Potassium test

	Hello out there,

		I had noticed over the past couple of months that it was stated by
different people that  'we' don't have a way of testing for potassium in
water. I looked around
at our lab at work and I found a couple of different methods; one was using
an Atomic Absorption
unit( we don;t have the right bulb for this test though), the other was
using the Hach
	The spectrophotometer test is the Tetraphenylbotrate method and measures
up to a
concetration of 7ppm. I am wondering  if anyone has heard of this type of
potassium test and if so
is it the kind of test that would give the information an aquarist would be
looking for. I have not had 
the opportunity to run this test as we do not test for potassium in our
process. I can however, get the 
necessasry reagents to do the test , but it will takea bit of doing.
	So, before I go to the trouble of getting the reagents, is this test
likely to give the information 
we can use or would I be wasting my time??

								Paul. Lesniak