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Measurement of sucrose concentration using Imbibition length on paper: A device for equipment-free and environmentally-friendly detection
(2024-04-01)
Sitanurak, Jirayu
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Kumpong, Anongnat
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Yaimai, Orawan
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Wilairat, Prapin
;
Teerasong, Saowapak
The Lucas-Washburn equation is commonly used to predict the distance (L) that a liquid travels through paper. This equation establishes that L2 is linear with time and inversely proportional to the viscosity of the liquid. However, there is currently no theoretical equation connecting the viscosity of a solution to its concentration. In this study, the imbibition flow of a sucrose solution was measured along the length of a horizontal strip of filter paper, featuring a printed, thermometer-shaped hydrophobic boundary. A sample (38 μL) was dispensed onto the bulb area, and the solution's flow was visually tracked using a red dye added to the sample. The imbibition length (L) was measured by a vernier caliper at 10.0 min after the sample addition. An empirical equation, based on literature values of the viscosity (η) and concentration (C) of sucrose solutions, was proposed. By integrating this empirical equation with the Lucas-Washburn equation, the following equation was derived: L = a⋅exp{-(bC + cC2)}, where ‘a’, ‘b’ and ‘c’ are parameters. This equation was fitted to the dataset of L and C, covering C values from 0 to 60 % w/w standard sucrose solutions, resulting in a coefficient of determination of 0.9987. The plot of L against C was observed to closely follow a linear line, with a fitting providing a coefficient of determination of 0.9986. The sucrose contents in samples, such as soft drinks, syrups, and sugarcanes, determined using the imbibition length method and conventional refractometry, were in statistical agreement via the paired t-test at the 95 % confidence level. This method is simple, instrument-free, requiring only a small amount of safe red food dye, and can be conducted on-site.
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Microfluidic paper-based analytical device for determination of sucrose in sugarcane juice using Benedict’s reagent
(2022-11-01)
Ratanawimarnwong, Nuanlaor
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Suksomphot, Vanlada
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Sornpipatpong, Khemika
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Lengwan, Supamit
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Donpudsa, Suchao
This work presents a microfluidic paper-based analytical device (μPAD) for the determination of sucrose using the Benedict’s test. An asymmetric dumbbell-shaped hydrophobic barrier was produced by rubber stamping the barrier pattern onto a laboratory filter paper. Hydrochloric acid and solution containing sucrose were successively deposited onto the sample reservoir of the μPAD attached to a glass slide. The device was placed in a plastic bag and dipped into boiling water for accelerating the hydrolysis of sucrose into the reducing sugars. Then the Benedict’s reagent was added at the narrow straight channel connecting the two circular zones of the μPAD, which was replaced in the plastic bag and heated again for reduction of Cu(II) by the reducing sugars. Precipitate of brick-red copper(I) oxide was formed. The image of the μPAD was recorded by a smartphone. The ratio of the red to blue intensities gave linear correlation with the concentration of sucrose in the range of 0.5–10% w/v. The relative standard deviation of the measurement was less than 5% for 2 and 4% w/v sucrose (n = 10), with limit of determination, calculated using standard deviation of regression divided by slope of calibration, of 0.26% w/v sucrose. The method was successfully validated using the dinitrosalicylic acid method for sucrose measurement. Percent recoveries of sucrose were evaluated using ten sugarcane samples. The recoveries were in the range of 89 to 101%, demonstrating that there were no significant sample matrix effects on the quantification.
