Determination of Labetalol Hydrochloride in Drug Formulations by Spectrophotometry

A validated, selective and sensitive spectrophotometric method has been developed for the determination of labetalol hydrochloride in commercial dosage forms. The method is based on the coupling reaction of positive diazonium ion of 4‐aminobenzenesulfonic acid with phenolate ion of labetalol to form a colored azo compound which absorbs maximally at 395 nm. Under the optimized experimental conditions, the color is stable up to 2 h and Beer's law is obeyed in the concentration range of 0.8–17.6 μg mL^?1 with a linear regression equation of A = 4.84 × 10^?4 + 7.864 × 10^?2 C and coefficient of correlation, r = 0.9999. The molar absorptivity and Sandell's sensitivity are found to be 2.874 × 10⁴ L mol^?1 cm^?1 and 0.013 μg cm^?2 per 0.001‐absorbance unit, respectively. The limits of detection and quantitation of the proposed method are 0.08 and 0.23 μg mL^?1, respectively. The intra‐day and inter‐day precision variation and accuracy of the proposed method is acceptable with low values of standard analytical error. The recovery results obtained by the proposed method in drug formulations are acceptable with mean percent recovery ± RSD of 99.97 ± 0.52 ‐ 100.03 ± 0.63%. The results of the proposed method compared with those of Bilal's spectrophotometric method indicated excellent agreement with acceptable true bias of all samples within ± 2.0%.     

A comparative study of essential oils of Cymbopogon citratus and some members of the genus Citrus

Steam distilled oils of some species of the genus Citrus and Cymbopogon citratus were analyzed by GC-MS. It is observed that citral b was the most common constituent of the oils, which could be a good inhibitor of beta-glucuronidase as all the tested essential oils showed significant inhibition of beta-glucuronidase. IC50 values of a mixture of citral a and b also proved the hypothesis. The same oils also exhibited positive response against tested microbes.     

Catching protein antigens by antibody affinity electrophoresis

A new kind of affinity electrophoresis called antibody affinity electrophoresis is a technique used to capture protein antigens based on their interactions with specific monoclonal or polyclonal antibodies incorporated in the polyacrylamide gel. Polyclonal anti-glutathione-S-transferase (anti-GST), monoclonal anti-bovine serum albumin (anti-BSA), and polyclonal anti-human alpha-lactalbumin are embedded in distinct areas of a 7.5% native polyacrylamide gel. Some of the embedded antibodies get covalently and/or noncovalently incorporated into the gel matrix network. Under electrophoresis conditions, these antibodies do not show significant electrophoretic mobility, as compared to their specific protein antigen analytes. We observed that electrophoretic migration of GST, BSA, and protein G ceases when they encounter anti-GST, anti-BSA, and immunoglobulin G, respectively.     

Solvent extraction of thorium from nitric acid solutions using di-N-butyl sulfoxide (DBSO) in xylene

The extraction of thorium(IV) from nitric acid solutions by di-n-butyl sulfoxide (DBSO) in xylene has been investigated as a function of acid, extractant and the metal concentration. The effect of contact time and diverse ions on the extraction has been examined. Phosphate, fluoride, oxalate and perchlorate reduce the extraction to some extent. The extraction of other metal ions, especially impurities associated with thorium in ores, has been measured under optimised conditions selected for thorium extraction. Na(I), K(I), Ca(II), Sr(II), Mn(II), Fe(II), Ni(II), Zn(II), Pb(II), Al(III), Ti(IV) and Hf(IV) are not extracted. Among the stripping solutions employed for back-extraction, deionized water is found to be the best and more than 99% thorium can be back-extracted in three stages. The extracted species is supposed to be Th(NO₃)₄·2DBSO. The extraction is found to be almost independent of the thorium concentration in the range between 4.3·10^–4–4.3·10^–2M and inversely dependent upon the temperature. The values of thermodynamic functions H, G and S for extraction equilibrium have been evaluated to be –19.6±2.9 kJ·mole^–1, –18.1±2.0 kJ·mole^–1 and –5.0±2.9 J·mole^–1·K^–1, respectively.     

