Solid-state characterization of chloroprocaine hydrochloride

Summary Chloroprocaine hydrochloride (2-CPCHC) is a local anaesthetic agent of the ester type preferentially used for epidural anaesthesia. The compound, official in the USP, was found to exist in two polymorphic crystal forms which have been characterized by thermomicroscopy, differential scanning calorimetry (DSC), pycnometry, FTIR-, FT-Raman-spectroscopy as well as X-ray powder diffractometry. Based on these data the relative thermodynamic stability of the two forms was determined and is represented in a semi-schematic energy/temperature diagram. Mod. I° is the thermodynamically stable form at room temperature. This form is present in commercial products and can be crystallized from ethanol. Mod. II can be obtained by annealing the supercooled melt in a temperature range between 100 and 130°C. Upon heating mod. II exhibits an exothermic phase transition (Δ_trsH_II-I: -5.0±0.5 kJ mol^-1) at about 134°C to mod. I° (melting point 175°C, Δ_fusH_I: 46.6±0.6 kJ mol^-1). The exothermic transformation of mod. II to mod. I° confirms that mod. I° is thermodynamically stable in the entire temperature range (heat of transition rule) whereas mod. II is monotropically related to mod. I°, i.e. is metastable at all temperatures below its melting point. Mod. II is of low kinetic stability at room temperature and the transformation to mod. I° starts within a few minutes at room temperature. The N-H band in the infrared spectrum of mod. I° (3433 cm^-1) lies at significantly higher wavenumbers than that of mod. II (3413 cm^-1) indicating differences in the hydrogen bonding arrangement. Furthermore, the measured density of mod. I° is lower than the density of mod. II and thus both, the IR- and the density-rule are violated in this polymorphic system.     

Crystal polymorphism of local anaesthetic drugs

Crystal polymorphs of pramocaine hydrochloride (PRCNC) and pramocaine (PRCN) free base were produced and characterized by means of thermomicroscopy, differential scanning calorimetry (DSC), FTIR- and FT-Raman-spectroscopy as well as X-ray-powder diffractometry. The relative thermodynamic stabilities of all forms were determined and are represented in semi-schematic energy/temperature diagrams. PRCN, which is a viscous liquid at room temperature and insoluble in water, was found to exist in two different crystal forms with the melting points 23.5°C (mod. I°) and 12.5°C (mod. II). The water-soluble PRCNC crystallizes in three different crystal modifications. Mod. II° is the thermodynamically stable form at room temperature and is present in commercial products. This form is obtained by crystallization from solvents and transforms on heating at about 95°C into the high temperature form mod. I which melts at 171.0°C. Both compounds show conformational polymorphism with forms of low kinetic stability. This revised version was published online in July 2006 with corrections to the Cover Date.     

Solid-state of pharmaceutical compounds

This article summarizes the different steps needed for a proper design and monitoring of the solid-state in pharmaceutical industry in order to fulfill the requirements of the guideline dealing with polymorphism of the International Conference of Harmonization. This revised version was published online in July 2006 with corrections to the Cover Date.     

A comparative study of two polymorphs of L‐aspartic acid hydrochloride

Two polymorphs of L‐aspartic acid hydrochloride, C₄H₈NO₄⁺·Cl⁻, were obtained from the same aqueous solution. Their crystal structures have been determined from single‐crystal data collected at 100 K. The crystal structures revealed three‐ and two‐dimensional hydrogen‐bonding networks for the triclinic and orthorhombic polymorphs, respectively. The cations and anions are connected to one another via N—H...Cl and O—H...Cl interactions and form alternating cation–anion layer‐like structures. The two polymorphs share common structural features; however, the conformations of the L‐aspartate cations and the crystal packings are different. Furthermore, the molecular packing of the orthorhombic polymorph contains more interesting interactions which seems to be a favourable factor for more efficient charge transfer within the crystal.     

New analytical method for determination and speciation of forms of carbon

A new analytical method is presented, allowing the identification and determination of various forms of carbon (elemental and combined) present in materials. The method is based on temperature-controlled heating of the sample in oxygen or an inert atmosphere, with continuous recording of the amount of carbon oxides evolved, as a function of temperature. The application of the method is demonstrated with typical examples (cast iron, artificial diamond, carbides isolated from steel, electrographite).     

Synthesis,crystal structure and thermal stability of new copper(II) trichloroacetate complexes

We have synthesized two novel complexes of copper(II) trichloro acetate, Cu₂(CCl₃COO)₃(OH)(H₂O)₄·H₂O and Cu(CCl₃COO)₂(MeCN), and determined their crystal structures and thermal stability. While the complex with acetonitrile has a discrete binuclear paddle-wheel structure, typical of copper carboxylates, the aqua-hydroxo complex belongs to a novel unique chain–molecular type of basic copper complexes.     

Thermal and structural properties of ambroxol polymorphs

Journal of Thermal Analysis and Calorimetry - The thermal and structural characteristics of two crystal forms of ambroxol, (trans-((amino-2-dibromo-3,5-benzyl)amino)-4-cyclohexanol), a drug with...     

