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121.
Priyanka G. Mandhane 《Tetrahedron letters》2010,51(23):3138-939
An environmentally benign aqueous Biginelli protocol for the synthesis of substituted 3,4-dihydropyrimidin-2(1H)-ones using thiamine hydrochloride as a catalyst has been achieved. These ultrasound-assisted reactions proceed efficiently in water in the absence of organic solvent. Utilization of ultrasound irradiation, simple reaction conditions, isolation, and purification makes this manipulation very interesting from an economic and environmental perspective. 相似文献
122.
Amr L. Saber 《Electroanalysis》2010,22(24):2997-3002
Simple, selective and accurate sensors were developed for the determination of melatonin and oxomemazine in biological samples (urine) and in pharmaceutical preparations. Potentiometric measurements were based on bismus tetraiodate‐drug ion‐pair as novel electroactive materials incorporating a plasticized PVC membrane with o‐nitrophenyl octyl ether or dioctyl phthalate. Each sensor was conditioned for at least two days in 0.1 M drug solution before use. It exhibited fast and stable Nernstian response for melatonin and oxomemazine over the concentration range of 1.0×10?6–1.0×10?2 M and 1.0×10?5–1.0×10?2 M, pH range of 3.0–6.5 and 3.5–6.0 for melatonin and oxomemazine sensors, respectively. Results with an average recovery not more than 101 % and a mean standard deviation less than 1.0 % of the nominal were obtained for the four sensors. The sensors showed reasonable selectivity towards investigated drugs in presence of many cations. 相似文献
123.
Nora H. Al-Shaalan 《Journal of Saudi Chemical Society》2010,14(1):15-21
Four methods have been developed for the simultaneous determination of phenylephrine hydrochloride and chlorpheniramine maleate without previous separation. In the first method both drugs are determined using first derivative UV spectrophotometry, with zero-crossing measurement. The second method depends on first derivative of the ratios spectra. The third method describes the use of multivariate spectrophotometric calibration for the simultaneous determination of the analyzed binary mixture where the resolution is accomplished by using partial least squares (PLS) regression analysis. In the fourth method (HPLC), a reversed-phase column and a mobile phase of methanol:water:acetonitrile (80:12:8 v/v/v/) at 0.9 ml/min flow rate have been used to separate both drugs with a UV detection at 270 nm. All the proposed methods are extensively validated. They have the advantage to be economic and time saving. All the described methods can be readily utilized for analysis of pharmaceutical formulations. The results obtained using the proposed methods are statistically analyzed and compared with some reported methods. 相似文献
124.
Zeid Abdullah Alothman Nausheen Bukhari Sajjad Haider Saikh Mohammad Wabaidur Abdulrahman A. Alwarthan 《Arabian Journal of Chemistry》2010,3(4):251-255
A novel sensitive fluorimetric method was investigated for the assay of fexofenadine hydrochloride (FEX) using silver nanoparticles (NPs) as a fluorescence probe. The NPs, which were prepared by chemical reduction of silver nitrate with sodium borohydride (reducing agent) in aqueous solution (without organic stabilizers) were water soluble, stable and had narrow emission band. The addition of drug to NPs solution caused considerable quenching of the emission band of silver NPs, which was likely due to the complexation of the drug to silver NPs. Under the optimum conditions, the quenched fluorescence (FL) intensity was linear with the concentration of FEX in the range of 1 × 10?7 to 2.5 × 10?5 mol L?1 (0.9985) with a detection limit of 1.2 × 10?8 mol L?1. The quenching mechanism of the studied drug on the emission band of silver NPs was explained by Stern–Volmer law. The developed method was applied to FEX determination in a pharmaceutical formulation (allegra tablets) and biological fluids (human serum and urine). 相似文献
125.
