氘代同位素内标气相色谱-质谱法测定食用香精中的二甲苯麝香

建立了氘代同位素内标气相色谱-质谱测定食用香精中二甲苯麝香含量的分析方法。采用漩涡混合器混合样品,使样品基质均匀分散于萃取溶剂中,再使用超声波提取目标物,探讨了萃取溶剂种类、溶剂用量及超声时间等因素对目标物萃取效率的影响;之后使用GC-MS选择离子监测模式检测,氘代同位素内标法定量,分析了不同极性色谱柱对目标物分离的影响,确定了较佳的特征离子及其丰度比。在优化实验条件下,二甲苯麝香在0.025～0.5 mg/L范围内具有良好的线性关系,相关系数(r2)为0.999 6,平均回收率为94%～116%,相对标准偏差(RSD)为4.2%～6.5%,检出限为0.11 mg/kg,定量下限为0.38 mg/kg。该方法简便、快速、灵敏、准确,适合于食用香精中二甲苯麝香含量的测定。     

涡旋混合辅助超声提取-高效液相色谱法同时测定水基胶中的苯系物和邻苯二甲酸酯类增塑剂

采用涡旋混合辅助超声提取样品的前处理方式,应用高效液相色谱法同时测定水基胶中的苯系物和5种邻苯二甲酸酯类增塑剂.基于样品基质的属性,采用漩涡混合器混合样品,使样品均匀分散于萃取溶剂中,再使用超声萃取的方式提取目标物.研究了不同萃取溶剂、提取方式及其条件对目标物检测结果的影响.优选了色谱分析所用的流动相、检测波长、流量和进样量等条件.在优化条件下,5种苯系物和5种邻苯二甲酸酯类增塑剂的峰面积与其质量浓度呈线性关系,相关系数(R2)都大于0.997,回收率分别在91.9%~111.4%和88.3%~121.4%之间,相对标准偏差RSD分别在1.41%~2.80%和1.24%~2.94%之之间.检出限分别在0.3~0.6 mg/kg和0.2~0.3 mg/kg之间.研究表明方法简便、耗溶剂量少、准确,与现行标准方法具有较好的吻合性,适合于同时测定水基胶中的苯系物和5种邻苯二甲酸酯类增塑剂.     

顶空/气相色谱-质谱法测定婴幼儿食品中54种挥发性有机污染物

该文建立了同时测定婴幼儿食品中54种挥发性有机污染物的气相色谱-质谱方法。称取适量样品于20 mL顶空进样瓶中,加入5 mL氯化钠饱和溶液分散,加热振荡,目标物经DB-VRX毛细管色谱柱分离,单四极杆质谱全扫描模式测定。结果表明：奶粉基质中各化合物的线性范围为0.010～0.100 mg/kg,定量下限均为0.010mg/kg;粉状辅食基质中各化合物的线性范围为0.010～0.250mg/kg,定量下限均为0.010 mg/kg;泥状辅食基质中各化合物的线性范围为0.002～0.250 mg/kg,定量下限均为0.002 mg/kg。在不同加标浓度水平下,奶粉、谷物粉和果泥中各化合物的回收率为80.6%～130%,相对标准偏差（RSD）不大于19%。采用所建方法检测了35批次市售婴幼儿食品,9批次样品中共检出5种挥发性有机污染物。该方法前处理简单快捷,适用于婴幼儿食品中挥发性有机污染物的检测。     

微波辅助萃取/气相色谱-质谱法对电子电气产品中多溴二苯醚的测定

建立了微波辅助萃取/气相色谱-质谱测定电子电气产品中多溴二苯醚(PBDEs)含量的方法,优化了萃取溶剂、萃取温度、萃取时间等微波萃取条件和GC-MS仪器分析条件.方法的准确度和重复性满足定量分析的要求,12种PBDEs组分的定量下限为0.27 ～4.3 mg/kg.将该方法用于分析6种电子电气样品,PBDEs的含量为0.3 ～1.7×104 mg/kg.该方法简单、快速、有机溶剂用量少,满足RoHS指令的要求和实际产品检测的需要 .     