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Simple and fast fabrication of microfluidic paper-based analytical device by contact stamping for multiple-point standard addition assay: Application to direct analysis of urinary creatinine
(2020-04-01)
Mathaweesansurn, Arjnarong
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Thongrod, Suthathip
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Khongkaew, Putthiporn
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Phechkrajang, Chutima Matayatsuk
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Wilairat, Prapin
In this work, a microfluidic paper-based analytical device (μPAD) for simultaneous multiple-point standard addition assay was fabricated by rubber stamping the hydrophobic barrier pattern onto a laboratory filter paper. The μPAD has a central zone from which an applied sample flows into eight surrounding narrow channels to which had been added the standard solutions. Each channel is connected to a circular area loaded with the reagent. The opposite end of this reagent zone is connected by second narrow channel to the final circular detection zone. The μPAD was applied to the measurement of creatinine in human urine. After addition of a urine sample, the orange-colored product arising from the Jaffé reaction is formed at the eight detection zones. A digital image of the μPAD is then recorded and the ratio of the red/green (R/G) intensity obtained using the ImageJ™ program is used in the quantitation of creatinine. The normal standard addition calibration line is constructed using the intensity ratio against the added creatinine concentrations (50–1000 mg L−1). Good linearity was achieved (r2 ˃ 0.99). There were no significant differences between the creatinine content using an HPLC method (paired t-test at 95% confidence, t<inf>stat</inf> = 1.78, t<inf>critical</inf> = 2.26, n = 10). The use of simultaneous multiple-point standard addition calibration allows rapid determination of creatinine in urine with elimination of matrix interference.
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Microfluidic paper-based analytical device for convenient use in measurement of iodate in table salt and irrigation water
(2020-01-01)
Duangdeewong, Chomphunud
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Sitanurak, Jirayu
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Wilairat, Prapin
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Nacapricha, Duangjai
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Teerasong, Saowapak
We report a convenient microfluidic paper-based analytical device (µPAD) for the determination of iodate. The µPAD was fabricated using an ink-stamp with a simple circle design. Colorimetric detection of iodate employs the oxidation of hydroxylamine by the iodate to generate nitrite which reacts with the Griess reagent producing an intense magenta color. The images were recorded by a digital camera, and converted to a green scale color intensity by ImageJ. Calibration of iodate was linear in the range of 50–400 mg L−1 with a detection limit of 38.1 mg L−1. With such a wide linear range, the method can be applied to various kinds of samples with the entire process completed in 50 s. Good precision of measurement was obtained (<2 %RSD). Iodate levels were determined using the µPADs in table salt and irrigation water samples. The measured concentrations of the samples correlated well with the values as found by the standard iodometric titration (no statistical difference at a 95% confidence level). The developed device is simple with easy fabrication and rapid operation. It is portable and cost-effective and therefore suitable for quality control of iodate levels in the manufacturing and agricultural industries.
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Simple and green method for direct quantification of hypochlorite in household bleach with membraneless gas-separation microfluidic paper-based analytical device
(2018-09-01)
Sitanurak, Jirayu
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Wangdi, Nidup
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Sonsa-ard, Thitaporn
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Teerasong, Saowapak
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Amornsakchai, Taweechai
This work presents development of a microfluidic paper-based analytical device (µPAD) for direct determination of hypochlorite in household bleach. The recent design of a membraneless gas-separation microfluidic paper-based analytical device (MBL-GS µPAD) was employed to fabricate the hypochlorite-µPAD. Chlorine gas is generated in the µPAD via acidification of an aliquot of sample loaded on to the donor reservoir located at the bottom layer of the μPAD. The liberated chlorine gas diffuses through the air space to oxidize iodide ion previously impregnated in the acceptor reservoir at the top layer of the μPAD, leading to formation of the brown color of the tri-iodide ions. Digital image of the brown zone was captured at exactly 5 min after loading the acid. Image J program is used for analysis of the image for quantification of the hypochlorite in unit of g Cl<inf>2</inf> L−1. It was found that employing a relatively large volume of the air space (ca. 270 µL) direct analysis of the high concentration of hypochlorite in the bleach was achieved without prior dilution. The method thus provides a linear working range of 25–100 g Cl<inf>2</inf> L−1, which is suitable for most commercial household products. The calibration line has a coefficient of determination of 0.999. The precision of measurements is 0.96% RSD and 0.30% RSD at 30 g Cl<inf>2</inf> L−1 and 80 g Cl<inf>2</inf> L−1 (n = 10), respectively. Using the paired t-test (P = 0.05, n = 8), the method agreed well with the iodometric titration method. Our μPAD for hypochlorite is portable and cost-effective. The method is also “green” since there is a significant reduction in use of reagents compared to other conventional methods.

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