MadSci Network: Biochemistry
Query:

Re: I.V. vitamins must be reduced to pH close to blood, HOW?

Date: Fri Oct 23 02:51:37 1998
Posted By: Ewen McLaughlin, Lecturer, Chemistry, Swansea College
Area of science: Biochemistry
ID: 909002906.Bc
Message:

Blimey, Shaun, that's a really technical question!

You have two options, one based on theory and one based on making 
measurements. I'm going to recommend the latter.

In theory, you could find the pKa of each vitamin. The pKa is the pH at
which a compound is half-acidified. Now, pKa's are often available in
texts but you would have to establish values for each vitamin and
correct the values for temperature and salt concentration.

Done that? No, I wouldn't have thought so; especially as you now have
to calculate how much buffer to add by finding the pKa's of the buffer
components and using an equation first derived by Henderson and
Hasselbach (quite a well-known one that I won't quote here).

I hope that I have put you off the theoretical method!

I would get myself a pH meter, measure the pH of a vitamin sample, and
add buffer until the required pH was obtained. You might need to do this
for each new vitamin mixture but soon you should have a good book of
recipes for making the solutions correctly.

If you are lucky, the manufacturers of the vitamin and buffer vials should
be able to give you recipes - after all, their products are designed for this
sort of use, so why not ask them how to do it?

I hope that  this is helpful - I know it's not the answer you were after but
I spent many years making up solutions to a given pH and found that the
only reliable method is to use a pH meter. Calculations are always going
to give approximate results anyway.

Do get back to me if there are any other points you need answering!

Ewen McLaughlin


Current Queue | Current Queue for Biochemistry | Biochemistry archives

Try the links in the MadSci Library for more information on Biochemistry.



MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci


MadSci Network, webadmin@www.madsci.org
© 1995-1998. All rights reserved.