Determination Of Ascorbic Acid Research Articles

Colorimetric and Fluorescent Determination of Alkaline Phosphatase and Ascorbic Acid based upon the Inner Filter Effect using up-Conversion Nanoparticles

A novel fluorescence and colorimetric dual probe based upon the inner filter effect (IFE) is reported to selectively and sensitively determine alkaline phosphatase (ALP). First, up-conversion nanoparticles (UCNPs) were prepared via a facile hydrothermal method and characterized by transmission electron microscopy (TEM), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), and zeta potential. Under near infrared (NIR) excitation at 980 nm, the prepared nanoparticles emit green light at 541 nm. The absorption band of p-phenylenediamine (PPD) overlaps the emission of UCNPs, which effectively quenches the fluorescence of UCNPs. However, ascorbic acid (AA) generated from the reaction of ascorbic acid 2-phosphate (AAP) and ALP impedes the oxidation of PPD and the fluorescence is restored. Based on this change, a “turn-on” sensor was used to determine AA and ALP with the limits of detection of 2.49 μM and 0.018 U/L, respectively. The constructed assay was applied to determine ALP in serum and the recoveries were from 93.3% to 101.3% with a relative standard deviation from 1.1% to 3.3%. A facile and efficient approach is reported for the determination ALP and offers a theoretical basis for the related diseases.

Voltammetric Detection of Ascorbic Acid at Organic Conducting Polymers Electrodes and Flow Injection Analysis

In this paper, a sensitive and rapid modified electrode for the determination of Ascorbic Acid (AA) is proposed. In this study, active compound AA was determined from commercial drug form based on electrochemical oxidation properties at various conducting polymer electrodes by voltammetric methods. Electrodes modified by the electrodeposition of conducting organic polymers such as poly(3-methylthiophene, PMT), polypyrrole (PPY) and polyaniline (PAN) were used as chemical sensors for voltammetric analysis and flow injection detection of AA. The electrochemical behavior of AA at conducting polymer electrodes was compared and the effects on behavior of electrolyte type and its pH and the film thickness were systematically examined. The results showed that the proposed modified surface catalyzes the oxidation of AA. Electrocatalytic efficiency decreases in order of PMT > PPY > PAN. Voltammetric peak positions were affected by the nature of the electrolyte and its pH. Also, the effect of increasing film thickness was to observe increased peak heights for oxidation potential of AA. The best results for the determination of AA were obtained by DPV in Na2SO4 (pH 2.0) and PMT electrodes. Polymer coated electrodes were also used in an amperometric detector for flow injection analysis of AA. The responses of the polymer electrode were 5–15 times larger as compared to those of bare platinum. PMT showed improved performance as an amperometric detector for flow injection analysis systems over other types of polymer electrodes. Detection limits as low as 1×10−9 M were achieved using the PMT, compared to 1×10−6 M using platinum electrodes.

Sulfonic-functionalized poly (dimethylsiloxane) network electrode for simultaneous determination of ascorbic acid, dopamine, and uric acid

Sulfonic-functionalized poly (dimethylsiloxane) network electrode for simultaneous determination of ascorbic acid, dopamine, and uric acid

Determination of ascorbic acid at solid electrodes modified with L-cysteine

Gold and glassy carbon electrode surfaces were modified with L-cysteine, and the electrochemical behavior of ascorbic acid (AA) was investigated on these new surfaces. To improve the efficiency of electrodes, the electrode surfaces were modified and optimum conditions for AA determination were established. Electrochemical experiments were performed at different potential ranges, the concentration of AA, scan rates, number of polymerization cycles and pH values. Using cyclic voltammetry (CV) technique, optimum conditions were determined as the potential scanning range of 0.2 to 1.5 V vs. Ag/AgCl in 0.1 M phosphate buffer solution (pH 7.02) for the L-cysteine/Au electrode, and -1.95 to 1.9 V vs. Ag/AgCl in 0.1 M phosphate buffer solution (pH 2.7) for the L-cysteine/GC electrode. For the characterization of both modified electrode surfaces, a series of physicochemical techniques was also applied. The usability and selectivity of these two proposed modified electrodes for the determination of AA were investigated using square wave voltammetry (SWV) in the presence of possible interferents, i.e., glycine, L-glutamic acid and uric acid.

