高效液相色谱法同时测定植物油中4种甾醇烯

建立了高效液相色谱法同时测定植物油中4种甾醇烯的方法。样品用石油醚提取,硅胶柱净化,反相C30柱(250 mm×4.6 mm i.d,5μm)分离,乙腈-叔丁基甲醚(75∶25,V/V)作流动相,等度洗脱,紫外检测(235 nm)。结果表明:4种甾醇烯的质量浓度在0.025～1.0 mg/L范围内;峰面积与质量浓度呈良好的线性关系,线性相关系数r2>0.999。在加标水平为0.050,0.10和0.50 mg/kg时,4种甾醇烯的加标平均回收率为89.2%～109.8%;相对标准偏差RSD<8%;方法检出限(LOD)为0.010 mg/kg。本方法已应用于实际样品分析。     

超临界色谱法测定化妆品中生育酚及α-生育酚乙酸酯

建立了化妆品中4种生育酚异构体及α-生育酚乙酸酯的超临界色谱分析方法。不同基质类型的化妆品经乙腈水溶液-正己烷溶剂体系按不同的添加顺序进行分散、提取、液液分配后,以二氧化碳为流动相,异丙醇-正己烷(1∶1)为改性剂,利用亚乙基桥杂化颗粒色谱柱(Viridis@BEH,250 mm×4.6 mm,5μm)对目标物和样品杂质进行有效分离,用光电二极管矩阵检测器(SFC-PDA)进行测定。系统考察了提取条件和色谱条件对实验结果的影响。结果表明:4种生育酚和α-生育酚乙酸酯的定量下限(S/N=10)分别为50 mg/kg和25 mg/kg,空白基质加标回收率为81.3%~109.5%,相对标准偏差(RSD)不大于12.8%。该方法前处理简单、快速、准确,可用于各类化妆品中4种生育酚异构体及α-生育酚乙酸酯含量的检测。     

美白化妆品中杜鹃醇的超高效液相色谱荧光检测及质谱确证

采用超高效液相色谱结合荧光检测建立了美白化妆品中杜鹃醇的分析方法,并采用液相色谱-串联质谱法进行确证。化妆品试样以5%三氯乙酸-乙腈混合溶液(70∶30)超声提取15 min,离心过膜后,采用通用型的反相C18色谱柱进行分离,以0.1%甲酸水-乙腈(75∶25)为流动相,荧光检测器(λex/λem=280nm/315 nm)检测,外标法定量;质谱确证采用水(含0.01%氨水)和乙腈作为流动相梯度洗脱,电喷雾负离子模式电离,多反应监测模式检测。结果显示,杜鹃醇在0.05~1.0 mg/L范围内线性关系良好,相关系数为0.999 6,方法的定量下限为2.5 mg/kg。面膜、乳霜、乳液和爽肤水等样品在加标浓度为5.0,10,25 mg/kg时的回收率为86.5%~103.4%,RSD(n=6)为1.1%~3.4%。该方法简便、灵敏,加标回收率和重现性良好,可用于化妆品中杜鹃醇的检测及其含量水平的普查。     

高效液相色谱测定水果中外源植物激素的快速前处理方法研究

建立了快速、简单的样品前处理技术(QuEChERS)-高效液相色谱双波长测定水果中氯吡脲、2,4-滴丙酸(2,4-D)和多效唑3种植物激素残留量的分析方法。采用Pak C18色谱柱(250×4.6mm,5μm),以乙腈-20mmoL H3PO4(60∶40)为流动相,流速1.0mL/min,双波长λ1=230nm和λ2=270nm紫外检测。考察了紫外双波长、流动相的pH和净化材料对三种植物激素残留测定的影响。对草莓、葡萄、苹果和桃进行加标回收率实验,其回收率大于80%,相对标准偏差小于12%。方法的检出限为0.03~0.008mg/kg,定量限为0.02~0.1mg/kg。该法简便、快速、灵敏度高,适用于日常大批量样品的检测。     

