用季铵盐定域体制备高碘酸根离子电极的研究

实验比较了若干种长链季铵盐制备高碘酸根离子电极,以十六烷基三辛基高碘酸季铵盐(HTOA-IO₄)制备的PVC膜电极性能较佳,能斯特响应区间为1.0×10^-1-6.3×10^-8M,检测下限1.0×10^-8M,工作pH范围2.5-7.5,高碘酸在溶液中存在复杂平衡,依据pH-电位曲线,认为电极响应的Ⅰ(ⅥI)离子的主要形态为IO₄^-,据此用电位法测试了H₅IO₆的酸离解常数:K₁=5.70×10^-4,K₂=1.97×10^-7,与文献值相符,测试了不同离子的电位选择性系数。     

Gran滴定增量法——微量氯的测定

本文讨论了沉淀溶解度对Gran滴定的影响。由修正的Gran函数字出误差方程:R_a=-Cs(V₀+V)/C,据此方程可以进行误差分析和计算。在测Cl^-时,若滴定剂(AgNO₃)浓度为2×10^-3M,测定的适宜范围为5×10^-6M-5×10^-5M。增量法的引入使5×10^-6M以下Cl^-的测定成为可能,测定下限浓度达1×10^-6M,变动系数为20%。     

铅-邻菲罗啉络合吸附波的研究

在0.06MHAc-0.14MNaAc(pH=5.1)和2×10^-5M邻菲罗啉(phen)溶液中,用单扫示波极谱法可得到Pb(Ⅱ)-phen络合波,峰电位在-0.49V处。其导数峰高与铅在5×10^-8-5×10^-6M范围内的浓度有线性关系,最低检出限2.5×10^-8M。此波可用于测定铅。研究确定该波为1:1铅-邻菲罗啉络合物的吸附波。     

阳极溶出催化伏安法测定微量钯的研究

本文提出了用阳极溶出催化伏安法测定微量钯的方法,找到了灵敏度较高的富集底液和催化体系,钯在3×10¹⁰-1×10^-7M浓度范围内呈线性关系,最低检出浓度为1.2×10^-10M。     

阴极溶出催化极谱法测定微量硒

本文提出将溶出伏安法和极谱催化法结合起来,用溶出催化波来测定微量硒;考察了各种试验条件及其它离子对分析结果的影响,并对实样进行了分析测定。用国产883型笔录式极谱仪,配用旋转玻碳电极测定硒,电解富集3-5分钟,可定量测定浓度在4×10^-9-1×10^-7M 范围内的硒;富集20-30分钟,硒的检出下限为7×10^-10M。测定时不必除氧。在测定硒的基础上,用玻碳电极和大汞电极相配合,对硒的溶出催化电极过程进行了研究,探讨了此过程中各步反应的机理。     

氟硼酸根离子-聚氯乙烯膜选择电极的研制

以季铵盐为活性物质,研制了氟硼酸根离子聚氯乙烯膜电极.实验比较了不同活性物质在膜相中浓度和不同增塑剂对电极性能的影响.结果表明,用2%三庚基十二烷基氟硼酸铵、68%邻苯二甲酸二(2-乙基己)酯,30%聚氯乙烯制成的电极,对氟硼酸根离子的线性测量范围为10^-1～1×10^-6M,检测下限8×10^-7M,较文献报道为好.测定了电极对常见离子的选择性系数,除ClO₄^-、CNS^-、I^-有干扰外,其余常见阴离子的选择系数值均在10^-3～10^-6数量级.电极的重现性、稳定性、寿命等均较好.     

HPLC分离化学发光检测药物中的马钱子碱、士的宁和麻黄类生物碱

在KMnO₄-H⁺-还原剂体系中研究了马钱子碱、士的宁和麻黄类生物碱的化学发光(CL)行为,建立了其快速灵敏的流动注射化学发光分析方法,将此法与HPLC联用,实现了上述物质的选择性测定,该方法的检出限为1.0×10^-10g/mL马钱子碱、1.0×10^-8g/mL士的宁、1.0×10^-5g/mL麻黄碱和伪麻黄碱,测定的相对标准偏差小于3%,HPLC流动相的脉动及其中的溶解氧不影响测定的精密度。此法已用于一些药物中马钱子碱等生物碱的测定,回收率为94%～101%.     

