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Digital image colorimetry smartphone determination of acetaminophen

James, Heather; Honeychurch, Kevin C.


Heather James


Acetaminophen can be determined colorimetrically via its reduction of ferricyanide to give ferrocyanide. The ferrocyanide formed can then be converted to the highly colored compound, Prussian Blue, via the addition of iron(III). Quantification is commonly obtained by measurement of the absorbance of Prussian Blue at 700 nm using a commercial spectrophotometry instrument. In this present investigation we show the possibility of using the camera of a smartphone to record the blue color developed and, via subsequent use of a downloadable free App, undertake the analysis of the red, green, and blue (RGB) color components to quantitatively determine the concentration of acetaminophen present. A number of free Apps can be downloaded and used to measure the RGB balance of the color of the solution formed. Based on these values a calibration curve to determine the concentration of acetaminophen present can be constructed. This can be undertaken in a number of ways, as demonstrated here, from the red value, expressed as a percentage of the total RGB recorded (%R). From this simple mathematical normalization, it was found possible to obtain a linear relationship with (R2 = 0.994) over the concentration range 5-40 μM of acetaminophen. An associated limit of detection (LOD) of 3.3 μM was recorded. This was found to compare well with that obtained by UV-vis absorbance spectroscopy at 700 nm (R2 = 0.996; LOD 2.7 μM).


James, H., & Honeychurch, K. C. (2024). Digital image colorimetry smartphone determination of acetaminophen. Journal of Chemical Education,

Journal Article Type Article
Acceptance Date Nov 21, 2023
Online Publication Date Dec 13, 2023
Publication Date Jan 9, 2024
Deposit Date Nov 21, 2023
Journal Journal of Chemical Education
Print ISSN 0021-9584
Electronic ISSN 1938-1328
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Keywords Education, General Chemistry
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