Smartphone-based Ellman’s colourimetric methods for the analysis of d-penicillamine formulation and thiolated polymer

Phadungcharoen, Noppharat; Patrojanasophon, Prasopchai; Opanasopit, Praneet; Ngawhirunpat, Tanasait; Chinsriwongkul, Akhayachatra; Rojanarata, Theerasak

doi:10.1016/j.ijpharm.2018.12.078

Cited by 31 publications

(14 citation statements)

References 33 publications

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“…−log 10 ( G / G 0 ) values showed the most obvious change corresponding to the nitrite concentration, whereas −log 10 ( R / R 0 ) and −log 10 ( B / B 0 ) showed negligible variations in their intensities with nitrite concentration. Thus, −log 10 ( G / G 0 ) values were chosen for further investigation with the Griess assay …”

Section: Resultsmentioning

confidence: 99%

Quantification of Nitrite in Food and Water Samples Using the Griess Assay and Digital Images Acquired Using a Desktop Scanner

Filgueiras¹,

Jesus²,

Borges³

2021

J. Chem. Educ.

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The Griess assay is widely used by regulation agencies as an official method for nitrite quantification in water and food samples. In Brazil, the official method, which has been used to determine nitrite in food, was described by Instituto Adolfo Lutz (283/IV) in 1984. It uses 8 mL of reactants and provides 50 mL (reactants plus sample) of waste per sample analyzed. Here, students scaled down the official method 50 times and quantified nitrite in water and food samples by using just 0.2 mL of the Griess reactant and 1 mL of sample. Quantitative analysis was carried out using absorbance measured at 540 nm (standard method) and 96-well-plate images (proposed method) obtained with a desktop scanner. The nitrite was extracted from solid food samples by heating it in a water bath. After heating, sample color and turbidity were eliminated by addition of K4[Fe(CN)6] and ZnSO4 solutions and filtering. During samples preparation, students evaluate the heating time effect in nitrite extraction from sausage samples using hypothesis tests. Students did a series of matrix matched samples to observe the matrix effect. Students also calculated the detection limit (DL) and the quantification limit (QL) for the proposed method (1.35 and 4.1 μmol/L nitrite, respectively) and for the standard method (1.1 and 3.4 μmol/L nitrite, respectively). DL and QL were determined using the standard deviation of the lowest concentration point on the standard curve. The major pedagogical value of this laboratory class was to scale down the official method and use it to prepare and analyze a solid food sample. As a learning model, finding real water samples, which have nitrite concentrations larger than method QL, was a hard task, but all sausage samples analyzed had larger nitrate concentrations than the method QL and nitrite quantification in sausages was a good learning model.

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Section: Resultsmentioning

confidence: 99%

Quantification of Nitrite in Food and Water Samples Using the Griess Assay and Digital Images Acquired Using a Desktop Scanner

Filgueiras¹,

Jesus²,

Borges³

2021

J. Chem. Educ.

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“… 18 Phadungcharoen et al, for instance, have conducted the Ellman’s assay via smartphone, providing an easy, fast, and reliable analysis of thiolated polymers without access to sophisticated equipment. 19 …”

Section: Chitosan: Its Chemistry and Thiolationmentioning

confidence: 99%

Thiolated Chitosans: A Multi-talented Class of Polymers for Various Applications

2020

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Various properties of chitosan can be customized by thiolation for very specific needs in a wide range of application areas. Since the discovery of thiolated chitosans, many studies have proven their advantageous characteristics, such as adhesion to biological surfaces, adjustable cross-linking and swelling behavior, controllable drug release, permeation as well as cellular uptake enhancement, inhibition of efflux pumps and enzymes, complexation of metal ions, antioxidative properties, and radical scavenging activity. Simultaneously, these polymers remain biodegradable without increased toxicity. Within this Review, an overview about the different possibilities to covalently attach sulfhydryl ligands to the polymeric backbone of chitosan is given, and the resulting versatile physiochemical properties are discussed in detail. Furthermore, the broad spectrum of applications for thiolated chitosans in science and industry, ranging from their most advanced use in pharmaceutical and medical science over wastewater treatment to the impregnation of textiles, is addressed.

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“…The mathematical transformation of R-, G-, and B-values to a logarithmic ratio (eq 1) improved the relationship between the analytical response and concentration, providing a linear standard curve with a better R 2 (Figure 5), compared with that plotted from untreated data (Figure 4). 62 In Figure 5, eq 1 provided the highest slope and R 2 , and it was used for further measurements. This was anticipated as the most complementary color channels should yield the most quantitative results.…”

Section: Standard Calibration Plotsmentioning

confidence: 99%

“…This was anticipated as the most complementary color channels should yield the most quantitative results. 16,21,30,38,62 For example, if a compound appears blue in solution, it probably absorbs red light.…”

Section: Standard Calibration Plotsmentioning

confidence: 99%

Using a Flatbed Scanner and Automated Digital Image Analysis To Determine the Total Phenolic Content in Beer

2019

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Here, students determine the total phenolic content in beers using the Folin–Ciocalteu assay. The Folin–Ciocalteu reagent is a yellow complex, in an alkaline medium; it reacts with phenols and non-phenolic reducing substances to form a blue complex. Quantitative analysis was carried out using absorbance measured at 765 nm (standard method) and digital images (proposed method). In the proposed method, samples were placed in a 96 microwell plate; then, a plate image was obtained with a flatbed scanner. The ImageJ plugin ReadPlate extracts red (R)-values from all wells of the scanned image at the same time; then, R-values were exported to a spreadsheet that converted these values to absorbances. Using absorbances obtained with R-values, the spreadsheet also provides standard calibration plots, limits of detection (LODs), limits of quantification (LOQs), and beer sample total phenolic contents. The proposed method and the standard method were compared using two-tailed significance tests; students observed that both methods provide equivalent results, that both methods were linear in a 2–10 mg L–1 gallic acid concentration range, and that both methods had close LODs and LOQs, 0.55 and 1.70 gallic acid mg L–1, respectively. Beer sample total phenolic contents were compared using one-tailed significance tests. This laboratory experiment provides an effective instrumental alternative to spectrophotometric methods, which can be especially beneficial, where purchasing and maintaining a spectrophotometer is a challenge, and it also presents to the students one-tailed and two-tailed significant tests.

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Smartphone-based Ellman’s colourimetric methods for the analysis of d-penicillamine formulation and thiolated polymer

Cited by 31 publications

References 33 publications

Quantification of Nitrite in Food and Water Samples Using the Griess Assay and Digital Images Acquired Using a Desktop Scanner

Quantification of Nitrite in Food and Water Samples Using the Griess Assay and Digital Images Acquired Using a Desktop Scanner

Thiolated Chitosans: A Multi-talented Class of Polymers for Various Applications

Using a Flatbed Scanner and Automated Digital Image Analysis To Determine the Total Phenolic Content in Beer

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