1-(2-吡啶偶氮)-2-萘酚-过氧化氢光度法测定土壤中痕量钒

对钒(V)与1-(2-吡啶偶氮)-2-萘酚-过氧化氢-十六烷基三甲基溴化铵显色反应进行了试验,结果表明:在1 mol·L-1盐酸介质中,在十六烷基三甲基溴化铵存在下,钒(V)与1-(2-吡啶偶氮)-2-萘酚和过氧化氢反应生成红色多元络合物,络合物的最大吸收波长为577 nm,表观摩尔吸光率为3.04×104L·mol-1·cm-1,钒(V)的质量浓度在1.0 mg·L-1以内符合比耳定律.络合物的组成比为n钒(V):nPAN:n过氧化氢=1:1:1.方法用于土壤试样中痕量钒的测定,测定值的相对标准偏差(n=6)均小于9%,回收率在97.8%～101.5%之间,测得标准样品(GSS-5)中钒的含量为170.45μg·g-1,与标准值(166±9)μg·g-1之间的相对误差为2.7%.     

高效液相色谱法测定食品中2-(4-甲氧基苯氧基)-丙酸钠

提出了高效液相色谱法测定食品中2-(4-甲氧基苯氧基)-丙酸钠的方法。食品样品的饱和氯化钠溶液以乙腈提取,提取液用正己烷净化,所得经净化的乙腈液层用Agilent TC-C18色谱柱(250mm×4.6mm,5μm)为分离柱,以0.05%(体积分数)磷酸溶液与甲醇以体积比50比50组成的混合液为流动相进行分离,在检测波长224nm处进行测定。2-(4-甲氧基苯氧基)-丙酸钠质量浓度在0.20~5.00mg·L-1范围内与峰面积呈线性关系,方法检出限(3S/N)为0.3mg·kg-1。以空白食品样品为基体进行加标回收试验,所得回收率在91.3%~107%之间,相对标准偏差(n=6)在1.7%~8.2%之间。     

气相色谱-质谱法测定蔬菜与水果中11种三唑类农药残留

建立了蔬菜和水果中11种三唑类农药残留的气相色谱-质谱(GC - MS)测定方法.样品用乙腈均质提取,经石墨化炭黑/氨基复合柱净化,乙腈-甲苯(3:1)洗脱.洗脱液经浓缩、溶剂交换后定容,采用气相色谱-质谱的选择离子监测方式( GC - MSD/SIM)进行测定,内标法定量.方法的线性范围为0.05～5 ng,相关系数...     

固相萃取-高效液相色谱-串联质谱法测定枸杞中9种红色合成色素

建立了固相萃取-高效液相色谱-串联质谱(HPLC-MS/MS)联用同时测定枸杞中酸性红1、酸性红9、诱惑红等9种红色合成色素的分析方法。样品经乙腈-甲醇(5∶5,V/V)提取,用Oasis WAX固相萃取柱净化,目标化合物以Zorbax Eclipse Plus C18柱(100×3.0mm,1.8μm)分离,采用乙腈-10mmol/L乙酸铵为流动相梯度洗脱,采用电喷雾负离子源(ESI-)、多重反应监测模式(MRM)检测,基质匹配外标法进行定量。9种红色合成色素在各自线性范围内相关系数(r2)均大于0.992;方法的定量限以信噪比(S/N)≥10计为0.01~3.00mg/kg,3个加标水平(1、2、10倍定量限)下,回收率为82.1%~99.8%,相对标准偏差(RSDs)为4.6%~16.1%。该方法准确度好、灵敏度高、重现性好,适用于枸杞中红色合成色素的测定。     

超声萃取-超高效液相色谱-串联质谱法测定玩具涂层中2种光引发剂残留量

建立了超声萃取-超高效液相色谱-串联质谱法(UHPLC-MS/MS)测定玩具涂层中2-二甲氨基-2-苄基-1-[4-(4-吗啉基)苯基]-1-丁酮(光引发剂IHT-PI 910)和2-甲基-1-[4-(甲基硫代)苯基]-2-(4-吗啉基)-1-丙酮(光引发剂IHT-PI 907)残留量的方法。用10 mL乙腈在60℃下超声提取样品30 min,加入0.1%(体积分数,下同)甲酸溶液,过0.20μm滤膜,滤液供UHPLC-MS/MS分析。以ACQUITY UPLC BEH C_(18)色谱柱为固定相,不同体积比的乙腈和0.1%甲酸溶液组成的混合溶液为流动相进行梯度洗脱,目标物经色谱分离后,在电喷雾离子源正离子(ESI~+)模式和多反应监测(MRM)模式下进行质谱分析。结果显示:在优化的试验条件下,2种光引发剂可在3.00 min内完成测定;标准曲线的线性范围均为0.5～100μg·L~(-1),检出限(3S/N)均为1.0μg·L~(-1);对阴性样品进行3个浓度水平的加标回收试验,所得回收率为87.9%～93.4%,测定值的相对标准偏差(n=7)为1.2%～8.6%。用此方法分析了20个随机样品,3个样品检测结果均为阳性,样品2中光引发剂IHT-PI 907的最高检出量为1 528 mg·kg~(-1),超出了REACH法规的限量(1 000 mg·kg~(-1))要求。     

