分散液液微萃取-气相色谱-质谱法测定水样中4种环境激素

以四氯乙烯作萃取剂,以四氢呋喃为分散剂对水样中4种环境激素甲草胺、乙草胺、三唑酮和三唑醇进行分散液液微萃取。提取液用气相色谱-质谱法测定。4种环境激素的质量浓度与其相应峰面积均在0.05～100μg.L-1范围内呈线性关系。甲草胺、乙草胺、三唑酮和三唑醇的检出限(3S/N)分别为0.016,0.015,0.023,0.032μg.L-1。在0.2,2.0mg.kg-1两个添加水平下进行回收试验,4种环境激素的回收率在86.8%～118%之间,测定值的相对标准偏差(n=6)在2.1%～6.2%之间。     

小体积液液萃取气相色谱-质谱法测定水体中邻苯二甲酸酯

采用小体积液液萃取气相色谱-质谱(GC-MS)法测定水体中邻苯二甲酸酯,有效地避免了各种空白干扰。该法以正己烷为萃取剂,对6种目标化合物的富集倍数达8～321倍。在0.40～20.0μg/L范围内线性良好,6种邻苯二甲酸酯的检出限在0.01～0.10μg/L范围内,适用于实际水体中低浓度邻苯二甲酸酯的测定。     

分散液液微萃取-气相色谱-质谱法测定水样中4种嗅味物质

以四氯乙烯作萃取剂,以丙酮为分散剂对水样中4种嗅味物质,二甲基异莰醇、土臭素、β-环柠檬醛和β-紫罗兰酮进行分散液液微萃取,提取液供气相色谱-质谱仪分析。在选择离子监测模式下,4种嗅味物质的线性范围均为0.05～20μg.L-1。二甲基异莰醇、土臭素、β-环柠檬醛和β-紫罗兰酮的检出限(3S/N)分别为0.03,0.01,0.02,0.01μg.L-1。方法用于自来水和河水样品分析,4种嗅味物质的回收率在87.7%～102%之间,测定值的相对标准偏差(n=6)在1.8%～7.8%之间。     

有机悬浮固化分散液-液微萃取测定水样中痕量铅

建立了以二乙基二硫代氨基甲酸钠为配位剂,十二醇为萃取剂,乙醇为分散剂的悬浮固化分散液-液微萃取—火焰原子吸收光谱法测定水样中痕量铅的方法。详细探讨了影响萃取效率的因素。优化条件为:二乙基二硫代氨基甲酸钠的用量为10-6 mol,十二醇体积为90.00μL,乙醇体积为1.00 mL,pH为7.00。在最佳条件下,铅的检出限为1.12μg/L,富集倍率为16.00,线性范围5.00～600.00μg/L,对含有20.00μg/L和600.00μg/L Pb的标准溶液平行萃取测定11次,测定结果的RSD分别为3.73%和2.62%。本方法应用于自来水、河水及海水中痕量铅的分析,加标回收率为90.10%～100.70%。     

凝固-漂浮分散液液微萃取-高效液相色谱法测定水样中氯酚

采用凝固-漂浮分散液液微萃取(SFO-DLLME)-高效液相色谱法测定水样中3种氯酚.以密度小于水,且凝固点为24 ℃的1-十二醇为萃取剂,甲醇为分散剂,对水样进行分散液液微萃取.将混合液离心,再通过冷冻凝固操作使漂浮的萃取剂和水相分离,萃取剂复溶后进样测定.本实验确定的最佳实验条件为:萃取剂200 μL、分散剂300 μL、1.2 g NaCl、1 mol/L H3PO4 200 μL、样品体积8.0 mL、萃取时间3 min.3种氯酚测定的线性范围为0.05～6.0 mg/L;检出限为20～38 μg/L.应用本方法分析实际水样,加标回收率在90.11%～107.7%之间;日间相对标准偏差在3.5%～4.6%之间.本方法扩展了分散液液微萃取萃取剂的选择范围,具有简便、快速、准确、环境友好等特点.     

