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How to test caffeine in coffee

Updated July 20, 2017

Many coffee drinkers prefer decaf coffee due to high caffeine sensitivity. However, the decaffination process does not eliminate all caffeine, resulting in varying levels of caffeine in a cup of decaf coffee. That is why many people chose to test their coffee in order to determine how much caffeine is still present. For these people, it is important to learn how to properly test the caffeine level in coffee.

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  1. Buy D+CAF caffeine testing strips at any local supermarket, natural food store, or online. These strips are relatively inexpensive and are able to quickly determine, with 98 per cent accuracy, the caffeine level in coffee. These strips are the easiest way for consumers to test the caffeine content of coffee.

  2. Measure six ounces of the coffee you wish to test. The strips are optimised to measure for 20 milligrams (mg) of caffeine in exactly six ounces of fluid.

  3. Place the strip into the coffee and let it sit for a while. Allow the strip to fully soak in the coffee.

  4. Remove the strip from the coffee once it has sufficiently soaked. Be careful to not touch the side of the tip that was soaking in the coffee. It may still contain excess liquid that is extremely hot.

  5. Examine the strip. If the "D" line is darker than the "C" line, the coffee does contain more than 20mg of caffeine. But, if the "C" line is darker than the "D" line, the coffee does not contain more than 20mg of caffeine.

  6. Retest the coffee if you are unable to determine whether the "D" or "C" line is darker. This is highly unlikely, due to the accuracy of the test, but a retest will be able to answer any doubts that may arise.

  7. Tip

    Always test your coffee if you are sensitive to caffeine. Many decaf coffees served at coffee shops do in fact contain high levels of caffeine when compared to regular decaf.


    Caffeine is a stimulant and can cause adverse side effects, such as abnormal heart rhythms, anxiety, irritability, restlessness and nausea, at high levels. Do not consume high levels of caffeine if you have type-2 diabetes, are pregnant or a senior.

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Things You'll Need

  • D+CAF testing strips

About the Author

Pranav Reddy started writing professionally in 2010. He has written automotive, society, culture and science articles for various websites. Reddy is pursuing his Bachelor of Science in molecular biology and neuroscience at the University of Colorado, Boulder.

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