Ascorbic Acid In Fruit Juices Research Articles

Multifunctional N, Fe-doped carbon dots with peroxidase-like activity for the determination of H2O2 and ascorbic acid and cell protection against oxidation.

Multifunctional N, Fe-doped carbon dots (N, Fe-CDs) were synthesized by the one-step hydrothermal method using ferric ammonium citrate and dicyandiamide as raw materials. The N, Fe-CDs exhibited peroxidase-like (POD) activity by catalyzing the oxidization of 3,3',5,5'-tetramethylbenzidine (TMB) to the green oxidation state ox-TMB in the presence of hydrogen peroxide (H2O2). Subsequently, based on the POD activity of N, Fe-CDs, an efficient and sensitive colorimetric method for the detection of H2O2 and ascorbic acid (AA) was established with a limit of detection of 0.40 µM and 2.05 µM. The proposed detection method has been successfully applied to detect AA in fruit juice, vitamin C tablets, and human serum samples and has exhibited excellent application prospects in biotechnology and food fields. Furthermore, N, Fe-CDs also showed a protective effect on the cell damage caused by H2O2 and could be used as an antioxidant agent.

A fluorescence “turn-on” sensor for ascorbic acid in fruit juice and beverage based on ascorbate oxidase-like activity of citric acid-derived carbon dots

Citric acid-derived carbon dots (CA-CDs) without any modifications were found to have the ascorbate oxidase (AAO)-like activity. The CA-CDs have high affinity for ascorbic acid (AA), which is similar to natural AAO. The robustness of CA-CDs is greater than that of AAO. Based on the AAO mimetic activity of CA-CDs, a sensitive turn-on mode and natural enzyme-free fluorescence detection method has been developed for AA in some fruit juice and beverage samples with satisfied recoveries. This study provides CDs-based AAO mimetic nanozymes to replace the expensive natural enzymes or heavy metal-based nanozymes, which will show great potential in biological and food assays.

Disposable three-dimensional graphene oxide electrode with sandwich-like architecture for the determination of ascorbic acid in fruit juices

This work reports the development of a three-dimensional graphene oxide structure on the screen-printed electrode surface for the detection of ascorbic acid. This electrode was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, RAMAN spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The present work also investigated the electrochemical behavior of ascorbic acid and its electrooxidation mechanism on the three-dimensional graphene oxide surface. The detection of ascorbic acid was conducted by linear scanning voltammetry in the concentration range from 1.0 × 10−5 to 1.0 × 10−2 mol L−1, and the limits of detection and quantification obtained for the proposed electrode were 3.4 × 10−6 and 1.1 × 10−5 mol L−1 (n = 3), respectively. The device also exhibited excellent selectivity, repeatability, reproducibility and stability. The methodology developed was applied for the determination of ascorbic acid in grape and orange juice samples with an accuracy rate ranging from 99% to 105%. These results show that the proposed electrode can be safely and reliably applied for the monitoring of ascorbic acid in fruit juices.

An off-on fluorescent probe based on graphene quantum dots intercalated hydrotalcite for determination of ascorbic acid and phytase

A new off-on fluorescent probe was successfully synthesized and used to detect ascorbic acid and phytase. The composite material of hydrotalcite and graphene quantum dots were synthesized through citrate intercalated hydrotalcite using hydrothermal carbonization method. The layered structure of hydrotalcite can prevent the aggregation and promote the uniformity of graphene quantum dots. The off-on fluorescent probe detection mechanism is as follows. Fe3+ ions were firstly added into the solution of the composite material, and the fluorescence was quenched. Then, ascorbic acid was added into the fluorescence probe system, which reduced iron ions and turned on fluorescence to realize the detection of ascorbic acid. In addition, the reaction of phytase and l-ascorbyl-2-phosphate can produce ascorbic acid, further achieving the purpose of phytase detection. The concentration of the analyte and the recovery of the fluorescence intensity show a linear relationship, the linear ranges were 5−300 μmol L−1 and 0.1–4 U mL−1 for ascorbic acid and phytase, respectively. The recoveries of the experiment were 96.3 %–103.1 % and 95.4 %–104.9 %, respectively. The fluorescence method has the advantages of fast, stable, high sensitivity and high selectivity, which has been successfully applied to the determination of ascorbic acid in fruit juice and phytase in feed.

Mix-Bricks and Flip-Lids: 3D Printed Devices for Simple, Simultaneous Mixing of Reactant Solutions.