Quantitation of Diltiazem Hydrochloride in Commercial Dosage Forms by Visible Spectrophotometry

A selective and sensitive visible spectrophotometric method has been described for the quantitation of diltiazem hydrochloride in commercial dosage forms. The method is based on the reaction of the tertiary amino group of the drug with sodium hypochlorite to form the chloro drug derivative, followed by the destruction of the excess hypochlorite by sodium nitrite and the subsequent development of blue color takes place by the reaction of chloro derivative of drug with starch and potassium iodide in sodium bicarbonate medium. The maximum absorbance of the resulting blue solution is read at 540 nm. Under the optimized experimental conditions, Beer's law is obeyed in the concentration range of 2.5–25.0 μg mL^?1 with a linear regression equation of A = 9.85 × 10^?4 + 4.90 × 10^?2 C and coefficient of correlation, r = 0.9999. The molar absorptivity is found to be 2.26 × 10⁴L mol^?1 cm^?1. The limits of detection and quantitation of the proposed method are 0.12 and 0.37 μg mL^?1, respectively. The proposed method has been successfully applied for the quantitation of diltiazem hydrochloride in commercial dosage forms. The results of the proposed method compared with those of Abdellatef's spectrophotometric method presented good mean recovery with acceptable true bias of all pharmaceutical samples within ± 2.0%.     

Determination of Trace Amounts of Nickel (Ⅱ) by Graphite Furnace Atomic Absorption Spectrometry Coupled with Cloud Point Extraction

A new method based on the cloud point extraction(CPE) for separation and preconcentration of nickel(Ⅱ) and its subsequent determination by graphite furnace atomic absorption spectrometry(GFAAS) was proposed, 8-hydroxyquinoline and Triton X-100 were used as the ligand and surfactant respectively. Nickel(Ⅱ) can form a hy-drophobic complex with 8-hydroxyquinoline, the complex can be extracted into the small volume surfactant rich phase at the cloud point temperature(CPT) for GFAAS determination. The factors af...     

Some Properties of Chromatic Coefficients of Linear Uniform Hypergraphs

In this paper a formula for the coefficient of λ ^n-gh+g-1 in the chromatic polynomial of a linear h-uniform hypergraph H of order n and girth g is proposed provided (g,  h) ≠ (3, 3). This formula involves 13 types of spanning subhypergraphs of H for 3 ≤ h ≤ 5.     

Isomeric states in 253No

Isomeric states in ²⁵³No have been investigated by conversion electron and γ -ray spectroscopy with the GABRIELA detection system. The 31μs isomer reported more than 30 years ago is found to decay to the ground state of ²⁵³No by the emission of a 167keV M2 transition. The spin and parity of this low-lying isomeric state are established to be 5/2⁺ . The presence of another longer-lived isomeric state is also discussed.     

Asymmetric synthesis and σ receptor affinity of enantiomerically pure 1,4-disubstituted tetrahydro-1H-3-benzazepines

A very short (three steps) asymmetric synthesis of enantiomerically pure 1,4-disubstituted tetrahydro-1H-3-benzazepines 14 has been elaborated upon, starting from the trans- and cis-configured 11a-substituted 3-phenyl-2,3,11,11a-tetrahydro[1,3]oxazolo[2,3-b]-[3]-benzazepin-5(6H)-ones 6 and 7. The stereoisomerically pure lactams 6 and 7 were benzylated to give 6-benzyl-substituted products 8 and 9. NOE experiments showed a trans-configuration of the benzyl residue and the residue in the 11a-position indicated that the stereochemistry of the benzylation reaction was controlled by the stereocenter at the 11a-position. Reduction of the benzylated tricyclic benzolactams 8 and 9 with AlCl₃/LiAlH₄ (1/3) yielded the 1,3,4-trisubstituted 3-benzazepines 12 and 13, which were formed stereoselectively with the retention of configuration. Finally, removal of the N-(2-hydroxy-1-phenylethyl) residue by hydrogenolytic cleavage resulted in the formation of enantiomerically pure 1,4-disubstituted 3-benzazepines 14. The σ₁, σ₂, and NMDA receptor affinities of the enantiomerically pure 3-benzazepines 14 and ent-14 were investigated in competitive receptor binding studies. The butyl derivative ent-14c showed a high affinity towards σ₁ and σ₂ receptors, with K_i-values of 26 nM and 41 nM, respectively.