气相色谱－串联质谱法测定电子烟烟液中的10种生物碱含量

建立了一种气相色谱－串联质谱法测定电子烟烟液中10种生物碱含量的分析方法,并对仪器分析条件、样品前处理条件等进行了优化。样品加入2.0 mL 2% NaOH水溶液后,以10 mL二氯甲烷-甲醇溶液（体积比4∶1）为萃取溶液,涡旋振荡萃取30 min,萃取液经无水硫酸镁除水后,以气相色谱－串联质谱法多反应监测（MRM）模式检测。结果显示：在优化条件下,烟碱及9种次要生物碱在25～1 000 μg/mL及0.002 5～20 μg/mL范围内呈良好的线性,相关系数（r2）不低于0.997,3个加标水平下的回收率为87.9%～109%,日内及日间精密度（RSD）分别不高于6.8%和7.9%,检出限（LOD）为0.0040～0.10 mg/kg,定量下限（LOQ）为0.013～0.33 mg/kg。用该方法测定23种品牌共计171种型号电子烟烟液中10种生物碱含量,结果发现,电子烟烟液中的烟碱含量为2.16～23.73 mg/g,9种次要生物碱的含量中位值为0.06～7.35 mg/kg,检出率为64.91%～99.42%,其中9种电子烟烟液样品的总次要生物碱含量与烟碱含量比例大于1.0%。该方法灵敏度高、准确性好、重复性好,完全满足电子烟烟液样品中10种生物碱的检测要求。     

气相色谱-质谱法同时测定烟用辅材中邻苯二甲酸酯与己二酸酯

提出了用气相色谱-质谱法同时测定烟用辅材中7种邻苯二甲酸酯类和4种己二酸酯类增塑剂的含量。样品用异丙醇-环己烷（3+2）溶液超声提取,通过DB-5MS色谱柱分离,采用选择离子监测模式进行测定。11种增塑剂的质量浓度均在0.012～1.2 mg·L^-1浓度范围内与其峰面积呈线性关系,方法的检出限（3S/N）在0.022～0.038μg·g^-1之间。以不同种类的烟用辅材样品为基体,在3个浓度水平下进行回收试验,方法的回收率在84.0%～112%之间,测定值的相对标准偏差（n=5）在3.2%～8.5%之间。     

10种有机酸对电子烟中陶瓷雾化芯的重金属迁移影响

为研究10种有机酸对电子烟中陶瓷雾化芯的重金属迁移影响,配制不同含量有机酸的电子烟烟液,采用电感耦合等离子体质谱法（ICP-MS）对陶瓷雾化芯在加速老化条件下迁移至烟液及气溶胶中的金属元素进行测定,评估重金属在该陶瓷芯中的雾化效率及有机酸的影响。结果表明：烟液、气溶胶方法中各元素的检出限分别均<10μg/kg、≤0.055μg/100口;不同类型和含量的有机酸对重金属的迁移影响不一,柠檬酸、乳酸、苹果酸、乙酸对金属元素的迁移影响相对较大。各元素在气溶胶中的雾化效率为21.2%～45.9%。与未添加有机酸的空白对照组相比,柠檬酸、乳酸、乙酸、苯甲酸、苹果酸对气溶胶中Ni含量提升有显著影响（P<0.05）,柠檬酸对气溶胶中Cu含量提升有显著影响,5种酸对其他元素无显著性差异（P>0.05）。该方法准确可靠,适用于评估电子烟烟液及气溶胶中有机酸对陶瓷芯的重金属迁移影响。     

差示火焰光度法测定硼酸盐中钾和钠

研究了火焰光度法测定硼酸盐中钾和钠含量的方法.分别在0～100 mg·L-1和0～200 mg·L-1的浓度范围内,采用差示测量法测定样品中钾和钠含量.考察了硼对钾、钠测定的影响以及钾、钠的相互影响.与四苯硼钠重量法(国家标准)相比,方法测定钾含量相对误差的绝对值≤3.91%,t检验和F检验也表明两种方法无显著性差异.与原子吸收光谱法相比,方法测定钾相对误差的绝对值≤3.63%.测定钠含量相对误差的绝对值≤3.76%,t检验和F检验表明两种方法无显著性差异.钾、钠的加标回收试验结果分别在97.5%～102.5%和97.1%～99.1%之间.     

碱熔-电感耦合等离子体原子发射光谱法测定废弃加氢脱硫(HDS)催化剂中的钒

本文建立了碱熔-电感耦合等离子体原子发射光谱法（ICP-OES）测定废弃加氢脱硫（HDS）催化剂中钒的方法,来协助加氢脱硫（HDS）催化剂回收实验的进行。试验采用过氧化钠熔解试样,用盐酸浸取后定容,稀释试液后控制盐酸酸度为10%,并选择钒292.401 nm为分析谱线。试验结果表明,为了消除基体效应的影响,需要使试液中钠元素、盐酸的含量和标准溶液中的钠元素、盐酸的含量相同。钒质量浓度在1.00-20.00 μg/mL时与发射强度呈线性关系,相关系数均为1。按照上述方法测定了5个废弃加氢脱硫（HDS）催化剂样品中的钒,并采用格拉布斯检验方法检验11次,测定结果无异常值,加标回收率为99%-101%。该方法有效解决了废弃加氢脱硫（HDS）催化剂中钒测定的难题,可用于测定钒质量分数为0.50%-10.00%的HDS催化剂,同时对其他产品中钒的测定提供一种新思路。     

