A high speed high performance liquid chromatography (HPLC) method for the quantification of putrescine, spermidine, and spermine in biological samples is described. The dansylation is followed by a sample cleanup. The isocratic HPLC-analysis with acetonitrile:H(2)O (72:28 volume/volume) on 10 centimeter long, 3 micrometer octadecyl silica columns (3 millimeter inner diameter) takes only 4.5 min...

A simple, sensitive isocratic method for the detection and quantification of ciprofloxacin in plasma and urine has been developed. The assay consisted of reversed-phase HPLC with ultraviolet detection. Plasma proteins were removed by a fast and efficient procedure. For the urine samples, the only required sample preparation was dilution. Separation was achieved on a C18 reversed-phase column. T...

This work aimed at determining 4-vinylguaiacol and 4-vinylphenol in the top-fermented wheat beers using different wavelength and the mobile phase for HPLC. Best results for isocratic elution were obtained at 260 nm and the mobile phase comprising methanol/ultrapure water/phosphoric acid (400/590/10, V/V). Under these conditions, the retention time of 4-vinylguaiacol and 4-vinylphenol was 25 and...

This contribution summarizes methods to compare bonded stationary phases for the compound-class HPLC separations of unsaturated polycyclic hydrocarbons and polar compounds. These strategies are based on the physical chemistry behavior of the functional group of the bonded stationary phase, behavior of the unsaturated polycyclic hydrocarbons under isocratic and gradient elution, regression analy...

This article describes a straightforward ion chromatographic method that uses isocratic elution and pulsed amperometric detection (PAD) to sensitively determine water-soluble polyols and sugar alcohols as well as mono-, diand oligosaccharides in essential and non-essential foodstuffs. While carbohydrate determination of most foodstuffs requires only minimal sample pretreatment such as dilution ...

Optimization of sample pre-treatment. Complete removal of cellular and further solid sample constituents, precipitation and removal of proteins, precipitation and removal of cholesterol from the blood sample and quantitative extraction of the analytes tryptophan, phenol, p-cresol and cholic acid in the diluted blood plasma phase. Step III: Combination and conversion of both isocratic HPLC/DAD/M...

A reversed-phase gradient elution system is described for the simultaneous separation of the type I and type III isomers of 8-, 7-, 6-, 5- and 4-carboxylated porphyrins and isocoproporphyrins. The method, adaptable for isocratic and stepwise separation of individual groups of isomers, is also suitable for preparative isolation of pure porphyrins. The analyses of porphyrin isomers in the urine a...

A simple and rapid method of reversed-phase ion-pair high-performance liquid chromatography (HPLC) with UV-detection on a common C(18) column in an isocratic mode with the addition of tetrabutylammonium phosphate for the separation of polyprenyl phosphate oligomerhomologues has been developed. The method was successfully applied to assay the composition of polyprenyl phosphates obtained from p...

A simple isocratic reversed phase high performance liquid chromatography was used to separate three impurities present in the sample of 8-chlorotheophylline. LC-MS was used for the characterization of impurities. Based on mass spectral data, the structures of these impurities were characterized as 3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione (impurity I), 3,7-dihydro-1,3,7-trimethyl-1H-purine-2...