超声辅助分散液-液微萃取/高效液相色谱联用富集分析环境水样中邻苯二甲酸酯类化合物

建立了超声波辅助分散液-液微萃取(DLLME)与高效液相色谱(HPLC)联用对环境水样中痕量邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)和邻苯二甲酸二辛酯(DOP)富集分离测定的方法,优化了色谱分离条件,考察了萃取剂与分散剂的种类与用量、萃取时间和离子强度对超声辅助DLLME/HPLC的影响。在优化实验条件下,邻苯二甲酸酯色谱峰面积与其浓度在1.00～100μg.L-1范围内呈良好的线性关系,相关系数均大于0.996,平均加标回收率为91%～103%,相对标准偏差(RSDs,n=5)为2.0%～6.8%,5种邻苯二甲酸酯类化合物的检出限(S/N=3)分别为0.08、0.04、0.03、0.01、0.07μg.L-1。建立的方法用于环境水样中邻苯二甲酸酯的测定,平均加标回收率为85%～119%,RSDs(n=3)为2.3%～11.1%。该方法适用于环境水样中痕量邻苯二甲酸酯类化合物的富集分析。     

超声辅助基质分散液-液微萃取/气相色谱-串联质谱法测定水中48种半挥发性有机物

建立了超声辅助基质分散液-液微萃取(UA-DLLME)/气相色谱-串联质谱(GC-MS)同时测定地下和地表水中15种硝基苯、19种苯胺和14种邻苯二甲酸酯类化合物的分析方法。采用Plackett-Burman设计从萃取剂、分散剂体积、萃取温度、萃取时间和离子强度等变量中筛选最显著的影响因素,并利用中心组合设计(CCD)结合响应曲面图优化显著因素,最终确定最佳的萃取条件:10 mL水样在2 g/L NaCl条件下迅速加入0.65 mL乙腈(分散剂)和40μL四氯化碳(萃取剂),于40℃超声2 min,混合液以3 500 r/min离心3 min。结果显示,目标分析物在1～200μg/L质量浓度范围内线性良好,相关系数不低于0.995 8,方法的检出限(MDL)为0.001～0.030μg/L,定量下限(LOQ)为0.004～0.120μg/L,在低、中、高3个加标浓度下的平均回收率为77.4%～113%,相对标准偏差(RSD)均不高于9.6%(n=6)。     

分散液液微萃取-上浮溶剂固化/高效液相色谱法测定沉积物中的十溴联苯醚

建立了沉积物中痕量十溴联苯醚的分散液液微萃取-上浮溶剂固化-高效液相色谱-紫外法(DLLME-SFO-HPLC-UV)。以正交试验数据为训练样本,采用BP(Back propagation)神经网络模型优化了分散液液微萃取-上浮溶剂固化条件:分散剂为1.00mL甲醇、萃取剂为35.0μL十二醇、NaCl质量浓度为10.00%、萃取时间10min和pH=5,其萃取率(ER)可达62.22%。方法的线性范围为3.5～1400ng/g(r=0.9960),检出限(LOD)和定量限(LOQ)分别为2.3pg/g(S/N=2)和5.6pg/g(S/N=5),实际样品的加标回收率为97.7%～104.2%。本方法集萃取、富集、分离步骤于一体,简化了沉积物中十溴联苯醚的前处理过程。     

凝固-漂浮分散液液微萃取富集分光光度法测定水中亚硝酸根

研究了凝固-漂浮分散液液微萃取（SFO-DLLME）-分光光度法测定水样中痕量亚硝酸根的方法。以1-十二醇为萃取剂,乙醇为分散剂进行分散液液微萃取,离心后通过冷冻凝固操作使漂浮的萃取剂和水相分离。最佳实验条件下,方法的线性范围为2.0-280μg/L（r=0.999 9）,检出限为0.34μg/L。方法已成功应用于环境水样分析,相对标准偏差在2.4%-3.3%,加标回收率在98.2%-102.4%。     