2,7-TADN极谱特性研究(Ⅱ)-铜(Ⅱ)-2,7-TADN-乙二胺配合物吸附波测定痕量铜

研究了Cu²⁺-2,7-TADN-乙二胺配合物的极谱行为。在氢氧化钠、乙二胺(en)和2,7-TADN底液(pH约为12)中,铜(Ⅱ)能产生Cu²⁺-2,7-TADN-en三元配合物吸附波,其峰电位为-0.86V。铜含量在2.0×10^-8-5.0×10^-6M范围内,峰高与铜浓度成线性关系。检测下限达1.0×10^-8M。     

稀土共发光效应的研究(Ⅱ)-Sm-Tb-TTA-邻二氮菲体系的共发光效应及其分析应用

本文报道了Sm-Tb-TTA-邻二氮菲体系的共发光现象并进行了较详细的研究。该体系的最佳形成条件:Tb³⁺的浓度为1-2×10^-5M,pH5.5-7.0.该荧光增强效应可用于测定超痕量的Sm³⁺,其浓度在1.0×10^-9-1.5×10^-7M范围内与荧光强度呈线性关系,检测限可达2.5×10^-11M。测定Sm³⁺的灵敏度比Sm-TTA-邻二氮菲体系提高二个数量级。用标准加入法测定样品中的钐,结果满意。     

稀土元素的电分析化学研究(Ⅵ)——钐-罗丹明B-氯化铵体系的极谱研究

在单扫示波极谱仪上,罗丹明B在氯化铵底液中(0.4M)的导数波(-1.45V,SCE)是一个吸附波,加入Sm³⁺能降低它的波高,二苯胍(1×10^-4M)的存在使罗丹明B(8.4×10^-5M)的波形稳定,Sm³⁺浓度为3×10^-7-2×10^-3M时,浓度与波峰的降低呈线性关系。在直流极谱仪上,在有二氧六圜存在的氯化铵底液中,钐(Ⅲ)-罗丹明B络合物在-1.7V(SCE)有一个吸附还原波。在最佳条件下(0.1M氯化铵,4.2×10^-5M罗丹明B和10%二氧六圜,pH=5.0),在浓度为2×10^-5-2×10^-5M范围内,波高与Sm³⁺浓度有正比关系。比较了稀土-罗丹明B在二氧六圜中的极谱波,销比钐灵敏,铒最灵敏;但是罗丹明B的吸附波妨碍了在它后面的络合物波的灵敏度进一步提高。     

Voltammetric Behavior of Strychnine, and its Determination in Strychno Nux-Vomica Seeds Extract

The voltammetric behavior of strychnine has been studied with a pyrolytic graphite (PG) electrode. The redox process taking place at the PG electrode is discussed. The cyclic voltammetric response has also been evaluated with respect to various experimental conditions, such as scan rate, pH of the supporting electrolyte, strychnine concentrations and accumulation time. A highly sensitive voltammetric method for the determination of strychnine is consequently developed. The linear calibration is in the range of 1×10⁻⁶ M – 1.1×10⁻⁴ M, with the limit of detection (LOD) being 1×10⁻⁸ M. The precision is excellent with a relative standard deviation (RSD) of 2.3%. The proposed cyclic voltammetric methodology has been applied to the determination of strychnine in the extract of Strychno nux-vomica seeds using the standard addition method. Consistent results have been obtained from both the electrochemical approach described here and the previously reported HPLC method.     

