乙基曙红光度法测定西地那非的含量

在pH3.5～4.0的NaAc HCl缓冲介质中,西地那非与乙基曙红反应,形成离子缔合物,使乙基曙红溶液颜色发生明显改变,最大吸收波长在550nm,比乙基曙红红移了30nm,并在520nm处产生最大褪色作用,从而建立测定西地那非(Sild)的光度法。在最大褪色波长520nm处,西地那非浓度在0.2～2.0×10-5mol·L-1范围内遵守比耳定律,表观摩尔吸光系数ε520为2.44×104L·mol-1·cm-1,检出限为9.3×10-7mol·L-1,若用双波长叠加,则表观摩尔吸光系数ε520+550达4.53×104L·mol-1·cm-1,检出限达5.0×10-7mol·L-1。本法操作简便,体系稳定,灵敏度较高,选择性好,用于柠檬酸西地那非片(万艾可)中西地那非含量的测定,结果满意。     

亚甲基蓝光度法测定西地那非的含量

在pH3.0～6.0的条件下,亚甲基蓝(MB)与西地那非(SD)反应,生成蓝色离子缔合物,最大吸收波长位于600nm,SD浓度在0～1.6×10-5mol/L范围服从比耳定律,由此建立了测定西地那非含量的分光光度法。缔合物的表观摩尔吸光系数(ε)为3.0×104L·mol-1·cm-1。该方法用于市售药物中西地那非含量的测定,结果满意。     

液膜分离富集二甲氧基羟基苯基荧光酮荧光猝灭法测定微量钼的研究

研究了在pH5．0～6．4的HAC-NaAC缓冲介质中和CTMAB存在下,Mo(Ⅳ)对二甲氧基羟基苯基荧光酮(DMH-PF)的荧光猝灭效应,建立了荧光猝灭法测定微量Mo(Ⅳ)的新体系,DMH-PF最大激发波长为λex=514nm、最大发射波长为λem=547nm,DMH-PF与Mo(Ⅵ）形成1：2配合物使荧光猝灭,荧光猝灭量与Mo(Ⅵ)在0～0．072mg／L范围内呈线性关系,方法的检出限为0．0022mg／L,体系稳定,灵敏度高,采用液膜分离富集钼,可应用于合金钢和石墨中微量钼的测定。     

基于铜纳米簇荧光猝灭选择性检测盐酸阿霉素

以聚乙烯亚胺(PEI)为稳定剂,抗坏血酸(AA)为还原剂,制备了铜纳米簇(PEI@CuNCs),并基于此建立了一种快速、简便的检测盐酸阿霉素(DOX)的方法.制备的PEI@CuNCs粒径约2.4 nm,最大激发波长为430 nm,最大发射波长为518 nm,具有良好的稳定性和抗光漂白性能.通过X射线光电子能谱以及傅里叶...     

1-(2-苯并噻唑)-3-(4-硝基苯)－三氮烯的合成 及其与镉(Ⅱ)的显色反应研究

报道了1-(2-苯并噻唑)-3-(4-硝基苯)－三氮烯(BTNPT)的合成及与镉(Ⅱ)的显色反应研究。在Triton X-100的存在下,pH 11.6时,镉(Ⅱ)与BTNPT形成摩尔比=1∶2型黄色络合物,在435 nm处有一最大正吸收,在530nm处有最大负吸收。以435 nm为参比波长,530nm为测量波长进行双波长测定,表观摩尔吸光系数为 2.52×10     

新型香豆素硼氟荧光染料的合成及其光学性能

以邻氨基苯甲酸甲酯和4-二乙胺基水杨醛为原料,合成了一个新的香豆素喹啉衍生物3-{2-［8-(1H-苯并咪唑-2-基)喹啉-2-基］乙烯基}-7-二乙胺基香豆素(QMC),再与BF₃·Et₂O配位合成了硼氟配合物(BQMC),其结构经¹H NMR和MS(ESI)表征。并对BQMC的光学性能进行了研究。结果表明：BQMC的最大吸收波长在二氧六环中为490 nm,在DMSO中为532 nm; BQMC的最大发射波长在正己烷中为618 nm,在DMSO中为679 nm,与配体QMC相比,最大吸收波长红移了近50 nm,最大发射波长红移了近100 nm, BQMC的Stokes位移值从115 nm增至183 nm。在固态下,BQMC在750~825 nm之间有较宽的荧光发射峰,具有较强荧光。     

TNT及RDX蒸气对基于芘氧敏感膜荧光猝灭的研究

制备了以芘为敏感材料,聚苯乙烯(PS)以及聚氯乙烯(PVC)粉末为支持体系的两种荧光猝灭氧敏感膜.PS以及PVC氧敏感膜的最大激发波长分别为349 nm和355 nm,最大发射波长分别为399 nm和398 nm.分子氧对PS以及PVC氧敏感膜的荧光均有猝灭作用.同时,实验发现2,4,6-三硝基甲苯(TNT)和环三亚甲基三硝基胺(RDX)对这两种氧敏感膜的荧光也有一定的猝灭.     

