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In this paper, a novel antioxidant analysis is proposed using a simple minimized device based on moving drops as solution handling and a smartphone as a detector. This approach is based on the colorimetric determination of the scavenging activity against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•), expressed as the half-maximal inhibitory concent...
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... from the assay for the percentage of DPPH • inhibition, the proposed platform can also be used for IC 50 , VCEAC, and TEAC values. More details are given in Table S1 (in the Supplementary Materials). ...Context 2
... IC 50 values of L-ascorbic acid, Trolox, and gallic acid are reported as the positive control and compared with the spectrophotometric method. The obtained sigmoid curves exhibiting the scavenging activity of positive controls are illustrated in Figure 2. A comparison between the proposed and reference method showed no statistically significant difference in the IC 50 values (as shown in Table 1) of the positive control and samples. Furthermore, the relative standard deviation (RSD) in triplicate was less than 5%, indicating that the proposed method is precise. ...Context 3
... IC50 values of L-ascorbic acid, Trolox, and gallic acid are reported as the positive control and compared with the spectrophotometric method. The obtained sigmoid curves exhibiting the scavenging activity of positive controls are illustrated in Figure 2. A comparison between the proposed and reference method showed no statistically significant difference in the IC50 values (as shown in Table 1) of the positive control and samples. Furthermore, the relative standard deviation (RSD) in triplicate was less than 5%, indicating that the proposed method is precise. ...Context 4
... the relative standard deviation (RSD) in triplicate was less than 5%, indicating that the proposed method is precise. Table 1, in accordance with other previous reports [24][25][26]. The sample throughput was 6 samples/h/platform for IC50 measurement, and the high-throughput operation was 60 samples/h/platform for VCEAC and TEAC. ...Context 5
... IC50 values of L-ascorbic acid, Trolox, and gallic acid are reported as the positive control and compared with the spectrophotometric method. The obtained sigmoid curves exhibiting the scavenging activity of positive controls are illustrated in Figure 2. A comparison between the proposed and reference method showed no statistically significant difference in the IC50 values (as shown in Table 1) of the positive control and samples. Furthermore, the relative standard deviation (RSD) in triplicate was less than 5%, indicating that the proposed method is precise. ...Context 6
... the relative standard deviation (RSD) in triplicate was less than 5%, indicating that the proposed method is precise. Table 1, in accordance with other previous reports [24][25][26]. The sample throughput was 6 samples/h/platform for IC50 measurement, and the high-throughput operation was 60 samples/h/platform for VCEAC and TEAC. ...Context 7
... sample throughput was 6 samples/h/platform for IC50 measurement, and the high-throughput operation was 60 samples/h/platform for VCEAC and TEAC. Table 1, in accordance with other previous reports [24][25][26]. The sample throughput was 6 samples/h/platform for IC 50 measurement, and the high-throughput operation was 60 samples/h/platform for VCEAC and TEAC. ...Context 8
... high-throughput operation was performed with 40 samples/h/platform. Molecules 2021, 26, x FOR PEER REVIEW 5 of 10 Table 1. IC50, VECAC, and TEAC of the positive controls and real samples. ...Context 9
... the application of DPPH • scavenging assay to Miang (fermented tea leaves) extracts using the proposed method, we obtained the IC 50 , VCEAC, and TEAC values compared to the reference method, as summarized in Table 1. Such antioxidant activity occurred from the antioxidant compounds in Miang that were reported in a previous work [29]. ...Context 10
... S5: Time-dependent of the inhibition percentage on 2,2-diphenyl-1-picrylhydrazyl radical by Miang extract sample No.2. Figure S6: Time-dependent of the inhibition percentage on 2,2-diphenyl-1-picrylhydrazyl radical by Miang extract sample No.3. Table S1: The parameters of the proposed method in comparison to the conventional spectrophotometric method and the previous method. ...Citations
... Smartphones can complement the conventional analysis equipment and methods [21]. With the growing interest in smartphones for chemical analysis, this approach can aid in examining the TPC of vegetable oils, similar to smartphone-based methods developed for estimating phenolics of a polar nature in aqueous and alcohol-derived extracts [22][23][24][25][26][27][28][29]. In addition to the analysis of the TPC, the applicability of a smartphone for the study of antioxidant activity, i.e., radical cation scavenging against 2,2 ′ -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and radical scavenging against 1,1-diphenyl-2-picrylhydrazyl (DPPH) of food products has been demonstrated [30]. ...
... Notably, there is a paucity of literature on the use of smartphone image analysis to quantify the TPC of vegetable oils. However, the observed TPC values utilizing spectrophotometer are consistent with those reported by Kalinowska et al. [23], indicating the TPC range from 0.4 to 15.4 mg GAE 100 g −1 oil. 0.05), thus indicating that there is no statistically significant difference between the TPC obtained using the two methods at the 95% confidence level. ...
