气相色谱/质谱测定水产品中氯霉素残留量

样品经均质后,用乙酸乙酯提取,正己烷脱脂,C18小柱净化,衍生后用GC ECD,NCI GC MS,NCI GC MSMS多种方法定性及定量测定,外标法定量。在0.1μg/kg水平,回收率为72%～110%,平行测定9次后相对标准偏差为16 5%。质量浓度在0～10μg/L范围内呈良好线性关系,相关系数r=0.9997。     

气相-质谱法测定粮谷中恶草酮的残留量

 应用微量化学法和固相萃取技术 ,建立了粮谷中恶草酮残留量的气相 质谱 (GC MS)测定方法。用苯 正己烷 (体积比为 1∶1)萃取 ,中性氧化铝小柱净化。净化液用GC MS测定 ,采用外标法定量。恶草酮在大米中的回收率为 90 4%～ 115 .7% ,RSD为 2 %～ 6 % ,在玉米中的回收率为 81 3%～ 10 9 7% ,RSD为 4%～ 9% ,最低定量检出限为 0 0 0 5mg/kg。该法快速、灵敏、准确 ,各项技术指标均满足农药残留检测的要求。     

反相高效液相色谱／质谱法同时测定鸡肉中5种喹诺酮药物残留

采用反相高效液相色谱／四级杆串联质谱（RP-HPLC／MS／MS）同时测定鸡肉中的5种喹诺酮药物（quinolones，QNs）。均质后的鸡肉样品采用磷酸盐缓冲溶液和乙腈的混和溶液提取。提取液经正己烷液-液分配（LLP）去除脂肪后，用C18固相萃取（SPE）柱净化，氨化甲醇洗脱，洗脱液用氮气吹干，流动相定容后，分析物采用LC／MS／MS电喷雾电离（ESI），正离子，多反应监测（MRM）模式检测，外标法定量。在添加浓度2．5～10μg/kg范围内，5种QNs的回收率在79．8％～95．1％之间；相对标准偏差（RSD）均小于11．7％。环丙沙星、丹诺沙星、恩诺沙星检出限（LOD）为0．5μg／kg，沙托沙星为1．0μg／kg，氟甲喹为0．1μg／kg。     

分散液液微萃取-气相色谱/质谱法测定中药甘草中邻苯二甲酸酯残留

建立了一种简单、快速、有效测定中药甘草中5种邻苯二甲酸酯(DBP、BBP、DCHP、DEHP、DNOP)的分散液液微萃取-气相色谱/质谱(DLLME-GC/MS)检测方法。甘草样品经甲醇浸泡提取,水分散和盐析后用100μL四氯化碳萃取浓缩,采用GC/MS法测定,标准曲线定量。5种目标物在1~5 000μg/L范围内呈良好的线性关系,相关系数均大于0.9990,方法的检出限和定量限在0.16~0.58μg/kg和0.34~1.92μg/kg范围。在3个加标浓度水平下的平均回收率为87.80%~120.63%,相对标准偏差小于7.43%。该方法适用于不同产地中药材甘草中环境激素邻苯二甲酸酯类残留的测定。     

液相色谱-串联质谱法测定水产品中亮绿、亚甲基蓝及其代谢物残留量

建立了水产品中亮绿、亚甲基蓝及其代谢物残留量同时测定的液相色谱-串联质谱(LC-MS/MS)方法。样品经乙酸铵缓冲溶液和乙腈提取,二氯甲烷液液萃取,PRS固相萃取柱净化,氮吹浓缩,定容后测定。以2 mmol/L乙酸铵(含0. 1%甲酸)、乙腈和甲醇为流动相,CAPCELL PAK C_(18)色谱柱进行分离,在选择反应监测(SRM)模式下测定,外标法定量。在最佳实验条件下,5种化合物在1. 0～100. 0μg/L范围内线性关系良好(r~2 0. 999),检出限(LOD,S/N≥3)均为1. 0μg/kg,定量下限(LOQ,S/N≥10)均为2. 0μg/kg;在水产品中加标水平为1. 0、5. 0、10. 0μg/kg时,回收率为70. 3%～92. 1%,相对标准偏差(RSD,n=6)为2. 3%～13%。该方法灵敏度高,能有效检测水产品中亮绿、亚甲基蓝及其代谢物的残留量。     

固相萃取-气相色谱/质谱法测定人参种植土壤中48种农药残留

采用固相萃取方法,结合气相色谱-质谱(GC/MS)建立了同时检测人参种植土壤中48种农药残留的分析方法。研究了萃取剂、固相萃取柱、洗脱剂种类和用量对样品提取及净化效果的影响,并考察了共萃取基质和基质效应,质谱采用选择离子监测(SIM)模式,外标法定量。结果表明,48种农药在各自的线性范围内,线性关系良好(r~20.995);在3个添加水平(10、20、100μg/kg)的回收率为86.3%～128.8%,相对标准偏差(RSD,n=6)为1.5%～14.6%。48种农药的检出限为2.0～6.0μg/kg,定量限为5.0～20.0μg/kg。该方法样品前处理简单、高效,测定的准确性好、灵敏度高,适用于人参种植土壤中多种类农药残留的筛选与测定。     

