氯唑沙宗的电化学行为及测定

建立灵敏快速测定氯唑沙宗的新方法。在0.24 mol·L-1KH2PO4-Na2HPO4(pH6.81±0.1)支持电解质中,氯唑沙宗于0.80 V(vs.SCE)电位处产生一还原波。加入过二硫酸钾后,该还原波峰电流增加约10倍,峰电位基本不变,产生一极谱催化波。其二阶导数峰电流Ip″与氯唑沙宗的浓度在2.0×10-7~8.0×10-5mol·L-1范围内呈良好线性关系(r=0.9981,n=8),检出限为1.0×10-7mol·L-1。该方法可用于药剂中氯唑沙宗含量的测定。     

光纤药物原位溶出度/释放度监测仪实时监测复方氯唑沙宗片体外溶出度

研制了光纤-光学传感-药物溶出监测仪并应用于复方氯唑沙宗片的实时-原位体外溶出度.分支光纤的一端与光源相接,另一端与检测器连接,其公共端部探头浸入于盛于溶出杯中的溶解液中.借联机的计算机进行数据记录及处理,对复方氯唑沙宗片的组分对乙酰氨基酚和氯唑沙宗的回收率在低、中、高三个浓度水平进行了试验,结果依次为98.3%,102.3%和103.1%及108.6%,98.7%和97.7%,其相应的RSD值为1.0%,1.4%和0.4%及1.7%,1.6%及1.3%.应用此监测仪对药片的溶出全过程进行了监控,并显示了药物的溶解曲线,相关的溶出参数可随时提取.试验证明,使用该仪器可获得药物溶出全过程的真实情况的信息.     

反相高效液相法同时检测3种探针药物

 用反相高效液相同时测定血清中咖啡因、氨苯砜、氯唑沙宗探针药物的质量浓度,以乙腈 磷酸盐缓冲体系(含0 02mol/L的磷酸二氢钾和0 02mol/L的三乙胺,pH6 5)(体积比为25∶75)为流动相,以安替比林为内标,经C18柱(250mm×4 6mmi d ,5 0μm)分离,紫外检测器检测,使3种探针药物得到较好的分离,并且在有效血药浓度范围内线性良好。该法简便、快速,能够为临床安全有效的用药提供科学的依据。     

氯代磺酚S吸光度比差测量法测定地表水中痕量铝

在pH5.4的乙酸盐缓冲介质中,氯代磺酚S与铝(Ⅲ)反应生成结合比为1比1的配合物,其波峰于649nm,波谷于552nm波长处。分别于649nm及552nm处测得含铝显色液及试剂空白液吸光度,按所给公式计算吸光度比和吸光度比差(△A_r),将此吸光度比差测量法应用于地表水中痕量铝的分光光度法测定。结果表明:铝(Ⅲ)的质量浓度在0.050mg·L~(-1)范围内与△A_r值呈线性关系,其检出限(3s/k)为0.8μg·L~(-1)。用此方法测定了长江水、黄浦江水、太湖水及自来水水样中痕量铝的含量,所得结果与石墨炉原子吸收光谱法测得结果相符,加标回收率在93.0%～107.0%之间。     

浊度法测定硼酸中氯

在硝酸酸度约为1.3 mol·L-1硼酸试样溶液中加入硝酸银溶液,使溶液中存在的微量氯离子与之反应生成氯化银胶悬体,加入适量的1,2,3-丙三醇作为胶悬体的稳定剂.选择在400 nm波长处测定此胶悬体的吸光度,其吸光度与氯离子浓度在0.017～0.20 mg·L-1范围呈线性关系,求测方法的检出限(3S/b)为0.016 mg·L-1.对此反应的各影响因素(如检测波长、试液酸度、硝酸银溶液及丙三醇的加入量、反应的适宜温度时间,以及进行吸光度测定的时间等)作了较系统的试验并予以优化.对方法的回收率及精密度也作了试验,所得回收率在96.0%～102.6%之间,测得的相对标准偏差(n=5)均小于2%.     

氧瓶燃烧-硫氰酸汞分光光度法测定无卤低烟阻燃电缆料中痕量氯

采用氧瓶燃烧法对无卤低烟阻燃电缆料样品进行燃烧,用去离子水作为吸收液吸收释出的氯化氢气体,并用硫氰酸汞分光光度法测定样品中氯含量。氯离子的质量浓度在0.20～5.00mg.L-1范围内与吸光度呈线性关系。该方法用于无卤低烟阻燃电缆料样品中微量氯的测定;用标准加入法测得回收率在96.0%～103%之间,测定值的相对标准偏差(n=5)均小于4.5%。     

火焰原子吸收光谱法及比浊法测定聚氯乙烯中氯

以无水碳酸钠为灰化固定剂,于瓷坩埚中加热将试样灰化,于高温炉中在700℃燃烧2 h,用水溶出残渣,分取部分试液用火焰原子吸收光谱法(FAAS)或浊度法测定其中氯离子.加入过量银以沉淀样品溶液中的氯离子,用FAAS法测定银以间接测定氯,或通过测定氯化银悬浮体的表观吸光度而测定氯,建立了FAAS法及比浊法测定聚氯乙烯中氯含量的方法.线性范围:FAAS法为0～140μmol·L-1,比浊法为0.4～4.8 mg·L-1.测定结果的相对标准偏差≤1.9%,加标回收率95.0%～102.5%.两种方法测定结果的相对误差小于士1.1%.     

