高效液相色谱法测定全价饲料中的喹乙醇

报道了全价饲料中喹乙醇的高效液相色谱分析方法。饲料样品用丙酮 -水溶液提取 ,在 Alltech-C185 μ(4.6× 2 5 0 mm)柱上进行分析 ,流动相为甲醇 -水 (2 5∶ 75 ,v/v) ,流速 0 .8m L/min,紫外检测波长 36 8nm,喹乙醇的平均回收率≥ 97.39% ,相对标准偏差 RSD≤ 1.78% (n=5 )     

高效液相色谱串联质谱法检测腰果中黄曲霉毒素

建立了腰果中4种黄曲霉毒素的高效液相色谱-串联质谱检测方法(HPLC-MS/MS)。样品用甲醇-水(8:2, v/v)溶液提取后用弗罗里硅土柱净化,5 mL丙酮-水-甲酸溶液(96:3.5:0.5, v/v/v)洗脱,氮吹至干,1 mL甲醇定容;在资生堂MG C18色谱柱(100 mm×3.0 mm, 3 μm)上梯度洗脱分离,然后采用电喷雾离子化三重四极杆串联质谱测定。实验结果表明,4种黄曲霉毒素在各自的线性范围内峰面积与其质量浓度线性关系良好,相关系数(r2)大于0.997;检出限(信噪比为3)为0.009～0.04 μg/kg,定量限(信噪比为10)为0.03～0.12 μg/kg;平均回收率为63.0%～78.5%,相对标准偏差为2.8%～9.1%,均符合痕量分析的要求。评价了基质效应,信号抑制/增强值为88.8%～99.4%,说明净化后的基质效应较小。该方法简单快速、准确可靠,可用于腰果中黄曲霉毒素的检测。     

快速溶剂萃取-超高效液相色谱法分析鱼肉中喹乙醇

以甲醇为溶剂,采用ASE快速、高压萃取鱼肉中喹乙醇,并实施了自动在线净化过滤,色谱分析采用了乙醇(色谱级)为流动相,超快速液相色谱法进行分析。喹乙醇的标准工作溶液的线性回归方程为y=0.0358x+0.0019,相关系数r=0.9999,线性范围为0.1～2.0μg/mL,方法检出限(以信噪比(S/N=3)计算)为5.0μg/kg,样品加标回收率平均值(n=3)为88%,同时对6个平行样进行精密度试验,保留时间与峰面积的RSD值分别为0.21%和2.0%,重现性较好。方法可以用来快速分析鱼肉等样品中的喹乙醇。     

高效液相色谱-串联质谱测定水产品中残留的喹乙醇代谢物

建立了高效液相色谱-质谱(LC-MS/MS)检测水产品中喹乙醇代谢物3甲-基-喹恶啉-2羧-酸(MQCA)的残留分析方法。样品先用Protease蛋白酶酶解,然后用乙酸乙酯萃取目标物,氮气吹干后用流动相溶解残渣,以甲醇、乙腈和0.1%甲酸溶液作为流动相,液相色谱串联电喷雾质谱在正离子模式下测定。MQCA在1~100μg/kg范围内线性关系良好(r0.999)。在2、4、8μg/kg3个添加水平上,回收率在82.5%~87.5%,相对标准偏差为4.5%~5.1%(n=6),定量限为1μg/kg。方法已用于水产品中喹乙醇代谢物的残留分析。     

动物组织中卡巴氧和喹乙醇以及相关代谢产物的液相色谱-串联质谱检测方法

建立了牛、猪肌肉和肝脏组织中卡巴氧(CBX)和喹乙醇(OQX)以及相关代谢产物--脱氧卡巴氧(DCBX)、喹噁啉-2-羧酸(QCA)和3-甲基喹噁啉-2-羧酸(MQCA)残留的LC-MS/MS的检测方法.组织样品中的卡巴氧用乙腈-乙酸乙酯(体积比1 : 1)溶液提取;代谢产物的提取则是经适当处理后的样品加入Protease蛋白酶进行酶解,后采用阴离子交换固相萃取柱Oasis MAX进行净化和富集.分析样品以甲酸溶液(体积分数为 0.1%)-甲醇-乙腈为流动相,经Inertsil ODS-3色谱柱分离,在LC-MS/MS多反应监测模式下进行定性、定量分析,采用正离子扫描.CBX、DCBX、QCA和MQCA的定量下限均为0.5 μg/kg,猪、牛肌肉和肝脏在0.5 ～5.0 μg/kg添加水平的平均回收率在76% ～97%之间,相对标准偏差(n＝10)在2.9% ～16.9%之间.     