Ratiometric Electrochemical Determination of Ascorbic Acid Using a Copper Nanoparticle@Resin Nanosphere (CuNPs@RNS) Modified Glassy Carbon Electrode (GCE) by Differential Pulse Voltammetry (DPV)

Ascorbic acid (AA) determination is of high importance in the diagnosis and treatment of diseases. Herein, we report a new ratiometric electrochemical sensor for ascorbic acid using a glassy carbon electrode (GCE) modified with a copper nanoparticle@resin nanosphere nanocomposite (CuNPs@RNS). The ratiometric strategy was established by immobilizing an internal reference (thionine) on the modified electrode using cyclic voltammetry (CV). The performance of the modified electrodes as well as the newly established ratiometric strategy was explored. The sensing platform had good electrocatalytic ability, reproducibility, and stability. In addition, the ratiometric strategy significantly improved the performance of electrochemical sensing with a wide linear range (0.0837 to 15.5 μM) and a low detection limit of 0.0279 μM under the optimal conditions. The original ratiometric electrochemical sensor was successfully applied to monitor ascorbic acid in tablets and urine. These results showed that the sensor provides a new strategy and broad prospects for biomolecular sensing with reliability and high sensitivity.

High-sensitivity integrated detector with nanostructured hydrogel electrode for ascorbic acid determination

This paper proposed a novel integrated detector with nanostructured hydrogel electrode (IDNHE) for ascorbic acid detection. The electrochemical detector was integrated on printed circuit board (PCB). The IDNHE employed the nanostructured multi-walled carbon nanotubes/polyaniline/polyvinyl alcohol (MWCNTs/PANI/PVA) hydrogel as the working electrode. The PVA hydrogel can not only effectively combine the PANI and substrate through hydrogen bonds, but also greatly improve the stability and durability of the detector. MWCNTs were used to fabricate the nanostructures, increasing the surface area of electrode. The detection mechanism is based on the redox reaction of PANI with ascorbic acid. The detection limit and the sensitivity of IDNHE were 0.9 μM (S/N = 3) and 161.46 mA·μM−1·cm−2, respectively. Moreover, IDNHE has a satisfactory reproducibility (RSD = 1.43 %), repeatability (RSD = 2.35 %) and long-term stability for 90 days. Therefore, this work undoubtedly provides a considerate choice for the lab on a chip, and further a promising application prospect for developing the portable real-time monitoring device.

Microwave prepared nitrogen and sulfur co-doped carbon quantum dots for rapid determination of ascorbic acid through a turn off–on strategy

A simple and eco-friendly microwave method was applied for the preparation of highly fluorescent nitrogen and sulfur co-doped carbon quantum dots (NS-CQDs) and used for the determination of ascorbic acid (ASC) in pharmaceutical dosage forms. The prepared NS-CQDs had bright blue fluorescence at a maximum emission wavelength of 440 nm, after excitation with 350 nm, with a quantum yield of 62.5 %. The developed NS-CQDs were prepared from citric acid and l-cysteine in one minute. The native fluorescence of NS-CQDs was quenched by ferric ions due to the formation of non-fluorescent CQDs/ Fe3+ complex. The quenched fluorescence could be restored by the addition of ASC due to the reducing properties of ASC which converts Fe3+ to Fe2+. The method was found linear over the concentration range of 2.0–100 μg/mL, with a limit of detection was 0.6 μg/mL and a coefficient of determination of 0.9965. The proposed method was cross-validated and statistically compared with a reported HPLC method. The results indicated that the developed method was greener, according to the analytical eco-scale and the green analytical procedure index (GAPI). The prepared NS-CQDs were used for spectrofluorometric determination of ASC in pharmaceutical dosage forms, with percentage recoveries ranging between 98 and 102 %, and relative standard deviations less than 2 %. The method was easy, rapid, reliable, and sensitive and did not require expensive reagents or sophisticated equipment.

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.

