Ultraviolet Photodiode Array Detection Research Articles

Application of HPLC Coupled with Ultraviolet-Photodiode Array Detection for the Analysis of Phytoestrogens in Biological Samples

HPLC/PDA methodology was developed for phytoestrogen analysis in human blood, urine, and breast milk. Applications of this technique in four different observational studies showed that urinary excretion rates of isoflavonoids reflects soy consumption reliably. A case-control study in Shanghai showed a decrease in risk to develop breast cancer for women with high urinary isoflavone excretion. These findings support a potential breast cancer preventive effect achieved by soy consumption in populations that eat soy foods habitually.

Determination of Aristolochic Acid in Rabbit Plasma by High-Performance Liquid Chromatography with Photodiode-Array Ultraviolet Detection and Its Pharmacokinetics Application

Abstract A simple and sensitive high-performance liquid chromatographic method for the determination of aristolochic acid (AA) in rabbit plasma has been developed. Up to 0.1 ml of plasma containing AA was deproteinized by acetonitrile, which contained an internal standard (indomethacin). The supernatant was injected onto a COSMOSIL 5C18-AR column (5 μm) using acetonitrile-0.1 % phosphoric acid (60:40, v/v, pH 2.5–2.8) as the mobile phase. UV detection at 227 nm was followed by ultraviolet spectrum identification (among 200 and 380 nm) with a photodiode-array detector. The method was rapid, easily reproduced, selective and sensitive. It was applied to pharmacokinetic studies of AA in rabbit, after a 5 mg/kg intravenous administration. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve. Compartmental analyses yielded a two-compartment model.

Determination of glycyrrhizin in rabbit plasma by high-performance liquid chromatography with photodiode-array ultraviolet detection and its pharmacokinetics application

A simple and sensitive high-performance liquid chromatographic method for the determination of glycyrrhizin in rabbit plasma has been developed. Up to 0.1 ml of plasma containing glycyrrhizin was deproteinized by acetonitrile, which contained an internal standard (indomethacin). The supernatant was injected onto a LiChrospher RP-18 column using a methanol—water—ammonia solution (80:20:0.1, v/v, pH 3.0–3.2, adjusted with perchloric acid) as the mobile phase and ultraviolet detection at 254 nm, followed by ultraviolet spectrum identification (between 200 and 380 nm) with a photodiode-array detector. The method is rapid, easily reproduced, selective and sensitive. It was applied to pharmacokinetic studies of glycyrrhizin in rabbit, after a 2 mg/kg intravenous administration. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration—time curve. Compartmental analysis yielded a two-compartment model.

Approach to studying proteinase specificity by continuous-flow fast atom bombardment mass spectrometry and high-performance liquid chromatography combined with photodiode-array ultraviolet detection

Fast atom bombardment mass spectrometry (FAB-MS) and high-performance liquid chromatography using a photodiode-array ultraviolet detector were applied to study a dynorphin-converting endopeptidase from the human pituitary gland. The specificity of the enzyme was tested towards various opioid peptides derived from the prodynorphin precursor, i.e. dynorphin A, dynorphin B and α-neoendorphin. Peptide fragments were analysed directly by continuous-flow FAB-MS and those containing aromatic amino acids were detected independently by the photodiode-array ultraviolet detector. The results obtained suggest a similar processing of these structure-related substrates and it appears that the enzyme recognizes the dibasic stretch in their sequence. It is also clear from this study that the combination of the above techniques provides a powerful tool for studies of enzymatic conversion among the prodynorphin-derived peptides and it should be applicable to studies of similar mechanisms in other peptide systems.