Authors:Ravi Bhushan, Jürgen Martens, Charu Agarwal, and Shuchi Dixit
Cu(II) complexes of L-threonine, L-serine, and L-tartaric acid were prepared and used as ligand exchange reagents for enantiomeric resolution of some of the β-blockers (bisoprolol, metoprolol, and propranolol) and a β2-agonist (salbutamol). Impregnated thin-layer plates were prepared by spreading slurry of silica gel prepared in the solutions of each of the three ligand exchange reagents. The spots were detected with iodine. Effect of temperature on enantioresolution was also studied. The detection limits were found in the range 0.19–0.26 μg for each enantiomer. L-Ser proved to be a good ligand using a common mobile phase in each case.
Impregnation of a stationary phase by organic and inorganic agents in high-performance thin-layer chromatography (HPTLC) may result in higher separation selectivity and resolution. This work is devoted to the application of novel core–shell polymers consisting of hyperbranched (poly(ethyleneimine)) core surrounded by oligosaccharide shell (PEI-OS) as a component of silica stationary phase in HPTLC for the separation of water-soluble vitamins, amino acids, and chiral β-blocker enantiomers. The influence of polymer structure (degree of substitution of PEI terminal amino groups with oligosaccharides and molecular weight of dendritic core [5 or 25 kDa]) as well as the content of PEI-OS in the stationary phase and a method of modification of the stationary phase on the efficiency of vitamin and amino acid determination and on the enantioselectivity factors of β-blockers separation were investigated. It was established that such polymers can be used as modifying agents of HPTLC systems for on-line preconcentration of vitamins (B2) and amino acids (lysine, tryptophan, and glutamic acids). These polymers can also be recommended as chiral selectors for the effective TLC separation of β-blockers.
ventricular wall thickness. Hypertension, 2011, 57 (6), 1122–1128.
Kotecha, D., Holmes, J., Krum, H., et al.: Efficacy of βblockers in patients with heart failure plus atrial fibrillation: an individual-patient data
Authors:Ahmad Makahleh, Kek Wan Cheng, Bahruddin Saad, and Hassan Y. Aboul-Enein
A hollow-fiber liquid-phase microextraction (HF-LPME), followed by high-performance liquid chromatography–ultraviolet (HPLC–UV) method for the trace determination of carvedilol (β-blocker) in biological fluids, has been described. The separation was achieved using Inertsil ODS-3 C18 (250 mm × 4.6 mm, 3 μm) column with a mobile phase composition of 10 mM phosphate buffer (pH 4.0)–acetonitrile (50:50, v/v) at a flow rate of 1.0 mL/min, under isocratic elution. Several parameters (i.e., type of organic solvent, donor phase pH, concentration of acceptor phase (AP), stirring rate, extraction time, and salt addition) that affect the extraction efficiency were investigated. The optimum HF-LPME conditions were as follows: dihexyl ether as an organic solvent; donor phase pH, 10.7; 0.1 M HCl (AP); 1100-rpm stirring rate; 60-min extraction time; and no salt addition. These parameters have been confirmed using design of experiments. Under these conditions, an enrichment factor of 273-fold was achieved. Good linearity and correlation coefficient were obtained over the range 5–1000 ng/mL (r2 = 0.9994). Limits of detection and quantitation were 1.2 and 3.7 ng/mL, respectively. The relative standard deviation at 3 different concentration levels (5, 500, and 1000 ng/mL) were less than 13.2%. Recoveries for spiked urine and plasma were in the range 80.7–114%. The proposed method is simple, sensitive, and suitable for the determination of carvedilol in biological fluids.
Resolution of the enantiomers of racemic atenolol, metoprolol, propranolol, and labetalol, commonly used β-blockers, has been achieved by TLC on silica gel plates using vancomycin as chiral impregnating reagent or as chiral mobile phase additive. With vancomycin as impregnating agent, successful resolution of the enantiomers of atenolol, metoprolol, propranolol, and labetalol was achieved by use of the mobile phases acetonitrile-methanol-water-dichloromethane 7:1:1:1 (
), acetonitrile-methanol-water 6:1:1 (
), acetonitrile-methanol-water-dichloromethane-glacial acetic acid 7:1:1:1:0.5 (
), and acetonitrile-methanol-water 15:1:1 (
), respectively. With vancomycin as mobile phase additive, successful resolution of the enantiomers of metoprolol, propranolol, and labetalol was achieved by use of the mobile phases acetonitrile-methanol-0.56 mM aqueous vancomycin (pH 5.5) 6:1:1 (
), acetonitrile-methanol-0.56 mM aqueous vancomycin (pH 5.5) 15:1:2 (
), and acetonitrile-methanol-0.56 mM aqueous vancomycin (pH 5.5)-dichloromethane 9:1:1.5:1 (
), respectively. Spots were detected by use of iodine vapor. The detection limits were 1.3, 1.2, 1.5, and 1.4 μg for each enantiomer of atenolol, metoprolol, propranolol, and labetalol, respectively.
Authors:M. Abou-Sekkina, M. El-Ries, A. Molokhia, N. Rabie, and A. Wassel
Timolol drug, has been investigated by using X-ray diffraction analysis, thermogravimetry (TG), differential thermal analysis
(DTA), IR, HPLC and electronic absorption spectra (UV/Vis), before and after exposure to γ-radiation. The interaction ofγ-rays
with timolol has been studied. Results obtained indicated high stability towardγ-absorbed dose over the range 5–50 kGy.
summary tables [ 1 ]. With the increase in the number of patients, the production of cardiovascular medications is increasing correspondingly worldwide. In particular, antihypertensive agents, such as β-blockers (BBs) and calcium channel blockers (CCBs
Enantiomeric resolution of two commonly used β-blockers, namely, (±)-propranolol and (±)-atenolol, has been achieved on silica gel layers which were bulkimpregnated with β-cyclodextrin. Solvent systems DMF-ethyl acetate-butanol (3:2:5, υ/υ) and butanol-acetic acid-ethyl acetate-ammonia (5:2:2:0.5, υ/υ) successfully resolved the enantiomers of (±)-propranolol and (±)-atenolol, respectively. The spots were located with iodine vapor. The effects of concentration of the chiral selector and mobile phase variation were also studied.
Resolution of racemic metoprolol, propranolol, carvedilol, bisoprolol, salbutamol, and labetalol, commonly used β-blockers, into their enantiomers has been achieved by TLC on silica gel plates impregnated with optically pure L
-Glu and L
-Asp. Acetonitrile-methanol-water-dichloromethane and acetonitrile-methanol-water-glacial acetic acid mobile phases in different proportions enabled successful separation. The spots were detected with iodine vapor. The detection limits were 0.23, 0.1, 0.27, 0.25, 0.2, and 0.2 μg for each enantiomer of metoprolol, propranolol, carvedilol, bisoprolol, salbutamol, and labetalol, respectively.