Expert: George Maxwell - 11/19/2007

Question
Hi there

I work in a hospital and we use various intravenous fluids.
I don't know why Normal saline(0.9% NaCl) and 5% dextrose are so acidic? (ph 5.5 and 4.5 respectively).

As far as I can see there are no acidic additives to either of these sterile solutions. I tried to contact Baxter but with no luck at all. Are they supposed to be intrinsically acidic? If so, why?

I appreciate your help.

Answer
Hi, and thank you for your uestion.

You're correct in saying that both saline and dextrose soltions are used at different pH's. Taking saline as an example - pure sodium chloride solution is neutral (pH 7). However, it's possible to add acid or alkali chemicals to the solution to change its pH. Your saline solution is probably described as "buffered" at some place on the pack or on the data sheet - this means that a small amount of a weak acid and weak acid salts have been added to maintain a constant pH. This is important  - the saline (assuming it is for intravnous use) will be going directly in to the bloodstream - any significant changes in pH could cause major circulatory problems.

A similar explantion applies to the dextrose, but becuse this is utilised by the body differently to the saline, its pH is optimised to the particular environment it will be found in.

Hope this helps.