Glucose Concentrations in Coconut Water via Microplate Spectrometry and Digital Image Colorimetry
9
Issued Date
2025-09-09
Resource Type
ISSN
00219584
eISSN
19381328
Scopus ID
2-s2.0-105035413904
Journal Title
Journal of Chemical Education
Volume
102
Issue
9
Start Page
4095
End Page
4101
Rights Holder(s)
SCOPUS
Bibliographic Citation
Journal of Chemical Education Vol.102 No.9 (2025) , 4095-4101
Suggested Citation
Yimkosol W., Dangkulwanich M. Glucose Concentrations in Coconut Water via Microplate Spectrometry and Digital Image Colorimetry. Journal of Chemical Education Vol.102 No.9 (2025) , 4095-4101. 4101. doi:10.1021/acs.jchemed.5c00609 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/116242
Title
Glucose Concentrations in Coconut Water via Microplate Spectrometry and Digital Image Colorimetry
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Abstract
Comparison of analytical methods is an essential skill for undergraduate students in chemistry and related sciences. This work describes a colorimetric assay for glucose quantification using the glucose oxidase/peroxidase assay with o-dianisidine. Students also studied the specificity of this assay against fructose and applied it to determine glucose concentrations in an actual coconut water sample. Results were obtained using both standard microplate spectrophotometry (MPS) and digital image colorimetry (DIC) approaches. Both methods are high-throughput, requiring small amounts of reagents and data collection time; therefore, three replicates of experiments were possible in one 4 h laboratory session. The green of the RGB channels yields the highest sensitivity, as expected from a maximum wavelength of absorption of the produced chromophore of 540 nm, corresponding to the green region of light. Analysis of students’ results shows that the linear quantifiable range obtained by most groups is 6–100 μg/mL of glucose for the MPS and 7–100 μg/mL for the DIC. Notably, fructose did not produce a detectable colored product under the same assay conditions, highlighting the selectivity of the assay. The paired samples t-test showed no significant difference (p > 0.05) between glucose concentrations determined by the MPS and DIC methods across all samples, suggesting that the DIC method is a viable and accessible alternative for undergraduate teaching laboratories. This experiment provides an engaging quantitative learning experience of fundamental analytical chemistry concepts, including spectrophotometry, calibration curves, and statistical data analysis with an actual and relevant sample, while exploring practical applications in food and biochemistry.