A novel fast high-performance liquid chromatography (HPLC) method coupled with diode array detection (DAD) and time-of-flight mass spectrometry (TOF/MS) was developed for qualitative and quantitative analysis of Radix Astragali products. The potential of fast HPLC on 1.8-microm particles was compared with the performance of HPLC on conventional 5-microm particles columns. Significant advantages...

Technical improvements have been applied to reduce the time required for the determination of calcidiol and calcitriol in serum or plasma. The modifications include the use of Sep-Pak C18 cartridges for the extraction of calciol metabolites from serum instead of a classical liquid/liquid extraction, a considerable shortening of the HPLC purification time compared with our previously described m...

This work proposes a procedure to estimate the measurement uncertainty for the quantification of cefazolin by high-performance liquid chromatography (HPLC) and microbiological assay (bioassay). HPLC method was performed according to United States Pharmacopeia (USP) and bioassay according to Brazilian Pharmacopeia (FB). The quantification of cefazolin by high-performance liquid chromatography wa...

In this article, we describe a fast and specific method to measure 5FU with HPLC tandem-mass spectrometry. Reversed-phase HPLC was combined with electrospray ionization tandem mass spectrometry and detection was performed by multiple-reaction monitoring. Stable-isotope-labeled 5FU (1,3-15N2-5FU) was used as an internal standard. 5FU was measured within a single analytical run of 16 min with a l...

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...

BACKGROUND Although high-performance liquid chromatography (HPLC) is the commonly used method for the analysis of retinol in biological samples, simple and rapid test kits are available. OBJECTIVES This study compared a rapid test kit (ICHECK Fluoro®) to HPLC for the assessment of serum retinol concentrations. METHODS For the analysis by HPLC, sample preparation included standard deproteini...

The HPLC/MS system, in which a monolithic silica capillary column is directly connected to an electronspray-ionization mass spectrometer, showed superior performance at high mobile phase linear velocity. A two-dimensional (2D) HPLC/MS system was established, using an ion-exchange particle-packed capillary column at the first dimension and a monolithic silica capillary column at the second dimen...

As one of the widely used veterinary macrolide antibiotics, the environmental risks of tylosin (TYL) received more and more attention. The purpose of the present study was to develop a modified, rapid and precise RP-HPLC method with PDA detection for the determination of the macrolide antibiotic tylosin in liquid samples. The proposed two HPLC methods offered short retention time (< 6.8 min), h...

Previously, we developed a reversed-phase HPLC method compatible to high performance liquid chromatography diffuse reflectance Fourier-transform infrared (HPLC-FTIR) thermospray interface for the analysis of dyes. Dye separation achieved with a mixed-mode (SCX-ODS) column using a small gradient (90 to 80% water with acetic acid) and pH 3.25; 10 to 20% acetonitrile was considered to be suitable ...

A multicomponent pharmaceutical that contains loratadine, paracetamol, and pseudoephedrine was quantified using HPLC-PDA. The three analytes were well-separated in the dosage form on a C-18 column gradient mobile phase. quality by design strategy followed to achieve challenging separation. Screening optimization steps carried out investigate effect of many factors studied responses with minimum...