The concentration 15 ppb in water is equivalent to which μg/L?

The concentration 15 ppb in water is equivalent to which μg/L?

• A. 0.015 mg/L
• B. 15 μg/L
• C. 150 μg/L
• D. 0.15 μg/L

Answer: (B)

In water, concisely expressed, 1 ppb is essentially the same as 1 μg per liter. This is because 1 liter of water has a mass close to 1 kilogram, so a ratio of micrograms of solute per kilogram of solution (ppb) translates directly to micrograms per liter. Therefore, a concentration of 15 ppb corresponds to 15 μg of solute per liter, or 15 μg/L. For reference, since 1 mg = 1000 μg, 0.015 mg/L also equals 15 μg/L, which matches the same value.

In water, concisely expressed, 1 ppb is essentially the same as 1 μg per liter. This is because 1 liter of water has a mass close to 1 kilogram, so a ratio of micrograms of solute per kilogram of solution (ppb) translates directly to micrograms per liter. Therefore, a concentration of 15 ppb corresponds to 15 μg of solute per liter, or 15 μg/L. For reference, since 1 mg = 1000 μg, 0.015 mg/L also equals 15 μg/L, which matches the same value.