甲基紫探针分光光度法测定利福平

在pH 7.3的Tris-HCl缓冲溶液中,甲基紫与利福平反应生成具有正吸收峰和负吸收峰的紫色络合物。其最大正吸收波长位于500 nm,最大和次大负吸收波长分别位于540 nm和605 nm,利福平的质量浓度在0.2～0.82 mg·L-1(正吸收)和0.0～0.82 mg·L-1(负吸收)以内与吸光度A呈线性关系,服从比尔定律,表观摩尔吸光系数分别为8.90×104(500 nm)、4.41×105(540 nm)和3.04×105(605 nm)L·mol-1·cm-1,该法用于市售利福平药物中利福平的测定结果满意。     

铽穴状双功能螯合剂的合成及其光学性能

以四甲基-4-H(2,2)-2-甲氧基异邻苯二甲酰胺-四噻唑啉起始原料,合成了一种新型镧系元素穴状有机配体四甲基-胺基-L-赖氨酸-H(2,2)-羟基间苯二甲酰胺,与Tb~(3+)连接制备了双功能螯合剂Tb~(3+)■四甲基-胺基-L-赖氨酸-H(2,2)-羟基间苯二甲酰胺[Tb~(3+)■Lay-BH(2,2)IMA]。荧光性质研究表明:Tb~(3+)■Lay-BH(2,2)IMA的激发波长范围是325～375nm,最大激发波长为357 nm;发射波长范围为525～575nm,最大发射波长为543 nm;特征峰位于487 nm(~5D_4-~7F_5),543 nm(~5D_4-~7F_4),581～586 nm(~5D_4-~7F_3),619 nm(~5D_4-~7F_2),658 nm(~5D_4-~7F_1),斯托克斯位移为186 nm,荧光寿命1 018μs,量子产率24.7%。     

偶氮氯膦Ⅲ双波长分光光度法测定奶粉中的Fe(Ⅲ)

在酸性介质中,Fe(Ⅲ)与偶氮氯膦Ⅲ反应生成具有明显正吸收峰和负吸收峰的螯合物,最大正吸收波长位于670nm,最大负吸收波长位于530nm,用双波长叠加测定,表观摩尔吸光系数(ε)为5.93×10~4 L/(mol·cm),线性范围为0.2~2.00mg/L,探讨了适宜的反应条件、考察了准确度、精密度及选择性。该方法用于奶粉中Fe(Ⅲ)的测定,结果令人满意。     

西地那非的合成

西地那非 (ｓｉｌｄｅｎａｆｉｌ,商品名 :Ｖｉａｇｎａ)是美国辉瑞公司于 1 997年开发上市的新型磷酸二酯酶 5型(ＰＤＥ5 )抑制剂 ,化学名为 5 〔2 乙氧基 5 (4 甲基哌嗪 1 磺酰基 )苯基〕 1 甲基 3 正丙基 1 ,6 二氢 7Ｈ 吡唑并〔4,3 ｄ〕嘧啶 7 酮。作者对文献[1- 3] 的合成路线及合成方法进行了改进 :在中间体 4 氨基 1 甲基 3 正丙基吡唑 5 甲酰胺制备中 ,采用水合肼作还原剂 ,收率达 91 5 % ,且后处理方便 ,易于操作 ,安全简单 ,产品质量稳定。ＨＮＭＲ谱 ,元素分析结果与对照品完全一致。在环合反应中使用表面活性剂十二…     

Efficiency of sildenafil encapsulation in poloxamer micelles

Abstract

The purpose of this study is to prepare and investigate the physicochemical and thermodynamic evidence of sildenafil (SIL) encapsulated poloxamer 188 (P188) micelles. The micelles were prepared by the thin-film hydration technique and investigated by pendant drop tensiometry and dynamic light scattering techniques. The closed association model was used to determine the micelle-monomer equilibrium parameters. The standard Gibbs free energy of the micelle formation was calculated from the partition coefficient. The change in the pattern of the surface tension, particle count rate, and particle size of the SIL encapsulated P188 micelles was observed. The corresponding critical micelle concentration (CMC) was approximately 0.04?mM. The hydrodynamic Z-average size of the micelles ranged from 6 to 9 d. nm. The encapsulation efficiency (EE) of SIL in the micelles was up to 54.3?±?0.2%. The obtained equilibrium constant was 0.67. The standard Gibbs free energy of the formation of SIL encapsulated micelles at 25?°C was ?32.9?kJ/mol. The formation of SIL encapsulated P188 micelles was confirmed by the change in the pattern of the surface tension, particle count rate and size of the micellar solution. The standard Gibbs free energy of the formation indicated the spontaneous partition process in the micellar systems.     

Synthesis of pyrazolopyrimidinones as sildenafil derivatives and sclerotigenin

A series of novel pyrazolo pyrimidinone derivatives (3(a–d), 4(a–d), and 6(a–d)) was synthesized from various pyrazolo amides (2a–d) which are synthesized by the reaction between ethyl 5-amino-3-methyl-1-phenyl-1H-pyrazole-4-carboxylate (1) and various lithium amides. In addition, we also described the synthesis of sclerotigenin drug molecule which has quinazoline moiety from simple 2-nitro benzoic acid with high yields.     

