Simultaneous Determination Of Glucose Research Articles

Electrochemical fabrication of Co(OH)2 nanoparticles decorated carbon cloth for non-enzymatic glucose and uric acid detection.

Cobalt hydroxide nanoparticles (Co(OH)2 NPs) were uniformly deposited on flexible carbon cloth substrate (Co(OH)2@CC) rapidly by a facile one-step electrodeposition, which can act as an enzyme-free glucose and uric acid sensor in an alkaline electrolyte. Compositional and morphological characterization were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), which confirmed the deposited nanospheres were Co(OH)2 nanoparticles (NPs). The electrochemical oxidation of glucose and uric acid at Co(OH)2@CC electrode was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry methods. The results revealed a remarkable electrocatalytic activity toward the single and simultaneous determination of glucose and uric acid at about 0.6 V and 0.3V (vs. Ag/AgCl), respectively, which isattributed to a noticeable synergy effect between Co(OH)2 NPs and CC with good repeatability, satisfactory reproducibility, considerable long-term stability, superior selectivity, outstanding sensitivity, and wide linear detection range from 1 uM to 2mM and 25nM to 1.5 uM for glucose and UA, respectively. The detection limits were 0.36nM for UA and 0.24μM for glucose (S/N = 3). Finally, theCo(OH)2@CC electrode was utilized for glucose and uric acid determination in human blood samples and satisfying results were obtained. The relative standard derivations (RSDs) for glucose and UA were in the range 6 to 14% and 0 to 3%, respectively. The recovery ranges for glucose an UA were 97 to 103% and 95 and 101%, respectively. These features make the novel Co(OH)2@CC sensor developed by a low-cost, efficient, and eco-friendly preparation method apotentially practical candidate for application to biosensors.

Electrochromic Sensor for Multiplex Detection of Metabolites Enabled by Closed Bipolar Electrode Coupling.

Biosensors based on converting electrochemical signals into optical readouts are attractive candidates as low-cost, high-throughput sensor platforms. Here, we described a closed bipolar electrode (CBE)-based two-cell electrochromic device for sensing multiple metabolites, using the simultaneous detection of lactate, glucose, and uric acid as a model system. In the two-cell configuration, an analytical cell contains a redox mediator combined with a specific oxidase, e.g., lactate oxidase, glucose oxidase, or uricase, to form an electrochemical mediator-electrocatalyst pair that supports redox cycling. A closed bipolar electrode couples the electron transfer event in the analytical cell to an electrochromic reaction in a separate reporter cell, such that the magnitude of the color change is related to the concentration of metabolites in the analytical cell. To demonstrate multiplex operation, the CBE-based electrochromic detector is modified by integrating three sets of detection chemistries into a single device, in which simultaneous determination of glucose, lactate, and uric acid is demonstrated. Device sensitivity can be tuned by using reporter cells with different volumes. Furthermore, the analytical cell of this device can be fabricated as a disposable, paper-based carbon electrode without any pretreatment, demonstrating the potential to screen phenotypes that require multiple biomarkers in a point-of-care format.

Monitoring multicomponent quality traits in tomato juice using portable mid-infrared (MIR) spectroscopy and multivariate analysis

In this study, a novel portable infrared spectrometer was evaluated for rapid and simultaneous determination of glucose, fructose, total reducing sugars, soluble solids (°Brix), serum viscosity, Bostwick consistency, predicted paste Bostwick value and pH. A total of 350 hot-break juices from two consecutive years (2013 and 2014) including 66 different varieties grown in 6 counties of California, USA, were used in this study. Duplicate spectra for each tomato juice were collected using the transmission accessory of the portable infrared spectrometer at 50 μm fixed path length. Samples were randomly divided into calibration (n = 280) and external validation (n = 70) sets and partial least squares (PLS) regression was used to develop calibration models to predict all the variables (quality traits) in the validation samples based on the tomato juice spectral data (rpred > 0.82). Overall, our validated chemometric models allowed rapidly (∼2 min) predicting all the quality traits in tomato juice samples with no sample preparation.