Quantitative Determination of Ascorbic Acid in Herbal Medicinal Products by HPLC

Ascorbic acid (vitamin C) is involved in many vital biochemical processes in the human body. Rose hips are a natural source of ascorbic acid. Rose hips are used in decoctions and many vitamin herbal teas. Russian compendial methods for the quantitative determination of ascorbic acid have certain limitations precluding its objective measurement in herbal drugs, herbal drug preparations, and herbal medicinal products.The aim of the study was to develop an analytical procedure for the quantitative determination of ascorbic acid in herbal drugs, herbal medicinal preparations, and herbal medicinal products using high performance liquid chromatography (HPLC).Materials and methods. The study involved two herbal medicinal products, Rose Hips (rose hips) and Vitamin Herbal Tea 2 (rose hips and rowan fruits), and reference standards for ascorbic acid, rutoside, quercetin, gallic acid, caffeic acid, chlorogenic acid, luteolin-7-glucoside, citric acid, DL-malic acid, thiamine, and pyridoxine hydrochloride. The authors used a 1260 Infinity II chromatograph with a diode array detector by Agilent and an Inertsil ODS-3 chromatographic column (250 mm × 4.6 mm, 5 µm) by GL Sciences. The HPLC system was operated in gradient elution mode, and the detector was set at 244 nm.Results. Ascorbic acid content in herbal drugs, herbal medicinal preparations, and herbal medicinal products can be determined by HPLC. Adequate sample preparation and chromatography conditions allow for inhibiting ascorbic acid oxidation in aqueous solutions for a period sufficient to complete testing (not less than 8 h).Conclusions. The authors developed a highly sensitive and selective HPLC procedure for the quantitative determination of ascorbic acid intended for the standardisation of herbal drugs, herbal medicinal preparations, and herbal medicinal products. The procedure is worthy of inclusion in the Rose Hips and Vitamin Herbal Tea 2 monographs of the State Pharmacopoeia of the Russian Federation. Switching to HPLC should not require lowering the limit for ascorbic acid (not less than 0.2%) established in the Rose Hips and Vitamin Herbal Tea 2 monographs for the titration method. The ascorbic acid content was below this limit in the vast majority of study samples. However, this discrepancy may be explained by the presence of dog rose (Rosa canina) species low in vitamin C, which should normally be used only as choleretics.

A New Method for the Determination of Total Content of Vitamin C, Ascorbic and Dehydroascorbic Acid, in Food Products with the Voltammetric Technique with the Use of Tris(2-carboxyethyl)phosphine as a Reducing Reagent

The objective of the study was to develop a new method for the determination of the total content of vitamin C and dehydroascorbic acid in food, based on the technique of differential pulse voltammetry with the use of a boron-doped diamond electrode modified with mercury film. A comparison was made between the results obtained with the developed method and a proposed reference method based on high-performance liquid chromatography with spectrophotometric detection. The reduction of dehydroascorbic acid was performed with the use of tris(2-carboxyethyl)phosphine. The interference caused by the presence of tris(2-carboxyethyl)phosphine during the voltammetric determination of ascorbic acid was effectively eliminated through a reaction with N-ethylmaleimide. The conducted validation of the voltammetric method indicated that correct results of analysis of the total content of vitamin C and ascorbic acid were obtained. Analysis of the content of dehydroascorbic acid was imprecise due to the application of the differential method. The results of the analyses and the determined validation parameters of the developed method are characterised by a high degree of conformance with the results obtained with the chromatographic reference method, which indicates the equivalence of the two methods.

Synthesis of MoO3- x nanosheets and its application in ascorbic acid detection of fruit and vegetables.

A new method combining ultraviolet (UV) spectrophotometry and MoO3- x nanosheets was developed for the rapid and accurate determination of ascorbic acid (AA) content in fruit and vegetables in this study. MoO3- x nanosheets were prepared by the liquid exfoliation method using AA as the reducing agent, and the content of AA can be determined by a UV spectrophotometer. Experimental conditions for the MoO3- x nanosheet method, including grinding time, ethanol concentration, sonication time, and water bath temperature were also optimized. The morphology of MoO3- x nanosheets was characterized by atomic force microscope. The results showed that the average thickness of MoO3- x nanosheets was 2.1-5.8nm. The MoO3- x nanosheets method had a good linearity in the AA concentration range of 0.01-0.05mg/ml (R2 =0.9996). The limit of detection was 0.031µg/ml, and the limit of quantitation was 0.095µg/ml. The spiked recoveries were in the range of 88.79%-116.76%. The MoO3- x nanosheets method was validated for the determination of AA content in five different fruit and vegetables samples with relative standard deviations less than 2%.

