表面活性剂辅助-凝固-漂浮分散液液微萃取/高效液相色谱法测定环境水样中酚类化合物

建立了表面活性剂辅助-凝固-漂浮分散液液微萃取(SA-DLLME-SFO)/高效液相色谱法同时测定环境水样中4种酚类化合物的分析方法。SA-DLLME-SFO实验中选用十二醇为萃取剂,Tween 20为分散剂,考察了萃取剂和非离子表面活性剂的体积、萃取时间、离心时间和盐效应等因素对萃取效率的影响。结果表明:对硝基苯酚、对甲酚、对溴酚和双酚A的检出限分别为0.13,0.13,1.02,0.25 ng/m L;对硝基苯酚、对甲酚和双酚A的线性范围为2~4 000 ng/m L,对溴苯酚的线性范围为10~4 000 ng/m L;加标浓度为0.2,0.8μg/m L时,4种酚类化合物的回收率为96.6%~105%,相对标准偏差(RSD,n=5)为1.9%~4.9%。该方法可用于池塘水和湖水等天然水体中对硝基苯酚、对甲酚、对溴酚和双酚A的测定。     

离子液体液-液萃取-高效液相色谱测定水中酚类化合物

建立了离子液体1-丁基-3-甲基咪唑六氟磷酸盐([C4mim][PF6])液-液萃取-高效液相色谱测定水中酚类化合物的方法.研究了水相pH值、萃取时间、水相体积及盐的浓度对萃取的影响.最佳萃取条件分别为:水相pH值为5,萃取时间为40 min,水相体积为60 mL.对比了离子液体对1-辛醇对苯酚、4-硝基苯酚、2-硝基苯酚、2,4-二甲基苯酚和双酚A的富集效率.在最佳条件下,离子液体对5种酚的富集倍率在9～151之间,方法对苯酚、4-硝基苯酚、2-硝基苯酚、2,4-二甲基苯酚和双酚A的检出限分别为:2.0、0.9、0.3、1.8和1.1 μg/L.将该方法应用于自来水、河水、湖水和污水的检测,回收率为87.9%～109.9%.     

液-液萃取气相色谱法测定地表水中痕量苯酚

建立了液-液萃取气相色谱法测定地表水中痕量苯酚的方法。用盐酸调节水样至pH2左右,以二氯乙烷-乙酸乙酯(体积比为2∶1)混合溶液为萃取剂,以CD-5色谱柱进行分离,氢火焰离子化检测器检测苯酚的含量。苯酚的质量浓度在1.00~20.0μg/L范围内与其色谱峰面积呈良好的线性关系,线性相关系数r=0.999 3,检出限为0.03μg/L。样品加标回收率为93.0%~97.0%,测定结果的相对标准偏差小于2%(n=7)。该方法检出限低,精密度和准确度高,操作简便,适用于地表水中微量苯酚的分析。     

基于碳纳米管的固相萃取-分散液液微萃取测定水中多种痕量环境雌激素

建立了基于碳纳米管的固相萃取-分散液液微萃取/ 上浮溶剂固化-高效液相色谱/荧光法测定水体中痕量雌激素雌三醇(E3)、 双酚A(BPA)、 17α-乙炔基雌二醇(EE2)及17β-雌二醇(E2)的方法. 利用中心复合实验设计分别对固相萃取和分散液液微萃取条件进行了优化, 通过响应曲面法得到的最佳萃取条件为碳纳米管用量30 mg, 水样体积210 mL, 流速2.0 mL/min, 萃取剂(十二醇)体积50 μL, 分散剂(甲醇)体积0.2 mL以及不添加盐. 在优化的实验条件下, E3, BPA, EE2和E2测定的线性范围分别为0.05~100, 0.05~100, 0.05~50和0.05~50 μg/L, 相关系数为0.9993~0.9999, 检出限分别为48.4, 3.3, 8.1和6.0 ng/L. 对不同加标浓度(0.40和4.00 μg/L)的实验室自来水、 排水沟污水及市售矿泉水3种实际水样进行了分析: E3, BPA, EE2和E2的加标回收率依次为107.5%~120.8%, 92.5%~108.3%, 103.5%~121.0%和102.5%~132.5%, 相对偏差分别为2.47%~13.28%, 1.73%~11.94%, 1.72%~8.36%和3.54%~11.95%, 富集因子平均值分别为461, 1075, 2074和949. 实际水样分析结果表明, 本方法可用于不同基质水样中雌激素的测定. 与其它方法相比, 本方法虽然固相萃取时间长及水样量大, 但检出限低、 富集因子高、 操作简便及费用低, 仍可作为一种可普及的水中痕量雌激素检测方法.     

