Parts Per Billion (ppb) represents the concentration of something in a sample. One ppb represents one piece of a whole divided into one billion pieces. In other words, one drop of oil in one billion drops of water (somewhere around 13,000 gallons) would be 1 ppb of oil in that water.

Parts Per Billion (ppb) can also be represented as Micrograms Per Liter (ug/l).

Click here for a more detailed explanation of Parts Per Million and Parts Per Billion (ppb).