PPM (Parts Per Million)
A PPM is an abbreviation for parts per million, and it also can be expressed as milligrams per liter (mg/L). That means, we can say 1ppm or 1mg/L.
This measurement is the mass of a chemical element or compound per unit volume of solvent. That is why; Seeing the abbreviation parts per million or mg/L on an e-liquid ingredient concentration, base, way of preparation, or in a lab report means the same thing.
Finally, when it comes to Mathematics, a one part per million is equivalent to the absolute fractional amount of a particular substance multiplied by one million.