基于低共熔溶剂的分散液液微萃取/超高效液相色谱-串联质谱法测定马肉中非甾体抗炎药

采用氯化胆碱和苯酚合成低共熔溶剂(DES),以其为萃取剂建立了分散液液微萃取(DLLME)结合超高效液相色谱-串联质谱(UPLC-MS/MS)测定马肉中10种非甾体抗炎药的方法。优化了提取溶剂、萃取剂、分散剂和盐的加入量等条件,最佳萃取条件为：以氯化胆碱和苯酚(比例为1∶2)合成的低共熔溶剂为萃取剂,马肉样品经5 mL含10 mmol/L抗坏血酸的20 mmol/L醋酸铵缓冲液(乙酸调至pH 3.5)提取,加入1.0 g氯化钠、0.8 mL萃取剂和0.8 mL分散剂,旋涡混合1 min,离心后取上清液经超高效液相色谱-串联质谱测定,外标法定量。结果显示,10种非甾体抗炎药在各自质量浓度范围内呈良好线性关系,相关系数(r2)均大于0.996,检出限为0.05~2.0 μg/kg,定量下限为0.10~5.0 μg/kg,平均回收率为73.5%~94.6%,相对标准偏差(RSD)为1.1%~8.1%。该方法操作简单、准确高效、绿色环保,可用于马肉中非甾体抗炎药的测定。     

分散固相萃取-分散液液微萃取/气相色谱-串联质谱法测定蔬菜中19种有机磷农药残留

采用分散固相萃取和分散液液微萃取联用方法,建立了气相色谱-串联质谱法(GC-MS/MS)同时测定蔬菜中19种有机磷农药残留量的分析方法。分散固相萃取方法以乙腈为萃取液,以N-丙基-乙二胺(PSA)和C18为吸附剂。对影响分散液液微萃取效率的因素(萃取溶剂种类及体积、分散剂体积等)进行优化,同时分析了实验过程中添加掩蔽试剂L-古洛糖酸γ-内酯(AP)对基质效应补偿作用的影响。在最佳实验条件下,19种有机磷在辣椒和大葱中3个添加水平(0.05,0.1,0.5 mg/kg)的回收率为76.9%~126.8%,相对标准偏差为0.6%~7.3%,检出限(S/N=3)为0.10~0.50μg/kg。该方法简单、高效、重现性好、富集倍数高,可用于蔬菜中有机磷农药的快速检测。     

固相萃取-高效液相色谱-串联质谱法测定香蕉中咪鲜胺及2,4,6-三氯苯酚残留量

提出了固相萃取-高效液相色谱-串联质谱法测定香蕉中咪鲜胺及2,4,6-三氯苯酚残留量的方法。香蕉样品经乙酸-乙腈(2+98)混合液提取,用基质分散固相萃取净化。以Agilent Eclipse AAA色谱柱为分离柱对所得净化液进行分离,以不同体积比的水和乙腈混合液为流动相进行梯度洗脱,采用电喷雾正、负离子源多反应监测模式检测。咪鲜胺和2,4,6-三氯苯酚的线性范围分别为0.05~100mg·L-1和2.5~200mg·L-1,检出限(3S/N)分别为0.02,1.5μg·kg-1。以空白样品为基体进行加标回收试验,测得咪鲜胺和2,4,6-三氯苯酚的回收率分别在90.3%~106%和85.5%~101%之间,相对标准偏差(n=6)分别在3.3%~8.5%和3.6%~9.6%之间。     