Two types of 3D printed devices for simultaneous mixing of small volumes (e.g., 50-500 μL) of reactant solutions are described. One device (a "Flip-Lid") is a specially designed lid for commercially available 96-well plates, with which solutions in adjacent wells can be mixed by inversion. The other type ("Mix-Bricks") consists of two 3D printed parts: an interlocking "brick" that contains a selected number of wells of specified volume and a lid for mixing solutions in adjacent wells by inversion. In both cases, the lids contain transparent windows through which reactions can be visually monitored or recorded. The application of these devices to quantitative measurements was evaluated by use of an iodine clock reaction to quantify ascorbic acid in fruit juices and vitamin C tablets. A smartphone was used to record, via time-lapse video, the times at which color appeared as a function of ascorbic acid concentration, producing a linear calibration curve with time as the dependent variable. Up to 12 reactions, each involving four reactant solutions, were monitored simultaneously in a single device. Replicate measurements within a given device consistently yielded standard deviations of less than 5% RSD. Accuracy was evaluated by comparison of the vitamin C tablet results to those obtained by iodine titration and by HPLC-UV; all three methods were within 1.3% of the overall mean of 543 mg/tablet. These 3D printed devices thus show promise for simultaneous reaction monitoring in a wide variety of applications.

The effect of selected substances on the stability of standard solutions in voltammetric analysis of ascorbic acid in fruit juices

AbstractThe objective of the study was to identify suitable additives stabilizing standard solutions of ascorbic acid (AA) that would not cause interference in the analytical process with the use of voltammetry in the determination of the AA content in food products. In addition, the effect of various conditions of storage of selected fruit juices and drinks on the concentration of vitamin C was studied. The study demonstrated that AA degradation was inhibited the most effectively by tartaric acid and its optimum concentration was set to 200 mg L-1. Analysis of selected fruit juices stored in various temperature conditions confirmed that an elevation of temperature and extension of the time of storage caused a decrease in the content of vitamin C in the analyzed samples, while closing the packages caused a limitation of the changes in concentration of this vitamin. On the basis of literature data and of the results obtained in the present study it can be concluded that fruit juices should be stored at a temperature lower than room temperature to retain their nutritive value.

Determination of ascorbic acid in natural fruit juices using digital image colorimetry

This work proposes a procedure using digital image colorimetry for the determination of ascorbic acid in natural fruit juices. The method was established by measuring the color of the iron(II)-1,2 ortho-phenanthroline complex. The digital images obtained during the experiments were stored in JPEG format, and the region of interest (ROI) was submitted to decomposition in color values according to the RGB additive color model. However, the analytical procedure recommended the employment of the blue channel because it presented higher sensitivity than the red and green channels.The optimization of the parameters of the colorimetric reaction was performed employing a full two-level factorial design. The influence of the distance from the webcam to the cuvette on the sensitivity and precision of the method was also evaluated. This experiment, demonstrated that there was no significant difference between the slopes obtained in the calibration curves under the conditions studied.When utilizing the optimized conditions, the method allows the determination of ascorbic acid in fruit juices with limits of detection and quantification of 0.005 and 0.015 mg L−1, and precision expressed as the relative standard deviation of 1.2% for lemon juice with an ascorbic acid concentration of 24.8 mg/100 g. So, the procedure was applied for the determination of ascorbic acid in lemon, orange, grape, cashew, lime, pineapple, tangerine and mango natural juices. The concentrations found varied from 4.5 to 182.5 mg/100 g. The fruit juice samples were also analyzed by molecular absorption spectrophotometry using a classical method established using 1,2 ortho-phenanthroline. The results obtained were compared using the t-test, which showed that there was no significant difference between the ascorbic acid contents found by the two methods.

Flow-Injection Chemiluminescence Method for Sensitive Determination of Ascorbic Acid in Fruit Juices and Pharmaceutical Samples Using a Luminol-Cetyltrimethylammonium Chloride Reversed Micelle System.