CuInS2：两步电沉积制备及性能

采用恒电位沉积法制备铜铟合金预制膜,并存管式炉中通过固态源蒸发硫化预制膜得到CuInS:薄膜.通过扫描电镜(SEM)、能量色散谱仪(EDS)和X射线衍射仪(XRD)对CuInS2薄膜的表而形貌、截面厚度、成分组成和薄膜的组织结构进行了研究,并利用紫外可见光吸收谱仪(UV-Vis)研究了不同硫化温度对CuInS:薄膜的形貌及其光学吸收性质的影响.结果表明:不同的退火温度能够影响CuInS:薄膜的表面形貌以及带隙的大小,从而影响其光学吸收特性.     

3-三氯化锡基丙烯酸乙酯与水杨醛缩m-溴-苯胺席夫碱配合物的室温固相合成及晶体结构

用室温固相合成法研究了酯基锡EtO2CCH2CH2SnCl3 1 与Schiff碱2-HOC6H4- CH=NC6H4Br-3 2 合成标题化合物(3-EtO2CCH2CH2SnCl3)?2-HOC6H4CH= N-C6H4Br-3) 3的配位反应。利用元素分析, UV-VIS, IR, 1H NMR等方法对配合物的结构进行了表征, 采用单晶X-射线衍射方法测定了3的晶体结构。3的分子式为C18H19BrCl3NO3Sn, Mr = 602.29。晶体属三斜晶系, P空间群, a = 7.75(2), b = 10.578(2), c = 13.936(3) , = 83.663(3), = 75.909(3), = 76.691(3), V = 1077(4) 3, Z=2, Dc = 1.858 g/cm3, F(000) = 588, = 3.433 mm-1, R = 0.0547, wR = 0.1341。Schiff碱是以酚羟基上的O原子与中心Sn原子配位, Schiff碱分子中的分子内氢键, 形成配合物后得到加强, 提出了3的2种共振式。与中心Sn原子配位的3个Cl原子、2个O原子和1个C原子形成畸变的八面体结构。     

单个体矢量性特征的固体纳米孔道分析研究

固体纳米孔道作为一种高灵敏的单分子检测技术,由于其机械强度高、尺寸可控、易于阵列化集成等方面的显著优势,已经被广泛应用于DNA,蛋白质以及聚合物等小分子的检测.具有矢量性特征的各向异性单个体在纳米孔道中的穿孔行为对具有空间限域效应的纳米孔道离子流特征信号具有显著影响.为解析单个体矢量性特征对纳米孔道分析的影响,本工作利用氮化硅固态纳米孔道,以单个纳米金棒为各向异性的单个体模型,实时观测了其在孔道中的迁移行为.研究发现当纳米金棒穿过纳米孔道时,产生两种不同阻断程度的特征电流信号,通过对电流信号事件的解析,实时获取了具有矢量特征的金棒所导致的两种特征过孔事件;进一步,建立了离子电流模型,分别对这两种各向异性的穿孔事件机制进行了验证.     

A validated HPLC method for assay of morphine hydrochloride and hydromorphone hydrochloride in pharmaceutical injections

Summary A sensitive and rapid routine HPLC method is proposed for quantitative estimation of morphine hydrochloride and hydromorphone hydrochloride in pharmaceutical dosage forms. The drugs were chromatographed on a C₁₈ reversed-phase column; the mobile phase was acetonitrile-water, 35:65 (v/v), containing sodium dodecyl sulphate (0.5%, w/v), as ion pairing reagent, and acetic acid (0.4% v/v). Detection was at 230 nm. The optimized method was validated and linearity (r>0.999), precision, and accuracy were found to be acceptable within the concentration ranges 86–124 μg mL⁻¹ for morphine hydroloride and 60–180 μg mL⁻¹ for hydromorphone hydrochloride. The method is being used to investigate the stability of morphine hydrochloride and hydromorphone hydrochloride in solution used for intramuscular injection.     

ZnS纳米粒子的固相合成及其光学性能

将不同的添加剂引入到低温固相反应中，快速合成了不同尺寸的ZnS纳米粒子。利用TEM表征了产物形貌，利用XRD研究了不同的添加剂、同一添加剂下不同的反应温度、不同反应时间对纳米粒子尺寸的影响。结果表明，不同的添加剂对粒子的尺寸影响较大，其中，十二烷基胺以其特殊的反应方式在较高温度下获得了较小的纳米粒子。另外，在PEG400存在条件下，反应温度和反应时间对粒子尺寸均有一定的影响。同时，对不同条件下所得产物的紫外-可见光吸收性能也进行了测试。     

Applications of thermal analysis in some solid-state reactions

TG-DTG-DTA has been used to characterize various isomers of CoCl₂·2(CH₃C₆H₄NH₂). Thermal analysis is further used to analyse the binary mixtures of these isomers. DTA recorded after different elapsed times follows the progress of reaction between cobalt chloride and benzocaine where progressively small endotherms are associated with starting materials. The application of thermal analysis to following the solid-solid reactions between metal acetates and 8-hydroxyquinoline was highlighted. The stoichiometry of such reactions was confirmed from the decrease in intensity of an endotherm as one increases the stoichiometry.Thanks are due to Drs. Keshav Chander, K. Kaur, Rajinder Singh and G. S. Chopra for helpful discussions and experimental work.     