Simultaneous determination of glucose, triglycerides, urea, cholesterol, albumin and total protein in human plasma by Fourier transform infrared spectroscopy: Direct clinical biochemistry without reagents

ObjectiveDirect measurement of chemical constituents in complex biologic matrices without the use of analyte specific reagents could be a step forward toward the simplification of clinical biochemistry. Problems related to reagents such as production errors, improper handling, and lot-to-lot variations would be eliminated as well as errors occurring during assay execution.We describe and validate a reagent free method for direct measurement of six analytes in human plasma based on Fourier-transform infrared spectroscopy (FTIR). Design and methodsBlood plasma is analyzed without any sample preparation. FTIR spectrum of the raw plasma is recorded in a sampling cuvette specially designed for measurement of aqueous solutions. For each analyte, a mathematical calibration process is performed by a stepwise selection of wavelengths giving the optimal least-squares correlation between the measured FTIR signal and the analyte concentration measured by conventional clinical reference methods. The developed calibration algorithms are subsequently evaluated for their capability to predict the concentration of the six analytes in blinded patient samples. ResultsThe correlation between the six FTIR methods and corresponding reference methods were 0.87<R2<1.00. The interassay imprecision meets international quality criteria for all the six analytes. The linearity of the FTIR methods extends over the clinically significant concentration ranges. Visible hemolysis and icterus have some influence on the measurements. Plasma samples can be stored at 2–8°C for at least 8days before the analysis. ConclusionsThe developed FTIR methods use a simple and robust technology to achieve stable and accurate results that meet international quality criteria for the measurement of glucose, triglycerides, urea, cholesterol, albumin and total protein in human plasma.

Accelerated reducing synthesis of Ag@CDs composite and simultaneous determination of glucose during the synthetic process

Carbonaceous nanodots (CDs) have drawn increasing attention owing to their inspiring properties. CDs based composites have been attracting extensive research interest because of the properties improvement of materials and introduction of new physical or chemical properties. In this work, we designed a quick, handy and extra-reductant needless method to synthesize Ag@CDs composites according to the direct reduction of Ag(NH3)2OH. TEM, XPS, XRD and optical properties were investigated, and a hypothetical synthesis mechanism was provided. Interestingly, glucose lowered the reaction difficulty and shortened the reaction time, which was well known as silver mirror reaction. Furthermore, a dual signal sensor for glucose was established through optical variations during the synthetic process. The simultaneous synthesis and detection avoided complicated pre-modification of the materials and thus simplified the procedure. The synthesis by a simple elementary reaction and “detection during the synthesis” would attract much interest.

A polymeric dual-channel amperometric biosensor chip capable of symmetrically splitting sample bands for parallel micro flow injection determination of glucose and lactate

This paper presents a chip-based dual-channel micro flow injection biosensor system for parallel determination of two components that potentially interference with each other. With glucose and lactate being the model analytes, a hybrid polydimethylsiloxane (PDMS)–polycarbonate (PC) microfluidic chip with a Y-shaped main-to-branch channel network was designed. Glucose oxidase (GOD) and lactate oxidase (LOD) biosensors of amperometric type were separately prepared inside each of the two branch channels. A sample band injected into the main channel was split into two daughter bands at the bifurcated point of the Y-shaped channel. The daughter bands were delivered into branches where the two analytes in the daughter bands were independently detected by the GOD and LOD sensors, preventing the potential chemical crosstalk between the two sensors. Factors influencing the symmetry of splitting a sample band, in turn, the sensitivity and reproducibility of the system, were discussed. Symmetric splitting was realized by using back pressure regulators (BPR). Under optimized conditions, detection limits of 78 μmol L−1 for glucose and 127 μmol L−1 for lactate were observed with a sample volume of 20 nL and a sample throughput rate of 40 h−1. RSDs of 0.8–0.9% for peak heights were observed for 11 runs of a standard solution containing glucose and lactate both at 2 mmol L−1. The designed dual-channel biosensor chip was applied to the simultaneous determination of glucose and lactate in human serum samples.