Potentiometric determination of some common alkaloids with a picrate-selective electrode

Potentiometric methods are described for the determination of alkaloids, based on the formation of insoluble alkaloid picrate salts, using a picrate ion-selective indicating electrode. Micro-amounts of strychnine, papaverine, quinine and cocaine were determined by direct potentiometry and titrimetrically, using Gran plots, with average errors of about 4% and 2%, respectively. The method was successfully applied to pharmaceutical preparations.     

二苯基乙二酮结构和电子光谱的理论研究

基于二苯基乙二酮结构优化,在TD-B3LYP/6-31+G*水平上讨论了两个异构体在气相和液相中的吸收和发射光谱.溶液中的计算采用可极化连续介质模型.结果表明,溶剂极性增加更有利于顺式非平面构型的形成,两个异构体的T1和S1态以及顺式非平面结构的S2态都源于双羰基上的n→π*.     

马钱子碱分子结构和振动光谱的密度泛函理论研究

用密度泛函理论B3LYP/6-31G*方法对天然药材马钱子中的生物碱马钱子碱的几何构型进行了优化,得到马钱子碱分子的平衡结构参数,并同实验结构进行了比较.计算了上述分子在平衡构型下的振动谐力场和振动基频.针对不同的振动模式,提出了相应的校正因子,并据此对计算频率进行了校正.理论计算和实验测定频率的平均误差为19.0cm-1.根据DFT计算的振动模式和IR光谱强度值对目标分子的实验振动基频进行了完善的和合理的指认和解释.     

Development and validation of a TLC-densitometric method for the simultaneous quantitation of strychnine and brucine from Strychnos spp. and its formulations

A simple, sensitive, and specific thin-layer chromatography densitometric method has been developed for the simultaneous quantitation of strychnine and brucine. These two marker compounds are quantitated in the seeds of Strychnos nux-vomica, Strychnos ignatii, and its formulations. The method involves densitometric evaluation of strychnine and brucine after resolving it by high-performance TLC on silica gel plate with toluene-ethyl acetate-diethyl amine-methanol (7:2:1:0.3 v/v) as the mobile phase. The method is validated for precision (interday and intraday), repeatability, and accuracy. The relationship between the concentration of standard solutions and the peak response is linear within the concentration range of 160 to 480 ng/spot for strychnine and 80 to 480 ng/spot for brucine. Instrumental precision is found to be 0.54 and 0.78 (% CV), and repeatability of the method is 1.01 and 1.06 (% CV) for strychnine and brucine, respectively. Accuracy of the method is checked by recovery study conducted at three different levels and the average percentage recovery is found to be 99.13% for strychnine and 100.16% for brucine. The proposed HPTLC method for the simultaneous quantitation of strychnine and brucine is found to be simple, precise, specific, sensitive, and accurate, and it can be used for routine quality control of raw material of Strychnos spp. It also can be applied in quantitating any of these marker compounds in other formulations.     

Toxicokinetics of strychnine and brucine after the oral administration of Biqi capsule to rats by RRLC–MS/MS

Biqi capsule is a well‐known traditional Chinese medicine formula that has been widely applied for the clinical treatment of such diseases as rheumatoid arthritis, scapulohumeral periarthritis and cervical spondylopathy. However, there is concern regarding the toxicity of Biqi capsule owing to its active ingredients, strychnine and brucine. To investigate the toxicokinetics of strychnine and brucine after oral administration of Biqi capsule to rats, a sensitive and simple rapid‐resolution liquid chromatography/tandem mass spectrometry method was developed to determine the levels of strychnine and brucine in rat plasma. Chromatographic separation was performed on a Capcell Pak C₁₈ MG II (3.0 μm, 2.0 × 35 mm) column by gradient elution with acetonitrile and 0.2% formic acid as the mobile phase. The method was validated over the range of 0.25–250 ng/mL for strychnine and 0.025–25 ng/mL for brucine. The intra‐ and inter‐day accuracies of strychnine and brucine in rat plasma were 100.3–106.6 and 90.75–106.1% respectively, and the precisions were within 14.2%. The established method was successfully applied to the toxicokinetic study of strychnine and brucine after single and multiple oral administration of Biqi capsule to male and female rats at 0.4, 0.8 and 1.6 g/kg doses. The results showed different toxicokinetic characteristics in the different groups.     

