Potassium test

[Wilsoni]

I have a friend that works in the lab a the University of Utah who said he may be able to test my Potassium level. The test would give a readout in mmol/L. My question is, will this be an accurate test for Potassium in saltwater? If so, how can I convert this to ppm?

 

[JimWelsh]

It's not possible to know the potential matrix effects of saltwater without knowing what analytical method they would be using, but to convert mmol/L of K to mg/L ("PPM") of K, multiply by the atomic mass of K, which is 39.0983. NSW has about 10.45 mmol/L of K at 25C.