Microfluidic paper-based chemiluminescence biosensor for simultaneous determination of glucose and uric acid

In this study, a novel microfluidic paper-based chemiluminescence analytical device (μPCAD) with a simultaneous, rapid, sensitive and quantitative response for glucose and uric acid was designed. This novel lab-on-paper biosensor is based on oxidase enzyme reactions (glucose oxidase and urate oxidase, respectively) and the chemiluminescence reaction between a rhodanine derivative and generated hydrogen peroxide in an acid medium. The possible chemiluminescence assay principle of this μPCAD is explained. We found that the simultaneous determination of glucose and uric acid could be achieved by differing the distances that the glucose and uric acid samples traveled. This lab-on-paper biosensor could provide reproducible results upon storage at 4 °C for at least 10 weeks. The application test of our μPCAD was then successfully performed with the simultaneous determination of glucose and uric acid in artificial urine. This study shows the successful integration of the μPCAD and the chemiluminescence method will be an easy-to-use, inexpensive, and portable alternative for point-of-care monitoring.

Simultaneous Determination of Glucose and Choline Based on the Intrinsic Fluorescence of the Enzymes

It has been possible to perform the simultaneous determination of choline and glucose using the intrinsic fluorescence of the corresponding enzyme as an analytical signal. This can be done in two ways. First, for low glucose and choline concentrations (about 0.55 mM and 0.75 microM respectively) two differentiated signals, without mutual interference, are obtained for both analytes in the same measurement. Second, when glucose and choline concentrations are higher, a new model has been designed which permits the concentrations to be accurately determined in samples containing from 0.55 mM to 3.75 mM glucose and from 0.75 microM to 11.0 microM choline; the method has been applied to simultaneous glucose and choline determinations in serum samples with good results. This method gives a better performance than multivariate calibration based on Partial Least Squares Regression. The methodology here shown could be also used for the simultaneous determination of other pairs of analytes.

Simultaneous determination of glucose, 1,5-anhydrod-glucitol and related sugar alcohols in serum by high-performance liquid chromatography with benzoic acid derivatization

A new, simple and sensitive pre-column high-performance chromatographic method for the determination of diabetes marker d-glucose, 1,5-anhydro-d-glucitol and related compounds is reported. Sugars (d-glucose, d-galactose, d-mannose, sucrose and arabinose) were derivatized with benzoic acid (BA) at 80 degrees C for 60 min. l-Fucose, fructose, d-lactose, l-rhamnose, arabinose and ascorbic acid were not reacted. Sugar alcohols (xylitol, erythritol, mannitol, sorbitol myo-inositol) were also derivatized with BA at 80 degrees C for 60 min. The fluorescence derivatives were separated on a TSK amide 80 column (4.6 mm i.d. x 250 mm, 5 microm) with acetonitrile-50 mm acetate buffer (pH 5.6; 4:96, v/v) as the mobile phase. The detection wavelength of beizoic acid derivatives was lambda(ex) 275 nm and lambda(em) 315 nm. The detection limits of sugars were 10-80 microg/mL. The calibration graphs were linear up to 10 mg/mL. The relative standard deviations of 500 microg/mL sugars were 7.0-7.3%. The proposed method was compared with the enzymatic photometric glucose analysis method (Glucose B-Test II Wako). The correlation coefficient was 0.83 (n = 20) and y = 0.82x + 5.91, where y and x are concentrations in microg/mL obtained by the proposed pre-column HPLC and enzyme-photometric method, respectively. The detection limits of sugar alcohols were 100-1000 ng/mL. The calibration graphs were linear to 50 microg/mL and relative standard deviations of 10 microg/mL were 7.2-8.2%. The 1,5-AG data by the proposed method was also compared with the enzymatic photometric 1,5-AG analysis method (Rana AG 1,5-AG determination kit, Nihon Kayaku) and good correlation (r = 0.91, n = 20) was also obtained. The proposed method was applied to the simultaneous determination of d-glucose, 1,5-AG and related sugar alcohols in serum from healthy males.

