超高效液相色谱-串联质谱法同时测定保健品中26种非法添加物

提出了超高效液相色谱-串联四极杆质谱法测定各类功能保健品中具有降糖、降压、利尿、减肥、壮阳、抗过敏、抗抑郁、抗疲劳等功效的26种非法添加物的快速分析方法。样品采用甲醇超声提取,提取液经固相萃取柱净化后,以Waters HSS T3超高效液相色谱柱为分离柱,以不同体积比的含2mmol·L~(-1)乙酸铵的0.1%(体积分数)甲酸溶液和乙腈混合液为流动相进行梯度洗脱,采用电喷雾正离子源多反应监测模式检测。26种非法添加物的质量分数在1.0~200μg·kg-1范围内与峰面积呈线性关系,方法的检出限(3S/N)在0.5~2.0μg·kg-1之间;测定下限(10S/N)在2.0~10μg·kg-1之间,在3个不同浓度水平上进行了回收试验,回收率在78.1%~109%之间,测定值的相对标准偏差(n=10)在7.0%~16%之间。     

超声辅助分散液相微萃取-高效液相色谱法测定蜂蜜中的咖啡因

采用超声辅助分散液相微萃取技术结合高效液相色谱法测定蜂蜜中的咖啡因。将样品用水溶解配制成100g·L-1样品溶液,取7.5 mL样品溶液,加入三氯甲烷120μL和甲醇1.5mL,混匀后超声5min,离心后吸取5μL沉积相,在WondasilTM C18色谱柱上分离,以甲醇(1+1)溶液为流动相进行洗脱,紫外检测波长为274nm。咖啡因的线性范围为10.0~500μg·L-1,检出限(3S/N)为9μg·L-1。测定值的相对标准偏差为2.7%~4.1%,加标回收率在96.6%~104%之间。     

液相色谱-串联质联法测定食品用塑料包装中邻苯二甲酸酯类增塑剂

采用液相色谱-串联质谱法(LC-MS/MS)测定了食品用塑料包装材料中的3种邻苯二甲酸酯(DBP、BBP、DEHP)的含量。样品经正己烷超声提取后,以Hypersil Gold色谱柱为固定相,以甲醇-水(95+5)溶液为流动相进行洗脱,采用电喷雾正离子源-多反应检测模式检测。3种邻苯二甲酸酯的质量浓度在5.00~250μg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.1~0.2μg·L-1之间。对空白样品进行加标回收试验,回收率在92.5%~101%之间,测定值的相对标准偏差(n=6)在4.6%~6.9%之间。     

高效液相色谱法测定化妆品中5种荧光增白剂

采用高效液相色谱法测定化妆品中5种荧光增白剂的含量。样品经甲醇超声提取,以C18色谱柱为分离柱,以甲醇和5mmol·L-1四丁基硫酸氢铵溶液以不同比例混合的溶液为流动相进行梯度洗脱,用荧光检测器测定。5种荧光增白剂在一定的质量浓度范围内与其峰面积呈线性关系,方法的测定下限(10S/N)在0.1~2.0μg·g-1之间。以空白样品为基体进行加标回收试验,所得回收率在85.1%~97.1%之间,测定值的相对标准偏差(n=6)在1.4%~5.7%之间。     

高效液相色谱-串联质谱法测定猪肉中9种β_2-受体激动剂残留量

采用高效液相色谱-串联质谱法测定了猪肉中9种β-受体激动剂的残留量。样品经β-葡萄糖醛苷酶/芳基硫酸酯酶酶解后加入高氯酸沉淀蛋白并离心,取上清液过PCX阳离子固相萃取小柱净化,用氨水-甲醇(5+95)混合液洗脱,氮气吹干后用乙腈定容至1 mL。以CAPCELL PAK CR色谱柱为分离柱,以10mmol·L-1乙酸铵溶液-乙腈(55+45)混合溶液(含体积分数为0.1%的甲酸)为流动相进行洗脱,采用电喷雾正离子源及选择反应监测模式进行测定,内标法进行定量。9种β-受体激动剂的质量浓度在4.00~100μg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.09~0.50μg·L-1之间。对空白样品进行加标回收试验,回收率在83.2%~102%之间,测定值的相对标准偏差(n=6)在5.0%~12%之间。     

