# insulin concentration for tissue culture - (Sep/03/2012 )

I'm will be culturing IEC-6 cells which require insulin. According to the ATCCwebsite, I need to add 0.1 Units/ml.

Can someone help me understand the mneaning of the units? How do I know the concentration required based on 0.1units/ml?

I bought 100 mg insulin (powder form) and it has a formula weight of 5733.5

-SF_HK-

Who did you get your insulin powder from? Have you had a look at the product info to see if they list the units per mg?

It seems like most suppliers that I just looked up (with good ol' google) provide their insulin powders at 27 units per mg.
Most list USP per mg and apparently a USP is essentially equal to an IU.

-leelee-

Thanks. I just checked and it says: 25.2 USP units/mg
The bottle insulin contains 100mg of powder
If the insluin formula weight is 5733.49
What conc of stock do I make and then to what conc do I dilute it to give me 0.1Unit/ml for 50ml culture medium

-SF_HK-

Unless I'm way off track here, the insulin formula weight is irrelevant for this calculation.
I think you might be confusing yourself and over thinking this?

There are 25.2 units/mg. And you have 100mg. So you have 2520 units in total.

You want 0.1 units/ml final concentration.

I would probably make a 100x stock, so you need 10units/ml

So how many ml do you dissolve your 100mg in to get 10units/ml?

2520 units/ 10 units = 252

So dissolve the entire 100mg into 252ml for your 100x stock

*disclaimer: I am TERRIBLE at calculations, maths etc etc and often (always) have someone check my calcs before proceeding, so hopefully someone will be on me in a flash if I'm wrong here!

-leelee-