A highly sensitive flow-injection (FI) method was developed for the determination of ascorbic acid using chemiluminescence (CL) based detection. This method involved the following processes: (1) reduction of tetrachloroaurate(III) in hydrochloric acid with ascorbic acid; (2) on-line extraction of the residual Au(III) with rhodamine B from the aqueous hydrochloric acid solution into toluene, followed by the separation of the Au(III)-containing organic phase from the aqueous phase through a microporous Teflon membrane in the flow system; and (3) the measurement of CL produced in a flow cell upon mixing of the extract stream of Au(III) in toluene with luminol in the reversed micellar medium of cetyltrimethylammonium chloride-water in 1-hexanol-cyclohexane, which was injected into a CL reagent stream. In this procedure, a reduction in the CL intensity occurred due to the addition of ascorbic acid to the Au(III) solution. The CL signal of Au(III) decreased with increasing concentration of ascorbic acid in the aqueous sample solution. The proposed procedure allowed the indirect quantitative determination of ascorbic acid in the range of 1.0 × 10-12 to 1.0 × 10-7 M with a correlation coefficient of 0.987 and relative standard deviation of 2.1% (n = 6) at 1.0 × 10-9 M. The proposed FI-CL methodology was successfully applied for quantitative determination of ascorbic acid in fruit juices and pharmaceutical samples.

Risk assessment of benzene in food samples of Iran's market

The concentration of benzene in ninety-eight collected food and drink samples (carbonated beverage, fruit juice, pickle, lime juice, mayonnaise and salad dressing, 16 samples from each) from Iran local markets were investigated using gas chromatography equipped with flame ionization detector (GC-FID). Moreover, the correlation of benzene concentration with sodium benzoate and ascorbic acid concentrations was assessed. Benzene concentration in carbonated beverages, fruit juices, pickle, lime juices, mayonnaise and salad dressing were 3.57 ± 1.70, 5.17 ± 3.63, 4.37 ± 2.24, 4.99 ± 0.54, 1.38 ± 0.87 and 1.47 ± 0.83 μg/L, respectively, being in all cases below the acceptable limit (10 μg/L) proposed by the World Health Organization (WHO) as a reference for drinking water. Benzene concentration exceeded the maximum tolerable limit in 12.5% of carbonated beverages and fruit juices (two samples from each). A significant correlation coefficient between the concentrations of benzene, sodium benzoate, and ascorbic acid in fruit juices, and levels of benzene, sodium benzoate in carbonated beverage samples was observed. To characterize the risk of exposure of urban and rural consumers of Iran (female in age group of 15–24 and male in age group of 25–64) to benzene in food and drink samples the Margin of Exposure (MoE) approach was applied revealing there is no severe concern regarding benzene intake through assessed food and beverages samples in Iran.

Silica-titania xerogel doped with Mo,P-heteropoly compounds for solid phase spectrophotometric determination of ascorbic acid in fruit juices, pharmaceuticals, and synthetic urine

BackgroundAscorbic acid is one of the most important vitamins to monitor in dietary sources (juices and vitamins) and biological liquids.ResultsSilica and silica-titania xerogels doped with Mo,P-heteropoly compounds (HPC) have been synthesized varying titanium(IV) and HPC content in sol. Their surface area and porosity have been studied with nitrogen adsorption and scanning electron microscopy, their elemental composition has been studied with energy-dispersive X-ray analysis. The redox properties of the sensor material with sufficient porosity and maximal HPC content have been studied with potentiometry and solid phase spectrophotometry and it has been used for solid phase spectrophotometric determination of ascorbic acid. The proposed method is characterized by good selectivity, simple probe pretreatment and broad analytical range (2–200 mg/L, LOD 0.7 mg/L) and has been applied to the analysis of fruit juices, vitamin tablets, and synthetic urine.ConclusionsNew sensor material has been used for simple and selective solid phase spectrophotometric procedure of ascorbic acid determination in fruit juices, vitamin tablets, and synthetic urine.Graphical abstractWe synthesized several silica-titania xerogels doped with Mo,P-heteropoly compounds, studied their properties, and designed the sensor material for solid phase spectrophotometric determination of ascorbic acid in fruit juices, pharmaceuticals, and synthetic urine.

Determination of ascorbic acid in pharmaceutical preparation and fruit juice using modified carbon paste electrode

Acrobic acid is key substance in the human metabolism and the rapid and accurate determination in food is of a great interest. Ascorbic acid is an electroactive compound, however poorly responded on the bare carbon paste electrodes. In this paper, brilliant cresyl blue and multi-walled carbon nanotubes were used for the modification of carbon paste electrode. Brilliant cresyl blue acts as a mediator improving the transition of electrons, whereas multiwalled carbon nanotubes increased the surface of the electrode. Both brilliant cresyl blue and multiwalled carbon nanotubes were added directly to the composite material. The electrochemical behavior of modified electode was determined in electrolyte at various pH, and the effect of the scan rate was also performed. It was shown that the electrochemical process on the surface of the modified carbon paste electrode was diffusion-controlled. The resulted modified carbon paste electrode showed a good electrocatalytic activity towards the oxidation of ascorbic acid at a reduced overpotential of +100 mV descreasing the risk of interferences. A linear response of the ascorbic acid oxidation current measured by the amperometry in the range of 0.1 - 350 µmol.L-1 was obtained applying the sensor for the standard solution. The limit of detection and limit of quantification was found to be 0.05 and 0.15 µmol.L-1, respectively. The novel method was applied for the determination of ascorbic acid in pharmaceutical vitamin preparation and fruit juice, and the results were in good agreement with the standard HPLC method. The presented modification of carbon paste electrode is suitable for the fast, sensitive and very accurate determination of ascorbic acid in fruit juices and pharmaceutical preparation.

