Science Buddies: "Ask an Expert"

How can I accurately measure the amount of quercetin in a specific fruit and the amount of curcumin in a powdered spice?
Basically, I need to measure the amount of quercetin in a bunch of fruits using metric measurements if possible. Also, I need to measure the amount of curcumin in turmeric, cayenne, and other spices. It would be great if the cost of a method/system needed is low, and the measurements are accurate. Below are the methods I have already considered and deemed unmeaningful. I will update this from time to time. If I am not satisfied with a method shown in the replies, I will explain why to make it clearer to others.

Methods:

1) measure the volume of each fruit and multiply it by the mg/100g of quercetin found in a quercetin chart
Why this will not work for me: The data would not be as meaningful if I use existing data from the chart- because what would be the use of my experiment if I am looking at already existing data? I would immediately know the answer to my hypothesis, making the experiment invalid.

Hello SabreenAlam,

Quercetin is present in small amounts (less than 0.2%) in many fruits and vegetables. And the quercetin is only one of a huge number of other chemicals that comprise these foods. To measure the amount of quercetin in one of these mixtures the quercetin must be separated from the other chemicals. Once separated, the amount of quercetin can be quantified. Both of these steps can be accomplished with a high-performance liquid chromatograph equipped with a UV detector. An on line search on “quercetin analysis methods” produced quite a few articles describing analyses that use this technique.

Curcumin is present in tumeric (3 to 5%) and other spices. It is one chemical of many that comprise these spices. As with quercetin, the curcumin must be separated from the mixture before the amount present can be quantified. An online search of “curcumin analysis methods” produced several articles on the use of high-performance liquid chromatography.

Unfortunately this is not something you could do in a typical high school lab. Your best bet may be to contact a university or commercial lab and ask if they can help with the analyses you want for your project.

I hope this helps. Please ask again if you have more questions.

A. Norman