Kinetic Determination of Ascorbic Acid
One method for determining the concentration of glucose in fruit juices is to take advantage of its enzymatic oxidation in the presence of glucose oxidase: β-D-glucose + O2 + H2O → δ-D-gluconolactone […]
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Kinetic Method for Manganese
Trace levels of manganese can be determined by measuring its catalytic effect on the oxidation of diethylamine by sodium periodate. The rate of formation of the oxidation product is followed spectrophotometrically. A […]
Standardization of a Kinetic Method of Analysis
Shown below is a plot of initial rate vs. substrate concentration for an enzyme-substrate reaction that follows Michaelis-Menton kinetics. An analyst developing a quantitative method for the substrate wishes to use a […]
HPLC Separation of Phenacetin, Salicylic Acid, Nicotine, Methylamphetamine, and Phenobarbatuic Acid
The graph shown below is a plot of retention time vs. pH for the reverse-phase HPLC separation of a mixture containing phenacetin, salicylic acid, nicotine, methylamphetamine, and phenobarbituic acid. Based on the […]
Separation of Amino Acids
In ion-exchange chromatography, a solution containing a mixture of compounds is passed through a column packed with a resin containing covalently attached anionic and/or cationic functional groups. One use of ion-exchange chromatography […]
Analysis of Anaerobic Sediments for Sulfides
A paper in the Journal of Chemical Education describes an experimental method for determining the concentrations of both insoluble metal sulfides, such as FeS2, and gaseous H2S in anaerobic sediments. Samples of […]
Neocuproine Method: Analysis of Procedure
One method for determining copper is the “Neocuproine Method”. In this method, copper in a +1 oxidation state reacts with neocuproine (2,9-dimethyl-1,10-phenanthroline) to form a complex of Cu(neocuproine)2. The complex is extracted […]
Standards and Samples
The spectrophotometric methods for analyzing Mn and for analyzing glucose use a chemical reaction to produce a useful signal. In the analysis for Mn in steel, colorless Mn2+ is oxidized to give the […]
Standards for the Spectrophotometric Analysis of Acetone
Suppose you need to prepare a set of calibration standards for the spectrophotometric analysis of acetone at a wavelength of 211 nm using a 1.00 cm cell. The molar absorptivity for acetone […]
Titrimetic Analysis of Mixtures
Shown below is a titration curve for a mixture of two monoprotic weak acids, HA and HB, where pKa,HA = 4.00 and pKa,HB = 8.00. The titrant is 0.200 M NaOH. (a) […]
Titration Curve for Amino Acid
Shown below is a potentiometric titration curve for a 0.050-g sample of an amino acid dissolved in water and titrated with 0.100 M NaOH. Based on this titration curve, answer the following […]
Titrimetric Analysis of Amino Acids
The quantitative titrimetric analysis of amino acids often is complicated by the high pKa of the —NH4+ group, which produces a titration break that is too small for the effective use of […]