高效液相色谱法同时测定洗涤产品中7种防腐剂

建立同时测定洗涤产品中4-氯-3-甲酚、双氯酚、苄氯酚、邻苯基苯酚、对氯间二甲苯酚、三氯生、三氯卡班7种防腐剂的高效液相色谱分析方法。不同基质的样品经甲醇涡旋混匀及超声提取后,用X–Bridge C18反相色谱柱(250mm×4.6 mm,5μm)进行分离,以甲醇–水为流动相,梯度洗脱,采用二极管阵列检测器(DAD)进行检测,检测波长为285 nm。在优化的实验条件下,7种防腐剂的质量浓度在0.2~500 mg/L范围内与其色谱峰面积呈良好的线性关系,相关系数(r2)均为0.999 9,方法的检出限(S/N=3)为1.0~2.5 mg/kg,定量限(S/N=10)为3.0~7.5 mg/kg。7.5,25.0,75.0 mg/kg 3水平加标回收率为92.1%~105.8%,相对标准偏差为0.8%~4.5%(n=6)。该方法简单、快速、准确,适用于洗涤产品中7种防腐剂的测定。     

高效液相色谱法同时测定化妆品中10种美白成分

建立一种同时测定化妆品中10种美白成分的高效液相色谱法。化妆品样品用80%甲醇提取，采用Agilent Eclipse plus C₁₈柱(250 mm×4.6 mm,5μm)分离，以甲醇-0.02%(体积分数)磷酸水溶液为流动相，梯度洗脱，采用二极管阵列检测器检测。10种美白成分在各自的质量浓度在范围内与对应色谱峰面积均呈现良好的线性关系，相关系数均大于0.999，方法检出限为2～10 mg/kg，定量限为6～25 mg/kg。3水平样品加标回收试验的平均回收率为93.43%～112.7%，相对标准偏差为0.05%～3.11%(n=6)。该方法样品处理简单，适用于化妆品中10种美白成分的测定。     

高效液相梯度洗脱法测定杏香兔耳风中绿原酸和芦丁

建立了反相高效液相色谱法同时测定不同来源的杏香兔耳风中的绿原酸和芦丁。采用Kromasil C18柱(4.6 mm i.d.×250 mm,5μm),以甲醇-0.5%H3PO4的水溶液为流动相,梯度洗脱程序为0 min(30∶70)-15 min(30∶70)-20min(50∶50)-40 min(50∶50);流速0.8 mL/min;检测波长350 nm;柱温25℃;光电二极管阵列检测器(PAD)。绿原酸线性范围为0.654~5.886μg,r=0.9997,样品的平均加标回收率为98.6%,RSD 1.7%;芦丁线性范围为0.218~1.962μg,r=0.9993,样品的平均加标回收率为97.1%,RSD 2.3%。本法可作为杏香兔耳风中绿原酸和芦丁的定量分析方法。     

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。     

鱼子酱中的合成色素反相高效液相色谱法同时测定

建立了反相高效液相色谱法同时测定鱼子酱中的柠檬黄、日落黄、偶氮玉红、苋菜红、胭脂红、赤藓红、红色2G和诱惑红8种合成色素的方法.样品中的合成色素经甲醇-4 mol/L尿素溶液(体积比1 ∶ 1)提取,固相萃取聚酰胺柱净化后,采用XDB-C18色谱柱(4.6 mm×250 mm×5 μm),以甲醇-乙腈(体积比1 ∶ 1)和0.01 mol/L乙酸钠溶液为流动相,在最佳梯度洗脱条件下,8种合成色素在17 min内实现分离.各色素在0.05 ～50 mg/L质量浓度范围内具有良好的线性关系.将该法用于实际样品的检测,8种合成色素的加标回收率为89% ～110%,相对标准偏差为1.4% ～4.7%.方法简单、高效,可用于鱼子酱中合成色素的日常监督检测.     

高效液相色谱法测定冷面、米线中乙二胺四乙酸二钠

建立高效液相色谱法测定冷面和米线中乙二胺四乙酸二钠的分析方法。样品用水提取后,经三氯化铁络合,用Shimpack VP-ODS C₁₈色谱柱(250 mm×4.6 mm,5μm)分离,以四丁基溴化铵-乙酸钠混合溶液(pH 4.0)-甲醇(体积比为85∶15)为流动相,等度洗脱,采用紫外检测器检测,检测波长为254 nm,用色谱峰面积外标法定量。乙二胺四乙酸二钠的质量浓度在0.5～50μg/mL范围内与色谱峰面积线性关系良好,相关系数为0.999 8,方法检出限为1.5mg/kg,定量限为5.0 mg/kg。冷面和米线样品加标回收率为90.7%～103.5%,测定结果的相对标准偏差为1.2%～5.0%(n=6)。该方法操作简单快速。     

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.     

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.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.