Ananya Paojinda a, Tanaporn Sribunpeng a,
Aumpika Kongsatjaviwat b, Nadia Mira Kusumaningtyas a,
Pichayaporn Nuihuaykaew a, Sittisak Phoolpho a,1, Thanthapatra
Bunchuay a, Wiboon Praditweangkum c, Rattikan Chantiwas a,*
a Department of Chemistry and Center of Excellence
for Innovation in Chemistry, Faculty of Science, Mahidol University, Rama VI
Rd., Bangkok 10400 Thailand
b Forensic Science Unit, Faculty of Science, Mahidol
University, Bangkok, Thailand
c Department of Chemistry, School of Science, King
Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520 Thailand
☆ This article is part of a special issue entitled: ‘PADs’ published in
Microchemical Journal.
* Corresponding author. E-mail address:
rattikan.cha@mahidol.ac.th (R. Chantiwas).
1 Deceased.
Abstract:
This study introduces a
stable and portable dry starch-KI paper sensor for detecting iodine vapor in
the headspace of a microwell plate, enabling sensitive quantification
of ascorbic acid (AA) in colored fruit and vegetable juices. The
method leverages the reaction between AA and potassium iodate (KIO3)
to generate iodine vapor, producing a strong colorimetric response upon
interaction with the starch-KI coating. The sensor maintains consistent color
intensity for up to 90 min, ensuring reliable on-site analysis. Uniformity
testing of 96-spot absorbance for 0.5 mM AA across three batches
(n = 3) yielded a mean absorbance of 0.264 ± 0.016 with a
%RSD of 6.1 %. Stability assessments at three AA concentrations produced
%RSD values of 9.4 %, 5.0 %, and 5.1 %, respectively. The
microwell plate format facilitates rapid analysis with minimal sample
preparation, effectively minimizing interference from juice color and matrix
effects. The sensor demonstrated a linear detection range of 0.1–0.75 mM
(r2 = 0.9942) with an LOD of 0.05 mM. Application to
fresh juice samples yielded a %recovery of 80–120 % (n = 13).
This approach addresses critical challenges such as stability, portability, and
matrix interference by effectively separating analytical signals from juice
pigments. With a high AGREE score of 0.7, reflecting strong alignment with
green analytical chemistry principles, this innovative method offers a
practical, eco-friendly solution for on-site AA quantification in nutritional
analysis.
KEYWORDS
Dry starch-KI paper
sensor; Ascorbic acid; Headspace colorimetry; Iodine
vapor; Juice analysis
Reference:
Paojinda, A.; Sribunpeng, T.; Kongsatjaviwat, A.; Kusumaningtyas, N. M.; Nuihuaykaew, P.; Phoolpho, S.; Bunchuay, T.; Praditweangkum, W.; Chantiwas, R. A portable and stable dry starch-KI sensor for headspace iodine vapor detection: A green approach for sensitive ascorbic acid quantification in colored juices. Microchemical Journal 2025, 210, 113009. doi: 10.1016/j.microc.2025.113009