Synthesis of novel pyrazolopyrrolopyrazines,potential analogs of sildenafil

Synthesis of novel pyrazolopyrrolopyrazines is herein described with the aim to reach new specific PDE‐5 inhibitors of potential clinical interest in male erectile dysfunction.     

Overview of the synthetic routes to sildenafil and its analogues

The biological and medicinal properties of sildenafil and its analogues have prompted enormous research aimed at developing synthetic routes to these heterocycles. This review focuses on the chemical properties associated with this system.     

Structure determination of a sildenafil analogue contained in commercial herb drinks

It was found from HPLC analysis that a commercial herb drink contains a putative sildenafil analog. In order to identify the sildenafil-like compound, separation and purification were carried out. The structure determination was performed based on routine 1D and 2D NMR experiments. Unlike sildenafil, the compound contains an ethylpiperazine instead of a methylpiperazine group. In addition, the piperazine and phenyl groups are connected through an acetyl group instead of the sulfonyl group of sildenafil.     

Reverse‐phase high‐performance liquid chromatography for the simultaneous determination of sildenafil and N‐desmethyl sildenafil in plasma of children

Sildenafil is a selective inhibitor of cGMP‐specific type 5 phosphodiesterase used for the treatment of pulmonary arterial hypertension (PAH) in the adults. In pediatrics, PAH treatment options include the off‐label use of sildenafil. Sildenafil is metabolized in the liver by cytocrome P450 into its active metabolite, N‐desmethyl sildenafil. The determination of plasma levels of sildenafil and N‐desmethyl sildenafil could be useful for therapy optimization and pharmacokinetic studies. We have developed and validated a method for the quantification of sildenafil and its metabolite in plasma of children by rapid extraction, using high‐performance liquid chromatography with ultraviolet detection. The calibration range was fitted at least square model (r² ≥ 0.999), with an accuracy and an intra‐ and inter‐day relative standard deviation <15% for both analytes. The mean recovery was 102.5% for sildenafil and 101.8% for N‐desmethyl sildenafil. This simple method could be successfully used in children with PAH under treatment with sildenafil.     

Electrochemical oxidation of sildenafil citrate (Viagra) on carbon electrodes

In aqueous solutions containing 30% (v/v) acetonitrile the unprotonated form of the piperazine ring of sildenafil (I) is oxidized on a glassy carbon electrode between pH 2 and 8. Whereas citrate anions under conditions used are not oxidized, the oxidation pattern of sulfonamides differs from that of sildenafil (I). On the other hand, the oxidation of I resembles that of the oxidation of piperazine ring in nefazodone (III) and trazodone (IV). A more positive peak of sildenafil corresponds to an adsorption-desorption process. Measurement of the peak current enables rapid determination of sildenafil (I) in pharmaceutical preparations with sufficient accuracy.     

Study of the electrospray ionization tandem mass spectrometry of sildenafil derivatives

A detailed analysis of the product ion spectrum generated from the protonated molecule of sildenafil (Viagra(R)) under multiple tandem mass spectrometry (ESI-MS(n)) conditions using an ion-trap mass spectrometer is reported. Molecular composition data of the fragment ions were obtained with the aid of comparisons of the multiple tandem mass spectra of eight sildenafil derivatives in two series, the structures of which are identical except for some substituted alkyl groups. Attempts have been made to provide rational pathways for the formation of the fragment ions from these protonated sildenafil derivatives. The structure-fragmentation relationships will facilitate the characterization of the structures of other sildenafil analogs.     

Fast detection of sildenafil in adulterated commercial products using differential scanning calorimetry

Adulteration of drugs is a serious issue and can have a great impact on human health. It is mainly done with the intention of boosting the effects of products. For many years, the enforcement officers in Malaysia have had difficulty deciding whether some products should be confiscated as they have not been able to produce fast reliable evidence of adulteration. For that reason, we explored the use of differential scanning calorimetry (DSC) as a potential fast detection method of commercial products marketed in Malaysia that may be adulterated. We confirmed the outcomes qualitatively with high pressure liquid chromatography. DSC was set at a heating rate of 10 °C min^?1 and within a temperature range of 100–250 °C with nitrogen as a purge gas at a flow rate of 20 mL min^?1 to analyse a sildenafil reference standard (RS), sildenafil tablets and sildenafil adulterated commercial products. Four sildenafil adulterated commercial products were analysed. Since the melting point of sildenafil in the mixture tended to shift, the presence of sildenafil in three of these adulterated commercial products was confirmed using the spiking method and was re-analysed using DSC. The re-analysed results indicated that the enthalphy of fusion (?H) and the resolution peak of sildenafil increased accordingly depending upon the amount of spiked sildenafil RS. Apart from these results, the DSC curves also showed different patterns for sildenafil RS and the mixtures. Therefore, we concluded that DSC can potentially be used to detect sildenafil in adulterated commercial products.