How to detect BPA

[deleted-223443]

For my science fair, I am testing different types of water bottles (plastic and metal) to see if they leach off any BPA. Also on top off of the type of water bottle, I'm seeing how long I keep the water bottle in the sun affect the BPA levels. I am currently looking for ways I would test the water bottles for BPA. I was doing some research and found some ways to detect BPA and I found that you can use Iron III Chloride, a UV- vis spectrometer, and gas chromatography. Also I was thinking since the pKa for BPA is 9.73 and the pKa for pure water is 15.74 can't I just do a pKa measurement? I am not sure which way is the best and if there are any methods that I missed that you think I should use can you please tell me? Thank you so much!!! A fast response would be greatly appreciated!

[deleted-213494]

Hi ayushibanerjee,

Check out this post on the forum for reference:
https://www.sciencebuddies.org/science- ... =29&t=8578

Hope it helps!

[bradleyshanrock-solberg]

This is actually a quite challenging problem.

Briefly, the amount of BPA (or anything else) that leaches into water from a plastic or plastic-lined container is extremely hard to detect. It can still be harmful in such small quantities, but you need pretty sophisticated tools to even attempt the experiment, probably the assistance of a modern laboratory and an adult chemist.

When I first started with Science Buddies I was in a mentoring project with a young woman who wanted to simulate a water bottle left in the sun long enough to make the water taste bad. It turned out that even that quantity of impurity (an amount large enough to taste) still required lab tools well beyond what a high school chemistry lab could supply to do anything beyond a blind taste test. She managed to make a connection with a friend of the family who worked in a lab with the right tools and get the measurements done, so she had something to compare to her taste tests, but if you lack such connections, I regret to say you may wish to pick a different topic, as in this case you do not get the benefit of having an easily available alternative tool to use (the tongue of friends and family) in case you can not get access to the right kind of laboratory equipment.

[deleted-211965]

Hi,
I don't know much about the others, but I know a lot about the spectrophotometer. I assume you have one in your class? Anyway, a spectrophotometer is very useful and should serve very well for your experiment. Make sure you make sure the bottled water is distilled (it should be already); because any impurities in the water will also be registered by the spectrophotometer. Anyways, using the spectrophotometer would be a very simple way of measuring the amount of bpa particles in the water at a given time. To do this, you would need to take a random sample of the water in the bottle and transfer it into a cuvette to put into the machine. What a spectrophotometer does is it measures how much light is absorbed by a sample by shining a light on it. After taking into account the amount that is absorbed by the water - by inserting a blank, the machine calculates the difference; the additional amount of light absorbed is nm, which can then be converted to concentration; be warned though, since a cuvette is so small, measurements will be very small. Hopes this helps.

-Chris

[bradleyshanrock-solberg]

Chris, in the grade 6-8 level, it would be unusual to have a spectrometer available. The student would usually have to get access to either a well-equipped high school lab, a university lab or a private lab (ie from a company), so that adds to the difficulty of performing the test if they do not have the correct contacts. Start by asking the science teacher at your school what options he or she knows about if you wish to pursue this experiment.