TY - JOUR
T1 - Development of a Digital Microscope Spectrophotometric System for Determination of the Antioxidant Activity and Total Phenolic Content in Teas
AU - Phansi, Piyawan
AU - Tumma, Pensri
AU - Thuankhunthod, Chutharat
AU - Danchana, Kaewta
AU - Cerdà, Víctor
N1 - Funding Information:
The support from Thepsatri Rajabhat University is gratefully acknowledged. This work has also been funded by the Spanish Ministry of Economy and Competitiveness and FEDER funds (project CTQ2016-77155-R).
Publisher Copyright:
© 2021 Taylor & Francis Group, LLC.
PY - 2021
Y1 - 2021
N2 - This work presents a simple, low cost, and portable spectrophotometer based on a digital microscope as a detector for the determination of the antioxidant activity and total phenolic content (TPC). The antioxidant activity was expressed as ascorbic acid equivalents (AAE) using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assay. The TPC value was measured using the Folin-Ciocalteu method. The color of the products was captured using a digital microscope powered through the USB output of a laptop. A digital microscope, held in a 3D printing device was used to take photos of the reaction product that was illuminated with the stable light source of the digital microscope. The pictures were analyzed for quantitation. For the DPPH assay, the developed method provided a working range from 0.6 to 6 mg L−1 of ascorbic acid with a limit of detection (LOD) of 0.2 mg L−1 and a relative standard deviation (RSD) of 2.2%. The TPC method provided a working range from 4.6 to 100 mg L−1 for gallic acid, with a LOD of 1.4 mg L−1 and a RSD of 1.3%. Results of the proposed system agree well with a conventional spectrophotometric method and have been successfully applied to measure the antioxidant activity and TPC of local Thai tea samples.
AB - This work presents a simple, low cost, and portable spectrophotometer based on a digital microscope as a detector for the determination of the antioxidant activity and total phenolic content (TPC). The antioxidant activity was expressed as ascorbic acid equivalents (AAE) using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assay. The TPC value was measured using the Folin-Ciocalteu method. The color of the products was captured using a digital microscope powered through the USB output of a laptop. A digital microscope, held in a 3D printing device was used to take photos of the reaction product that was illuminated with the stable light source of the digital microscope. The pictures were analyzed for quantitation. For the DPPH assay, the developed method provided a working range from 0.6 to 6 mg L−1 of ascorbic acid with a limit of detection (LOD) of 0.2 mg L−1 and a relative standard deviation (RSD) of 2.2%. The TPC method provided a working range from 4.6 to 100 mg L−1 for gallic acid, with a LOD of 1.4 mg L−1 and a RSD of 1.3%. Results of the proposed system agree well with a conventional spectrophotometric method and have been successfully applied to measure the antioxidant activity and TPC of local Thai tea samples.
KW - 2,2-diphenyl-1-picrylhydrazyl radical assay
KW - Antioxidant activity
KW - digital microscope
KW - spectrophotometry
KW - tea
KW - total phenolic content
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U2 - 10.1080/00032719.2021.1886304
DO - 10.1080/00032719.2021.1886304
M3 - Article
AN - SCOPUS:85100907566
SN - 0003-2719
VL - 54
SP - 2727
EP - 2735
JO - Analytical Letters
JF - Analytical Letters
IS - 17
ER -