流动注射光度法测定盐酸普鲁卡因

在盐酸介质中,利用盐酸普鲁卡因－亚硝酸钠－α萘胺的重氨化－偶合反应,建立了流动注射光度法测定盐酸普鲁卡因的新方法。利用控制加 权形心单纯形优化法选择最佳实验条件,测定的线性范围为0－30μg/mL,该法已用于药物中盐酸普鲁卡因含量的测定。     

Structural elucidation of amino amide‐type local anesthetic drugs and their main metabolites in urine by LC‐MS after derivatization and its application for differentiation between positional isomers of prilocaine

The demand for clinical toxicology analytical methods for identifying drugs of abuse and medicinal drugs is steadily increasing. Structural elucidation of amino amide‐type local anesthetic drugs and their main metabolites by GC‐EI‐MS and LC‐ESI‐MS/MS is of great analytical challenge. These compounds exhibit only/mostly fragments/product ions representing the amine‐containing residue, while the aromatic amide moiety remains unidentified. This task becomes even more complicated when discrimination between positional isomers of such compounds is required. Here, we report the development of a derivatization procedure for the differentiation and structural elucidation of a mixture of local anesthetic drugs and their metabolites that possess tertiary and secondary amines in water and urine. A method based on two sequential “in‐vial” instantaneous derivatization processes at ambient temperature followed by LC‐ESI‐MS/MS analysis was developed. 2,2,2‐Trichloro‐1,1‐dimethylethyl chloroformate (TCDMECF) was utilized to selectively convert the secondary amines into their carbamate derivatives, followed by hydrogen peroxide addition to produce the corresponding tertiary amine oxides. The resulting derivatives exhibited rich fragmentation patterns, enabling improved structural elucidation of the original compounds. The developed method was successfully applied to the differentiation and structural elucidation of prilocaine and its four positional isomers, which all possess similar GC and LC retention times and four of them exhibit almost identical EI‐MS and ESI‐MS/MS spectra, enabling their structural elucidation in a single LC‐ESI‐MS/MS analysis. The developed technique is fast and simple and enables discrimination between isomers based on different diagnostic ions/fragmentation patterns.     

晋城煤中汞的热稳定性与赋存形态的研究

利用程序升温热解反应器─元素汞在线检测系统联用装置,研究了晋城煤中汞的热稳定性以及与热稳定性相关的晋城煤中汞的赋存形态。研究表明,煤中大部分汞与煤中无机矿物质伴/共生,少部分与煤中有机质伴/共生。其中,在200℃~300℃和900℃~1200℃释放的汞与煤中无机矿物质伴/共生,在300℃~600℃释放的汞部分与无机矿物质伴/共生,部分与煤中有机质伴/共生。     

Synthesis,Crystal Structure and Optical Properties of KPr（MoO4）2 with the Scheelite-type Structure

Solid-state reaction of praseodymium （III） oxide,K2CO3 and MoO3 at high temperature leads to a potassium lanthanide double molybdate,namely,KPr（MoO4）2. The structural and optical properties of the title compound have been investigated by means of single-crystal X-ray diffraction and spectroscopic measurements at room temperature. KPr（MoO4）2 crystallizes in tetragonal,space group I41/a with a = 5.401（3）,c = 12.044（10）,Z = 2 and R （I 〉 2σ（I）） = 0.0416. It features the famous scheelite-type structure （CaWO4）,which can be thought as the substitution of two Ca^2＋ ions in CaWO4 by a couple of K^＋ and Pr^3＋ ions in a statistical manner,and W^6＋ by Mo^6＋ cations.     

流动注射化学发光法测定氯化血红素

在甲醛存在的条件下,在酸性溶液中KMnO4与氯化血红素能够发生化学发光反应,产生很强的化学发光。据此采用流动注射技术,建立了一种利用KMnO4-甲醛-氯化血红素化学发光体系测定氯化血红素的化学发光分析法。方法的检出限为6×10-8g/mL;相对标准偏差为1.8%(2.0×10-6g/mL氯化血红素,n=11);线性范围为2.0×10-7~8.0×10-6g/mL。本法用于新鲜鸡血中氯化血红素的测定,结果与标准方法测得值一致。并对化学发光反应的机理进行了探讨。     

Polymorphic Study of 2-(2-benzofuryl) Δ-2 Imidazoline

The compound 2-(2-benzofuryl) Δ-2 imidazoline, has been studied by DSC, TG, X-ray diffraction and thermomicroscopy. We shall see that in the case of a study by DSC this compound presents a strange behaviour, which apparently is in contradiction with the thermodynamic rules. In a case of monotropy, if we have the α-phase (stable) and the γ-phase (metastable), after melting and cooling only theα-phase could crystallise. But this compound can give, according to the rate of cooling, theγ-phase metastable. The rate of cooling is of fundamental importance and the monotropic behaviour of this compound will be explained using the Gibbs function G=f(T) for P=1 atm. This revised version was published online in August 2006 with corrections to the Cover Date.