电子烟烟液中烟碱旋光异构体的手性液相色谱分离及测定

建立了手性色谱柱-液相色谱-二极管阵列检测器(HPLC-DAD)法测定电子烟烟液中烟碱旋光异构体,即左旋烟碱(S-(-)-烟碱)和右旋烟碱(R-(+)-烟碱),对分析方法进行了优化和表征。结果表明:(1)最优的色谱条件为:采用大赛璐手性柱CHIRALPAK-IC,流动相为正己烷/异丙醇(体积比为95:5,含0. 1%二乙胺),流速1. 0 m L·min-1,等度洗脱。在优选条件下,电子烟烟液中左旋烟碱和右旋烟碱能实现基线分离,分析时间仅需18 min;(2)左旋烟碱和右旋烟碱分别在15～700μg·m L-1、0. 75～30μg·m L-1浓度范围内线性关系良好,二者检出限均为0. 02 mg·g-1。本方法左旋烟碱的日内、日间精密度分别为0. 73%、1. 67%,右旋烟碱的日内、日间精密度分别为4. 50%、8. 60%;二者回收率的结果在95. 50%～104. 5%之间;(3)选取不同口味、不同焦油量的电子烟烟液样品67个,对烟碱旋光异构体分别进行测定,结果表明电子烟烟液中主要为左旋烟碱,右旋烟碱检出率仅为12%,其含量占总烟碱的比例为0. 41%～4. 55%;(4)选取电子烟烟液样品20个,采用所建立的方法测定电子烟烟液和对应的电子烟气溶胶中左旋烟碱和右旋烟碱的含量,结果表明含有右旋烟碱的电子烟烟液所对应的电子烟气溶胶中未检出右旋烟碱。     

微量分析法用于火焰原子吸收光谱测定高含量钠

将微量分析方法与火焰原子吸收法结合用于测定高钠样品中的钠含量。通过选择合适的钠吸收谱线,确定了标准曲线和测定参数,建立了适合测定高钠样品的方法。方法的线性工作范围为0~5 mg/L,方法检出限为0.02 mg/L,RSD为0.5%。运用方法测试含钠有机物和无机钠盐中不同浓度的钠含量,结果表明,实际样品中钠含量的测定值与计算值间的绝对误差小于0.3%,相对误差小于1%,回收率99.2%~100.6%。     

水和氯化铵提取-电感耦合等离子体发射光谱(ICP-AES)法测定石灰性土壤中交换性钾钠钙镁

为了提高石灰性土壤中交换性钾钠钙镁的分析效率及分析准确度,本文创新性采用水和氯化铵对石灰性土壤进行处理,并采用振荡交换、离心分离的方式进行石灰盐清洗、钾钠钙镁离子交换提取,提取液直接在电感耦合等离子体发射光谱仪(ICP-AES)上测定。该方法交换性盐基钙、镁、钾、钠的检出限分别为0.01、0.009、0.004、0.012cmol/kg。用国家一级标准物质GBW07498-新疆棕漠土和新疆地区石灰性土壤进行验证,方法精密度均小于5%,回收率在97％~105%。方法适用于石灰性（碱性）土壤（特别是新疆土壤）样品中交换性钾、钠、钙、镁的分析测定。     

超高效液相色谱法测定食用菌中L-麦角硫因及质谱确证

建立了超高效液相色谱（UPLC）结合亲水相互作用色谱（HILIC）测定食用菌中L-麦角硫因含量的方法,并采用UPLC-四极杆串联飞行时间质谱（UPLC-Q-TOF-MS）进行确证。对食用菌样品前处理及色谱条件进行优化,样品经提取过膜后,采用HILIC-UPLC检测,外标法定量。结果显示,在不同食用菌样品中,加标回收率为80.0%～120.0%;日内、日间相对标准偏差（RSD）范围分别为0.4%～4.6%和1.7%～6.0%;采用科克伦和格拉布斯检验法,对7个不同实验室测定的4个相同食用菌样品数据的有效性进行检验,全部符合要求,计算得其重复性、再现性相对标准偏差范围分别为1.6%～2.4%和2.7%～7.5%。采用该方法对23个食用菌样品进行测定,其中牛肝菌中L-麦角硫因含量最高。方法可用于食用菌中L-麦角硫因含量的检测。     

应用搅拌棒吸附萃取-热脱附-气相色谱-质谱分析烟用香料的化学成分

应用搅拌棒吸附萃取法(SBSE)提取烟用香料的化学成分,并利用热脱附(TD)和色谱-质谱联用(GC-MS)进行分析。对影响萃取效果的因素(萃取时间和氯化钠的加入量)进行了考察,并采用正交试验法对影响热脱附的3个主要因素(脱附温度、脱附时间和冷阱温度)进行了优化,得到了较优的实验条件。对方法的重现性进行了考察,同一样品6次测定所得30个组分的峰面积的相对标准偏差（RSD）平均值小于10%,说明所建立方法的重现性较好。在样品中鉴别出酯类、酮类和醛类等30种不同化学组分,这些物质反映了该香料的香气特点。实验证明SBSE和TD适用于烟用香料的快速分析测定。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.