Simultaneous determination of glucose and sucrose by HPLC with an immobilized enzyme membrane electrode

Simultaneous determination of glucose and sucrose by HPLC with an immobilized enzyme membrane electrode

Simultaneous determination of glucose and ascorbic acid by using gold electrode modified with ferrocenylundecanethiol monolayer

Self-assembled monolayer of 11-ferrocenylundecanethiol on gold electrode was used for the potential dependent catalyst for chemiluminescence of luminol. Ferrocene groups adsorbed on gold were oxidized to ferricinium cation species electrochemically, and then catalyzed the chemiluminescene of luminol. The presented system was adopted for detection of glucose in the presence of glucose oxidase since the light emission was detected even in the neutral and weak acid solution. We attempted to use this system for simultaneous detecting of glucose and ascorbic acid by individually measuring the current response and light emission.

Amperometric multidetection with composite enzyme electrodes

The use of composite biosensors for multianalyte detection strategies is discussed. Graphite–Teflon rigid composite biosensors offer the possibility of coimmobilization of several enzymes by simple physical inclusion in the bulk of the electrode matrix with no covalent linkages. A novel trienzyme graphite–Teflon–glucose oxidase (GOD)–alcohol oxidase (AOD)–peroxidase (HRP)–ferrocene bisosensor yielded amperometric steady-state currents similar to those obtained with graphite–Teflon–GOD–HRP–ferrocene and graphite–Teflon–AOD–HRP–ferrocene electrodes for the same concentration of glucose and ethanol, respectively. The performance of the trienzyme biosensor for multianalyte detection was evaluated with the simultaneous determination of glucose and ethanol after separation by HPLC, in samples of sweet wine. The simultaneous analysis of several analytes in the same sample should imply that, with an adequate dilution, the concentration levels of the analytes can be included within the ranges of linearity of the corresponding calibration plots. The use of two composite biosensors in a parallel configuration, so that different analytes can be simultaneously detected with no need of chromatographic separation, is also discussed. The usefulness of this approach was evaluated by the simultaneous analysis of glucose and ethanol in sweet wine, and of glucose and lactic acid in red wine.

Development of a sequential injection analysis system for the simultaneous biosensing of glucose and ethanol in bioreactor fermentation

An on-line sequential injection analysis system using amperometric detection for the simultaneous monitoring of glucose and ethanol in fermentations media is presented. The automatic analytical procedure developed is based in a sequential injection analysis (SIA) strategy and uses catalytic reactors of oxidase enzymes immobilized on controlled-pore glass. The proposed method allows the simultaneous determination of glucose (linear range between 5 and 750 mg dm −3 with a RSD better than 1.2%) and ethanol (linear range between 0.15 and 30 mg dm −3 with a RSD better than 2.2%). It was applied to monitor both species in beer fermentation. In a way to adjust the levels of ethanol present in the broth to the characteristics of the proposed system a dialysis unit was used between fermenter and SIA manifold. The sampling rate optimized was 50 samples h −1.

Simultaneous determination of glucose and L-lactate in rat brain by an electrochemical in vivo flow-injection system with an on-line microdialysis sampling.

