Question: How to meassure plastics for BPA?

Ironman is asking a question about general
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by Ironman | December 29, 2021 23:10 | #28595

I would love to check different baby toys or things my child uses as a toy (TV control, bags, or anything else). Is there anything I could do to check it at home?

I thought about an Arduino with a NIR spectroscope.

Thanks for your help


A better approach would be Uv/ vis. Phenols, such as BPA, absorb at about 280 nm. So you would set up an extraction to pull out the BPA and run a UV/vis on it. The trouble is, there are many other additives to plastic compounds that can absorb in that same range. The usual way this is solved in industry is to do extractions and inject into a GC/MS. Hope this helps.

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There are some potential leads in this Twitter thread (screenshot below)


Thanks @liz and @sara for these!

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Please go to the web page mentioned. You will see that this test works by reacting the extract with iron (III) chloride. Many other materials will react with the same iron (III) chloride, giving false positives. Please use this as a screening test only. If BPA is detected, further confirming testing will be needed.

Thanks for this vital information @Ag8n!

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Thanks for all your answers and help. But solving all kind of plastics or swapping them with iron (III) chloride and having a high chance of false negative results is not ideal ;-)

I thought there is maybe an easy way with a self made spectroscope or a ready to use Arduino sensor.

Of course it doesn't need to be 100 % perfect but it should give results with a confidence of let's say 80 % whether there is BPA in that toy or not.

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The nir instruments are heavily used in agriculture. The company I worked for wanted to use Near Infra-Red (reflectance), also called NIRR, to determine the plasticizers present in PVC. The common methods used were GPC, soxhlet reflux, and other messy methods. The company selling the instrument came in to help us separate the individual components in the NIRR. This was with powdered samples. The major components were PVC, dioctyl phthalate, and epoxidized soybean oil. When dealing with the NIR, it's often overtones of the infra red being used. That can lead to interesting math. Some of the plots included first derivative and second derivative plots. While the math worked, there were intercompany problems. The instruments and methods never got used. That's just to give you an idea of what you may be dealing with. But, many people have gotten these type of instruments to work on this application. A starting point might be looking for NIR instruments and seeing how they can be simplified. Or looking at the NIR instruments used in agriculture. Good luck.

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