副溶血性弧菌细胞猝灭及代谢物组提取方法的优化

以气相色谱-质谱联用(GC-MS)为分析方法,比较了液氮和75%甲醇(-80℃)两种溶液对副溶血性弧菌细胞的猝灭效果,以及氯仿、75%冰甲醇、水、甲醇-氯仿-水(10∶3∶1,V/V)、甲醇-氯仿-水(3∶1∶1,V/V)、甲醇-氯仿(1∶1,V/V)6种提取剂对副溶血性弧菌代谢物组的提取效果。结果表明,用75%甲醇(-80℃)猝灭副溶血性弧菌时,出现了代谢物泄漏现象,而液氮猝灭则不存在这个现象;检索发现,采用75%冰甲醇提取获得了47种代谢物,峰面积标准偏差为8.02%,其它5种提取剂获得代谢物种类少于40种,且重现性差。比较色谱峰数量、面积和重现性后发现,液氮猝灭、75%冰甲醇提取适于副溶血性弧菌代谢物组提取。     

超高效液相色谱法测定水产品中喹乙醇的残留量

称取经粉碎并匀浆后的水产样品(5.00±0.05)g,先后用水12mL及8mL在60℃水浴中提取2次,每次10min。离心分离,合并2次提取液。向提取液中加入饱和硼砂溶液9mL和300g·L-1硫酸锌溶液3mL,充分混匀进行脱色和除去杂质。离心分离,取上清液,通过固相萃取柱(SPE)使被测组分吸附在柱上,SPE柱用5mL水淋洗,弃去淋洗液。用甲醇-乙酸乙酯(10+90)混合液10mL将被测组分从柱上洗脱。收集洗脱液并在50℃条件下吹氮至近干,残渣用色谱分离所用的流动相1.0mL溶解,以下按色谱条件操作。用BEH C18色谱柱为固定相,甲醇-水(15+85)混合液为流动相进行色谱分离;用紫外检测器,检测波长为380nm。结果表明:喹乙醇的质量浓度在0.150～50.0mg·L-1内与其峰面积之间呈线性关系,检出限(3S/N)为30μg·kg-1。用标准加入法进行回收试验,测得回收率在76.4%～90.2%之间,测定值的相对标准偏差(n=5)在3.3%～9.0%之间。     

稻田土壤及水中多抗霉素残留量的分析与检测方法研究

采用高效液相色谱法建立了稻田土壤及水中多抗霉素残留量的分析方法。水样品经氨水调节pH值至8.0,以乙酸乙酯萃取去除有机杂质,水相经浓缩后定容;土壤样品用碱性甲醇和水的混合溶液(70∶30)提取,提取液经浓缩后定容。上述萃取液采用C18亲水性不锈钢色谱柱(AQ-C18,4.6 mm×250 mm,5μm)进行液相色谱分离,紫外检测器检测,外标法定量,流动相为水(用冰乙酸调节pH值为4.0)-甲醇(87∶13),流速:0～8 min为1.0 mL/min,8～16 min为0.3 mL/min,柱温30℃,检测波长272 nm。结果表明,多抗霉素的浓度在0.05～2.00 mg/L范围内与其对应的峰面积呈良好的线性关系,相关系数(r2)为0.998 8;多抗霉素的最小检出量为1.00×10-9g,在稻田水中的最低检出浓度为0.05 mg/L,在稻田土壤中的最低检出浓度为0.05 mg/kg;在0.06、0.60、1.00 mg/kg加标水平下,多抗霉素在稻田水中的平均加标回收率为97%～99%,相对标准偏差为0.71%～2.4%;在稻田土壤中的平均加标回收率为95%～97%,相对标准偏差为1.7%～4.5%。该方法操作简便,分离效果好,准确度和精密度良好,符合农药残留的检测要求。     

磁性聚苯乙烯-Fe3O4固相萃取-超高效液相色谱-串联质谱法测定水中双酚A

建立了磁性聚苯乙烯-Fe_3O_4(HCP-Fe_3O_4)固相萃取联用超高效液相色谱-串联质谱(UHPLC-MS/MS)的检验方法,用于测定水中双酚A(BPA)的含量。水样经HCP-Fe_3O_4固相萃取,用甲醇洗脱后进样,以ACQUITY UPLC BEH C_(18)色谱柱为分离柱,以不同体积比的甲醇和水作为流动相进行梯度洗脱;质谱分析采用电喷雾负离子(ESI~-)模式电离、多反应监测(MRM)模式检测。BPA的质量浓度在1.000～1 000μg·L~(-1)内与其峰面积呈线性关系,方法的检出限(3S/N)为0.04μg·L~(-1)。加标回收率为98.4%～99.9%,测定值的相对标准偏差(n=6)为2.6%～8.2%。     

高效液相色谱法测定五味子和含五味子的制剂中五味子乙素及多种活性成分时流动相体系的选择

建立了用高效液相色谱法测定五味子和含五味子的制剂中五味子乙素的流动相体系。用Shim-pack VP-ODS (250 mm×4.6 mm,5 μm)色谱柱,在柱温30 ℃、检测波长285 nm、流速1.0 mL/min的条件下,用不同的流动相组成及其不同比例研究了五味子提取液中3种木脂素(五味子乙素、安五脂素和五味子甲素)的保留时间及其分离情况,从中选择测定五味子乙素的最佳流动相体系。结果表明,在甲醇-水、甲醇-冰醋酸-水的流动相体系中,安五脂素和五味子乙素很难完全分离;而在乙腈-甲醇-水和乙腈-冰醋酸-水流动相体系中,3种木脂素可很好地分离。以乙腈-甲醇-水(体积比为17:58:25)为流动相测定五味子和护肝片中3种木脂素的含量,相对标准偏差(n4)为0.95%～5.8%,平均加标回收率为94.50%～105.6%。将该流动相体系用于供试品中3种木脂素含量的测定,分离效果好,结果令人满意。     

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.     

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.     

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.