Science Buddies: "Ask an Expert"

I'm a 9th grade honors physical science student and my question is, " Does the brand of sports drink have an effect on the amount of electrolyes in it and I plan to test this with a conductivity meter but I wanted an experts opinion. Any help is greatly appreciated.

Some things to consider when deciding on your methods of measurement of electrolytes in various sports drinks.

In your body, there are several major electrolytes, to include: bicarbonate, calcium, chloride, magnesium, phosphate, potassium, sodium and sulfate. Sports drinks usually attempt to reintroduce lost electrolytes during and after exercise by including either sodium chloride or potassium chloride in various amounts in the drink. The amount, per serving, should be included in the nutrition facts on the label. Now down to a potential issue with using conductivity as your measurement.

Potassium chloride and sodium chloride have sligtly different conductivity properties and depending on if the drink is potassium chloride based or sodium chloride based may skew your results.

Additionally, the conductivity method is more a measure of the total dissolved solids in a solution. In general, the more impure a solution is, the more conductive it will be following Kohlrausch's laws for dilute solutions. For example, sea water is around 5 siemens per meter (S/m) vs purified, deionized water around 5 micro-S/m (approximately 5 million times less conductive). Although the electrolytes will play a significant role, there is alot of other "stuff" in those drinks, such as protein, carbohydrates and flavorings that could induce additional error to the readings.

If you want to use the conductivity method, it may be useful to develop a baseline with sodium chloride and potassium chloride solutions so you can identify variations in the two. Also, if you have the ability, it may be more useful to get the sodium chloride and/or potassium chloride to precipitate out of the solution to be measured directly. More research would need to be done to figure out how to do that (perhaps evaporation).

Sounds like a fun project with lots of potential for expanded research. Hope this helps. Have fun.