An electrochemical in vivo flow-injection system with an on-line microdialysis sampling is proposed for the simultaneous monitoring of L-lactate and glucose in rat brain. In the first stage of the operation, the dialysate from the microdialysis probe is delivered to a sample loop of the six-way autoinjector by perfusing Ringer's solution for 80 s at 5 microl min(-1). In the second stage, the dialysate collected in the sample loop is automatically injected for 10 s into the flow-injection line. Injected dialysate is split into two streams and two portions pass through two channels with two different immobilized enzyme reactors (glucose oxidase and lactate oxidase immobilized reactors) to produce hydrogen peroxide from glucose and L-lactate in the dialysate. After a subsequent confluence of the streams, produced hydrogen peroxide can be detected amperometrically at a downstream poly(1,2-diaminobenzene) film-coated platinum electrode, without any interference from oxidizable species and proteins present in the dialysate. Because each channel has a different residence time, two peaks are obtained. The first peak corresponds to L-lactate and the second peak to glucose. The peak current is linearly related to the concentrations of L-lactate between 0.2 and 10 mM and glucose between 0.1 and 20 mM. The present method can be successfully applied to the simultaneous in vivo monitoring of L-lactate and glucose in rat brain. The analytical speed is 45 dialysates h(-1).

A Simple FIA-System for Simultaneous Measurements of Glucose and Lactate with Amperometric Detection

A flow injection system for the simultaneous amperometric determination of glucose and lactate is described. Glucose oxidase and lactate oxidase were immobilized, separately, into two-parallel immobilized enzyme reactors (IERs). The enzymatically produced hydrogen peroxide was detected by anodic amperometry at platinum electrodes coated with an electropolymeric-permselective layer of m-phenylenediamine to enhance the selectivity of H2O2 detection. The configuration of the flow system was designed to give a response output in the form of a train of two successive peaks. The heights of these two peaks were directly proportional to the concentration levels of glucose and lactate in the sample, respectively. The presented flow system proved to offer the advantages of i) simplicity, ii) operational stability, up to 3 months, iii) simultaneous determination of glucose and lactate using a single 20-µL sample injection iv) insensitivity of the signal of a given component by wide variations in the concentration of the second component, v) high sample throughput, more than 50 samples/hour, vi) high accuracy and precision, and vii) a reasonable dynamic range of about two-orders of magnitude. The reliability of the present system was assessed by measuring glucose and lactate simultaneously in several samples of blood plasma, urine and dairy products. The obtained results were in good agreement with those obtained by standard spectrophotometric methods.

Simultaneous Determination of Glucose and Sucrose using a Flow System with Two Enzyme Reactors and an Octadecylsilica Column in One Line

ABSTRACT Simultaneous determination of glucose and sucrose was achieved with an apparatus containing two enzyme reactors and an octadecylsilica column positioned between the two reactors in tandem in a single flow line. The enzymes used were mutarotase and glucose dehydrogenase for glucose analysis, and sucrose phosphorylase, phosphoglucomutase and glucose-6-phosphate dehydrogenase for sucrose analysis. The pH and the concentration of the phosphate buffer used as the medium for immobilization of mutarotase and glucose dehydrogenase to activated aminopropyl glass were studied. Several aqueous buffers and their pH values were also examined for use as the carrier medium, and HEPES buffer (pH 7.5) was the most favorable. In this apparatus under these conditions, NADH due to glucose and that due to sucrose were observed separately. The calibration curve for glucose was linear in the range of 1 - 500 μM, and that for sucrose, 5 - 500 μM. This method was applied to the analyses of glucose and sucrose in several beverages. The results were in good agreement with those obtained by a commercially available test-kit method.

Post-column enzyme reactors for chemiluminometric detection of glucose, 1,5-anhydroglucitol and 3-hydroxybutyrate in an anion-exchange chromatographic system.