Automatic Flow-Batch Approach Using CdTe Quantum Dots for Fluorescent Determination of Ascorbic Acid in Fruit Juices

This paper introduces, for the first time, the combination of the advantageous features of the automatic flow-batch system for implementing quantitative chemical analysis involving the use of quantum dots (QDs). For illustration, the combined QD-flow-batch system was applied for the fluorescent determination of ascorbic acid in fruit juices. Cadmium telluride (CdTe) QDs were selected in this work because they are the most commonly synthesized and used ones for the analytical applications. Water-soluble CdTe QDs were successfully produced using mercaptopropionic acid. The analytical method is based on the quenching effect produced by ascorbic acid on the fluorescence of CdTe. All calibration solutions were prepared in-line, and all analytical processes were completed by simply changing the operational parameters in the control software. The limit of detection and relative standard deviation were estimated at 3 μg L−1 and ≤1.4 % (n = 5), respectively. The accuracy was assessed through recovery test (97.9 to 103.1 %). The ruggedness of the method was assessed by comparison of the intra- and interday using the official AOAC method at a confidence level of 95 %. The proposed system presented satisfactory robustness, high sampling rate (69 h−1), and reduced chemicals consumption. Thus, the combination of flow-batch system and QDs is potentially useful as an alternative for other fluorimetric determinations.

A colorimetric probe for ascorbic acid based on copper-gold nanoparticles in electrospun nylon

We report on a colorimetric probe based on copper-gold alloy nanoparticles (NPs). The probe is capable of selectively detecting ascorbic acid (AA) as a result of the distance-dependent colour change of the nanoparticles immobilized in an electrospun nylon-6 nanofiber. The resulting white nanofibres undergo a colour change to blue as a result of the aggregation of the NPs induced by AA in the pH range 2–7. The probe is selective for AA even in the presence of dopamine, uric acid, saccharides, amino acids and certain organic acids. It covers the 1.76 x10−2 mg L−1 to 1.76 x105 mg L−1 concentration range, and exhibits a limit of detection of 1.76 x10−2 mg L−1 based on visual detection. Its application was demonstrated by the determination of ascorbic acid in fruit juices, urine, serum, and vitamin C tablets.

Determination of Ascorbic Acid in Commercial Juices, on a Modified Carbon Paste Electrode, by Using a Taguchi Experimental Design

In this paper, a simple and rapid analytical method development for ascorbic acid determination by using differential pulse voltammetry method on copper(II)-phthalocyanine carbon paste electrode is shown. For this, several parameters, such as copper(II)-phthalocyanine (gram)/carbon (gram)/Nujol (millilitre) ratio, supporting electrolyte, pH and some others have been studied. In order to know the copper(II)-phthalocyanine influence on voltammetry peak height, a comparison between the analytical behaviour of a chemically modified carbon paste electrode and a conventional carbon paste electrode was carried out. The experimental conditions have been optimised by means of the experimental design using the Taguchi methodology. The catalytic oxidation peak current showed a linear depending on the ascorbic acid concentration in the range between 0.88 and 10.03 mg L−1, with the detection limit of 0.55 mg L−1. The proposed procedure was successfully applied to the determination of ascorbic acid in fruit juices without previous preparation and was compared with HPLC method applied at the same samples previously filtered.

