固相萃取-高效液相色谱-串联质谱法测定葡萄干中105种农药残留

建立了固相萃取前处理-高效液相色谱-串联质谱(HPLC-MS/MS)法测定葡萄干中105种农药残留的分析方法。样品以乙腈提取,采用TPH固相萃取小柱净化。待测物经Zorbax Eclipse Plus C18柱(3.0 mm×100 mm,1.8μm)分离,以乙腈-0.1%甲酸水为流动相梯度洗脱;采用电喷雾正离子源(ESI+)、多重反应监测(MRM)模式检测;以基质匹配标准曲线外标法定量。105种农药在各自线性范围内相关系数均大于0.991;检出限(S/N≥3)为0.03~3.0μg/kg;定量限(S/N≥10)为0.1~10.0μg/kg;3个加标水平(1,2,10倍定量限)下,回收率在67.3%~117.8%之间,相对标准偏差在3.9%~20%之间。适用于葡萄干样品中农药残留的日常检测。     

加速溶剂萃取-固相萃取净化-气相色谱-串联质谱法检测茶叶中9种拟除虫菊酯类农药残留

建立了加速溶剂萃取（ASE）-固相萃取净化（SPE）-气相色谱-串联质谱（GC-MS/MS）同时测定茶叶中9种拟除虫菊酯类农药残留的方法。ASE萃取溶剂为丙酮-正己烷（1：1,v/v）,萃取温度为100℃,萃取压力为10 MPa,加热时间为3 min,静态萃取时间为5 min,循环1次,冲洗体积为40%萃取池体积,氮气吹扫100 s。萃取结束后用Cleanert TPT固相萃取柱净化,净化液浓缩定容后,采用GC-MS/MS测定,外标法定量。9种拟除虫菊酯类农药在2~1000 μg/L范围内呈现良好的线性关系,相关系数（r²）均大于0.99,方法检出限为0.2~4.5 μg/kg,定量限为0.8~15.0 μg/kg。在绿茶、红茶空白基质中做加标回收试验,添加水平为0.02、0.1、0.4 mg/kg以及定量限水平,得到的平均回收率为69.87%~110.0%,相对标准偏差（RSD）为0.7%~11.2%。该方法背景干扰低、灵敏度高、重现性好、回收率稳定,适用于茶叶中拟除虫菊酯类农药残留量的检测。     

QuEChERS-凝胶渗透色谱/气相色谱-质谱法同时测定降尘中18种有机氯农药

建立了在线凝胶渗透色谱/气相色谱-质谱(GPC/GC-MS)测定大气降尘中18种有机氯农药残留的分析方法。样品经过简化QuEChERS方法处理后,经乙腈萃取,石墨化炭黑(GCB)净化,一步离心后过膜上机检测。采用该方法能在30 min内处理8~10个样品,配合GPC净化,不仅缩短了分析时间,而且提高了工作效率和结果的准确性。检测结果表明,18种有机氯农药在0.025~2.0 mg/L质量浓度范围内线性关系良好,相关系数为0.991 9~0.999 6,样品检出限为3.2~14.6μg/kg,定量下限为10.7~48.7μg/kg。在0.2、1.0 mg/kg 2个加标水平下,18种有机氯农药的平均回收率为78.6%~117.3%,相对标准偏差(RSD,n=5)为1.3%~5.1%。     

全自动凝胶净化-浓缩-固相萃取/气相色谱-质谱法测定紫皮石斛中有机磷农药残留

建立了以凝胶渗透色谱(GPC)和固相萃取(SPE)净化、气相色谱-质谱(GC-MS)法同时测定紫皮石斛中10种有机磷农药残留的方法。样品用乙腈超声提取,提取液经GPC去除类脂杂质和大分子物质,后经Envi-Carb/NH2固相萃取柱净化,选择离子(SIM)监测模式检测,外标法定量。在26min内10种农药得到很好的分离,农药残留量在0.02~0.5μg/mL,方法的线性良好,相关系数为0.997 3~0.999 9,农药加标浓度为0.05mg/kg和0.2mg/kg时,加标回收率在70.4%~115.8%,相对标准偏差在2.8%~9.6%,满足国家标准要求,检出限为0.005 2~0.011mg/kg。方法简便、快速、灵敏、准确,能够运用于石斛中多组分有机磷农药残留的定性和定量分析。     

分散固相萃取-气相色谱法测定对虾中12种有机磷农药残留

建立了分散固相萃取-气相色谱测定对虾中12种有机磷农药残留的分析方法。样品经V(冰乙酸):V(乙腈)=1:99溶液提取,采用乙二胺-N-丙基硅烷(PSA)、C18与石墨炭黑(GCB)为吸附剂进行分散固相萃取净化。以DB-17毛细管色谱柱分离,GC-FPD(P)检测。方法在0.01~0.50μg/mL范围内线性关系良好,相关系数(r2)均不低于0.9971,12种有机磷农药的方法检出限均为0.01 mg/kg。在0.01~0.10 mg/kg的添加水平下,平均加标回收率为80.7%~101.2%,相对标准偏差为3.7%~7.6%。     