A liquid chromatographic system consisting of a co-immobilized 3-hydroxybutyrate dehydrogenase-NADH oxidase reactor and an immobilized pyranose oxidase reactor in series and a chemiluminometer was developed for the simultaneous determination of glucose, 1,5-anhydroglucitol and 3-hydroxybutyrate in plasma. The enzymes were immobilized on toresylated poly(vinyl alcohol) beads. Separation was achieved on a TSK gel SAX column (40 x 4 mm I.D.) with an eluent of 50 mM NaOH containing 30 mM sodium butyrate. The hydrogen peroxide produced was detected by measuring the chemiluminescence emitted on admixing with luminol and potassium hexacyanoferrate(III). The calibration curves were linear from 0.8 to 500 microM (7 ng-4 micrograms) for glucose, from 0.8 to 400 microM (7 ng-3 micrograms) for 1,5-anhydroglucitol and from 1 to 700 microM (5 ng-4 micrograms in a 50-microliter injection) for 3-hydroxybutyrate. The sample throughput was four per hour. The reactors were stable for at least ten days.

Direct and simultaneous determination of uric acid and glucose in serum with electrochemical filter/biosensor flow-injection analysis system

A flow-through electrolysis cell, named an electrochemical filter (ECF), with a three-electrode configuration was developed for the elimination and determination of electrochemically active components in biofluids, which give generally a nonspecific response to electrochemical biosensors. The use of a reference electrode ensured the precise control of the working electrode potential of the ECF and thus the quantitative current efficiency of the electrolysis. A flow-injection analysis setup was constructed by connecting two ECFs and a flow-through amperometric biosensor for glucose in series for the direct and simultaneous determination of glucose and uric acid in serum. The first ECF coulometrically determined uric acid, and the second one eliminated interferents with the biosensor: the sample was thus treated on-the-fly and then delivered to the biosensor, so that it determined glucose amperometrically without interference. The concentrations of glucose and uric acid measured in human control sera agreed well with the values determined with conventional methods. The system exhibited the wide dynamic range in the high glucose concentration region, thus can be applied to the analysis of serum of hyperglycaemic patients.

Simultaneous determination of glucose and 1-deoxyglucose in serum by anion-exchange chromatography with an immobilized pyranose oxidase reactor

A liquid chromatographic system for the determination of glucose and 1-deoxyglucose in serum using an immobilized pyranose oxidase reactor and chemiluminescence detection is described. Separation was achieved on a TSK gel SAX column (2 cm × 4 mm I.D.) with an eluent of 0.1 M sodium hydroxide solution. Serum was diluted 30-fold with 0.1 M NaOH. Sample solution (50 μl) was injected into the system. The hydrogen peroxide produced was detected by measuring the chemiluminescence emitted on admixing with luminol and potassium hexacyanoferrate (III). The calibration graphs were linear from 1 to 600 μ M glucose and from 0.6 to 400 μ M 1-deoxyglucose; the detection limits for glucose and 1-deoxyglucose were 0.5 and 0.3 μ M, respectively. The sample throughput was 10/h. The immobilized enzyme reactor was stable for at least 2 months.

Simultaneous determination of glucose, ethanol and lactate in alcoholic beverages and serum by amperometric flow injection analysis with immobilized enzyme reactors

Glucose, ethanol and lactate were determined simultaneously in a flow injection system by using a parallel configuration of immobilized enzyme reactors. Hydrogen peroxide produced was monitored amperometrically at the potential of +0.65 V vs. Ag/AgCl. Linear relations between sensor responses and each species were observed in the ranges of 0.02–10 mM (glucose), 5 × 10 −4−0.1% (v/v) (ethanol) and 0.005–1 mM (lactate) with correlation coefficients larger than 0.999 for each species. The relative standard deviations for 10 successive injections were 1.4, 0.5 and 1.1% for glucose (1 mM), ethanol (5 × 10 −3% (v/v)) and lactate (0.05 mM), respectively. Analysis of serum samples was performed with urate-eliminating reactors which were set just before each immobilized enzyme reactor. Interference of ascorbate in a serum sample was completely eliminated by using an ascorbate-eliminating reactor which was set before the sample injection valve. Application of the system to alcoholic beverages and control serum was described and the results were compared with those of free enzymatic, spectrophotometric analysis (F-kit or C-test method).