液相色谱-串联质谱法与气相色谱-串联质谱法测定茶叶中苦参碱残留量

建立了茶叶中苦参碱残留检测的两种前处理方法,比较了液相色谱-串联质谱(LC-MS/MS)与气相色谱-串联质谱(GC-MS/MS)检测茶叶中苦参碱残留量分析方法的适用性。结果表明,在添加标准样品10~100μg/kg 3个水平时,两种前处理方法的回收率和精密度无显著差别;GC-MS/MS和LC-MS/MS回收率分别为81%~85%、82%~86%,相对标准偏差(RSD)分别为4.6%~11.5%和2.9%~4.2%。结果表明两种样品前处理方法以及LC-MS/MS与GC-MS/MS检测均能满足茶叶中苦参碱残留量的测定,但采用前处理方法二,LC-MS/MS检测茶叶中苦参碱残留更具优势。     

SPME/GC-MS鉴别地沟油新方法

采用固相微萃取(SPME)气相色谱-质谱联用(GC-MS)技术,研究了油脂内源及外源物质的微量化学成分。结果发现:纯正花生油和大豆油不含反式脂肪酸,地沟油含有反式脂肪酸trans-C18∶1、trans-C18∶2;纯正花生油和大豆油中含有正己醛、正壬醛和正癸醛等杂质,而地沟油中除了这几种醛类外还含有乙酸、3-丁烯腈、2,5-二甲基吡嗪等特征杂质成分。通过测定内源性物质和外源性物质的存在,两种检测结果互相印证,综合判断,最终可确定是否为地沟油,据此首次建立了SPME/GC-MS鉴别地沟油的新方法。该方法不但可用于地沟油的鉴别,还可用于掺假食用油的检测。     

色谱-串联质谱法测定天麻中53种禁用农药残留

建立超高效液相色谱-串联质谱联用（UPLC-MS/MS）及气相色谱-串联质谱联用（GC-MS/MS）法测定天麻中53种禁用农药残留。采用乙腈直接提取和基于QuEChERS原则的固相萃取法对样品进行处理。UPLC-MS/MS法采用电喷雾离子源，正离子模式下多反应监测，色谱峰面积外标法定量；GC-MS/MS法采用电子轰击离子源，色谱峰面积内标法定量。53种农药的质量浓度在一定范围内与响应值线性关系良好，相关系数均大于0.990，检出限为0.001～0.005 mg/kg，定量限为0.002～0.01 mg/kg。样品平均回收率为71.4%～118.2%，测定结果的相对标准偏差为1.4%～6.3%(n=6)。该方法能快速、有效地检测天麻中的禁用农药残留量，可用于天麻质量评价。     

3种方法测定植物源性农产品中霉灵残留量

建立了测定大豆、糙米、黄瓜、甜菜等6种植物源性农产品中(噁)霉灵残留的气相色谱-火焰光度法(GC-FPD)、气相色谱-氮磷检测法(GC-NPD)和液相色谱-串联质谱法(LC-MS/MS).GC-FPD法采用丙酮-正己烷提取样品,O,O-二甲基硫代磷酰氯衍生,GC-FPD分析,外标法定量;GC-NPD法采用丙酮-正己烷提取样品,十八烷基键合硅胶(C18)净化,GC-NPD分析,外标法定量;LC-MS/MS法,样品采用乙腈提取,石墨化碳黑(GCB)净化,LC-MS/MS分析,基质匹配外标法定量.结果表明,(噁)霉灵的响应值与其浓度间呈良好的线性关系,3种方法的相关系数均大于0.998.在3个加标浓度下,GC-FPD法中(噁)霉灵的日间平均回收率为82%~96%,日间相对标准偏差(RSD)为3.4%~12.1%,方法的定量下限为0.25 mg/kg (甜菜为0.05 mg/kg);GC-NPD法的日间平均回收率为81%~103%,日间RSD为4.1%~14.3%,定量下限为0.25 mg/kg (甜菜为0.05 mg/kg);LC-MS/MS法的日间平均回收率为74%~110%,日间RSD为2.5%~10.7%,定量下限为0.05 mg/kg.3种方法均具有良好的准确性和稳定性,可满足(噁)霉灵残留分析的要求.     

气相色谱-负化学离子源质谱法同时检测蔬菜中103种农药残留

本文比较了负化学电离(NCI)和电子轰击电离(EI)两种电离方式下采用气相色谱-质谱(GC-MS)同时检测103种农药的灵敏度,发现在NCI方式下103个化合物信噪比分别提高1.2~447.0倍。将GC-NCI/MS方法应用于蔬菜中103种农药的检测,检出限在0.06~13.1μg/kg之间,添加水平为20μg/kg和100μg/kg时,回收率在63.5%~123.8%之间,相对标准偏差为3.6%~13.3%。研究结果表明,相对于常用的GC-EI/MS检测方法,上述103个农药更适合采用NCI方式进行GC-MS同时分析。     

气相色谱-串联质谱法测定贝类中指示性多氯联苯

研究并建立了测定贝类中多氯联苯残留的气相色谱-串联质谱(GC-MS/MS)方法.通过正己烷和丙酮的混合溶液超声提取,硅胶柱净化,旋转蒸发浓缩,采用GC-MS/MS多反应监测(MRM)方式测定,可同时对贝类中的7种指示性多氯联苯进行定性和定量.研究结果表明:7种指示性多氯联苯的检出限(S/N=3)为0.0066～0.0098μg/kg,定量限(S/N=10)为0.02 μg/kg;在0.1～50.0 ng/mL时峰强度与质量浓度的线性关系良好(r>0.99).方法的平均回收率为73%～113%.该法简便快捷,降低了分析成本,在一定程度上实现了持久性污染物的快速检测和确证.     