凝胶渗透色谱-超高效液相色谱-串联质谱法测定水产品中多种同化激素残留

结合凝胶渗透色谱净化技术,建立了超高效液相色谱-串联质谱法测定水产品中6种同化激素的残留。样品经叔丁基甲醚提取,以乙酸乙酯-环己烷(1+1)溶液为流动相进行凝胶渗透色谱净化,用C18固体吸附剂净化,以C18色谱柱分离,采用电喷雾正离子源、多反应监测模式检测,外标法定量。6种激素的线性范围均为0.5~50μg·L-1,测定下限(10S/N)在0.20~1.50μg·kg-1之间。对空白样品进行加标回收试验,回收率在81.7%~90.8%之间,日间精密度(n=5)在5.8%~7.9%之间。     

固相萃取-超高效液相色谱法测定水体中4种硝基呋喃类药物

采用固相萃取-超高效液相色谱法测定水体中呋喃西林、呋喃它酮、呋喃妥因、呋喃唑酮等4种硝基呋喃类药物的含量。样品经HLB固相萃取柱净化后,用氨水-甲醇(5+95)溶液洗脱。以BEH C18色谱柱为分离柱,以乙腈和含有0.1%(体积分数)甲酸的2mmol·L-1乙酸铵溶液以体积比23比77组成的混合液为流动相,在检测波长360nm处进行测定。4种硝基呋喃类药物的质量浓度均在5.0~200μg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)为0.02μg·L-1。以空白样品为基体进行加标回收试验,所得回收率在84.5%~97.2%之间,测定值的相对标准偏差(n=6)在1.5%~4.5%之间。     

高效液相色谱法测定食用菌中10种荧光增白剂

采用高效液相色谱法同时测定食用菌中10种双三嗪氨基二苯乙烯型荧光增白剂的含量。色谱分离中,以Athena C18-WP色谱柱(4.6 mm×200 mm,5μm)为固定相,用乙腈和0.02mol·L-1乙酸铵溶液以不同比例混合的溶液为流动相进行梯度洗脱,用荧光检测器测定,激发波长为350nm,发射波长为430nm。10种荧光增白剂的质量浓度均在2.0~100μg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.002~0.005mg·kg-1之间。以空白样品为基体进行加标回收试验,所得回收率在73.0%~121%之间,测定值的相对标准偏差(n=6)在0.90%~7.8%之间。     

QuEChERS-超高效液相色谱-串联质谱法快速测定鱼肉中22种磺胺类药物残留

结合QuEChERS前处理技术,提出了测定鱼肉中22种磺胺类残留的超高效液相色谱-串联质谱法。样品用含0.1%(体积分数,下同)甲酸的乙腈溶液提取后,经QuEChERS试剂盒净化。净化液在Agilent ZORBAX Eclipse Plus C18色谱柱上分离,以0.1%甲酸溶液-甲醇为流动相进行梯度洗脱。采用电喷雾正离子源及计划式多反应监测模式进行测定,以内标法定量。磺胺硝苯、磺胺、磺胺喹噁啉的线性范围为0.5~50μg·L-1,检出限(3S/N)为0.5μg·L-1;其他19种磺胺类兽药的线性范围为0.1~50μg·L-1,检出限(3S/N)为0.1μg·L-1。加标回收率在78.2%~118%之间,测定值的相对标准偏差(n=6)在3.4%~19%之间。方法用于鱼肉中多种磺胺类药物残留的快速测定,结果与标准方法测定结果一致。     

气相色谱-质谱法同时测定土壤中30种农药残留

采用气相色谱-质谱法同时测定土壤中30种农药残留。样品经过丙酮-正己烷(1+1)混合溶液均质提取,再用正己烷进行萃取,弗罗里硅土柱净化后,采用HP-5MS色谱柱分离,选用电子轰击离子源和选择离子监测模式进行质谱分析,外标法定量。30种农药的线性范围为0.1~1.0mg·L-1,检出限(3S/N)为3.8~9.6μg·kg-1。加标回收率在75.8%~103%之间,测定值的相对标准偏差(n=6)在5.6%~9.7%之间。     

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.     

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.     

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.     

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.