分散固相萃取-分散液液微萃取/高效液相色谱法测定西瓜中氟唑菌酰羟胺残留

采用分散固相萃取和分散液液微萃取联用的方法,建立了高效液相色谱快速检测西瓜中氟唑菌酰羟胺残留的分析方法。使用乙腈和水混合溶液作为萃取溶剂,经N-丙基-乙二胺硅烷(PSA)固相萃取吸附剂净化提取液,分散液液微萃取将目标物富集到1,1,2,2-四氯乙烷溶剂中,采用高效液相色谱进行分析。考察了萃取溶剂的种类与体积、分散剂体积及盐浓度等因素对分散液液微萃取萃取效率的影响。结果表明:分析物的质量浓度在0.01~5 mg/L范围内与峰面积的线性关系良好,相关系数(r)为0.999 9,定量下限(S/N=10)为0.01 mg/kg。加标水平为0.01、0.1、1 mg/kg时,平均回收率为89.2%~94.5%,相对标准偏差(n=5)为3.0%~8.7%。该方法简单、高效、灵敏度高,适用于西瓜中氟唑菌酰羟胺的残留检测。     

液-液-液三相液相微萃取-高效液相色谱法检测尿样中的安非他明和氯胺酮

建立了液-液-液三相液相微萃取与高效液相色谱联用技术测定尿样中的安非他明和氯胺酮的方法。考察了萃取溶剂、料液相pH值、搅拌速度、萃取时间和接受相HCl浓度等因素对富集因子的影响,得到了萃取溶剂为300 μL甲苯,料液相pH值为11,接受相为1.0 μL 0.1 mol/L HCl,搅拌速度为600 r/min,萃取时间为50 min的最佳实验条件。在该条件下,获得了较高的富集因子;方法的线性范围为安非他明0.01～10 μg/mL,氯胺酮0.01～5 μg/mL,相对标准偏差均小于2%,检测限均为5 ng/mL (S/N=3)。建立的三相液相微萃取方法能有效地去除复杂基体的干扰,有机溶剂消耗少,萃取效率高,是一种有效、灵敏的样品前处理方法,适合于尿样中安非他明和氯胺酮的测定。     

分散液-液微萃取-气相色谱-质谱法同时测定中毒样品中有毒生物碱和鼠药

建立了分散液-液微萃取(Dispersive liquid-liquid micro-extraction,DLLME)与气相色谱-质谱(GCMS)联用同时测定中毒样品中3种鼠药(毒鼠强、溴鼠灵、溴敌隆)和5种有毒生物碱(莨菪碱、东莨菪碱碱、钩吻碱、士的宁、马钱子碱)的方法。100μL萃取剂氯仿与600μL分散剂甲醇混合后,迅速注入样品,萃取过程在乳化体系中完成;以8000 r/min离心5 min,使两相分层,取下层有机相进行GC-MS分析。考察了萃取剂、分散剂的种类和体积、萃取时间、pH值及盐浓度对萃取效率的影响。在优化条件下,各目标物在水样、尿样、黄酒样的检出限为0.003~1.0μg/L,在米饭样品检出限为0.002~0.2μg/kg;各目标物低、中、高加标回收率为81.0%~110%,精密度均小于7%。本方法灵敏度高,快捷高效,适用于中毒样品中有毒生物碱和鼠药的同时测定。     

固-液金属界面上金属间化合物的非平衡生长

钎焊过程是一些液态的低熔点金属合金（钎料）与过渡金属（引线）在钎焊温度下相互作用,冷却后形成电路接头的过程[1],其间,金属间化合物生长和存在的特征,极大地影响钎焊接头的强度,抗蠕变性,抗腐蚀性和可焊性,本文拟以纯液态金属与固体金属的快速反应来观察金属间化合物的生长,从而阐述钎焊过程的特征。     

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.