... Notably, there is a paucity of literature on the use of smartphone image analysis to quantify the TPC of vegetable oils. However, the observed TPC values utilizing spectrophotometer are consistent with those reported by Kalinowska et al. [23], indicating the TPC range from 0.4 to 15.4 mg GAE 100 g −1 oil. Additionally, these data can be supported by observations made by Mikołajczak et al. [2], revealing the range of TPC in hemp oil from 2.45 to 267.5 mg GAE 100 g −1 . ...
This study addressed the need for a more accessible and efficient method of analyzing phenolic content in vegetable oils. The research aimed to develop a method that could be widely adopted by both researchers and industry professionals, ultimately revolutionizing the way phenolic content in vegetable oils is analyzed. This study developed a method of determining the total phenolic content (TPC) in vegetable oils using smartphone image analysis in the RGB color model. The method employed a gallic acid calibration solution and demonstrated exceptional determination coefficients for the RGB colors. The R—red color was selected as the basis for the analyses, and the method was statistically equivalent to standard UV/Vis spectrophotometry. The highest TPC was determined in hemp and olive oils, while the lowest was found in rice bran, grapeseed, and macadamia nut oils. This study concluded that smartphone image analysis, mainly using the R component of the RGB color model, was a superior alternative to traditional spectrophotometric methods for determining the TPC in vegetable oils. This innovative approach could revolutionize phenolic content analysis by providing researchers and industry professionals with a cost-effective, safe, and efficient tool. The estimated limit of detection (LOD) of 1.254 mg L−1 and limit of quantification (LOQ) of 3.801 mg L−1 further confirmed the reliability and comparability of the method. With these findings, it was expected that the method would be widely adopted in the future.
... Most of the mentioned studies used the RGB colour system as the basis for the analyses for the determination of antioxidant properties, however, Ledesma and Apichai used only the R or red colour spectrum for the determination of total phenols, justifying it with a very high detection coe cient R 2 = 0.9995, unlike G -green and B -blue lights. It was concluded that the coe cient of determination of the gallic acid calibration curve of the reference method using a spectrophotometer was slightly lower R 2 = 0.998 (p > 0.05) [12,13]. ...
... Only two of the eleven available studies were related to the determination of DPPH, where each of the researchers used drastically different systems. Autor Apichai used CMYK to characterize DPPH, while Nguyen used the RGB colour system, where both studies have concluded that there is no signi cant difference with the proposed smartphone and commercial UV-VIS spectrophotometer [13,14]. ...
In this research, a Python algorithm was developed that calculated one of the total concentrations of phenol in vegetable oils using the RGB colour system. The algorithm converts data obtained in the RGB colour system into absorbance values using NumPy, Pandas, Matplotlib and SciPy libraries. It allows for complex data calculations and analyses that are particularly accurate and more efficient than traditional methods such as MS Excel.
Algorithm development is divided into six stages: library import, user data input and processing, absorbance calculations, linear regression and calibration curve drawing, data analysis and saving results in Excel format. The algorithm offers flexible use in both local Python development environments and online platforms such as Kaggle (https://www.kaggle.com/).
It can also be used in the analyses of other plant extracts or chemical substances, where interpretations of RGB colour system data are used as a basis. This algorithm opens up new possibilities in scientific data analysis by taking advantage of modern technology and programming language.
... Color changes are analyzed using a scanner and imageJ software at the detection zone and are proportional to the concentration/activity of the antioxidants [78]. A simple minimized device based on moving drops as solution handling and a smartphone as a detector has been invented, basing on the reaction of DPPH • reduction [79]. ...
Assays of total antioxidant capacity (TAC) are popular in the analysis of food products. This review presents the most popular assays of TAC and their limitations, databases of TAC of food products, their application in clinical studies, and the effect of processing on the TAC of food. The importance of sample preparation for TAC assays and striking effects of digestion in the gastrointestinal tract on the TAC of food are discussed. Critical opinions on the validity of food TAC assays are considered. It is concluded that TAC methods can be useful as screening assays for food quality control and as low-cost, high-throughput tools used to discover potential antioxidant sources and follow changes in the content of antioxidants during food processing. However, effects revealed by TAC assays should be followed and explained using more specific methods.
... However, these alternative methods require specially designed equipment. Digital imaging, incorporating widely accessible smartphone cameras and image processing software, has recently become a choice of colorimetric analytical alternative sensing methods [21][22][23]. Using a digital color analyzer, "colors" are measured and converted into numerical values. ...