气相色谱-串联质谱法快速测定调味品中3种糠醛类物质

建立了同时测定调味品中糠醛、5-甲基糠醛和5-羟甲基糠醛的气相色谱-串联质谱法(GC-MS/MS)。对样品的前处理方法及GC-MS/MS分析条件进行优化,样品经乙酸乙酯萃取,GC-MS/MS多反应监测模式(MRM)进行测定。3种糠醛类物质在0.001～20 mg/L范围内均呈良好的线性关系,相关系数为0.999 0～0.999 5;检出限(S/N=3)均为0.005 mg/kg,加标回收率为86%～95%。该法简便、快速、溶剂用量少,可消除调味品中复杂基质的干扰,结果准确可靠、灵敏度高,适用于调味品中3种糠醛类物质的同时测定。     

气相色谱–加速溶剂萃取法测定油墨中的7种多氯联苯

建立了测定油墨中多氯联苯含量的气相色谱法。使用加速溶剂萃取法进行样品前处理,对加速萃取溶剂、萃取时间进行了优化,采用内标法定量,并对油墨样品中7种常见的多氯联苯物质含量进行了验证试验。结果表明,该方法回收率为91.0%~97.6%,测定结果的相对标准偏差为5.1%~8.3%(n=6),定量限为0.03 mg/kg。该方法易于操作,实验时间短,灵敏度高,重现性好,适用于油墨样品中多氯联苯含量的测定。     

中空纤维液相微萃取-高效液相色谱法测定纺织品中10种含氯苯酚类化合物

建立了中空纤维液相微萃取-高效液相色谱法测定纺织品中10种含氯苯酚类化合物的方法。系统地优化了影响萃取效率的因素,得到的最佳萃取条件为：萃取溶剂为正己烷,接受相NaOH溶液的浓度为0.10 mol/L,萃取时间为60 min,搅拌速度为600 r/min。在最佳萃取条件下,10种含氯苯酚在0.01～1.00 mg/L范围内线性关系良好（r>0.999）,10种含氯苯酚的检出限（信噪比为3）为0.01 mg/kg,富集倍数为95～101。在空白样品中添加0.01、0.05和0.1 mg/kg 3个不同水平的10种含氯苯酚类化合物,其平均回收率为78.8%～105.1%,相对标准偏差为0.3%～7.3%。研究结果表明该方法灵敏度高、简便、准确,可用于纺织品中含氯苯酚类化合物的测定。     

多壁碳纳米管固相萃取/超高效液相色谱-串联质谱测定茶油中12种氨基甲酸酯类农药

建立了多壁碳纳米管(MWCNTs)为吸附剂的固相萃取净化/超高效液相色谱-串联质谱(UPLC-MS/MS)检测茶油中12种氨基甲酸酯类农药残留的快速分析方法。样品经乙腈超声提取,MWCNTs固相萃取小柱净化,以乙腈进行洗脱,旋蒸浓缩后以0.1%乙酸-乙腈(5∶5,体积比)定容,采用UPLC-MS/MS多反应监测模式(MRM)测定,外标法定量。考察了提取方式、吸附材料类型、洗脱溶剂用量等因素对目标物萃取效率的影响。在优化实验条件下,MWCNTs固相萃取小柱对茶油样品的净化效果理想。12种氨基甲酸酯类农药在0.005～0.1μg/mL范围内线性关系良好,相关系数(r)均不小于0.998 88;在0.01、0.025、0.05 mg/kg加标水平下,12种目标物的平均回收率为78.3%～116%,相对标准偏差为2.6%～12%,方法的定量下限为0.2～3.0μg/kg。     

