Capillary electrophoresis of cardiovascular drugs

Quantitative Analysis of β-Blockers inPharmaceutical Preparations by Capillary Electrophoresis

A simple capillary electrophoresis method was developed for the analysis of four beta-blockers (atenolol, metoprolol, pindolol, and propranolol) in pharmaceutical preparations. The method was validated regarding accuracy, precision, linearity, and detection/quantification limits, and the obtained values were in accordance to those reported in the literature. The method was applied to the determination of the drugs in commercial tablet preparations and proved to be fast and reliable for the quantitative analysis of the beta-blockers.

Newly synthesized tetraoxa-diaza crown ether derivatives versus commercialized crown ethers in the separation of positional isomers with capillary electrophoresis

Three new tetraoxa-diaza derivatives of 1,4,10,13-tetraoxa-7,16-diazacyclo-octadecane (R-1, R-2 and R-3) and three commercially available crown ethers, 18-crown-6 (18C6), (+)-18-crown-6-tetracarboxilic acid (18C6H4) and 1,4,10,13-tetraoxa-7,16-diazacyclo-octadecane, were investigated to separate the positional isomers of aminophenol, aminobenzoic acid and aminocresol. The running electrolyte, in which the crown ethers were dissolved, was a 50 mM Tris solution adjusted to pH 2.0 with hydrochloric acid. Using 50 mM H3PO4 buffer, whose pH was adjusted to 2.0 with Tris, or only hydrochloric acid solution with the same pH, did not allow good separations for the tested components. The effect of the crown ether concentration on the separation of the 11 positional isomers was studied in the concentration range of 10-50 mM. The best separations were achieved using the 18C6 and the 18C6H4 crown ethers: 9 isomers out of 11 could be separated within one run. The m- and p-aminophenol isomers could not be separated under the investigated experimental conditions. The newly synthesized tetraoxa-diaza crown ether derivatives were only found suitable for the separation of aminobenzoic acid positional isomers. The macrocyclic ring of the tetraoxa-diaza crown ethers was not able to form a stable inclusion complex with the tested positional isomers. Consequently, the aminophenol and aminocresol isomers were not separated, the isomers migrated with the same or very similar velocities.

Enantioselective capillary electrophoretic separation of tryptophane- and tyrosine-methylesters in a dual system with a tetra-oxadiaza-crown-ether derivative and a cyclodextrin

Different dual selector systems containing a cyclodextrin derivative (methyl-beta-cyclodextrin and dimethyl-beta-cyclodextrin) and a new diaza-crown-ether derivative (N-[2-(1,4,10,13-tetraoxa-7,16-diazacyclooctadecan-7-yl)propanoyl]glycine) were studied in the enantioselective separation of tryptophan-methylester and tyrosine-methylester enantiomers. This paper deals with the systematic study of the effects of changing the composition of the background electrolyte on the resolution of the d- and l- forms using an experimental design approach. It was found that the dual systems allowed a better chiral separation of the amino acid derivatives. The experimental design approach also allowed improving the separation compared to the starting conditions (center point of the design), which were adopted from a previous study.

Application of tetraoxadiaza-crown ether derivatives as chiral selector modifiers in capillary electrophoresis

Two new diaza-crown ether derivatives (R-1, RS-1) have been synthesized from 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane and tested as potential chiral selectors in capillary electrophoresis (CE) for the chiral separation of five amino acid derivatives. The individual use of the selectors did not lead to chiral differentiation. However, they enhanced the enantioselective effect of different cyclodextrins in dual selector systems. In this paper, we report the effect of different substituted diaza-crown ether derivatives on the separation results obtained in dual systems with cyclodextrins.

Preparative-scale isoelectric focusing separation of enantiomers using a multicompartment electrolyzer with isoelectric membranes

The IsoPrime multicompartment electrolyzer, equipped with a series of isoelectric membranes with closely spaced pI values, was used for the first time for the preparative-scale separation of the enantiomers of dansyl phenylalanine with hydroxypropyl beta-cyclodextrin as resolving agent. The final separation conditions could be established easily in three successive experiments by rationally narrowing the pH steps between the neighboring isoelectric membranes. The final separation yielded products with an enantiomeric excess greater than 99.9%, at production rates of about 0.1 mg/h. The greatest experimental difficulty was caused by the relatively high salt content of the hydroxypropyl beta-cyclodextrin used, which resulted in high conductivity and limited the maximum field strength one could use.

