Why normal saline PH is acidic(5.5)?

Answer 1

It probably has to do with carbon dioxide in the air. The carbon dioxide dissolves slightly into the saline, and therefore makes it a little acidic. Some claim the PVC packaging can contribute as well. I don't know how well these hypotheses were tested, but they seem to make sense.

Clinically, it doesn't make a big difference. If you infuse large amounts of normal saline into a patient, you can get a hyperchlorermic metabolic acidosis, but the reasons for that aren't related to the starting pH of NS.

To the above poster-- I can't criticize your answer, that's how I would have thought prior to entering medicine. High school and college chemistry would predict a pH of 7.0 exactly as sodium ions and chloride ions are extraordinarily weak bases and acids. Thus, we would expect the pH to resemble the pKa of pure water, 7.0.

But, reality doesn't always agree with theory. Take a look at a bag of normal saline from the hospital. It gives the pH as 5.5 (actually part of a range). I don't think the manufacturers have broken pH electrodes.

Answer 2

Ph Of Normal Saline

Answer 3

Normal saline is actually more acidic than blood (pH 5.5 or so). Normal blood pH is 7.35-7.45. The reason that it is given is by tradition. Sometimes lactated ringers or plasmalyte is given which actually contains some HCO3 (a weak anion) that causes the pH to be somewhat more physiologic. There is actually a trend in medicine toward these fluids for resusitation fliuds for pH reasons. The negative is that plasmalyte contains potassium which could elevate potassium further in the face of renal failure.

Answer 4

It isn't

Your pH detection method is faulty or your sample is contaminated.