we use parts per million, parts per trillion, but what about parts per billion?

[stewy14]

Why dont we use parts per billion?
@Randy Holmes-Farley

 

[Randy Holmes-Farley]

I rarely see parts per trillion used here. ppt in salinity is parts per thousand. Parts per trillion would be for trace elements at very low levels.

I use ppb fairly often, and is close to interchangeable with ug/L. ICP companies most often quote values in ug/L.

 

[DaJMasta]

ppb are very small, we do use them, but it's generally in ICP test results (and ICP OES isn't super accurate in that range). We don't actually use parts per trillion, though you're not the first person to think we do. ppt in terms of salinity is parts per thousand, there's a comparatively high portion of salt in the water, so the larger scale is used.

 

[Gribbles]

Why dont we use parts per billion?
@Randy Holmes-Farley

I see phosphate often measured in parts per billion. Also lots of the trace minerals, especially on ICP tests

 

[stewy14]

what about parts per gazillion? what would that be used to measure?

 

[jaayy]

Parts per billion (ppb) is definitely useful, might not just be often used as ppm and ppt. ppb is used as unit for smaller concentrations where it’s necessary to bridge gap between ppm and ppt, for more precise readings.

 

[Randy Holmes-Farley]

what about parts per gazillion? what would that be used to measure?

The size of Japanese science fiction monsters?