柱后加碱脉冲积分安培检测-离子色谱法测定水产品中十种生物胺

建立了利用淋洗液自动发生梯度淋洗的离子交换色谱法同时测定水产品中酪胺、5-羟色胺、腐胺、尸胺、组胺、庚二胺、苯乙胺、亚精胺、精胺、色胺等10种生物胺的方法。样品经处理后用Ionpac CS17分离柱和Ionpac CG17型保护柱分离,以EG40自动淋洗液发生器生成的5.0～55 mmol/L的MSA为淋洗液梯度洗脱,脉冲积分安培检测器检测。对梯度进行优化,10种生物胺都能基线分离,并且浓度和峰面积在一定范围内呈良好的线性关系。检出限在0.04 mg/kg以下,回收率在91.2%～102.5%之间,样品的RSD(n=6)小于5%。方法可用于水产品的检测。     

液相色谱-串联质谱法测定葡萄酒中7种生物胺含量

提出了液相色谱-串联质谱法测定葡萄酒中2-苯乙胺、色胺、尸胺、组胺、腐胺、精胺、亚精胺等7种生物胺含量的方法。样品经0.45μm滤膜过滤后,直接通过Zorbax Eclipse XDB C8色谱柱(4.6mm×150mm,5μm)进行分离,以不同体积5mmol·L-1乙酸铵-10mmol·L-1全氟己酸甲醇溶液(A)和5mmol·L-1乙酸铵-10mmol·L-1全氟己酸水溶液(B)的混合液为流动相梯度洗脱,串联质谱法进行测定。7种生物胺的质量浓度均在0.1～5.0mg·L-1范围内与其峰面积呈线性关系,检出限(3S/N)在0.005～0.02mg·L-1之间。以空白葡萄酒样品为基体进行加标回收试验,测得回收率在84.1%～97.5%之间;测定值的相对标准偏差(n=5)在6.3%～13%之间。     

非衍生化液相色谱-串联质谱法测定动物源性食品中8种生物胺

采用液相色谱-串联质谱技术建立了同时测定动物源性食品中组胺(HIS)、色胺(TRP)、2-苯乙胺(2-PHE)、腐胺(PUT)、尸胺(CAD)、酪胺(TYR)、亚精胺(SPD)和精胺(SPM)8种生物胺(BAs)的分析方法。样品用乙腈-甲酸水溶液提取,用强阳离子交换柱(MCX)净化。在不进行衍生化的条件下,采用亲水作用色谱(HILIC)柱、以5 mmol/L的乙酸铵溶液和甲醇为流动相分离8种生物胺。结果表明,8种生物胺的线性范围为0.001～100 μg/L,相关系数(r2)均大于0.99。方法的检出限(LODs,信噪比为3)在0.001～1 μg/kg之间,定量限(LOQs,信噪比为10)在0.003～5 μg/kg之间。在8种基质中3个加标水平的回收率都在73.9%～106.3%之间,加标含量范围为0.003～50 μg/kg,相对标准偏差(RSD, n=6)在5.65%～18.6%之间。方法的灵敏度和回收率高,选择性好,能满足日常动物源性食品检测工作的要求。     

胶束电动毛细管色谱检测鱼肉中的七种生物胺

建立了一种利用胶束电动毛细管色谱同时检测鱼肉中组胺、腐胺、2-苯乙基胺、尸胺、色胺、亚精胺及精胺7种生物胺的方法。样品经6%过氯酸萃取后,由苯甲酰氯衍生化,以含0.06 mol/L脱氧胆酸钠的0.02 mol/L硼酸(pH 9.2)-甲醇(体积比为95∶5)混合液为电泳介质,电泳电压25 kV,温度25 ℃,检测波长214 nm,在12 min内实现了7种生物胺的完全分离。7种生物胺的浓度与其峰面积在一定的范围呈良好的线性关系,检出限除组胺为15 μg/g外,其余均为5 μg/g。迁移时间和峰面积的日内、日间相对标准偏差均小于5%。该法用于海鱼中7种胺类物质含量的测定,结果令人满意。     

离子色谱法同时测定水源水中的5种生物胺

建立了离子色谱(IC)同时测定水源水中5种生物胺(BA)(腐胺、尸胺、组胺、亚精胺和精胺)的方法。样品经0.45 μm水膜过滤后,用TSK-GEL SuperIC阳离子交换柱(150 mm×4.6 mm)分离,以甲磺酸水溶液为流动相梯度淋洗,流速为1.0 mL/min,非抑制电导检测,进样量为100 μL。实验结果表明,5种生物胺可以实现基线分离;在1.0～30.0 mg/L范围内,其峰面积与质量浓度之间的线性关系良好;保留时间的相对标准偏差(RSD)均不高于0.02%,峰面积的RSD小于2.08%;加标回收率为96.0%～107.0%。该法简便、快捷、准确,可以用于水源水中腐胺、尸胺、组胺、亚精胺和精胺5种生物胺的同时测定。     

