Have you ever wondered if sports drinks are better for you than ordinary juice drinks?

Sports drinks are marketed as a way to replace electrolytes following exercise, but are they better at accomplishing this than common fruit juices?


The purpose of this project is to analyze common sports drinks for their electrolyte content and compare the results to the electrolyte content in common fruit juices.


If fruit juices were to be compared to sports drinks for electrolyte content, then orange juice would contain the most electrolytes.

Background Information

Sports drinks can be divided into three major types, which are Isotonic, Hypertonic, and Hypotonic. They are categorized by their concentration of electrolytes. Isotonic sports drinks contain similar concentrations of electrolytes as those found in the human body. Hypertonic sports drinks contain higher concentrations of electrolytes than what is found in the body and hypotonic sports drinks contain a lower concentration of electrolytes than what is contained in the body. Fruit juices, on the other hand, typically have higher concentrations of electrolytes compared to the human body, and would be considered a hypertonic beverage.

The concentration of electrolytes in bodily fluids depends on the balance between how much is present in food and drink, how efficiently electrolytes are absorbed in the stomach, and the rate at which they are excreted from the body. During exercise, we lose electrolytes primarily through perspiration, and the more that we sweat, the more electrolytes are lost. It's essential to replace the lost electrolytes after a long period of perspiration, and this can be accomplished by drinking beverages that contain high concentrations of electrolytes.

Most food and beverages contain some level of electrolytes. Electrolytes can be divided in cations (positively charged ions) and anions (negatively charged ions). Sodium and potassium are the main cations that the body requires and chloride is a required anion2. Electrolytes serve three general functions in the body, which include provision of essential minerals, control of osmosis of water between body compartments, and maintenance of the acid-base balance required for normal cellular activities. The body regulates the level of electrolytes, but when they become depleted due to excessive sweating, the following symptoms may develop: impaired performance, headaches, hallucinations, heat exhaustion, and heart and circulatory problems.

It is hypothesized that if orange juice is compared to sports drinks for electrolyte content, then orange juice would be found to have a higher electrolyte content. This hypothesis is based on the fact that oranges contain a high level of potassium, which is a key electrolyte for the body. Sports drinks contain potassium, but the level is typically lower than that found in orange juice and other common fruit juices.



Step 1 - Make conductance sensor

Electrode 1
1. Using the wire cutters, cut two pieces of copper wire to 6 inches in length.

2. Cut a 6 inch piece of plastic tube and thread the two wires through the tubing.

3. Remove 1 inch of insulation from the wires that were threaded through the tub and wrap them around the end of the tube being careful that the wires do not touch each other. Secure the wires to the plastic tubing with hot glue (figure 1).

4. Attach alligator clips to the opposite end of the wires and complete circuit as illustrated in figure 2.

*electrode 1 produced very low currents when analyzing beverages. Therefore, a second electrode was designed with a greater surface area to produce higher currents.

Electrode 2
1. Using wire cutters, cut two pieces of copper wire, each about 12 inches long.

2. Solder one end of both wires to a separate 1 inch galvanized washer and attach the opposite end of the wire to alligator clips.

3. Assemble the two washers on a nonconductive plastic tube leaving an ¼ inch gap between the washers (figure 4).

4. Attach alligator clips to the wires coming off of the electrode.

5. Attach one of the alligator clips to the positive terminal on a nine volt battery and the other electrode wire to the positive input on the multimeter.

6. Compete the circuit by attaching the negative terminal of the nine volt battery to the negative input on the multimeter (see figures 2 and 3 for a complete view of the circuit).

Step 2: Set-up test solution

1. Label clean plastic cups 1 through 11 which will serve as identifiers for the test solutions.

2. Add ½ cup of test solution to each plastic cup (all test solutions were at room temperature for the experiment).

3. Label 2 spare cups as wash solution and fill the cups completely with distilled water (These cups will server to wash the electrode between tests).

Step 3: Measuring the Conductance
1. Turn the multimeter to read direct current and set the range at the most sensitive setting of 200 microamps.

2. Place the conductance sensor in the distilled water making sure that it is completely immersed.

3. Allow the electrode to equilibrate for 5 seconds and record the current reading in a data table.

The conductance of pure distilled water should be 0 since distilled water doesn’t contain electrolytes. Distilled water serves as a negative control to ensure that the system is working properly and that the solutions are not being contaminated.

4. Next, test the conductance of each solution using the steps above to record the conductance. It’s important that the electrode be cleaned in between each assessment to ensure that the solutions are not being contaminated. Use distilled water to thoroughly clean the electrode between assessments and completely dry the electrode before immersing it in the next solution.

5. Once all test solutions have been tested once, repeat the entire process two more times so that there are three readings for each solution. Average all three readings and use the resulting average current to calculate the conductance for that solution. All current readings in this experiment are recorded in microamperes. Microamperes can be converted to Amps by dividing by 1,000.

6. Calculate the conductance by using the following equation.
G = I/V

• G is conductance, measured in Siemens.
• I is current, measured in Amperes
• V is the voltage, measured in volts (9 volts)

7. The resulting conductance was converted to Nano Siemens by multiplying the resulting value by 1,000,000,000.
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