The English term parts per billion (ppb to German "parts per billion ") stands for the number 10-9 and is sometimes used in the context of relative quantities, ie for specifying those content sizes, the proportions are.
Because billion not denote the same thing in English and American language usage, but recommended the IEC 1978 ppm, ppb, etc. not to be used. This considers that the international ISO standardization has joined.
Mixing ratio (ppbv, ppbw )
Moreover, in the literature occasionally following variants are used:
- Ppbv parts per billion by volume ( volume mixing ratio ) corresponds, Vol - %
- Ppbw parts per billion by weight (weight mixing ratios ) corresponds, by weight - %
The term ppb is often used in microelectronics, for example, when specifying a dopant or impurity concentration in the characterization of normal time, and in the chemical and environmental concentration and trace analysis.