高效液相色谱-串联质谱法测定猪肉中9种β_2-受体激动剂残留量

采用高效液相色谱-串联质谱法测定了猪肉中9种β-受体激动剂的残留量。样品经β-葡萄糖醛苷酶/芳基硫酸酯酶酶解后加入高氯酸沉淀蛋白并离心,取上清液过PCX阳离子固相萃取小柱净化,用氨水-甲醇(5+95)混合液洗脱,氮气吹干后用乙腈定容至1 mL。以CAPCELL PAK CR色谱柱为分离柱,以10mmol·L-1乙酸铵溶液-乙腈(55+45)混合溶液(含体积分数为0.1%的甲酸)为流动相进行洗脱,采用电喷雾正离子源及选择反应监测模式进行测定,内标法进行定量。9种β-受体激动剂的质量浓度在4.00~100μg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.09~0.50μg·L-1之间。对空白样品进行加标回收试验,回收率在83.2%~102%之间,测定值的相对标准偏差(n=6)在5.0%~12%之间。     

气相色谱-串联质谱法快速测定禽蛋中203种农药及化学污染物残留

建立了禽蛋中203种农药及化学污染物残留的气相色谱-串联质谱(GCMS/MS)检测方法.样品用乙腈振荡提取,经ODS C18+Carb串联固相萃取柱净化,乙腈-甲苯(3:1,v/v)洗脱,洗脱液浓缩至0.5mL,氮吹至近干,加1mL正己烷超声溶解后,在气相色谱-串联质谱多反应监测(MRM)模式下进行测定.在1倍MRL(...     

高效液相色谱法测定制药中间体7-甲氧基-1-萘基乙腈

提出了用高效液相色谱法测定制备抗抑药物中间体7-甲氧基-1-萘基乙腈含量的方法.采用Diamonsil-C18色谱柱(250 mm×4.6 mm,5μm)进行分离,柱温为20℃,用甲醇-水(80+20)的混合液为流动相,流量为0.8 mL·min-1,检测波长为231 nm,进样量为20μL.结果表明:在此色谱条件下,7-甲氧基-1-萘基乙腈与相关杂质得到了分离.7-甲氧-基-1-萘基乙腈的质量浓度在2～48 mg·L-1范围内呈线性关系,方法的检出限(3S/N)为105μg·L-1.在40 mg·L-1浓度水平上平行测定6次,对方法的精密度和回收率做试验,测得其相对标准偏差为0.034%,平均回收率为99.7%.     

微乳液介质-4-(6-甲氧基-8-喹啉偶氮)-间苯三酚分光光度法测定痕量镓(Ⅲ)

对由溴化十六烷基吡啶(CPB)、辛基苯基聚氧乙烯醚(OP)、正丁醇、正庚烷和水组成的微乳溶液存在下,4-(6-甲氧基-8-喹啉偶氮)-间苯三酚与镓(Ⅲ)的显色反应,进行了研究并提出了分光光度法测定痕量镓(Ⅲ)的方法.结果表明:在pH 9.80的硼砂-氢氧化钠缓冲溶液中,镓(Ⅲ)与试剂形成1:2的红色络合物,络合物的最大吸收峰在525 nm波长处,表观摩尔吸光率为1.6×105mol-1·cm-1.镓(Ⅲ)量在μg·L-1范围内符合比耳定律,检出限(3S/N)为1 μg·L-1.方法用于煤和矿石中微量镓的测定,测得结果与原子吸收光谱法的结果相符,测定值的相对标准偏差(n=6)均小于5%.在两实样的基础上用标准加入法做回收试验,测得其平均回收率为102.7%.     

新型荧光试剂1-(8-喹啉)-3-(3,5-二溴-2-吡啶)-三氮烯的合成及其应用

将具有荧光特性的杂环8-氨基喹啉和吡啶类试剂结合,并引入三氮烯结构,合成了新型荧光试剂1-(8-喹啉)-3-(3,5-二溴-2-吡啶)-三氮烯(QBPyT)。其结构经元素分析、红外光谱、核磁共振波谱证实。研究结果表明,在pH 9.5硼酸-氢氧化钠缓冲溶液的介质存在下,该试剂在λex/λem=248nm/496nm处产生强荧光,并且能与铅(Ⅱ)形成配合物从而使荧光增强。据此建立了三氮烯测定铅(Ⅱ)的新型荧光分析法。铅的浓度在5.0×10-7～1.2×10-5 mol.L范围内与其荧光强度呈线性关系,检出限(3S/N)为9.5×10-8 mol.L。将其应用于水样中铅(Ⅱ)的测定,测得回收率在92.6%～94.0%之间,测定值的相对标准偏差(n=5)小于3.5%。     

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。     

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.     

Simultaneous determination of mercury and arsenic by anodic stripping voltammetry

An electrochemical method for the simultaneous determinations of Hg^II concentration and total As^III and As^V concentration has been developed. The method does not require the additional preliminary step of the chemical reduction of As^V to As^III, or oxidation of As^III to As^V before stripping analysis takes place. Also, the method for the simultaneous determination of Hg^II concentration and As^III concentration is described. Measurements were performed in 0.1 M HCl using a gold-plated graphite electrode as sensor. Detection limits for both methods are below 0.4 ppb. Relative standard deviation did not exceed 15%. The possible interference by other trace metals was investigated. Analyses of natural water and industrial solutions were made using proposed methods and AAS. The t-test demonstrates that there was no significant difference between the results obtained with these methods. Proposed methods decrease the time of analysis because concentrations of the Hg^II and arsenic ions were measured simultaneously. Also, the removal of the additional step of chemical reduction of As^V to As^III or oxidation of As^III to As^V decreases analysis time, and also reduces the chance of contamination due to the use of additional reagents.