离子液体液-液萃取高效液相色谱测定水中邻苯二甲酸酯类物质

采用1-辛基-3-甲基咪唑六氟磷酸盐[C8mim][PF6]离子液体液-液萃取高效液相色谱法测定水中邻苯二甲酸酯类物质。实验选择邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二环己酯(DCHP)和邻苯二甲酸二正辛酯(DNOP)作为研究对象,对萃取时间、萃取体积比和盐的加入量进行了优化。实验表明最佳萃取条件为:萃取时间为20min、萃取体积比为1:150,而盐加入对萃取效率无显著影响。在最佳条件下离子液体对3种邻苯二甲酸酯的富集倍率在17～84之间,方法对DBP、DCHP和DNOP的检出限分别为0.98、0.91和6.6μg/L。将该方法用于河水、塑料瓶装矿泉水和一次性塑料袋浸出液中邻苯二甲酸酯类的检测,加标回收率为85.2%～110%。同时与正已烷在最佳萃取条件下的富集方法进行了对比,结果表明:离子液体液-液萃取法方法简便,试剂用量少,富集倍率高。     

PMDA-BPDA-HAB聚苯并噁唑的合成及耐热性

PMDA-BPDA-HAB聚苯并噁唑的合成及耐热性;均苯四甲酸二酐;联苯四羧酸二酐;二羟基联苯胺;聚酰亚胺;聚苯并噁唑;耐热性     

Studies on the Formation of Catalytically Active PGM Nanoparticles from Model Solutions as a Basis for the Recycling of Spent Catalysts

The paper presents basic studies on the precipitation of platinum, palladium, rhodium, and ruthenium nanoparticles from model acidic solutions using sodium borohydride, ascorbic acid, and sodium formate as reducing agents and polyvinylpyrrolidone as a stabilizing agent. The size of the obtained PGM particles after precipitation with NaBH₄ solution does not exceed 55 nm. NaBH₄ is an efficient reducer; the precipitation yields for Pt, Pd, Ru, Rh are 75, 90, 65 and 85%, respectively. By precipitation with ascorbic acid, it is possible to efficiently separate Pt, Rh, and Ru from Pd from the two-component mixtures. The obtained Pt, Pd, and Rh precipitates have the catalytic ability of the catalytic reaction of p-nitrophenol to p-aminophenol. The morphological characteristic of the PGM precipitates was analyzed by AFM, SEM-EDS, and TEM.     

Synthesis of Some Novel Class of Bis(isoxazoline) and Bis(aziridine) Derivatives

Synthesis of some new bis(isoxazoline) derivatives has been described from terepthaldehyde derived bis(nitrones) using microwave irradiation via 1,3‐dipolar cycloaddition reaction. Bis(isoxazoline) derivatives in turn successfully converted into new bis(aziridine) derivatives via Baldwin rearrangement. Simple reaction methodology, non involvement of catalysts, and good to excellent yields are the important features noticed in this synthesis.     

柴油加氢精制催化剂制备技术

柴油加氢精制催化剂制备技术的发展大致经历了3个阶段,由此形成了三代柴油加氢催化剂:单层分散的负载型金属硫化物催化剂,多层分散的负载型金属硫化物催化剂和非负载型金属硫化物催化剂。本文对金属硫化钼基柴油加氢精制催化剂的应用背景、制备思想及催化剂研究开发现状进行了系统的总结,对柴油加氢催化剂的发展方向进行了展望。     

Direct Quantitation of Phytocannabinoids by One-Dimensional 1H qNMR and Two-Dimensional 1H-1H COSY qNMR in Complex Natural Mixtures

