!