A novel spot test based on digital images for determination of methanol in biodiesel

Soares, Samara; Torres, Ketheny G.; Pimentel, Eduardo L.; Martelli, Patrícia Benedini; Rocha, Fábio R.P.

doi:10.1016/j.talanta.2018.11.028

Cited by 28 publications

(15 citation statements)

References 13 publications

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“…23 It is important to highlight that the present study presents a sum of explanatory variables using only 2 PCs: 99.35% (obverse) and 98.55% (reverse) for R$100, and 99.75% (obverse) and 99.62% (reverse) for R$50. Although this study is more complex since it groups the banknotes (authentic and counterfeit) of the same value, it demonstrates that using the universal microscope accessory coupled to Photometrix ® (widespread application in the scientific middle) [24][25][26][27][28][29][30][31][32][33][34] provide greater confidence and robustness to the classification of banknotes.…”

Section: Resultsmentioning

confidence: 99%

Use of a Portable Microscope Combined with a Smartphone to Determine the Authenticity of Brazilian Banknotes and National Driver’s Licenses

Costa¹,

Vittorazzi²,

Barbosa³

et al. 2022

J. Braz. Chem. Soc.

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This study proposed using a portable microscope combined with a smartphone and application (PhotoMetrix® application) to evaluate the authenticity of Brazilian banknotes (R$50 and R$100) and national driver’s licenses (NDL) through image acquisition (Samsung S7) and chemometric treatment (principal component analysis (PCA)). Six regions of the banknote were analyzed: holographic band; lower and upper tactile regions containing the number referring to the value of the note; microprints above the effigy (obverse); and numbers and the surroundings of the animal formed by microprints (reverse). For NDLs, the regions were the following: the coat of arms of the republic; the state map with microprints; optical ink variation; distorted positive microletters with technical failure; negative guilloche; typographic numbering; micro letter wire; and region with line printing. For the chemometric study with Photometrix®, we selected a region of interest (ROI) of 32 × 32 and 64 × 64 pixels with autoscaled data using the channels red (R), green (G), blue (B), hue (H), saturation (S), value (V), lightness (L) and intensity (I). We obtained excellent results for differentiating banknotes and NDLs, both by visual and chemometric analyses (PCA). This study demonstrates the effectiveness of using a portable microscope and a smartphone as a portable forensic tool that is fast, robust, low-cost and reliable.

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Section: Resultsmentioning

confidence: 99%

Use of a Portable Microscope Combined with a Smartphone to Determine the Authenticity of Brazilian Banknotes and National Driver’s Licenses

Costa¹,

Vittorazzi²,

Barbosa³

et al. 2022

J. Braz. Chem. Soc.

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“…Another interesting application of spot tests is found in the field of quality control of new eco-friendly vehicle fuels, the so-called biofuels, obtained from more sustainable sources. A series of methods has been proposed in recent years, which are based on combining spot tests and smartphone digital image evaluation [ 260 , 261 ].…”

Section: Spot Tests In Practice: Past and Present Of This Classical Methodsmentioning

confidence: 99%

Spot tests: past and present

Doménech‐Carbó

2021

ChemTexts

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Graphic abstract Microchemistry, i.e., the chemistry performed at the scale of a microgram or less, has its roots in the late eighteenth and early nineteenth centuries. In the first half of the twentieth century a wide range of spot tests have been developed. For didactic reasons, they are still part of the curriculum of chemistry students. However, they are even highly important for applied analyses in conservation of cultural heritage, food science, forensic science, clinical and pharmacological sciences, geochemistry, and environmental sciences. Modern pregnancy tests, virus tests, etc. are the most recent examples of sophisticated spot tests. The present ChemTexts contribution aims to provide an overview of the past and present of this analytical methodology.

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“…A methodology for the determination of methanol in biodiesel by digital images was proposed by Soares et al 131 , and the procedure was based on the colorimetric oxidation reaction of methanol to formaldehyde and subsequent reaction with Schiff reagent. Methanol quantification was performed using the PhotoMetrix ® in the univariate module, and images were acquired with illumination and controlled distance, directly from the 1.5-ml polypropylene microtube, where the reaction was performed.…”

Section: Photometrix ®mentioning

confidence: 99%

“…Through the researches that used PhotoMetrix ® early presented, it is possible to visualize the versatility of this application, because it was used in different analysis, presenting significant results. It is possible to carry out direct analysis, 126,136 that is, without performing sample preparation, analysis of solid 120 and liquid samples, [131][132][133]135 with the use of chambers to store the samples, 121,124,125,129,134 or without lighting control accessories, 127 in addition to allowing the sample to be conditioned in different ways to capture images such as paper 122,123 and SDS-PAGE 128,130 for example. Figure 12 shows four different ways of acquiring images related to the previously presented articles that used Photo-Metrix app in their analysis, where in some works, chambers were made to capture images, and in others, the image acquisition was performed without light control.…”

Section: Introductionmentioning

confidence: 99%

PhotoMetrix and colorimetric image analysis using smartphones

Böck

Helfer

Costa

et al. 2020

Journal of Chemometrics

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The steady advances in technology employed in smartphones, coupled with the high availability and the ease access to these devices, increased the interest in applying it to analytical purposes. The main goal is to develop simple, fast, and low-cost analytical methods, generating immediate results. Different analytical strategies using smartphones have been proposed to identify or determine different analytes in a wide range of matrices. Some of them use the smartphone to capture the images, to process them, and to provide the analytical results. Others use this device just for image acquisition. In this context, this review aimed to relate previous works that used smartphones to acquire images for analytical purposes, with a special focus on PhotoMetrix application, which is a tool for chemical analysis. This application allows the decomposition of digital images acquired by smartphone cameras and to process them within the same device, allowing in situ chemical analysis.

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A novel spot test based on digital images for determination of methanol in biodiesel

Cited by 28 publications

References 13 publications

Use of a Portable Microscope Combined with a Smartphone to Determine the Authenticity of Brazilian Banknotes and National Driver’s Licenses

Use of a Portable Microscope Combined with a Smartphone to Determine the Authenticity of Brazilian Banknotes and National Driver’s Licenses

Spot tests: past and present

PhotoMetrix and colorimetric image analysis using smartphones

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