气相色谱-质谱法测定土壤中14种苯胺类和联苯胺类化合物

针对土壤基质复杂及部分苯胺类化合物提取效率低的特点,基于气相色谱-质谱建立了土壤中14种苯胺类和联苯胺类化合物的分析方法。在采集后的土壤样品中加入5%亚硫酸钠水溶液进行密封,以防止目标物氧化变质,并于4℃以下冷藏保存,保存期限可达7天。实验比较了加速溶剂提取和振荡分散提取两种方式的提取效率,最终采用提取时加入碱性水溶液和乙酸乙酯-二氯甲烷(1∶4, v/v)的方法,在土壤-水相-有机相共存的条件下进行振荡分散萃取。萃取完成后经离心弃去土壤固相,将水相和有机相转移至分液漏斗中,并分离出有机相,再经弗罗里硅土固相净化柱净化、浓缩后,采用气相色谱-质谱联用仪测定,并以苯胺-d₅和苊-d₁₀为内标进行定量分析。实验考察了抗氧化剂和萃取溶剂种类、有机相与水相比例、盐析等对目标物萃取效率的影响,并在优化的实验条件下考察了方法的回收率及精密度。结果表明,14种目标化合物在0.5～100 mg/L范围内有良好的线性关系,相关系数(R)>0.999,方法检出限和定量限分别为0.02～0.07 mg/kg和0.08～0.28 mg/kg,在实际样品中的加标...     

食品纸包装材料中指示性多氯联苯的固相萃取/气相色谱-质谱联用法测定

建立了一种简单、快速测定食品纸包装材料中指示性多氯联苯的分析方法.采用溶剂超声萃取样品,通过C18固相萃取柱、浓硫酸净化后,用气相色谱-质谱联用仪(GC-MS)进行测定.并对不同的萃取溶剂和萃取方法进行了系统地比较,优化了实验条件,方法的回收率为88%～102%,相对标准偏差为3%～7%,定量下限为1.0 μg/kg.     

Gels from a semifluorinated n-alkane in fluorinated solvents as a probe for intermolecular interactions

Diblock semifluorinated n-alkanes can form aggregates and gels in fluorinated solvents. We have investigated the thermal behavior of binary mixtures comprising F(CF₂)₈(CH₂)₁₆H and fluorinated solvents. The solvents were perfluorohexane, perfluoroheptane, perfluorooctane, perfluorooctyl bromide, perfluorodecalin, and perfluorotributylamine. The phase diagrams were used to calculate the activity coefficients of the two components and the main excess thermodynamic functions. The solubility and self-assembly behavior of F₈H₁₆ in the fluorinated solvents are related to the different solute–solvent dispersion interactions that depend on the polarizabilities and ionization potentials of the interacting species, and on the structural properties of the solvent.     

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.     

HCOO在Cu(110)、Ag(110)和Au(110)表面的吸附

采用密度泛函理论(DFT)以及广义梯度近似方法(GGA)计算了甲酸根(HCOO)在Cu(110)、Ag(110)和Au(110)表面的吸附. 计算结果表明, 短桥位是最稳定的吸附位置, 计算的几何参数与以前的实验和计算结果吻合. 吸附热顺序为Cu(110)(-116 kJ·mol-1)>Ag(110)(-57 kJ·mol-1)>Au(110)(-27 kJ·mol-1), 与实验上甲酸根的分解温度相一致. 电子态密度分析表明, 吸附热顺序可以用吸附分子与金属d-带之间的Pauli 排斥来关联, 即排斥作用越大, 吸附越弱. 另外还从计算的吸附热数据以及实验上HCOO的分解温度估算了反应CO2+1/2H2→HCOO的活化能, 其大小顺序为Au(110)>Ag(110)>Cu(110).     

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.     

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.     

SYNTHESIS AND CHARACTERIZATION OF METAL COMPLEXES WITH AMPICILLIN

Abstract

The reaction, in water, of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) ions with sodium ampicillinate at room temperature has allowed isolation of dimers with the following general formula [M(amp)Cl]₂ × nH₂O (n = 1.5?3.2). The complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibilities and spectroscopic methods (IR, Raman, EPR and UV-Visible). A dinuclear structure based on octahedrally coordinated metal ions is proposed.     

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.     

具有聚集诱导发光性质的近红外荧光染料

聚集诱导发光(AIE)现象的发现为解决传统有机荧光分子在高浓度和聚集形态下存在的荧光猝灭问题提供了最佳方案,并实现了在光电器件、化学传感、生物成像和靶向治疗等众多领域的广泛应用.随着对AIE 发光机理研究的不断深入,AIE 分子体系得到了极大的扩展.其中,一类具有给体-受体结构的AIE分子能够显著降低分子能隙,使发光分...     

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.