BACKGROUND The measurement of renin activity is complicated by difficulties in the quantification of angiotensin 1 (Ang1), the product of the renin-catalyzed reaction. We report an HPLC-electrospray-tandem mass spectrometry (HPLC-ESI-MS/MS) method for the quantification of Ang1 as a measure of plasma renin activity (PRA). METHODS After incubation (37 degrees C for 3 or 18 h), samples were pre...

In an effort to replace HPLC for whole-blood determination of cyclosporine (CsA), we compared HPLC with radioimmunoassay (RIA; INCSTAR, Cyclo-Trac SP assay), fluorescence polarization immunoassay (FPIA; Abbott TDx), and in-house modified enzyme-multiplied immunoassay technique (EMIT; Syva Co.). For blood samples from 200 various transplant recipients, RIA = 1.262 (HPLC) - 8.16, r = 0.983; FPIA ...

Methods: The study was initiated by preliminary phytochemical screening to detect the presence of carbohydrates, flavonoids, alkaloids, saponins and tannins. Quantitative analysis of phenolic and flavonoids was carried out by Folins Ciocalteau reagent method. In vitro antioxidant activities were performed by DPPH free radical scavenging assay, Reducing power assay, Total antioxidant assay and T...

A new selective high-performance liquid chromatography (HPLC) method with UV detection for the determination of the investigational triazole voriconazole in human plasma by using acetonitrile precipitation followed by reverse-phase HPLC on a C(18) column was compared with a simple agar well diffusion bioassay method with Candida kefyr ATCC 46764 as the assay organism. Pooled plasma was used to ...

The zearalenone (ZEA) monoclonal antibody (mAb) 2D3, one of the highest sensitivity antibodies, was developed. Based on this mAb, it was established of an immunoaffinity column (IAC) coupled with an indirect competitive enzyme-linked immunosorbent assay (icELISA). After optimization, the icELISA allowed an IC50 against ZEA of 0.02 µg L(-1). The mAb 2D3 exhibited a high recognition of ZEA (100%)...

A rapid and simple high-performance liquid chromatographic (HPLC) method has been developed and validated for determination of scopoletin in rat plasma using psoralen as internal standard. Chromatographic separation was achieved on a C(18) column using methanol and distilled water (49:51, v/v) containing 0.05% (v/v) phosphoric acid as mobile phase. The UV detector was set at 345 nm. The calibra...

An analytical methodology was developed to quantitate the intracellular nucleotides including mono-, di-, and triphosphates and the diphosphocholine derivative of (-)-2', 3'-deoxy-3'-thiacytidine (3TC) in human peripheral blood mononuclear cells (PBMCs). The procedure includes the resolution of 3TC nucleotides by solid-phase extraction (SPE) on an anion-exchange cartridge, with subsequent enzym...

Semen Oroxyli, derived from the seed of Oroxylum indicum L., is a commonly used Traditional Chinese Medicine with beneficial effects against several respiratory disorders. Antioxidative flavonoids may be partly responsible for its medicinal functions. The aim of this study was to rapidly determine the antioxidants in Semen Oroxyli based on a HPLC-DPPH method. Four major flavonoids, baicalein-7-...

The purpose of the research described herein was to develop simple, precise and accurate isocratic stability indicating reversed phase HPLC assay method for determination of Tapentadol solid dosage forms. Isocratic RP-HPLC method was developed on Phenomenex Luna C8 150 4.6mm, 5μm column using mobile phase as methanol – 0.002 M potassium dihydrogen phosphate buffer pH 3.0 (60: 40 v/v) at a flow...

Hemoglobin A1c (HbA1c) is an important parameter for evaluating long-term (6-8 weeks) control of blood glucose levels in patients with diabetes mellitus. We report a Japanese diabetic case who harbored abnormal Hb and demonstrated falsely low HbA1c levels in the regular ion exchange HPLC-based assay. His abnormal β-globin chain had an amino acid replacement that corresponded to glycine to serin...