MXene-derived Ti3C2 quantum dots-based ratiometric fluorescence probe for ascorbic acid and acid phosphatase determination

As a burgeoning zero-dimensional nanomaterial, MXene quantum dots which are derived from two-dimensional transition-metal carbides have attracted a lot of interest lately. The transformation of two-dimensional MXene into zero-dimensional structures of a few nanometers enables these recently discovered materials to possess an exceptional quantum size effect and remarkable photoluminescence characteristics. Hence, we synthesized N doped Ti3C2 MXene quantum dots (N-Ti3C2 MQDs) exhibiting bright blue fluorescence through small-molecule amine-assisted solvothermal strategy. In this work, we constructed a novel ratiometric fluorescence biosensor for the determination of ascorbic acid (AA) and acid phosphatase (ACP) based on the excellent optical performance of N-Ti3C2 MQDs and combined o-phenylenediamine (OPD). This ratiometric strategy was established based on the inner filter effect between N-Ti3C2 MQDs and the oxide of OPD. Sensitive fluorometric analyses of AA and ACP were achieved successfully in the respective ranges of 2–240 μM and 0.15–3.75 U/L with respective limits of detection down to 0.82 μM and 0.02 U/L. Moreover, the response time of this fluorescence sensor for AA and ACP determination was less than 1.5 h. The intraday and interday relative standard deviations for AA and ACP assay were all below 8.3 %, suggesting the good reproducibility of this sensor. In addition, the profuse color changed under UV light with analytes concentrations increased and exhibited great potential for visual detection and on-site application. The proposed method was further utilized to screen of potential ACP inhibitors, indicating that this probe has great potential in clinical practice.

Equipment-free determination of ascorbic acid based on the UV-induced oxidation of 3,3′,5,5′-tetramethylbenzidine in a paper-based analysis device

A portable paper-based analysis device is developed for quantitative determination of ascorbic acid (AA) based on the UV-induced oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB).

Polyaniline-poly (methylene blue) nano-rod composites as an electrochemical sensor for sensitive determination of ascorbic acid

Polyaniline-poly (methylene blue) nano-rod composite has been prepared by a chemical oxidative polymerization method. The PANI-PMB composite was characterized by scanning electron microscopy, spectrophotometry, Fourier transforms infrared spectrometry, and X-ray diffraction. The electrochemical performance of the PANI-PMB composite was studied by electrochemical impedance spectroscopy, cyclic voltammetry, and differential pulse voltammetry. The prepared nanocomposite was applied for the electrochemical sensing of ascorbic acid. The results show that the PANI-PMB modified carbon paste electrode (PANI-PMB/CPE) had better catalytic activity to the electrochemical oxidation of ascorbic acid compared with PANI/CPE, PMB/CPE and CPE, which was due to the fast electron transfer efficiency of the PANI-PMB composite. Under the optimized experimental conditions, the differential pulse voltammetric peak current was linear with the ascorbic acid concentration in the range from 4 to 110 μM with a detection limit of 1.3 μM. Furthermore, the proposed method has been applied for the determination of ascorbic acid content in vitamin C tablets.

An electrochemical microsensor based on a specific recognition element for the simultaneous detection of hydrogen peroxide and ascorbic acid in the live rat brain.

A novel electrochemical microsensor was developed for the ratiometric and simultaneous determination of hydrogen peroxide (H2O2) and ascorbic acid (AA) based on the borate-phenol "switch" recognition mechanism and carbon nanotube (CNT) catalytic characteristics. First of all, a carbon fiber microelectrode (CFME) was coated with CNTs. Then, a specific probe, 9-anthraceneboronic acid pinacol ester (9-AP), was screened and decorated on CNTs through π-π stacking for the recognition of H2O2 based on the transformation of boric acid ester into electroactive phenols. CNTs not only served as the amplifiers of current signals, but also as catalysts facilitating AA oxidation. Meanwhile, ferrocenecarboxylic acid (Fc), inert to H2O2 and AA, was modified on another amino-functionalized CNT microelectrode via an amide bond as an internal reference channel for avoiding errors caused by environmental discrepancies. The two-channel ratiometric microsensor enabled the sensitive and accurate detection of H2O2 and AA simultaneously, and the detection limits were estimated to be 0.09 μM and 4.12 μM, respectively. The developed microsensor with remarkable analytical performance was finally applied for the simultaneous detection of H2O2 and AA in the live rat brain.

