# Thread: A little bit of help with diffusion rates PLEAASEE!

1. Hi,

Im a student currently in the field of Marine Biology and need a bit of help (have never used a forum so here goes, I'll try to include as much information as possible if there not enough apologise same as if there's too much).

I need to calculate the rate at which Acetylcholine (1x10^6 moles concentration) will diffuse out of Agarose.

I know that the Molecule radius of Agarose is 20.30nm, molecular mass of Acl is 146.2074 gmol-1 and I've also found (but seems like a massive number) this for the molecular weight of agarose 'The molecular weight assigned to non-degraded agarose is approximately 120 000. This weight has been determined by sedimentation measurements and it represents 400 agarbiose (or 800 hexose) units linked together.' The viscosity of the agarose is ≤1,500 cP, 10 %(80 °C)(lit.) and it would be diffusing into sea water.

Thanks if any one can help,

Carl Sorrell

2.

3. Sorry , No can help, I don't really even know what you are talking about.

4. Originally Posted by carlsorrell
Hi,

Im a student currently in the field of Marine Biology and need a bit of help (have never used a forum so here goes, I'll try to include as much information as possible if there not enough apologise same as if there's too much).

I need to calculate the rate at which Acetylcholine (1x10^6 moles concentration) will diffuse out of Agarose.

I know that the Molecule radius of Agarose is 20.30nm, molecular mass of Acl is 146.2074 gmol-1 and I've also found (but seems like a massive number) this for the molecular weight of agarose 'The molecular weight assigned to non-degraded agarose is approximately 120 000. This weight has been determined by sedimentation measurements and it represents 400 agarbiose (or 800 hexose) units linked together.' The viscosity of the agarose is ≤1,500 cP, 10 %(80 °C)(lit.) and it would be diffusing into sea water.

Thanks if any one can help,

Carl Sorrell
This sounds like a very tough thing to calculate. From a brief web search, I found quite a number of articles such as this: Size Effects on Diffusion Processes within Agarose Gels

that seem to suggest people resort to experimental measurement rather than calculation for such problems. But I am not an expert in this type of thing so I could be wrong.

5. Just run the gel.

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