Determination of propafenone and its main metabolite 5-hydroxypropafenone in human serum with direct injection into a column-switching chromatographic system

Surface functionalized quantum dots as biosensor for highly selective and sensitive detection of ppb level of propafenone

Monodispersed CdTe quantum dots (QDs) were prepared by using thioglycolic acid as surfactants in aqueous solution. The thioglycolic acid was chemically adsorbed on the surface of CdTe QDs that enables the QDs positively charged. In week acidic media, propafenone is positively charged, which can combine with the CdTe QDs to form larger ion-association complex via electrostatic attraction and hydrogen bond. Moreover, the formed ion-association complex could increase the intensity of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling-scattering (FDS) of CdTe QDs, and quench the CdTe QDs fluorescence. Importantly, under optimal experimental conditions, the increased RRS, SOS and FDS intensity, and quenched fluorescence intensity of CdTe QDs were in direct proportion to the propafenone concentration in a certain range, respectively. Among them, the RRS method exhibited the highest sensitivity. In a wide concentration range of propafenone from 0.003 to 7.0 μg mL^-1, the detection limit could reach 0.96 ng mL^-1, which was much lower than previously reported methods. To simulate practical applications, the possible foreign interfering substances were also investigated, such as common ions, amino acid, and glucide. The proposed method here is rapid, sensitive and shows promising application for detection of ppb level of propafenone in human serum.

Restricted access materials and large particle supports for on-line sample preparation: an attractive approach for biological fluids analysis

An analytical process generally involves four main steps: (1) sample preparation; (2) analytical separation; (3) detection; and (4) data handling. In the bioanalytical field, sample preparation is often considered as the time-limiting step. Indeed, the extraction techniques commonly used for biological matrices such as liquid-liquid extraction (LLE) and solid-phase extraction (SPE) are achieved in the off-line mode. In order to perform a high throughput analysis, efforts have been engaged in developing a faster sample purification process. Among different strategies, the introduction of special extraction sorbents, such as the restricted access media (RAM) and large particle supports (LPS), allowing the direct and repetitive injection of complex biological matrices, represents a very attractive approach. Integrated in a liquid chromatography (LC) system, these extraction supports lead to the automation, simplification and speeding up of the sample preparation process. In this paper, RAM and LPS are reviewed and particular attention is given to commercially available supports. Applications of these extraction supports, are presented in single column and column-switching configurations, for the direct analysis of compounds in various biological fluids.

A Rapid HPLC Assay for the Simultaneous Determination of Propafenone and Its Major Metabolites in Human Serum

A rapid and specific HPLC method has been developed and validated for the simultaneous determination of propafenone, an antiarrhythmic agent, and its major metabolites in human serum. The sample preparation was a simple deproteinization with a mixture of ZnSO4 and methanol, yielding almost 100% recoveries of three compounds. Separation was developed on a reverse-phase tracer excel C18 column (25 x 0.46 cm i.d., 5 microm), using an acetonitrile-phosphate buffer gradient at a flow rate of 1.7 ml min(-1), and UV detection of 210 nm. The calibration curves were linear (r2 > 0.999) in the concentration range of 10 - 750 ng ml(-1). The lower limit of quantification was 10 ng ml(-1) for all of the compounds studied. The within and between day precisions in the measurement of QC samples at four tested concentrations were in the range of 1.4 - 8.1% and 4.2 - 11.5% RSD, respectively. The developed procedure was applied to assess the pharmacokinetics of propafenone and its major metabolites following administration of a single 300 mg oral dose of propafenone hydrochloride to three healthy male volunteers.

Role of biological matrices during the analysis of chiral drugs by liquid chromatography

The review article covers advances of chiral drugs analysis by high-performance liquid chromatography (HPLC) methods achieved during last 10 years. Emphasis is given to various aspects of influence of biological matrix in pharmacodynamics, pharmacokinetics, HPLC analysis. Discussed is composition of main biological matrices from the point of view of potential interferences to above-mentioned fields of study. Beside typical analytical approaches to chiral recognition in HPLC, sample pretreatment and/or clean-up by conventional extraction procedures, column switching (CSW) techniques using restricted access materials (RAMs), microdialysis (MCD) is discussed. Measurement of unbound drug concentration and discussion of column maintenance and remedy is an additional source of information and field where knowledge on complex properties and interactions of biological matrix is usefully applicable.

Liquid chromatography/atmospheric pressure ionization-mass spectrometry in drug metabolism studies

The study of the metabolic fate of drugs is an essential and important part of the drug development process. The analysis of metabolites is a challenging task and several different analytical methods have been used in these studies. However, after the introduction of the atmospheric pressure ionization (API) technique, electrospray and atmospheric pressure chemical ionization, liquid chromatography/mass spectrometry (LC/MS) has become an important and widely used method in the analysis of metabolites owing to its superior specificity, sensitivity and efficiency. In this paper the feasibility of LC/API-MS techniques in the identification, structure characterization and quantitation of drug metabolites is reviewed. Sample preparation, LC techniques, isotope labeling, suitability of different MS techniques, such as tandem mass spectrometry, and high-resolution MS in drug metabolite analysis, are summarized and discussed. Automation of data acquisition and interpretation, special techniques and possible future trends are also the topics of the review.

Influence of various biological matrices (plasma, blood microdialysate) on chromatographic performance in the determination of beta-blockers using an alkyl-diol silica precolumn for sample clean-up

A HPLC column-switching system with LiChrospher RP-8 ADS precolumn was applied for the determination of beta-blockers (atenolol, pindolol, propranolol) in human plasma. The influence of biological matrices on the changes of the chromatographic parameters such as retention time, peak symmetry, area and selectivity were investigated. After injection of 5 ml plasma a decrease of retention times of the analytes was observed of up to 25% and an increase of asymmetry factors of up to 5%. Peak areas and selectivities were not changed. The observed effect could indicate changes of chromatographic performance caused by contributions of the analytical column or the ADS precolumn. The experiments with microdialysis excluded the contribution of the analytical column. A detailed investigation of experiments have been discussed in this paper.