PPM stands for parts per million. Concentration is expressed in parts per million and is numerically the same as milligrams of silver per liter of water (mg/l)
A colloid’s concentration is often expressed in terms of PPM. Parts per million, or PPM for short, is the measurement that states the mass of a chemical, metal, or contaminate per unit of volume of water. One PPM is equivalent to the absolute fractional amount multiplied by one million.
For instance, the following analogies may help you understand PPM better:
1 second in 11,5 days
1 minute in 2 years
In other words, PPM expresses how many milligrams of our colloidal particles are present for every litre of water. Therefore, a colloidal silver product of 10 PPM will have 10 mg of silver within one litre.
Effective working surface area
Many people assume that concentration is the best way to determine the quality of a colloidal product, however, this can be quite misleading if other factors are not taken into account. It is like looking at one part of the equation, but not the whole thing.
First, it is important to understand how the effective working area is defined and how it relates to concentration.
The effective working surface area is defined as the total surface area in centimeters (cm2) of all the particles in one milliliter (ml) of a colloid. It is important to note that partical surface area is inversely proportional to particle size, which means that with a constant concentration of particles, the surface area increases as the particle size decreases.
For example, if you have a colloidal solution that is 10 PPM and has a particle size of 1 nanometer then the total effective working surface area is 6 m2. If you have the same concentration of 10 PPM, but now the particle size decreases from 1 nanometer to 0,65 nanometers, then the total effective working surface area increases from 6m2 to 7,1 m2.
The particle surface area for colloids is an extremely important calculation because this determines the overall effectiveness of the product. Particle working surface area directly determines the colloid’s ability to react with its environment. Therefore, the higher the particle surface area the more effective the colloidal silver.
Furthermore, you will never find colloidal silver with a particle size smaller than 0.65 nanometer, because it cannot be made smaller. This is because it consists of the minimum number of atoms needed to form a particle. For silver that is 20 atoms.
You can calculate something yourself with the content of silver and particle size with the help of a tool that you will find under the chapter quality.