超高效液相色谱-串联质谱法测定乳制品中三聚氰胺的残留量

建立一种用超高效液相色谱-电喷雾质谱联用技术测定乳制品中三聚氰胺残留量的方法.样品经含5%乙酸铅的三氯乙酸溶液提取,离心分离后经PCX-C18混合填料固相萃取柱净化.色谱分离采用Agilent ZORBAX-CN柱(250 mm×4.6 mm i.d.,5 μm),以10 mmol/L V(乙酸铵)∶V(乙腈)＝10∶90混合溶液为流动相.采用电喷雾离子源,正离子多反应监测(MRM)模式检测.该方法在1～1000 ng/mL范围内线性关系良好.在添加水平为10,30,45 μg/kg时,回收率在78.5%～92.6%之间,相对标准偏差在3.5%～8.6%之间,检出限为10 μg/kg.该方法适合于乳制品中三聚氰胺残留量的检测.     

固相萃取-液相色谱-串联质谱法检测小鼠肌肉组织中矮壮素

建立了快速检测小鼠肌肉组织中矮壮素的固相萃取-液相色谱-串联质谱(SPE-LC-MS/MS)方法。小鼠肌肉样品经乙腈提取,弱阳离子交换(WCX)固相萃取柱净化,3 mL甲酸-甲醇(1∶99,V/V)重力洗脱。采用亲水作用色谱柱(HILIC),含10 mmol/L乙酸铵、0.1%甲酸水溶液-乙腈(40∶60,V/V)为流动相,以电喷雾正离子(ESI+)、多反应监测模式(MRM)进行矮壮素的定性分析,采用基质标准曲线外标法进行定量分析。结果表明:矮壮素的线性范围为5.0～500.0μg/L,线性相关系数为0.9991。在10.0,100.0和200.0μg/kg添加浓度下的回收率为73.2%～82.3%;相对标准偏差小于9.3%;方法定量限为10.0μg/kg,能够满足小鼠肌肉组织中痕量矮壮素检测的要求。     

液相色谱-串联质谱法同时测定红茶和绿茶中7种硫代氨基甲酸酯类除草剂

建立了红茶和绿茶中7种硫代氨基甲酸酯类除草剂(禾草敌、克草敌、灭草敌、野麦畏、禾草丹、茵草敌和丁草敌)的高效液相色谱-串联质谱(LC-MS/MS)检测方法.样品制备后,取2.0 g样品,加6 mL水浸润1 h.然后加入2.5 g NaCl,并用20 mL乙腈分两次进行提取,提取液吹氮浓缩后过HLB柱,并用3 mL乙腈洗脱.洗脱液浓缩后用2.0 mL正己烷-丙酮(7∶ 3,V/V)溶解残渣,然后过Envi-Carb固相萃取柱,再用5 mL正己烷-丙酮洗脱,洗脱液浓缩后用乙腈-水(5∶ 5,V/V)定容.采用LC-MS/MS电喷雾电离,多反应监测模式对样品进行分析.以D_3-甲萘威为内标,测定7种硫代氨基甲酸酯除草剂的线性范围为0～200 μg/L,线性相关系数在0.9954～0.9988范围内,检出限在0.093～1.77 μg/L范围内.在添加浓度5～20 μg/kg范围内,7种硫代氨基甲酸酯除草剂的回收率均在77.3%～91.5%,相对标准偏差(RSD)小于15%.本方法被成功用于红茶和绿茶样品中硫代氨基甲酸酯除草剂的测定.     

液相色谱-串联质谱法测定鸡组织中沃尼妙林残留

建立了鸡组织中沃尼妙林残留的液相色谱-电喷雾串联质谱(LC-ESI-MS /MS) 检测方法.样品用乙腈提取后,过Strata-X-C固相萃取小柱净化.以乙腈-0.1%甲酸水溶液(35∶ 65,V/V)为流动相,经Luna C18色谱柱分离,采用电喷雾电离,多反应监测(MRM)正离子模式对沃尼妙林进行定性与定量分析.采用基质匹配法,对鸡皮肤、肌肉、肾脏和肝脏中沃尼妙林的含量进行标准校正,在5(7.5)～500 μg/kg范围内线性良好(r>0 998),在鸡肝脏中的检出限(LOD)及定量限(LOQ)分别为4.0和7.5 μg/kg;其它3种组织中的LOD及LOQ分别为2.5和5.0 μg/kg.在5(7.5), 50及500 μg/kg添加水平下,4中组织中沃尼妙林的平均回收率为78 5%～104.0%.日内相对标准偏差(RSD)为1.2%～9.8%,日间相对标准偏差为3.7%～13.2%.     

高效液相色谱-电喷雾串联质谱法测定蜂蜜中5种头孢菌素

建立了用高效液相色谱-电喷雾串联质谱(LC-MS-MS)测定蜂蜜中5种头孢菌素残留量的方法.蜂蜜样品用磷酸盐缓冲溶液溶解,经Oasis HLB固相萃取柱净化.5种头孢菌素在C18柱上以乙腈-水为流动相梯度洗脱条件下完成分离,电喷雾电离串联质谱在正离子多反应监测模式下进行测定.添加浓度在2～100 μg/kg范围时,回收率为84.2%～103.6%; 相对标准偏差为3.89%～9.08%.本方法头孢唑啉的定量限为10 μg/kg, 头孢匹林、头孢氨苄、头孢洛宁、头孢喹肟的定量限为2.0 μg/kg.     