The widespread use of phytocannabinoids or cannabis extracts as ingredients in numerous types of products, in combination with the legal restrictions on THC content, has created a need for the development of new, rapid, and universal analytical methods for their quantitation that ideally could be applied without separation and standards. Based on previously described qNMR studies, we developed an expanded ¹H qNMR method and a novel 2D-COSY qNMR method for the rapid quantitation of ten major phytocannabinoids in cannabis plant extracts and cannabis-based products. The ¹H qNMR method was successfully developed for the quantitation of cannabidiol (CBD), cannabidiolic acid (CBDA), cannabinol (CBN), cannabichromene (CBC), cannabichromenic acid (CBCA), cannabigerol (CBG), cannabigerolic acid (CBGA), Δ9-tetrahydrocannabinol (Δ9-THC), Δ9-tetrahydrocannabinolic acid (Δ9-THCA), Δ8-tetrahydrocannabinol (Δ8-THC), cannabielsoin (CBE), and cannabidivarin (CBDV). Moreover, cannabidivarinic acid (CBDVA) and Δ9-tetrahydrocannabivarinic acid (Δ9-THCVA) can be distinguished from CBDA and Δ9-THCA respectively, while cannabigerovarin (CBGV) and Δ8-tetrahydrocannabivarin (Δ8-THCV) present the same ¹H-spectra as CBG and Δ8-THC, respectively. The COSY qNMR method was applied for the quantitation of CBD, CBDA, CBN, CBG/CBGA, and THC/THCA. The two methods were applied for the analysis of hemp plants; cannabis extracts; edible cannabis medium-chain triglycerides (MCT); and hemp seed oils and cosmetic products with cannabinoids. The ¹H-NMR method does not require the use of reference compounds, and it requires only a short time for analysis. However, complex extracts in ¹H-NMR may have a lot of signals, and quantitation with this method is often hampered by peak overlap, with 2D NMR providing a solution to this obstacle. The most important advantage of the COSY NMR quantitation method was the determination of the legality of cannabis plants, extracts, and edible oils based on their THC/THCA content, particularly in the cases of some samples for which the determination of THC/THCA content by ¹H qNMR was not feasible.     

Magnetism of metal-nitroxide compounds involving bis-chelating imidazole and benzimidazole substituted nitronyl nitroxide free radicals

Coordination compounds based on imidazole and benzimidazole substituted nitronyl nitroxide radicals with transition metal ions and trivalent lanthanide ions are described from the perspective of their magnetic properties.For the transition metal compounds the crystal structures show various metal-nitroxide dimensionalities including mononuclear (0D), one-dimensional (1D) and two-dimensional (2D) complexes. The mononuclear complexes were isolated with most metal ions of the first transition series. One copper(II) complex shows a copper(II)-radical ferromagnetic coupling (J = +75 cm⁻¹) while for the other mononuclear compounds, mainly with manganese(II), the metal-radical interactions are antiferromagnetic. The one-dimensional and two-dimensional complexes are manganese(II) compounds which show canting effects leading to weak ferromagnetism.For the trivalent lanthanide ions [La(III), Gd(III) and Eu(III)], three series of mononuclear complexes were obtained in which the metal center is bound to four, two or one nitroxide radicals depending on the counter ions and ancillary ligands. Unexpectedly, in most gadolinium(III) complexes, the Gd(III)-radical interactions were found to be antiferromagnetic in contradiction with other foundings and previous theoretical models. In support to the magnetic studies, the optical properties of the lantanide complexes have also been investigated and are briefly described.     

Transition metal complexes of the tripodal ligand 4-(2′-pyridylmethyl)-4-azaheptane-1,7-diamine. Crystal structures of [CuLCl]ClO4 and [NiL(MeCN)2](ClO4)2

The tripodal ligand 4-(2′-pyridylmthyl)-4-azaheptane-1,7-diamine has been prepared by reaction of 2-aminemethyl pyridine with acrylonitrile, followed by the reduction of the nitrile groups. Copper(II), nickel(II), zinc(II), cobalt(III) and chromium(III) complexes of the ligand have been prepared and characterized and the crystal structures of the complexes [CuLCl]ClO₄ and [NiL(MeCN)₂](ClO₄)₂ determined. The copper complex is five coordinate with approximate square pyramidal stereochemistry with the apical position occupied by a primary amine donor. The nickel complex is octahedral with the pyridine nitrogen donor lying trans to an acetonitrile ligand.     

