Praditweangkum, Wiboon

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A simple and green approach for colorimetric ammonia determination by combining pervaporation with paper impregnated anthocyanins extracted from red cabbage
(2020-09-01)
Jongprakobkit, Jurairat
;
Wisaichon, Wannakan
;
Praditweangkum, Wiboon
This work reports on the development of a simple, green and inexpensive analytical method utilizing a microwell plate for ammonia determination by combining pervaporation with a paper-based colorimetric sensor. The method is based on the conversion of ammonium ions to ammonia gas by alkalinization of water samples using powdered calcium hydroxide. The generated ammonia gas diffuses freely across the headspace to a paper-based sensor impregnated with natural anthocyanins extracted from red cabbage using deionized water as a non-toxic solvent. The reaction causes the paper sensor to change color from pink to blue, and the sensor is then scanned on a flatbed scanner to quantify ammonia by correlation to the reflectance of the blue spot on the paper sensor. Under the optimal conditions, a working range of 1.00-25.0 mg N l-1 was obtained. The limit of detection and the limit of quantification were found to be 0.29 and 0.98 mg N l-1, respectively. The method was successfully applied for determining total ammonia in water samples with recoveries in the range of 89.6-110.5%. No significant difference was observed between this method and the phenate spectrophotometric standard method.
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A Microfluidic Paper-based Analytical Device for Simultaneous Measurement of Albumin, Creatinine and Uric Acid in Urine based on Standard Addition Method
(2024-01-03)
Wisaichon, Wannakan
;
Choengchan, Nathawut
;
Praditweangkum, Wiboon
This work describes a simple method for the simultaneous measurement of urinary albumin, creatinine and uric acid using a standard addition approach on a microfluidic paper-based analytical device (µPAD). Hydrophobic barrier of the µPAD was created by stamping indelible ink onto a filter paper. The µPAD was designed with a flower-liked configuration. After aliquoting urine to a central sample zone, the sample flowed to ten surrounding channels, namely “the inner channels”, where the blank (water) or standard solutions had been added. The inner channels were connected to circular reagent zones where reagents had been immobilized. Tetrabromophenolphthalein ethyl ester, alkaline picrate, and a mixed solution of ferric chloride and ferric cyanide were used as the chromogenic reagents for the colorimetric detections of albumin, creatinine, and uric acid, respectively. Each reagent zone was linked with a circular detection zone through a second channel, namely “the outer channels”. The blue-, orange-and greenish-blue colored products were observed in the detection zones for the measurement of albumin, creatinine, and uric acid, correspondingly. A digital image of the µPAD was captured with a mobile phone. The color intensities were evaluated by ImageJ™ and were employed for the quantitative analyses. The standard addition calibrations were found to be linear (r2 > 0.99) for the spiked analyte concentrations up to 100 mg L-1 albumin, 1000 mg L-1 creatinine, and 50 mg dL-1 uric acid. The paper platform provided high precision (RSD < 5 %) and good analytical recovery (91.8-109.7 %). Under paired t-test, the results obtained by the developed µPAD and the validating methods were not significantly different at 95 % confidence (albumin: t<inf>stat</inf> =-0.130, t<inf>cri</inf> = 3.182, creatinine: t<inf>stat</inf> =-0.133, t<inf>cri</inf> = 3.182, and uric acid: t<inf>stat</inf> = 1.119, t<inf>cri</inf> = 3.182).

Praditweangkum, Wiboon

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