Combination of hollow fiber-based liquid-phase microextraction with sweeping techniques in micellar electrokinetic chromatography for the determination of Strychnos alkaloids in human urine

A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase microextraction (LPME) based on porous polypropylene hollow fibers in combination with on-line sweeping in micellar electrokinetic chromatography was developed. The calibration curve was linear over the range of 20-200 ng mL-1 for both strychnine and brucine in human urine sample. The detection limits (S/N=3:1) for strychnine and brucine were 1 ng mL-1 and 2 ng mL-1, respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine samples.     

Preparation of molecularly imprinted polymers for strychnine by precipitation polymerization and multistep swelling and polymerization and their application for the selective extraction of strychnine from nux‐vomica extract powder

Monodisperse molecularly imprinted polymers for strychnine were prepared by precipitation polymerization and multistep swelling and polymerization, respectively. In precipitation polymerization, methacrylic acid and divinylbenzene were used as a functional monomer and crosslinker, respectively, while in multistep swelling and polymerization, methacrylic acid and ethylene glycol dimethacrylate were used as a functional monomer and crosslinker, respectively. The retention and molecular recognition properties of the molecularly imprinted polymers prepared by both methods for strychnine were evaluated using a mixture of sodium phosphate buffer and acetonitrile as a mobile phase by liquid chromatography. In addition to shape recognition, ionic and hydrophobic interactions could affect the retention of strychnine in low acetonitrile content. Furthermore, molecularly imprinted polymers prepared by both methods could selectively recognize strychnine among solutes tested. The retention factors and imprinting factors of strychnine on the molecularly imprinted polymer prepared by precipitation polymerization were 220 and 58, respectively, using 20 mM sodium phosphate buffer (pH 6.0)/acetonitrile (50:50, v/v) as a mobile phase, and those on the molecularly imprinted polymer prepared by multistep swelling and polymerization were 73 and 4.5. These results indicate that precipitation polymerization is suitable for the preparation of a molecularly imprinted polymer for strychnine. Furthermore, the molecularly imprinted polymer could be successfully applied for selective extraction of strychnine in nux‐vomica extract powder.     

Separation and determination of strychnine and brucine in Strychnos nux-vomica L. and its preparation by capillary zone electrophoresis

A capillary zone electrophoresis method was developed for the separation and determination of strychnine and brucine in Strychnos nux-vomica L. and its preparation. The factors that could affect the separation were studied, such as the types and concentrations of electrolytes, pH, ionic strength and organic modifier. The optimum running buffer was 20 mmol/L of ammonium acetate containing 0.2 mol/L of glacial acetic acid (pH 3.64). The applied voltage was 25 kV and the wavelength of the UV detector was set at 214 nm. The established method with dopamine hydrochloride as internal standard was linear in the range of 5-100 microg/mL for both strychnine and brucine. The recovery was 102.96% for strychnine and 98.56% for brucine. The extracts of Strychnos nux-vomica and its preparation could be directly injected for analysis.     

Rapid separation of strychnine and brucine on a dynamically modified poly(dimethylsiloxane) microchip followed by electrochemical detection

A method has been developed for rapidly separating and detecting strychnine and brucine using a poly(dimethysiloxane) (PDMS) microchip and electrochemical (EC) detection. PDMS microchannels dynamically modified by Brij35 are shown to be more efficient than native ones. The two analytes are well separated within 90 s in 70 mmol/L acetate buffer (pH 5.5) containing 0.01% (v/v) Brij35. Detection limits were found to be 1.0 μmol/L for strychnine and 0.2 μmol/L for brucine at S/N=3. The method was used to determine trace strychnine and brucine in rat serum, and the results obtained correlate well with those obtained via high-performance liquid chromatography (HPLC).