Automated Micro Measurement of Glucose by Means of o-Toluidine (original) (raw)
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A study of the direct o-toluidine blood glucose determination
Clinica Chimica Acta, 1973
The acetic acid-a-toluidine method for measuring serum glucose concentration was studied. Changes in concentrations and conditions were performed manually and by continuous variation. Maximum absorbance at 630 nm was produced at concentrations less than IOo% acetic acid solvent. The effects of increasing water concentration for a variety of samples and conditions are shown. A wide disparity of patterns was observed when patient and lyophilized con;trol sera were studied. At water concentrations less than IO% (v Jv) marked enhancement of color due to borate ion was observed; in glacial acetic acid, borate more than doubles color produced. Addition of trichloroacetic acid showed inhibition of the reaction, Absorbance was found to increase with increasing a-toluidine concentration over the range studied {I to n%). At concentrations of water greater than I5% significant serum blanks were observed. This blank was not due solely to protein turbidity, and is dependent upon the presence of both glucose and P-lipoprotein. Effects of other reagent parameters, color development time, and sample constituents were investigated.
Journal of Pharmacological and Toxicological Methods, 2000
In experimental models of diabetes, glucose levels in plasma and blood are commonly determined by colorimetric assay and by automated analyzers based on the glucose oxidase conversion of glucose and O 2 to gluconate and H 2 O 2. We have compared the glucose levels obtained by these two methods in control Wistar rats, streptozotocin diabetic Wistar rats, Zucker fa/fa fatty rats and Zucker Diabetic Fatty rats. We found that the manual glucose assay and the glucose analyzer produced comparable values up to concentrations of about 25 mM. Above this level, samples should be diluted.
Measurementof Glucose in Plasmaby a DifferentialpH Technique
A new automatic apparatus based on the differential measurement of pH between two solutions has been developed. Two 25-FL (internal volume) glass capillary electrodes are used to measure the results of automated (under microcomputer control) chemical reactions that lead to the liberation or the uptake of hydrogen ions. The sensitivity of the differential pH measurements is better than ± 0.0001 pH unit, and the change in H concentration that can be detected by such an apparatus is 1 mol/L for plasma and 3 tmol/L for whole blood. The technique has been applied to the measurement of glucose in plasma, giving results in agreement with the specifications of the Food and Drug Administration reference method for quantitative determination of glucose (hexokinase/glucose-6-phosphate dehydrogenase method). Additional Keyphrases: change in pH as related to enzyme activity . glass capillary electrodes We have previously shown (1) that differences in pH between two solutions can be measured by using two glass electrodes, and we have applied this technique to the determination of glucose in aqueous solutions by measuring the change in pH produced by the hexokinase-catalyzed ATP-glucose reaction (2). The sensitivity of the method was about 5 x io-pH units, indicating that the pH method might be useful in the measurement of analytes of analytical and climco-chemical interest. However, our previously described apparatus was not suitable for routine work and we sought to develop a fully automated instrument that could perform a variety of analytical functions, i.e., addition of reagents, filling and standardization of the electrodes, and calculation of results. Here we describe this new instrument and report the results of its application to the routine determination of glucose in plasma. We have also developed theoretical equations that predict the sensitivity of the method when applied to the determination of analytes in human plasma or whole blood.
Application to the determination of glucose in serum samples
Rotating bioreactor based on an electron transfer 3 mediated by osmium complexes incorporating 4 a continuous-flow/stopped-flow system 5 Abstract 12 A recently introduced redox osmium complex of the type [Os(bpy) 2 Cl(pyX] + , where pyX corresponds to a pyridine deriva-tive bearing an aldehyde group, and glucose oxidase [EC 1.1.3.4] were covalently immobilized on the glassy carbon electrode surface (upper cell body). This approach has been designed in a sealed cell to be used under continuous-flow/stopped-flow/ continuous-flow processing. The operating characteristic of the integrated bioreactor/detector unit has been utilized in the determination of glucose in serum samples using the electroactive polymer as mediator in the re-oxidation of GOx and am-perometric monitoring. The determinations are based on the rate of response under stopped-flow conditions. The trend in values of the apparent Michaelis–Menten constant confirms the validity of the approach to sensitive determination u...
Determination of serum glucose by isotope dilution mass spectrometry: candidate definitive method
Clinical chemistry, 1992
We report a rather simple method to determine glucose concentration in serum, using isotope dilution mass spectrometry and [13C6]glucose as internal standard. The procedure involves a single step of sample purification and the conversion of the analyte into its aldononitrile pentaacetate. The between-day and within-day contribution to total variance for a single measurement was determined by assaying Standard Reference Material (SRM) 909 serum. The method was then applied to measurement of glucose concentration in three lyophilized sera: SRM 909 and two other commercially available sera. In the two studies, the concentration of SRM 909 serum was found to be 0.8% above and 0.3% below the reported value (6.25 mmol/L), respectively; the overall coefficient of variation for determinations in all sera ranged from 0.37% to 0.56%. The precision and the accuracy of the method satisfy the requirements for a Definitive Method.
Measures of Glucose Homeostasis
2020
This document summarizes the rationale, equipment, protocol, assays, internal quality control, data cleaning, external quality control, and procedures for the measurement and classification of glucose homeostasis at the Wave V home exam. Whenever possible, data collection and methods in Wave V mirrored those of Wave IV to ensure comparability of data between waves, although important inter-Wave differences exist and are grey-highlighted herein. This document is one in a set of Wave V user guides.
Analusis, 1999
A flow injection system for the determination of high levels of glucose in parenteral solutions based on amperometric detection of hydrogen peroxide produced in the glucose oxidase reaction was developed. The determinations were made without any sample pre-treatment. The flow injection manifold includes two dialysis units to perform dilution of the samples and to maintain the enzyme in a closed re-circulation loop. Due to the hydrodynamic characteristics of the analytical system, the variables were optimized using a parameter design of Taguchi. Under optimal conditions, a linear response for glucose concentrations, between 0.1 and 1.0 M was achieved. A good reproducibility (r.s.d. < 3%) and a sampling rate of 30 determinations/hour were observed. The results obtained are in a good agreement with those obtained using the spectrophotometric enzymatic method.