... By selecting a chemical reaction, a procedure can be developed for accuracy, precision, sensitivity, selectivity and sample throughput. The technique is useful to determine inorganic analytes such as calcium and magnesium in biodiesel [25] and organic species such as carbaryl residues in herbal medicines [21], formaldehyde in seafood [22] and antioxidant activity of Miang (fermented tea) [23]. The digital image colorimetric technique employing a scanner as a detector has been reported to determine manganese in water using mixed reagents 4-(2-pyridylazo)resorcinol (PAR) and poly(diallyldimethylammonium chloride) and a paper-based analytical platform [26]. ...
A sustainable downscaled procedure using smartphone-based colorimetric determination of manganese (Mn(II)) was developed. This novel Mn(II) determination procedure is proposed using a simple, available microwell-plate platform and a smartphone as a detector. This approach is based on the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by periodate using Mn(II) as a catalyst. The catalytic kinetics of Mn(II) under different conditions was investigated to determine the optimum condition where the different catalytic activities of various concentrations of Mn(II) evince. Under the optimum condition, the bluish-green product of oxidized TMB, proportioned to the concentration of Mn(II), was monitored using a smartphone camera, and the color signals were processed using ImageJ Software. The developed procedure showed great selectivity and sensitivity as linearity ranged from 1.8 × 10−6 to 4.6 × 10−5 M (0.1 to 2.5 μg/mL). The limits of detection and quantitation were 3.6 × 10−6 and 1.1 × 10−5 M (0.2 and 0.6 μg/mL), respectively. The determination of Mn(II) in freshwater samples was demonstrated to assess environmental water quality as an initial model to more easily promote water management according to the United Nations Sustainable Development Goals (UN-SDGs). The intensity of the red could be successfully applied to evaluate Mn(II) in canals and river water with no significant differences compared with the reference method of Inductively Coupled Plasma Optical Emission Spectrometry at a confidence level of 95%.
... In this work, only 2.5 µL of sample and reagents were used for the molybdenum blue reaction. Although smartphone colorimetric determination can be employed for liquid samples, the volume of the sample solution must be sufficient (≥ 60 µL) to detect changes in the transmittance [39][40][41]. Table 2 compares our proposed µPAD method with other paper-based methods for phosphorus determination. It can be seen that the detection limit of our work is higher than that of other methods. ...
A simple one-step drawing for the cost-effective fabrication of microfluidic paper-based analytical devices (µPADs) for the determination of phosphate content in water and fertilizer samples is presented in this paper. The hydrophobic barrier of µPAD was patterned using a 2-mm tip marker pen using a transparent acrylic sheet template. The molybdenum blue reaction using ascorbic acid as a reducing agent was used. A pre-concentration step of samples is proposed to improve the sensitivity of the measurement. The blue complex produced on the µPADs was recorded using a smartphone camera. The color intensities (red, green, blue and gray) were analyzed using ImageJ program. The proposed µPAD method provides a linear calibration range from 0 to 100 mg L-1 P. The limit of detection (LOD) was found to be 0.7 mg L-1 P with a precision of 3.1%RSD for 50 mg L-1 P (n = 10). The proposed method was successfully applied to the determination of phosphorus contents in water and liquid chemical fertilizer samples. The results obtained from µPAD agreed with a spectrophotometric method using paired t test at a 95% confidence level.
A green and sustainable downscaled procedure was developed to perform smartphone-based colorimetric determination of fluoroquinolones in extemporaneous syrup formulations. The procedure functioned by complexing fluoroquinolones with metal ions, the most suited of which is a ferric ion, to produce a colored product in a 96-well plate combined with smartphone detection and image processing. It performs on a microscale with 1 min detection time providing high throughput at 960 samples in triplicate/h/a well plate. Linear calibrations constituted the concentration of fluoroquinolones and the relative intensity of blue, yielding LODs (3.3σ) and LOQs (10σ) for ciprofloxacin, norfloxacin, ofloxacin and levofloxacin at 4.6, 8.3, 9.1 and 10.6 μg/mL and 14.0, 25.1, 27.5 and 32.0 μg/mL, respectively, (where σ served as the standard deviation of the intercept, divided by the slope of the linear calibration graph). The developed procedure was applied to real extemporaneous oral ciprofloxacin syrup samples. The results obtained by the developed procedure agreed with that of a standard method, with no significant differences at a confidence level of 95%. The developed procedure is aimed at real-world applications in assays for quality and stability of the extemporaneous formulations in community and health-promoting hospitals. This promotes health and well-being for individuals of all ages by ensuring that everyone gains access to quality essential healthcare services as well as safe, effective, high-quality and affordable pharmaceuticals.
