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Specialty Chemistry Forums => Nuclear Chemistry and Radiochemistry Forum => Topic started by: mayphd on March 26, 2009, 06:43:36 AM

Title: Half life
Post by: mayphd on March 26, 2009, 06:43:36 AM

Hi All,

I am not from a chemistry background, so please bear with me.  I am trying to find half-life values for (H+, CO2, HCO3, lactate )
I've got half-life values by searching in the litreture:
Hydrogen : 12.32 years, CO_2: 100 years, lactate: 60 minutes after exercise.  However I couldn't find half-life values for bicarbonate (HCO3) though I got one for NaHCO3 (100 hours in plasma).  Does any one have any ideas the rate of decay of HCO3, and if the above half-life values are relevant in a human cell? 

Many thanks for your help,

M

Title: Re: Half life
Post by: Borek on March 26, 2009, 07:55:59 AM

I think you are miximng different half-lifes from different processes, you can't do that. Same substance in different situations will have different half-lifes.

What it is what you are really looking for? What do you need these half-lifes for?

Title: Re: Half life
Post by: mayphd on March 26, 2009, 10:05:35 AM

Thanks for replying.

I am trying to mathematically model pH regulation in a biological cell.  For this, I want to know whether : H+, CO2, HCO3 and lactate decay as time proceeds, so that I can include a decay term for each differential equation.  I have been looking in the web for their half-life values but didn't get standard ones that are in a normal functioning cell. 

"Same substance in different situations will have different half-lifes."
Borek, does this mean that the half life for a substance inside the cell is different than that outside? Is there even data available to account for intra- and extra- half-lives?

Any guide or reference is much appreciated.

Title: Re: Half life
Post by: gippgig on March 26, 2009, 05:03:46 PM

Radioactive decay has a (nearly) constant & generally well known value but this is unrelated to what you are trying to do.
The half-life of a compound in a cell relates to undergoing chemical, not nuclear, change. Biological half-lives vary, often wildly, depending on the type of cell (even different normal functioning cells can have very different properties) & outside conditions. Since cells actively regulate their pH it cannot be modeled as a passive process based on constant half-lives.
Your question relates to biological, not nuclear, chemistry. Try a biological chemistry forum.