QuEChERS/超高效液相色谱-串联质谱法快速测定土壤中19种氟喹诺酮类抗生素残留

建立了一种基于QuEChERS前处理技术,结合超高效液相色谱-串联质谱(UPLC-MS/MS)和内标法,快速测定土壤中19种氟喹诺酮类抗生素(FQs)残留的分析方法。5. 0 g土壤样品添加200μg/kg基质匹配同位素内标后,经20 m L 0. 1 mol/L EDTA-McIlvaine缓冲液和乙腈混合溶剂(体积比1∶1)提取,基质分散固相萃取(150 mg无水MgSO4、15 mg PSA、15 mg C18)净化后,采用UPLC-MS/MS进行测定。质谱分析采用电喷雾电离,正离子扫描,多反应监测模式。在优化条件下,19种抗生素的相关系数(r~2)为0. 992～0. 998,检出限为0. 2～1. 0μg/kg,定量下限为1. 0～5. 0μg/kg;在10、50、200μg/kg加标水平下的回收率为65. 2%～104%,相对标准偏差(n=5)不大于14%。该方法操作简单快速、准确度高,适用于土壤中氟喹诺酮类抗生素残留的检测。     

分散液液微萃取/超高效液相色谱-四极杆/静电场轨道阱质谱法快速筛查化妆水中139种药物残留

建立了分散液液微萃取(DLLME)结合超高效液相色谱-四极杆/静电场轨道阱质谱(UPLC-Q Exac-tive Orbitrap MS)同时测定化妆水中抗生素、激素、禁用染料、农药以及真菌毒素5大类共139种药物残留的分析方法。考察了DLLME各条件对萃取效果的影响,确定最佳萃取条件为：取样量5.0 g,萃取剂为四氯乙烷(50μL)、分散剂为乙腈(300μL)、氯化钠用量为0.30 g、超声时间为8 min。样品经萃取后,采用岛津Shimpack XR-ODS II(150 mm×2.0 mm,2.2μm)色谱柱分离,通过Q-Exactive Orbitrap MS以全扫描确定母离子精确质量数的离子丰度,实现多种类目标物的定量,结合保留时间和子离子数据依赖模式扫描(DD-MS2)确定子离子的精确质量数,并配合谱库检索进行快速确证与筛查。结果表明：139种化合物的质量浓度在10～1 000 ng/m L范围内与峰强度呈良好线性关系(r> 0.99),检出限为10～30μg/kg,回收率为63.0%～95.9%,相对标准偏差(RSD)为3.0%～9.5%;各精确质量数偏差小于3×1...     

活性炭固相微萃取-气质联用对海水中痕量-丁基三氯锡的测定

利用自制的活性炭纤维结合固相微萃取-气质联用技术（ACF—SPME／GC～MS）分析了水相中的一丁基三氯锡（MBT,monobutyltin trichloride）。对实验影响因素如萃取温度、离子强度、萃取时间进行了研究。结果表明,该方法的线性范围为0．1～100μg/L,检出限为4．5ng/L,相对标准偏差为8．6％。将ACF—SPME／GC—MS技术用于实际海水样品的分析,取得了理想的效果。     

加速溶剂萃取-QuEChERS/超高效液相色谱-串联质谱法同时测定药食同源性食品中双酚类化合物

建立了加速溶剂萃取(ASE)-QuEChERS/超高效液相色谱-串联质谱(UPLC-MS/MS)同时测定药食同源性食品中11种双酚类化合物残留的分析方法。样品经ASE萃取,萃取溶剂为乙腈-乙酸-水(89∶1∶10,体积比),萃取温度为80℃,静态萃取时间为6 min,循环2次。萃取液经QuEChERS法净化,采用ACQUITY UPLC HSS T3色谱柱(2.1 mm×100 mm,1.8μm)分离,以甲醇(含0.1%甲酸)和5 mmol/L乙酸铵水溶液(含0.1%甲酸)为流动相进行梯度洗脱,电喷雾电离源正、负模式下同时进行多反应监测(MRM)测定,同位素内标法定量。11种双酚类化合物在0.5～50.0μg/L范围内呈良好线性,相关系数(r~2)不小于0.996 0,检出限为0.1～0.5μg/kg,定量下限为0.3～1.5μg/kg;3个加标水平的回收率为72.4%～108%,相对标准偏差(RSD)为1.7%～15%。该方法操作简单、快速、灵敏度高、重现性好,适用于药食同源性食品中双酚类化合物的同时快速测定。     

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%.     

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.     

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.     

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%).     

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.     

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.