In the series entitled "How You Rot & Rust" which is in other areas of this website, we introduce the concept of pH and its relationship to one's health. In this series we will show you how measuring the pH of body fluids like urine and saliva can help you assess the body's balance.
To recap, pH is the acronym for potential hydrogen. It is a measure of the degree of saturation of the hydrogen ion in a substance or solution.
From a mildly technical perspective, let's look at the molecule of water, H2O. H=Hydrogen and O=Oxygen.
If water and water is combined we get H2O + H2O => H3O + OH-
H3O (the hydronium ion+) is the acid element and OH- (the hydroxyl ion-) is the base or alkaline element. (You may also note that the +ion is a cation and the -ion is an anion as discussed in the section on Zeta Potential.) In pure water these are balanced and upon measuring with a pH meter the reading would be 7.
7 is neutral on a pH scale which goes from 0 to 14. This scale corresponds to the hydrogen ion concentration from 100 to 10-14 moles per liter. This is a huge range which sensitive instruments can measure.
When the H3O and OH- are out of balance a pH meter will detect this and the reading will move above or below 7. Like a teeter-totter, if one goes up the other goes down and vice versa.
In the human body a pH balancing act is continuously going on to maintain homeostasis. When defining measurement values of certain pH levels of human fluids, there are no absolutes that can be written in stone because the value that "should be here" has to be balanced against other values "that should be there". In essence, in the human body things never happen in a vacuum and you need to be ever mindful of these things as you make your measurements.