分光光度法测定黄花菜中总黄酮

建立了一种黄花菜中总黄酮的Al(NO3)3显色分光光度测定方法。研究表明:以芦丁为标样,在一定条件下,芦丁的浓度与吸光度呈线性关系,回归方程为A=0.0121c 0.0014,R2=0.9999,方法的回收率为98.1%~102.3%,相对标准偏差(RSD)为2.1%,测得黄花菜中总黄酮量为3.71 mg/g。     

十氯酮-二氯甲烷溶液标准物质的定值与不确定度评定

制备了十氯酮-二氯甲烷溶液标准物质,采用气相色谱-质谱联用法(GC-MS)和红外光谱法(IR)对十氯酮原料定性鉴定,并采用气相色谱法(GC/FID)及多家实验室联合定值法对十氯酮的纯度进行定值,测得十氯酮原料纯度为99.9%。在(20±4)℃下,以重量-容量法配制十氯酮-二氯甲烷溶液标准物质,对溶液进行均匀性与稳定性分析、量值核验,并对其量值结果进行了不确定度评定。     

指示剂取代测定法分析2-氯扁桃酸的对映异构体

手性化合物对映体之间的生物活性往往存在明显不同。应用最广的手性分析方法是色谱,但其所需仪器及手性分析柱贵,在实际应用中受到一定程度的限制。本研究将应用"对映异构体选择性指示剂取代测定"的原理、基于"手性配体交换色谱"中的可逆化学反应,得到2-氯扁桃酸与L-脯氨酸-Cu(Ⅱ)-邻苯二酚紫(PV)体系中的"吸光度变化值(ΔA)—对映体过剩值(e.e.%)"的线性关系曲线,研究了2-氯扁桃酸的对映异构体测定,建立了操作简单、成本低廉、新型的可见分光光度手性分析方法,为手性化合物2-氯扁桃酸的定量分析开辟了一个途径。     

Determination of Chlorzoxazone in Rat Plasma by LC-ESI-MS/MS and Its Application to a Pharmacokinetic Study

A sensitive LC-ESI-MS/MS method for determination of chlorzoxazone in rat plasma has been developed. Chromatographic separation was achieved on a Zorbax SB-C₁₈ column, with 45:55 (v/v) acetonitrile–water as the mobile phase. A LC-ESI-MS/MS was performed in a multiple reactions monitoring (MRM) mode using target ions m/z 167.5→131.6 for chlorzoxazone and m/z 230.7→185.6 for phenobarbital (internal standard). The calibration plots were linear over the range of 10.0–2,000 ng/mL. Intra-day and inter-day precisions were better than 5.1% and 6.8%, respectively. The validated method was successfully used to analyze the drug in samples of rat plasma for pharmacokinetic study.     

Reversed-phase HPLC method for the estimation of acetaminophen, ibuprofen and chlorzoxazone in formulations

A simple, precise and rapid reversed-phase HPLC method was developed for the simultaneous estimation of acetaminophen, ibuprofen and chlorzoxazone in formulations. The method was carried out on a Kromasil® C₈ column using a mixture of 0.2% triethylamine:acetonitrile (adjusted to pH 3.2 using dilute orthophosphoric acid), and detection was carried out at 215 nm using ketoprofen as internal standard. All these drugs showed linearity in the range of 2–10 μg ml⁻¹, and limits of quantification was found to be 10, 50 and 20 ng ml⁻¹ for acetaminophen, ibuprofen and chlorzoxazone, respectively.     

Development of an Isocratic SFC Method for Four Centrally Active Muscle Relaxant Drugs

Abstract

A reproducible and selective supercritical fluid chromatography (SFC) method was developed for the estimation of four centrally active muscle relaxants, viz., chlorzoxazone, methocarbamot, tizanidine, and baclofen, using guaifenesin (expectorant, muscle relaxant) as the internal standard. The effect of temperature, pressure and the modifier concentration on retention of the five solutes has been explored and the parameters optimised. An arbitrary mixture of 5 components was base line resolved on a JASCO- RP- C₁₈ (150 × 4.6 mm) 5μ metaphase column with a tertiary mobile phase of 9.1 % modifier [methanol containing 2 % glacial acetic acid, v/v] in carbon dioxide at 1.5 ml/min, 50°C temperature, and 12.75 MPa outlet pressure. UV detection at 235 nm was employed. Without the acetic acid in the mobile phase it was not possible to elute tizanidine and baclofen. With the additive, all the analytes produced symmetrical peaks. Quantitative validation concentration ranges have been found, and the performance data evaluated.     

Spectrophotometric Determination of Chlorzoxazone in pure State and Formulations Through Oxidative Coupling of its Hydrolysis Product

ABSTRACT

Three simple and sensitive procedures (Methods A, B and C) for the assay of chlorzoxazone (CZZ) in pure form and in formulations are described. The methods are based on the oxidative coupling reaction of the hydrolysis product of chlorzoxazone (HCZZ) with 3-methyl-2-benzothiazolinone hydrazone (MBTH) in the presence of Fe (III) (Method A, λ_max 445 nm), N, N-dimethyl-p-phenylene diamine (DMPD) in the presence of periodate (IO₄) (method B, λ_max 605 nm) and 2, 6-dichloroquinone chlorimide (DCQC) (Method C, λ, _max 560 nm). The Beer's law limits were found to be 5.0 to 25.0 μg/ml in the case of methods A and B and 2.0 to 12.0 μg/ml in the case of method C. The results are statistically validated and the reactions involved are presented.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.