## Chemistry: The Molecular Science (5th Edition)

1 ppb = 1 part per billion= $\frac{1}{10^{9}}=\frac{10^{-6}}{10^{3}}= \frac{10^{-6}\,g}{10^{3}g}$ ( Multiplying and dividing by gram does not make any difference). Prefix for $10^{-6}$= micro or $\mu$ Prefix for $10^{3}$=kilo or k Then, 1 ppb= $\frac{10^{-6}g}{10^{3}g}=\frac{1\,\mu g}{1\,kg}$