Systematic toxicological analysis procedures for acidic drugs and/or metabolites relevant to clinical and forensic toxicology and/or doping control

This paper reviews systematic toxicological analysis (STA) procedures for acidic drugs and/or metabolites relevant to clinical and forensic toxicology or doping control using gas chromatography, gas chromatography-mass spectrometry, liquid chromatography, thin-layer chromatography and capillary electrophoresis. Papers from 1992 to 1998 have been taken into consideration. Screening procedures in biosamples (whole blood, plasma, serum, urine, vitreous humor, brain, liver or hair) of humans or animals (horse, or rat) are included for the following drug classes: angiotensin-converting enzyme (ACE) inhibitors and angiotensin II (AT-II) blockers, anticoagulants of the 4-hydroxy coumarin type, barbiturates, dihydropyridine calcium channel blockers (calcium antagonists), diuretics, hypoglycemic sulfonylureas and non-steroidal anti-inflammatory drugs (NSAIDs). Methods for confirmation of preliminary results obtained by screening procedures using immunoassay or chromatographic techniques are also included. Furthermore, procedures for the simultaneous detection of several drug classes are reviewed. The toxicological question to be answered and the consequences for the choice of an adequate method, the sample preparation and the chromatography itself are discussed. The basic information about the biosample assayed, work-up, separation column, mobile phase or separation buffer, detection mode and validation data of each procedure is summarized in 16 tables. They are arranged according to the drug class and the analytical method. Examples of typical applications are presented. Finally, STA procedures are reviewed and described allowing simultaneous screening for different (acidic) drug classes.

Automated in-tube solid-phase microextraction coupled with liquid chromatography/electrospray ionization mass spectrometry for the determination of beta-blockers and metabolites in urine and serum samples

The technique of automated in-tube solid-phase microextraction (SPME) coupled with liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) was evaluated for the determination of beta-blockers in urine and serum samples. In-tube SPME is an extraction technique for organic compounds in aqueous samples, in which analytes are extracted from the sample directly into an open tubular capillary by repeated draw/eject cycles of sample solution. LC/MS analyses of beta-blockers were initially performed by liquid injection onto a LC column. Nine beta-blockers tested in this study gave very simple ESI mass spectra, and strong signals corresponding to [M + H]+ were observed for all beta-blockers. The beta-blockers were separated with a Hypersil BDS C18 column using acetonitrile/methanol/water/acetic acid (15:15:70:1) as a mobile phase. To optimize the extraction of beta-blockers, several in-tube SPME parameters were examined. The optimum extraction conditions were 15 draw/eject cycles of 30 microL of sample in 100 mM Tris-HCl (pH 8.5) at a flow rate of 100 microL/min using an Omegawax 250 capillary (Supelco, Bellefonte, PA). The beta-blockers extracted by the capillary were easily desorbed by mobile-phase flow, and carryover of beta-blockers was not observed. Using in-tube SPME/LC/ESI-MS with selected ion monitoring, the calibration curves of beta-blockers were linear in the range from 2 to 100 ng/mL with correlation coefficients above 0.9982 (n = 18) and detection limits (S/N = 3) of 0.1-1.2 ng/mL. This method was successfully applied to the analysis of biological samples without interference peaks. The recoveries of beta-blockers spiked into human urine and serum samples were above 84 and 71%, respectively. A serum sample from a patient administrated propranolol was analyzed using this method and both propranolol and its metabolites were detected.

Capillary electrophoresis as a versatile tool for the bioanalysis of drugs--a review

This review article presents an overview of current research on the use of capillary electrophoretic techniques for the analysis of drugs in biological matrices. The principles of capillary electrophoresis and its various separation and detection modes are briefly discussed. Sample pretreatment methods which have been used for clean-up and concentration are discussed. Finally, an extensive overview of bioanalytical applications is presented. The bioanalyses of more than 200 drugs have been summarised, including the applied sample pretreatment methods and the achieved detection limits.

Recent chromatographic and electrophoretic enantioseparations of cardiovascular drugs

The chromatographic and electrophoretic enantiomeric separation and analysis of several clinically used cardiovascular drugs have been reviewed. Several examples of recently reported applications of enantioselective analysis and various cardiovascular agents are presented.

Determination of degradation products from the calcium-channel blocker isradipine

Mass Spectrometry has been used to determine the identity of a number of degradation products from the bulk drug form of Isradipine (DynaCirc). Liquid chromatography coupled with mass spectrometry (LC/MS) was used to analyze the degraded samples and tentative identifications were made based upon the known reactivity of the molecule, molecular weight measurements and mass spectral fragmentation patterns. Isradipine was found to be stable to heating, acidic and basic conditions, but susceptible to degradation from exposure to UV light and oxidative processes.

Capillary electrophoretic separations of enantiomers using cyclodextrin-containing background electrolytes

The 1996 primary literature papers which deal with the separation of enantiomers using cyclodextrins are reviewed here. Though the majority of the papers still use the neutral native cyclodextrins or the neutral derivatized cyclodextrins as resolving agents, there was a significant increase in number of separations which relied on charged cyclodextrins, both weak electrolytes and strong electrolytes, as resolving agents. Also, there was an increase in the number of papers which reported binding constants and correlated them with other physical or chemical characteristics of the analytes. Several successful minor enantiomer determinations were presented, pushing the reliable quantitation levels below 0.1%. Work continued on the simultaneous use of neutral and charged cyclodextrins to improve separation selectivity or peak resolution.