Enantioseparation of chiral ß-blockers using polynorepinephrine-coated nanoparticles and chiral capillary electrophoresis.

A method of combining magnetic solid-phase separation (MSPE) and chiral capillary electrophoresis (CE) is developed for enantioseparation of trace amounts of ß-blockers. Polynorepinephrine-functionalized magnetic nanoparticles (polyNE-MNPs) are synthesized and applied to simultaneously extract three ß-blockers (carteolol, metoprolol, and betaxolol). The prepared polyNE-MNPs are spherical with a diameter of 198 ± 17 nm and the thickness of the polyNE coating is about 14 nm. PolyNE possesses abundant catechol hydroxyl and secondary amine groups, endowing the MNPs with excellent hydrophilicity. Under the optimum conditions, the extraction efficiencies of polyNE-MNPs for ß-blockers are in the range of 89.6 to 100%, with relative standard deviations (RSDs) below 3.5%. The extraction process can be finished in 4 min. Field-enhanced sample injection (FESI) in chiral CE is constructed to further enhance the sensitivities of ß-blocker enantiomers. The limits of detection for ß-blocker enantiomers by the FESI-CE with polyNE-MNPs are in the range of 0.401 to 1.59 ng mL-1. The practicability of this method in real samples is evaluated by analysis of human urine samples. The recoveries for each enantiomer of ß-blockers in the real samples range from 89.5 to 92.8%, with RSDs ranging from 0.37 to 5.9%. The whole detection process can be finished in less than 0.5 h. The method demonstrates its great potential in the pharmacokinetic and pharmacodynamic studies of chiral drugs in humans. Graphical abstract ᅟ.

On-line coupling of Micro-Extraction by Packed Sorbent with Sequential Injection Chromatography system for direct extraction and determination of betaxolol in human urine.

A novel approach for automation of Micro-Extraction by Packed Sorbent (MEPS), a solid phase extraction technique, is presented, enabling precise and repeatable liquid handling due to the employment of sequential injection technique. The developed system was used for human urine sample clean-up and pre-concentration of betaxolol before its separation and determination. A commercial MEPS C-18 cartridge was integrated into an SIChrom™ system. The chromatographic separation was performed on a monolithic High Resolution C18 (50×4.6 mm) column which was coupled on-line in the system with Micro-Extraction using an additional selection valve. A mixture of acetonitrile and aqueous solution of 0.5% triethylamine with acetic acid, pH adjusted to 4.5 in ratio 30:70 was used as a mobile phase for elution of betaxolol from MEPS directly onto the monolithic column where the separation took place. Betaxolol was quantified by a fluorescence detector at wavelengths λ(ex)=220 nm and λ(em)=305 nm. The linear calibration range of 5-400 ng mL(-1), with limit of detection 1.5 ng mL(-1) and limit of quantification 5 ng mL(-1) and correlation r=0.9998 for both the standard and urine matrix calibration were achieved. The system recovery was 105±5%; 100±4%; 108±1% for three concentration levels of betaxolol in 10 times diluted urine - 5, 20 and 200 ng mL(-1), respectively.

Determination of betaxolol and its metabolites in blood and urine by high-performance liquid chromatography with fluorimetric detection.

Analytical methods for the determination of betaxolol and two of its metabolites in blood and urine are described. Betaxolol, alpha-hydroxybetaxolol, and the acid metabolite were extracted, with over 65% efficiency, from biological samples by liquid-liquid extraction methods. Analysis was performed using reversed-phase high-performance liquid chromatography with fluorimetric detection. N,N-Dimethyloctylamine (0.005 M) was used to improve the chromatography of betaxolol and alpha-hydroxybetaxolol, while acetic acid (1%) was used for the acid metabolite. An excitation wavelength of 200 nm was found to produce the best detector response. Linear standard curves were obtained for all three compounds with detection limits (signal-to-noise ratio = 3) varying between 1 and 10 ng/ml. The coefficients of variation of the determination for all three compounds in blood and urine varied between 3.0 and 8.7%. The metabolism of betaxolol was studied in twelve healthy male subjects. The amounts (mean +/- S.D.) of betaxolol, alpha-hydroxybetaxolol and the acid metabolite renally excreted in the first 48 h after intravenous administration of 10 mg of betaxolol hydrochloride are 17.1 +/- 6.2, 0.4 +/- 0.1 and 14.5 +/- 3.7%, respectively, of the administered dose.