Individual and simultaneous electrochemical determination of nitrofurantoin and ascorbic acid in biological samples using a novel La2YBiO6 double perovskite deposited on MWCNTs as a nanocomposite

La2YBiO6 double perovskites were prepared by a sol–gel method, and La2YBiO6 double perovskites decorated on multiwalled carbon nanotubes (LYB/MWCNTs) were prepared for the individual and simultaneous detection of nitrofurantoin and ascorbic acid in biological samples.

Rapid microwave fabrication of red-carbon quantum dots as fluorescent on-off-on probes for the sequential determination of Fe(III) ion and ascorbic acid in authentic samples.

In this study, fluorescent red-carbon quantum dots (R-CQDs) with an ultrahigh fluorescence quantum yield of 45% were rapidly and easily synthesized by thermal pyrolysis of 2,5-diaminotoluene sulfate and 4-hydroxyethylpiperazineethanesulfonic acid using a one-step microwave-assisted hydrothermal approach. R-CQDs possessed the excitation-independent fluorescence property with the optimal emission peak at 607 nm under the excitation wavelength of 585 nm. R-CQDs exhibited excellent fluorescence stability under extremely harsh conditions in a pH range of 2-11, high ionic strength (1.8 M of NaCl), and long UV light irradiation time (160 min). The fluorescence quantum yield of these R-CQDs was as high as 45%, implying their preferable application in chemosensors and biological analysis. Because Fe3+ ion bound with R-CQDs and statically quenched the fluorescence of R-CQDs, the fluorescence intensity of R-CQDs was recovered after the addition of ascorbic acid (AA) via its redox reaction with Fe3+ ion. R-CQDs were developed as highly sensitive fluorescent on-off-on probes for sequentially sensing Fe3+ ions and AA. Under the optimal experimental conditions, the linear range for Fe3+ ion detection was 1-70 μM with a detection limit of 0.28 μM, and the linear range for AA detection was 1-50 μM with a detection limit of 0.42 μM. The successful detection of Fe3+ ions in authentic water samples and the successful sensing of AA in human body fluids and vitamin C tablets further proved the practical application prospects of this efficient strategy in the environmental protection and disease diagnosis fields.

Rapid and sensitive determination of ascorbic acid based on label-free silver triangular nanoplates

In this study, a new method for the detection of ascorbic acid (AA) was proposed. It was based on the protective effect of AA on silver triangular nanoplates (Ag TNPs) against Cl− induced etching reactions. Cl− can attack the corners of Ag TNPs and etch them, causing a morphological shift from triangular nanoplates to nanodiscs. As a result, the solution changes color from blue to yellow. However, in the presence of AA, the corners of Ag TNPs can be protected from Cl− etching, and the blue color of the solution remains unchanged. Using this effect, a selective sensor was designed to detect AA in the range of 0–40.00 μM with a detection limit of 2.17 μM. As the concentration of AA varies in this range, color changes from yellow to blue can be easily observed, so the designed sensor can be used for colorimetric detection. This method can be used to analyze fruit juice samples.

Synthesis of MnO2 sub-microspheres with effective oxidase-mimicking nanozymes for the colorimetric assay of ascorbic acid in orange fruits and juice

An efficient colorimetric platform for the sensitive determination of ascorbic acid was developed based on an oxidase-mimicking nanozyme of MnO2 sub-microspheres, with a linear detection range of 1.0–100 μM and a limit of detection of 0.33 μM.

Synthesis and application of mixed-spinel magnesioferrite: structural, vibrational, magnetic, and electrochemical sensing properties

This article presents an efficient non-enzymatic electrochemical sensor based on catalytic oxidation by the MgFe2O4 magnetic spinel for the sensitive determination of ascorbic acid.