气相色谱-质谱法测定蔬菜和水果中193种农药的残留量

在系统优化固相萃取吸附剂填料类型、洗脱溶剂种类及体积的基础上,建立了蔬菜和水果中193种农药残留的气相色谱-质谱(GC-MS)检测方法。样品经乙腈均质提取,C₁₈/PSA固相萃取柱净化,乙腈洗脱,GC-MS选择离子监测(SIM)模式检测,以磷酸三苯酯内标法定量。结果表明,130种农药在10~1000 μg/L、34种农药在20~1000 μg/L、26种农药在50~1000 μg/L、3种农药在100~1000 μg/L范围内线性关系良好,相关系数为0.9967~1.0000,方法检出限(以信噪比为3计)为0.04~8.26 μg/kg,添加回收率为71.6%~117.9%,相对标准偏差为3.0%~11.8%。该方法样品处理简单快速,相比其他多残留分析方法净化效果好,其灵敏度和选择性明显提高,适用于日常检测工作。     

分散固相萃取-超高效液相色谱-串联质谱法测定生脉饮及其原料药中19种农药残留

建立了同时测定中成药生脉饮及其原料药(麦冬和党参)中19种农药的分散固相萃取-超高效液相色谱-串联质谱(DSPE-UPLC-MS/MS)的分析方法。样品以0.1%的乙酸乙腈提取,Na Cl和无水Mg SO4盐析后,提取液经含有N-丙基乙二胺(PSA)、石墨化炭黑(GCB)、C18和无水Mg SO4填料的净化管分散净化,利用UPLC-MS/MS在多反应监测模式(MRM)下进行确证和测定,外标法定量。19种农药含量在1~100μg/kg范围内线性关系良好,相关系数均大于0.9917。在1,5,10μg/kg 3个浓度添加水平下的回收率范围为80.1%~107.1%,相对标准偏差(RSD)为2.9%~19%,检出限为0.0040~0.38μg/kg,定量限为0.013~0.96μg/kg。方法满足生脉饮及其原料药中农药残留的分析检测要求。     

固相萃取-高效液相色谱-串联质谱法测定坚果中62种农药残留

建立了固相萃取-高效液相色谱-串联质谱(SPE-HPLC-MS/MS)法测定坚果中62种农药残留的分析方法。样品以乙腈提取,经正己烷脱脂后,采用TPH固相萃取小柱净化。待测物经Zorbax Eclipse Plus C18柱(100×3.0mm,1.8μm)分离,以乙腈-0.1%甲酸为流动相,梯度洗脱;采用电喷雾正离子源、多重反应监测模式检测;以保留时间和特征离子对(母离子和两个碎片离子)信息比较进行定性和定量分析。62种农药在各自线性范围内相关系数均大于0.993;在核桃、杏仁、花生仁三种基质中方法的定量限(以S/N≥10计)为0.1~10.0μg/kg,1、2、4倍定量限3个加标水平下,回收率为71.2%~112.7%,相对标准偏差为5.8%~14.1%。该方法灵敏度高、重复性好,检出限能够满足国内外对农药残留的最高限量要求,适合于坚果中农药残留的测定。     

气相色谱-三重四极杆串联质谱结合QuEChERS测定三七中有机磷农药残留

建立了改良的QuEChERS样品前处理法,结合气相色谱-三重四极杆串联质谱(GC-MS/MS)同时测定三七中18种有机磷农药残留的方法。样品经1%乙酸-乙腈提取,改良QuEChERS技术净化,利用GC-MS/MS采取多反应离子监测模式测定,基质匹配校准曲线外标法定量。18种有机磷农药残留在2.5~120.0μg/kg范围内线性良好,相关系数(R2)大于0.99;检出限为0.4~1.5μg/kg,定量限为0.8~2.5μg/kg。在3个加标水平(2.5,8.0,60.0μg/kg)下平均回收率为70.5%~118.9%,相对标准偏差为1.0%~9.8%。     

超高效液相色谱-质谱联用法测定蔬菜中多杀霉素等4种农药残留

采用固相萃取/超高效液相色谱-串联质谱(SPE/UPLC-MS/MS)建立了多种蔬菜中4种农药残留量的分析方法,并对净化方法、色谱及质谱条件进行优化。蔬菜样品经乙腈提取、提取液经盐析后,取上清液经PC/NH2(或NH2)固相萃取小柱净化,浓缩后,用甲醇定容并过膜,采用超高效液相色谱-串联质谱多反应监测(MRM)正离子模式进行外标法定量测定。结果表明,4种农药在5~500μg/L范围内线性关系良好(r≥0.999 2),在8种蔬菜中的检出限和定量下限分别为0.033~0.167μg/kg和0.10~0.50μg/kg。在10,50,250μg/kg 3个浓度加标水平下,4种农药的回收率为70.9%~123.4%,相对标准偏差(RSD)小于15%。方法准确、灵敏、简单、快速,适用于多种蔬菜中多杀霉素等4种农药残留的同时测定。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.