Scientific Opinion on the substantiation of health claims related to: flavonoids and ascorbic acid in fruit juices, including berry juices (ID 1186); flavonoids from citrus (ID 1471); flavonoids from Citrus paradisi Macfad. (ID 3324, 3325); flavonoids (ID

Scientific Opinion on the substantiation of health claims related to: flavonoids and ascorbic acid in fruit juices, including berry juices (ID 1186); flavonoids from citrus (ID 1471); flavonoids from Citrus paradisi Macfad. (ID 3324, 3325); flavonoids (ID

A New Spectrophotometric Method for the Determination of Ascorbic Acid Using Leuco Malachite Green

AbstractA new simple and sensitive and selective spectrophotometric method has been developed for the determination of ascorbic acid (AA) at trace level using a new reagent, leuco malachite green (LMG). AAreacts with potassium iodide‐iodate solution under acidic conditions to liberate iodine and the liberated iodine selectively oxidizes LMG to MG dye. The colour of the dye was measured at 620 nm. Beer's law is obeyed over the concentration range of 0.8–8 iμg μAA per 25 mL of final solution (0.032–0.32 ppm). The apparent molar absorptivity and Sandell's sensitivity of the method were found to be 2.98 × 105 l mol−1 cm−1, 0.0042 μg cm−2, and respectively. Statistical treatment of the experimental results indicates that the method is precise and accurate. The method is free from interference of common ions and many of the ingredients commonly found in pharmaceuticals. The reliability of the method was established by parallel determination against Leucocrystal violet (LCV) method. The method described was satisfactorily applied for the determination of AA in fruit juices, pharmaceuticals and biological samples.

A screening method for the determination of ascorbic acid in fruit juices and soft drinks

Abstract A simple and rapid liquid chromatographic method based on a new stationary phase Teknokroma, Tr-010065 Mediterranea sea18 (15 cm × 0.4 cm, id 3 μm), to determine ascorbic acid in beverages is reported. With the proposed method the samples were analysed by direct injection without a previous treatment. The total analysis time does not exceed 6 min. The method showed a good repeatability (RSD

Enzymatic methods in food analysis: determination of ascorbic acid

The feasibility and expediency of enzymatic methods application in food analysis is demonstrated by the example of ascorbic acid (AsA) determination in foods. Enzymatic determination of ascorbic acid is based on its action as a second substrate of horseradish (HRP) and peanut (PNP) peroxidases in the reactions of o-dianisidine (OD) and 3,3’,5,5’-tetramethylbenzidine (TMB) oxidation with hydrogen peroxide. The rates of the reactions are monitored spectrophotometrically by measuring the duration of the induction period on kinetic curves plotted in coordinates absorption-time. The proposed procedures are sensitive ( c L = 0.1 μM), simple, and rapid. The procedure using horseradish peroxidase and the reaction of TMB oxidation was used to determine ascorbic acid in fruit juices, milk and sour-milk products for babies’ nutrition.

A Prussian blue-based flow-through renewable surface optosensor for analysis of ascorbic acid

Ascorbic acid is determined by a simple Bead Injection Spectroscopy–Flow Injection Analysis (BIS–FIA) system with spectrophotometric detection. The sensor is based on the decrease of absorbance obtained (720 nm) when Prussian blue (PB) is reduced by ascorbic acid. Commercial available flow-cell (Hellma 138-OS) is used and an appropriate volume of homogeneous bead suspension of Sephadex QAE A-25 was injected to fill this flow-cell for each measurement. The chromogenic reagent (PB) is injected into the carrier and immobilized on beads. When sample is injected, reaching the bead surface where PB is sorbed, ascorbic acid converts it to Prussian white form, which is transparent, producing the discoloration of the detection zone. At the end of the analysis, beads are discarded by reversing the flow and instantaneously transported out of the system. The calibration graph was linear over the range 5.1×10 −6–6.8×10 −5 M. The detection limit and RSD (%) were 4.5×10 −7 M and 5.0%, respectively, using 800 μl of sample volume. This method is highly selective in the presence of other species that are normally encountered with the analyte. The sensor was applied satisfactorily to the determination ascorbic acid in fruit juices, pharmaceuticals, sweets and conservative liquids.

Multipurpose chamber for the implementation of gas diffusion, dialysis, solid-phase extraction and precipitation/dissolution in continuous flow analyzers

A multipurpose chamber capable of implementing a variety of continuous separation techniques is reported. The proposed module can be used in conjunction with flow manifolds coupled on-line to optical detectors in order to develop simple autoanalyzers for full sample pretreatment. The analytical applicability of such a device is discussed with specific regard to gas diffusion, dialysis, solid-phase extraction (SPE), and precipitation/dissolution techniques. Its versatility and simplicity are among the main advantages. Four different automated analyzers based on the use of the multipurpose chamber have been developed for monitoring of different quality control parameters of liquid food samples, namely, carbon dioxide in beer, ascorbic acid in fruit juice, caffeine in soft drinks and lactose, fat and protein in milk. The results obtained were compared with those provided by the existing alternatives for the same applications in terms of sensitivity and precision.