色谱-串联质谱法测定双氧水工作液中的降解物

建立了超高效液相色谱-串联质谱(UPLC-MS/MS)测定双氧水工作液中降解物的分析方法。样品用乙腈溶解后,采用ACCHROM C18(150 mm×4.6 mm,5μm)色谱柱,0.1%甲酸水溶液-乙腈为流动相体系,梯度洗脱,流速0.3 m L/min,柱温30℃,紫外检测波长254 nm;质谱采用电离子喷雾正离子模式检测。结果表明,双氧水工作液中有4种明显的降解物,采用面积归一法计算该4种降解物含量占降解物总量的80%以上;其它一些含量较低的降解物也能定性分析出。实验还采用了气相色谱-串联质谱法(GC-MS/MS)分析双氧水工作液,两种分析方法的结果能相互印证和互补,表明用色谱-串联质谱法能准确、全面地测定双氧水工作液中降解物,能为蒽醌法生产双氧水的企业对工作液中降解物的抑制和脱除提供参考。     

气相色谱-串联质谱法同时测定化妆品中28种香料成分北大核心CSCD

随着化妆品种类的日益增多,化妆品中的香精香料成分受到了越来越多人的关注,建立化妆品中香精香料成分的分析测定方法是消除人们担忧最有效的措施之一。该研究建立了气相色谱-串联质谱(GC-MS/MS)同时测定化妆品中28种香料残留的方法。样品由甲醇提取,含油脂较多的经中性氧化铝固相萃取小柱净化,色素多、基质复杂的由QuEChERS净化,待测物采用GC-MS/MS测定,以保留时间和特征离子对定性,外标法定量。实验结果表明,分析物质的检出限(S/N=3)为2~20μg/kg,定量限(S/N>10)为5~50μg/kg。28种物质分别在1~100、2~200、4~200、10~1 000μg/L范围内线性关系良好,分析物质的线性相关系数(r^(2))>0.999。在空白样品中添加28种香料,添加水平为50~500μg/kg时,回收率范围为71.3%~120.4%, RSD范围为1.5%~14.6%。该方法可对28种香料成分进行准确测定,不但可以有效排除复杂基体的干扰,而且简单、灵敏、稳定,能够很好地应用于化妆品中香料的含量测定。通过该方法对16种化妆品中的香精香料成分进行测定,发现12种化妆品中均检出相关香料成分,说明化妆品中的香精香料安全应引起重视。     

高效液相色谱-串联质谱法测定豆芽中8种药物残留

建立了豆芽中8种药物(4-氯苯氧乙酸、吲哚乙酸、吲哚丁酸、1-萘乙酸、6-苄基腺嘌呤、2,4-二氯苯氧乙酸、赤霉素和多菌灵)残留的高效液相色谱-串联质谱(LC-MS/MS)检测方法。豆芽样品经0.1%冰醋酸-乙腈溶液提取、浓缩,分散固相萃取剂净化后,用液相色谱-串联质谱测定,外标法定量。8种药物在5~100μg/L范围内呈良好的线性关系(r20.99),定量下限为5μg/kg。在5,10,20μg/kg 3个加标水平下,8种药物的回收率为71.6%~87.9%,相对标准偏差不大于14.6%。方法准确、简单、快速,可用于豆芽中8种药物的同时测定。     

凝胶过滤层析结合液相色谱-串联质谱法测定血清中游离甲状腺激素

基于凝胶过滤层析(GFC)进行前处理,结合液相色谱-串联质谱(LC-MS/MS)建立了血清中游离三碘甲腺原氨酸(FT3)和游离甲状腺素(FT4)的高通量、高灵敏检测新方法。选用Sephadex LH-20凝胶小柱对150μL血清样本进行过滤分离,先用Tris-HCl缓冲液(0.1 mol/L,pH 7.4)淋洗去除结合蛋白的甲状腺激素,然后用甲醇对游离的甲状腺激素进行洗脱,采用LC-MS/MS法进行检测和定量,并进行方法学验证。结果显示：FT3和FT4的线性相关系数(r²)均不小于0.999 5,批内及批间相对标准偏差为1.8%～10%,准确度为85.4%～110%,基质效应为85.8%～114%,回收率为85.8%～107%。采用该方法与平衡透析法(ED)同时检测了95份血清样本,使用IBM SPSS Statistics 26和MedCalc统计软件(v. 20.0. 0)对检测结果进行配对t检验分析、PassingBablok回归分析和Bland-Altman一致性分析。结果表明,GFC/LC-MS/MS与ED/LC-MS/MS法对血清中FT3、FT4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.     

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.     

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.     

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.     

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.     

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.