高效液相色谱法测定畜禽肉中8种生物胺含量国家标准方法的改进北大核心CSCD

针对国家标准方法GB 5009.208-2016操作繁琐,检测时间较长(约6 h)等问题,改进了提取方法和衍生方法,并应用于畜禽肉中色胺、尸胺、β-苯乙胺、酪胺、亚精胺、腐胺、组胺和精胺等8种生物胺含量的测定。取绞碎样品10 g,加入50 g·L^(-1)三氯乙酸溶液20 mL、正己烷10 mL及1 000 mg·L^(-1) 1,7-二氨基庚烷内标溶液1.0 mL,混匀后涡旋15 min,超声提取15 min,离心5 min。取0.5 mL上清液置于10 mL比色管中,依次加入2 mol·L^(-1)氢氧化钠溶液100μL、饱和碳酸氢钠溶液300μL、10 g·L^(-1)丹磺酰氯衍生溶液2.0 mL,振荡混匀,于60℃反应15 min。加入100μL氨水,于60℃保温15 min,以终止衍生反应。加入乙腈稀释至5 mL,用0.22μm滤膜过滤,滤液注入高效液相色谱仪,在Phenomenex Kinetex色谱柱上以不同体积比的甲醇-水体系进行梯度洗脱,并用二极管阵列检测器检测。结果显示:样品可在1.5 h内完成检测,8种生物胺的质量浓度均在5.00~250 mg·L^(-1)内与其对应的峰面积与内标物峰面积的比值呈线性关系,检出限(3S/N)为4~21μg·kg^(-1);对实际样品进行加标回收试验和日内、日间精密度试验,回收率为80.4%~95.6%,日内(n=6)、日间(n=5)精密度试验测定值的相对标准偏差分别为1.9%~5.1%和2.3%~6.2%;方法用于20批畜禽肉的分析,除组胺外,其他7种生物胺均有不同程度检出。     

固相萃取-气相色谱法测定腌肉中5种生物胺北大核心CSCD

采用固相萃取-气相色谱法测定腌肉中酪胺、组胺、精胺、亚精胺和β-苯乙胺等5种生物胺的含量。腌肉样品用50g·L^(-1)三氯乙酸溶液提取,强阳离子交换固相萃取柱净化。用Agilent DB-1701色谱柱(30m×0.25mm,0.25μm)分离,氮磷检测器检测。5种生物胺的质量浓度均在1.0~50.0mg·L^(-1)内与其对应的峰面积呈线性关系,方法的检出限(3S/N)为0.12~0.32 mg·kg^(-1)。以空白样品为基体进行加标回收试验,所得回收率为78.0%~96.8%,测定值的相对标准偏差(n=6)为2.2%~7.1%。     

固相萃取-气相色谱法测定腌肉中5种生物胺

采用固相萃取-气相色谱法测定腌肉中酪胺、组胺、精胺、亚精胺和β-苯乙胺等5种生物胺的含量。腌肉样品用50g·L~(-1)三氯乙酸溶液提取,强阳离子交换固相萃取柱净化。用Agilent DB-1701色谱柱(30m×0.25mm,0.25μm)分离,氮磷检测器检测。5种生物胺的质量浓度均在1.0~50.0mg·L~(-1)内与其对应的峰面积呈线性关系,方法的检出限(3S/N)为0.12~0.32 mg·kg~(-1)。以空白样品为基体进行加标回收试验,所得回收率为78.0%~96.8%,测定值的相对标准偏差(n=6)为2.2%~7.1%。     

高效液相色谱-四极杆/静电场轨道阱高分辨质谱检测葡萄酒中8种生物胺

利用分散固相萃取结合高效液相色谱-四极杆/静电场轨道阱高分辨质谱对进出口葡萄酒中组胺、酪胺、尸胺、腐胺、色胺、精胺、亚精胺和苯乙胺8种生物胺进行分析。葡萄酒样品用去离子水稀释,加入200 mg十八烷基硅烷粉(Octadecylsilyl,ODS)和50 mg N-丙基乙二胺粉(Primary secondary amine,PSA)吸附剂分散固相萃取净化后,以高效液相色谱-四极杆/静电场轨道阱高分辨质谱进行定性和定量分析。选择Phenomenex C18(100 mm×4.6 mm×2.6μm)分析柱,乙腈-0.1‰七氟正丁酸水溶液作为流动相进行梯度洗脱分离。质谱采用正离子模式,通过高分辨质谱全扫描模式提取目标化合物精确质量数,利用阈值自动触发全扫描二级质谱功能提高了定性的准确性。8种生物胺在0.2~10.0 mg/L浓度范围内线性关系良好,相关系数均大于0.99。方法的定量下限可达1.0 mg/L。在1.0、5.0、10.0 mg/L 3个浓度加标水平下,葡萄酒中8种生物胺的平均回收率为83.7%~101.6%,相对标准偏差(RSDs)为3.1%~12.9%。此方法准确灵敏且前处理简单,可作为葡萄酒中生物胺筛选和确认的检测方法。     

高效液相色谱法分析柿子中多胺

采用高效液相色谱法,用1,6 己二胺为内标,定量测定柿子中的精胺(Spermine)、亚精胺(Spermidine)、尸胺(Cadaverine)和腐胺(Putrescine)。样品经丹磺酰氯衍生,硅胶柱净化,LichrosorbNH2柱分离后,以氯仿∶乙酸乙酯∶三乙胺(98.4∶1.5∶0.1)为流动相,流速为1 5ml·min-1,荧光检测器检测。激发波长为336nm,发射波长为495nm,精胺、亚精胺、尸胺和腐胺的线性相关系数均大于0.99,其回收率分别为98.99%、94.02%、96.46%和105.44%。     

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.     

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.     

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.     

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.     

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.     

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.