Optical evaluation of antioxidant activity: a comparison between a spectrophotometer and a homebuilt photometer.
1
Issued Date
2025-12-18
Resource Type
ISSN
25550403
eISSN
22671242
Scopus ID
2-s2.0-105031373436
Journal Title
E3s Web of Conferences
Volume
679
Rights Holder(s)
SCOPUS
Bibliographic Citation
E3s Web of Conferences Vol.679 (2025)
Suggested Citation
Luengviriya P., Kiatsommart K., Leelakanok C., Patumorathai S., Sibsiri K., Wangkham T. Optical evaluation of antioxidant activity: a comparison between a spectrophotometer and a homebuilt photometer.. E3s Web of Conferences Vol.679 (2025). doi:10.1051/e3sconf/202567901029 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/115593
Title
Optical evaluation of antioxidant activity: a comparison between a spectrophotometer and a homebuilt photometer.
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Corresponding Author(s)
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Abstract
The antioxidant activity of an orange peel extract is determined using a DPPH (2,2-diphenyl-1-picrylhydrazyl) solution. Sample absorption is measured with both a commercial spectrophotometer and a homebuilt photometer equipped with a 525-nm LED. Small, dried pieces of orange peel are extracted using 95% ethanol. Seven DPPH solutions with concentrations ranging from 0.1 to 0.4 mM are measured to establish calibration equations. For the spectrophotometer, absorbance exhibits a linear increase with DPPH concentration at both 517 nm (absorbance peak) and 525 nm (matching the LED in the photometer). In the homebuilt photometer, three piecewise linear fittings for concentration 0.1– 0.4 mM provide a better representation of absorption data compared to a single overall fitting across 0.1–0.4 mM. Different volumes of orange peel extract are added into the DPPH solution (0.4 mM DPPH after mixing) and stored in darkness for 30 minutes before the measurement. In both spectrophotometer and photometer analyses, antioxidant activity increases with the extract volume. Using spectrophotometer measurements as reference, the photometer with piecewise fittings produces significantly lower errors compared to those obtained with overall fitting.