研究了盐酸克伦特罗(CLB)在乙炔黑电极上的电化学行为,发现阴离子表面活性剂十二烷基苯磺酸钠(SDBS)能显著提高CLB的氧化峰电流并降低其氧化过电位。优化了实验参数,建立了一种直接测定CLB的新电分析方法,其线性范围为1.0×10-7~7.5×10-5mol/L,开路富集1 min后的检出限为2.5×10-8mol/L。平行10次测定1.0×10-5mol/L盐酸克伦特的RSD为3.1%。方法用于猪尿中盐酸克伦特罗含量的测定。 相似文献
126.
多壁碳纳米管修饰电极检测盐酸氯丙嗪的研究 总被引:1,自引:0,他引:1
制备了多壁碳纳米管修饰玻碳电极,采用循环伏安法(CV)研究了盐酸氯丙嗪在修饰电极上的电化学特性,发展了一种新的检测盐酸氯丙嗪的电化学分析方法。在最佳实验条件下,用循环伏安法检测盐酸氯丙嗪,其响应电流与盐酸氯丙嗪的浓度在8.0×10-5~1.0×10-3mol/L范围内有很好的线性关系,线性方程为Ip(A)=0.0106c(mol/L)-8×10-8(R2=0.999,n=6),检出限为6.2×10-6mol/L(S/N=3)。方法可用于盐酸氯丙嗪片的测定。 相似文献
127.
The interaction between promethazine hydrochloride (PMT) and bovine serum albumin (BSA) in vitro was investigated by means of fluorescence spectroscopy and absorption spectroscopy. The fluorescence of BSA was quenched remarkably by PMT and the quenching mechanism was considered as static quenching by forming a complex. The association constants Ka and the number of binding sites n were calculated at different temperatures. The BSA-PMT binding distance was determined to be less than 8 nm, suggesting that energy transfer from BSA to PMT may occur. The thermodynamic parameters of the interaction between PMT and BSA were measured according to the van’t Hoff equation. The enthalpy change (ΔH) and entropy change (ΔS) were calculated to be −23.62 kJ mol−1 and −0.10 J mol−1 K−1, respectively, which indicated that the interaction of PMT with BSA was driven mainly by van der Waals forces and hydrogen bonds. The binding process was a spontaneous process in which Gibbs free energy change (ΔG) was negative. In addition, the results of synchronous fluorescence spectra and three-dimensional fluorescence spectra showed that binding of PMT with BSA can induce conformational changes in BSA. 相似文献
128.
Islam Ullah Khan Tehseen Aman Muhammad Asif Iqbal Asrar Ahmad Kazi 《Mikrochimica acta》2000,134(1-2):27-31
Fluoxetine hydrochloride reacts with benzoyl peroxide and potassium iodide, after heating for 1 min at 30 °C, to give a blue
colour having maximum absorbance at 570 nm. The reaction is selective for fluoxetine with 0.01 mg/mL as visual limit of quantitation
and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer’s law from 0.1 mg/10 mL to
2.0 mg/10 mL of fluoxetine and the relative standard deviation is 0.68%. The qualitative assessment of tolerable amounts of
other drugs is also studied.
Received September 21, 1998. Revision September 10, 1999. 相似文献
129.
Stacy P. Ali 《Journal of carbohydrate chemistry》2013,32(4):185-196
The order of reactivity of OH and NH groups of glucosamine hydrochloride (GlcNH2.HCl) and N-acetyl glucosamine (GlcNAc) toward benzylation with NaH/BnBr in DMF was investigated. For GlcNH2.HCl, benzyl groups were introduced in the order of N-Bn > N-Bn2 > 1-O-Bn > 6-O-Bn > 4-O-Bn > 3-O-Bn; for GlcNAc, benzyl groups were introduced in the order of 1-O-Bn > 6-O-Bn > 4-O-Bn > 3-O-Bn > N-Bn. A range of partially benzylated 2-N,N′-dibenzyl glucopyranosides and GlcNAc derivatives were obtained in a single step. 相似文献
130.