1. Concentrations

2. Part Per Hundred Represented by the percent (%) symbol 1 part per 100 parts 1 part in 10 2 A value of 1 × 10 -2 Equivalent to about 15 minutes in one day Prefix: centi Symbol: c

3. Part Per Thousand 1 part per thousand should be spelled out in full and not as “ppt” Represented by the permille (‰) symbol. 1 part per 1,000 parts 1 part in 10 3 A value of 1 × 10 -3 Equivalent to about 1 ½ minutes in a day Prefix: milli Symbol: m

4. Part Per Million 1 part per million (ppm) 1 part per 1,000,000 parts 1 part in 10 6 A value of 1 × 10 -6 Equivalent to about 32 seconds out of a year Prefix: micro Symbol: 

5. Part Per Million A liter of water weighs 1,000 grams, and a milligram is 1/1,000 th of a gram Therefore, a milligram of a substance dissolved in a liter of water represents one millionth (1,000 divided by 1/1,000) of the weight, or one part per million (1 ppm) One drop of water is 2 ppm of a bathtub full of water

6. Part Per Billion 1 part per billion (ppb) 1 part per 1,000,000,000 parts 1 part in 10 9 A value of 1 × 10 -9 Equivalent to about 3 seconds out of a century One drop of water is 1 ppb of a swimming pool full of water Prefix: nano Symbol: n

7. Part Per Trillion 1 part per trillion (ppt) 1 part per 1,000,000,000,000 parts 1 part in 10 12 A value of 1 × 10 -12 This is equivalent to about 3 seconds out of every hundred thousand years Prefix: pico Symbol: p

8. Part Per Quadrillion 1 part per quadrillion (ppq) 1 part per 1,000,000,000,000,000 parts 1 part in 10 15 A value of 1 × 10 -15 Equivalent to 2 ½ minutes out of the age of the Earth (4.5 billion years) Prefix: femto Symbol: f

9. Practice Problems 1.How much is 6 ppm in ppb? 2.What concentration is 4,000 ppt in ppm? 6 1,000,000 1,000 6,000 1,000,000,000 6,000 ppbx== 4,000 1,000,000,000,000 1,000,000 0.004 1,000,000 0.004 ppm ÷ = =