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I am a 9th grader in Souderton school District in PA. I stumbled upon your website while searching for BPA testing. I am interested in testing BPA content in receipts from several stores around my area for my 9th grade science project. I am also interested in finding out whether BPA leaches more after using hand sanitizers. I am having a hard time figuring out how to test for BPA . Is there a way I can test for BPA without using blood/urine samples ? Is it possible to test for BPA content directly on the thermal papers? Your help is deeply appreciated in this matter.
Answer 1:

As you know, Bisphenol A (BPA) is a colorless small molecule and present in relatively low concentrations in plastics and dyes. It can have harmful effects on humans, particularly women and young children, even at those low concentrations because it mimics the hormone estrogen.

BPA can be detected directly from paper, plastics BPA dissolves more easily in alcohol, which is the primary component of hand sanitizers, than in water. You can extract BPA by soaking the thermal paper in alcohol. “Rubbing” (isopropyl) alcohol from the drug store or vodka (an ethanol/water solution) will work but ask your parents/teacher before seeking these out. To get BPA from your skin, you can swish your fingers in the solution for about 10 seconds. (This procedure was used in Biedermann, S., et al “Transfer of bisphenol A from thermal printer paper to the skin.” Anal Bioanal Chem 2010, 398, 571–576. doi:10.1007/s00216-010-3936-9).

Detecting BPA in that solution effectively and cheaply is a challenging problem and an area of active research. It is detected analytically using fluorescence – BPA absorbs 280nm light and emits strongly at 310nm. However, both of these wavelengths are in the UV range (invisible to the naked eye) and concentration will hard to quantify without a UV-sensitive spectrometer.

You may be able to detect BPA using chromatography, a technique that detects how a compound is drawn through a medium by a flow of solvent. (See this page for more information: orgchem ) This technique can be used to separate and identify BPA, but you’d need a way to see the BPA spot. If you use a fluorescent silica sheets (available in some Chem labs), the BPA will dampen the fluorescence of the sheet when present, so a dark spot will appear under UV light. However, many other organic compounds will appear as a dark spot, so this isn’t a definitive test for BPA. If you have pure BPA, you can compare how far it travels up the sheet to your unknown for a more confident identification.

To address this challenge, a research group at the National University of Singapore has developed a dye that complexes with BPA. When bound specifically to BPA, the dye turns bright orange, making it easier to detect BPA in the field. The stronger the orange color, the more concentrated the BPA in your sample. Unfortunately, this is dye is not commercially available yet. (Zhang, L., et al. “Orange alert: A fluorescent detector for bisphenol A in water environments.” Analytica Chimica Acta 2014, 815, 51–56. doi:10.1016/j.aca.2014.01.038)

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