Ask A Scientist Chemistry Archive

name         Mary L.
status       student
age          13

Question -   I am doing an experiment for a science fair in which I need to measure the electrolytes 
in fluids such as cranberry juice in order to find out which is best to rehydrate your body.  How do 
you measure electrolytes in a drink?
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This is not an easy experiment to do!! Electrolytes, in its most general definition is any substance 
that when it is dissolved in water causes the water solution to conduct electricity. There are 
dozens (maybe hundreds) of ionic compounds that fit that definition. When the term is used in the 
context of fruit juices, exercise beverages, and so on the implication is balancing out the levels 
of Na(+1), K(+1), Mg(+2), and Ca(+2) on the cation side and mainly the Cl(-1) and HCO3(-1), and to 
a lesser extent SO4(-2), and some organic anions. This is a vastly more complicated subject than 
just knowing the nominal amounts of the various ions present in the particular juice. Likewise the 
rehydration process is a complicated metabolic process that involves a lot more than just drinking 
the fluids. There are all sorts of osmotic processes going on also. Your project needs to be 
narrowed considerabely if you are going to have a chance to obtain any meaningful results.

Vince Calder
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