液相色谱-质谱联用技术测定无糖食品中果糖、葡萄糖、蔗糖、麦芽糖和乳糖

建立了无糖食品中葡萄糖、果糖、蔗糖、麦芽糖、乳糖的高效液相色谱-串联四极杆质谱联用测定方法.本方法以水提取样品,以Waters Carbohydrate Analysis柱(300 mm×3.9 mm, 10 μm)分离,流动相为水-乙腈(15∶ 85, V/V),电喷雾负离子MRM模式检测.方法的检出限为0.1 g/kg;线性范围为2.5～125.0 mg/L;加标回收率为86.2%～97.7%;相对标准偏差为3.1%～8.7%.     

固相萃取-高效液相色谱/串联质谱检测谷物中黄曲霉毒素B1、B2、G1、G2和M1

建立了高效液相色谱/串联质谱(LC-MS/MS)同时检测谷物中的黄曲霉毒素B1、B2、G1、G2和M1的方法.并优化了液相色谱条件和质谱的相关参数.谷物样品经研磨成粉末后,直接经甲醇-水( V∶V=10∶90)提取,Oasis HLB固相萃取净化,乙腈-水(0.2％甲酸)梯度洗脱,选择电喷雾离子源(ESI),正离子扫描...     

高效液相色谱-串联质谱法同时测定鸡蛋中头孢噻肟及其主要代谢物残留

建立了高效液相色谱-串联质谱(HPLC-MS/MS)法同时测定鸡蛋中头孢噻肟及其代谢物去乙酰头孢噻肟残留量的检测方法.样品经乙腈-水(9∶1, V/V)提取,正己烷除脂,C18固相分散萃取除杂,Agilent Eclipse Plus C18色谱柱(100 mm×2.1 mm, 3.5 μm)分离,以0.2%(V/V)甲酸-乙腈为流动相,进行梯度洗脱,目标物采用电喷雾正离子(ESI+)模式电离,多反应监测(MRM)模式检测,基质匹配标准溶液外标法定量.结果表明,头孢噻肟和去乙酰头孢噻肟分别在1.0~143.0 μg/L和1.0~120.0 μg/L浓度范围内线性关系良好(R.2>0.999).方法检出限(LOD, S/N=3)分别为0.07和0.14 μg/kg,定量限(LOQ, S/N=10)分别为0.23和0.99 μg/kg. 在5.0、50.0和100.0 μg/kg 3个添加水平下,头孢噻肟和去乙酰头孢噻肟的回收率分别为83.1%~103.0%和88.2%~101.0%,相对标准偏差(RSD, n=6)均介于2.0%~6.2%.实际样品测定结果表明,本方法简便、快速、灵敏、准确, 可用于鸡蛋中头孢噻肟及去乙酰头孢噻肟的残留分析检测.     

液相色谱-串联质谱法测定大鼠血浆中福斯克林

建立了测定大鼠血浆中福斯克林的液相色谱-串联质谱法(LC-MS/MS).血浆样品经液-液萃取后,以V(甲醇):V(10 mmol/L 醋酸铵):V(甲酸)=75:25:0.1为流动相,用Hypersil ODS柱分离,流速0.8 mL/min(柱后分流50%),通过电喷雾离子化四极杆串联质谱,以多反应监测方式(MRM)检测.用于定量分析的离子分别为m/z 428/375(福斯克林)和m/z 494/369(格列本脲,内标).福斯克林血浆浓度测定方法的线性范围为0.8～800 μg/L; 日内、日间精密度(RSD)均小于10%;准确度(RE)小于±9%.每个样品测试时间4.5 min.应用此法测试了大鼠口服或静注福斯克林后的血药浓度.     

硅胶固相萃取净化/高效液相色谱-串联质谱法测定海洋生物体中六溴环十二烷

建立了海洋生物体中六溴环十二烷(HBCDs)的硅胶固相萃取净化/液相色谱-串联质谱法。样品采用正己烷提取,经硅胶固相萃取柱净化,液相色谱-串联质谱分析。根据硅胶固相萃取柱的使用特性,对洗脱条件进行优化。在ACQUITY UPLC BEH C18色谱柱上进行分离,流动相为水和甲醇乙腈(V甲醇∶V乙腈=4∶6)混合溶液,梯度洗脱。质谱采用电喷雾负离子电离,多反应监测模式,内标法定量。六溴环十二烷在0.50~100.0μg/L范围内线性关系良好,相关系数(r2)大于0.995,定量下限为0.20μg/kg,回收率为85.6%~97.3%,相对标准偏差为3.9%~8.8%。该方法基质干扰小、重复性好,适用于海洋生物中六溴环十二烷的测定。     

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%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.