Simple,Selective, and Sensitive Spectrophotometric Method for Determination of Trace Amounts of Nickel（Ⅱ）, Copper （Ⅱ）, Cobalt （Ⅱ）, and Iron （Ⅲ） with a Novel Reagent 2-Pyridine Carboxaldehyde Isonicotinyl Hydrazone

A selective and sensitive reagent of 2-pyridine carboxaldehyde isonicotinyl hydrazone（2-PYAINH） was synthesized and studied for the spectrophotometric determination of nickel, copper, cobalt, and iron in detail. At a pH value of 7.0, 9,0, 9.0, and 8.0, respectively, which greatly increased the selectivity; nickel, copper, cobalt, and iron reacted with 2-PYAINH to form a 1：2 yellow-orange, 1：2 yellow-green, 1：2 yellow and 1：1 yellow complexes, with absorption peaks at 363, 352, 346, and 359 nm, respectively. Under the optimal conditions, Beer＇s law was obeyed over the ranges of 0.01-1.4, 0.01-1.5, 0.01-2.7, and 0.01-5.4 mg/L respectively. The apparent molar absorptivity and Sandell＇s sensitivities were 8.4×10^4, 5.2×10^4, 7.1×10^4, and 3.9×10^4 L·mol^-l·cm^-1, respectively, and 0.00069, 0.0012, 0.00078, and 0.0014 μg·cm2, respectively. The detection limits were found to be 0.001, 0.002, 0.003, and 0.01 mg/L, respectively. The detailed study of various interfering ions to make the method more sensitive was carried out and selective and several real samples were analyzed with satisfactory results.     

The development and application of guidance on equipment qualification of analytical instruments

 This paper describes the development of guidance for the equipment qualification (EQ) of analytical instruments. EQ is a formal process that provides documented evidence that an instrument is fit for its intended purpose and kept in a state of maintenance and calibration consistent with its use.     

Electrochemically selective determination of dopamine in the presence of ascorbic and uric acids on the surface of the modified Nafion/single wall carbon nanotube/poly(3-methylthiophene) glassy carbon electrodes

A voltammetric method based on a combination of incorporated Nafion, single-walled carbon nanotubes and poly(3-methylthiophene) film-modified glassy carbon electrode (NF/SWCNT/PMT/GCE) has been successfully developed for selective determination of dopamine (DA) in the ternary mixture of dopamine, ascorbic acid (AA) and uric acid (UA) in 0.1M phosphate buffer solution (PBS) pH 4. It was shown that to detect DA from binary DA-AA mixture, the use of NF/PMT/GCE was sufficient, but to detect DA from ternary DA-AA-UA mixture NF/SWCNT/PMT/GCE was required. The later modified electrode exhibits superior electrocatalytic activity towards AA, DA and UA thanks to synergic effect of NF/SWCNT (combining unique properties of SWCNT such as high specific surface area, electrocatalytic and adsorptive properties, with the cation selectivity of NF). On the surface of NF/SWCNT/PMT/GCE AA, DA, UA were oxidized respectively at distinguishable potentials of 0.15, 0.37 and 0.53 V (vs. Ag/AgCl), to form well-defined and sharp peaks, making possible simultaneous determination of each compound. Also, it has several advantages, such as simple preparation method, high sensitivity, low detection limit and excellent reproducibility. Thus, the proposed NF/SWCNT/PMT/GCE could be advantageously employed for the determination of DA in real pharmaceutical formulations.