高效液相色谱法同时测定软饮料中20种食品添加剂

建立了高效液相色谱同时测量软饮料中20种食品添加剂（咖啡因、3种甜味剂、9种防腐剂和7种着色剂）的方法。确定的最佳分离条件为:C₁₈反相色谱柱（250 mm×4.6 mm×5μm）,流动相为0.10 mol/L乙酸铵缓冲溶液（pH 7.2）和乙腈-甲醇混合有机相（10:90,V/V）,梯度洗脱,二极管阵列检测器在190～700 nm监测。20种食品添加剂浓度在0.10～300 mg/L范围内具有良好的线性,相关系数大于0.998;20种食品添加剂的检出限在0.005～0.110 mg/L范围内;20种食品添加剂的加标回收率为91.4%～100.5%;相对标准偏差计为0.6%～4.0%。本方法可应用于16个品牌的软饮料中食品添加剂的检测。     

固相萃取-高效液相色谱-蒸发光散射检测法同时检测食品中5种人工合成甜味剂

建立了高效液相色谱-蒸发光散射检测仪(HPLC-ELSD)同时检测食品中安赛蜜、糖精钠、甜蜜素、三氯蔗糖和阿斯巴甜5种甜味剂的方法。甜味剂经0.1%(v/v)甲酸缓冲液提取后,利用C18固相萃取小柱净化浓缩,以3 μm C18柱为分离柱,0.1%(v/v)甲酸(氨水调节pH=3.5)-甲醇(61:39, v/v)为流动相,经高效液相色谱法分离,蒸发光散射检测器进行检测。结果表明,5种甜味剂在30～1000 mg/L的范围内,具有良好的线性关系(相关系数大于0.997);在3个添加水平下,样品的平均回收率为85.6%～109.0%,相对标准偏差小于4.0%;方法检出限(LOD,信噪比(S/N)=3)分别为安赛蜜2.5 mg/L、糖精钠3 mg/L、甜蜜素10 mg/L、三氯蔗糖2.5 mg/L及阿斯巴甜5 mg/L。该方法简单、灵敏、操作成本低,可用于不同形态食品中多种甜味剂的同时检测。     

基于Au@Ag纳米颗粒的表面增强拉曼检测血浆中的法莫替丁

该文开发了一种基于Au@Ag纳米颗粒(Au@AgNPs)快速检测法莫替丁(FMD)的表面增强拉曼光谱(SERS)方法。通过种子介导法合成了Au@AgNPs,再采用场电子发射显微镜(SEM)、透射电子显微镜(TEM)、紫外可见吸收光谱(UV-Vis)和X射线衍射仪(XRD)对Au@AgNPs进行表征,以罗丹明6(RG6)为分子探针对合成的Au@AgNPs的SERS性能进行了测试。结果显示,合成的Au@AgNPs形貌均匀,具有良好的增强效果,增强因子为6.66×10~5,将其用于法莫替丁标准溶液的SERS检测,在0.5～50μmol/L范围内法莫替丁浓度的对数和1 540 cm~(-1)处峰强度的对数具有较好的线性关系,相关系数(r~2)为0.978,检出限(LOD)为4.18×10~(-8) mol/L。在同样的条件下对稀释血浆中的法莫替丁进行了SERS检测,LOD为1.11×10~(-7) mol/L,加标回收率为91.6%～122%,相对标准偏差为6.6%～12%,表明该方法快速、灵敏,在生物样本检测方面具有潜在的应用价值。     

表面增强拉曼光谱检测鱼肉中禁用和限用药物研究

应用表面增强拉曼光谱(surface-enhanced Raman spectroscopy,SERS)技术,结合化学计量学方法对水产品中常被检出的禁用或限用药物,包括孔雀石绿(0.5～50μg/L)、结晶紫(5～100μg/L)、氯霉素(50～5.0×103μg/L)和磺胺甲基嘧啶(500～5.0×103μg/L)进行检测.采用偏最小二乘回归法(partial least squares regression,PLSR)对谱图进行分析处理,建立定量分析模型.结果表明运用SERS技术对染料类渔药,孔雀石绿和结晶紫的分析效果较好,对于其标准溶液的最低检测浓度分别为0.8和10μg/L;对抗生素药物,氯霉素和磺胺甲基嘧啶的最低检测浓度分别为50和500μg/L.4种药物的PLSR模型的预测值与实际值的R2为0.865～0.954.运用SERS技术最低能检测到鱼肉中孔雀石绿和结晶紫的含量分别为1.0和20μg/kg,显示出SERS技术对食品中痕量药物残留检测的巨大潜力.     

应用表面增强拉曼光谱技术快速检测尿样中的β-兴奋剂

应用表面增强拉曼光谱技术与化学计量法相结合分析克伦特罗、沙丁胺醇和莱克多巴胺3种β-兴奋剂的标准溶液.在取自10头猪的尿样中,分别添加5个不同浓度的莱克多巴胺(1～20 mg/L),采用快速的液液萃取法对样品进行前处理,再进行表面增强拉曼测试.结果表明,克伦特罗和沙丁胺醇标准溶液的最低检测浓度为2 μg/L,莱克多巴胺标准溶液的最低检测浓度为0.1 mg/L;通过偏最小二乘法建立模型进行定量分析,3种药物的实际值与预测值的相关系数(R2)为0.9134～0.9368;本方法可检测尿样中1 mg/L莱克多巴胺,经外部验证后模型的实际值与预测值的相关系数(R2)为0 881,相对分析误差(RPD)为2.83;分析尿液中的莱克多巴胺含量所需时间小于30 min,为快速检测莱克多巴胺提供新途径.     

表面增强拉曼光谱快速检测蜂蜜中的金霉素残留

利用表面增强拉曼光谱(SERS)技术对蜂蜜中的金霉素(CTC)残留进行了快速、无损检测.以自制的金纳米粒子作金霉素的拉曼增强基底,对金纳米粒子与金霉素混合体积比及混合时间进行了讨论与优化,检测了不同浓度梯度的金霉素标准溶液,绘制了特征峰处浓度-拉曼信号强度的线性方程,对蜂蜜进行前处理后,运用加标回收法考察其回收率.结果表明,金霉素溶液在1450 cm-1处的特征峰可以作为蜂蜜中金霉素残留量检测的特征峰,金纳米基底和金霉素标准液的最佳混合体积比为1∶1,最佳混合时间为1 min.金霉素的浓度(X)在10~250 mg/L范围内与其在1450 cm-1处的SERS特征峰强度(Y)有着良好的线性关系,线性方程为Y=1×10-4X+0.0110(R2=0.9948).检测实际蜂蜜样品中金霉素含量的加标回收率均在80%~120%之间.该检测方法操作简单、快捷、准确度高,为检测食品中抗生素残留提供了新的思路和方法.     

表面增强拉曼光谱法测定鸭肉中替米考星残留

建立了鸭肉中替米考星(Tilmicosin,TMS)残留的表面增强拉曼光谱(SERS)检测方法。分析了鸭肉提取液、TMS水溶液和含有TMS的鸭肉提取液的SERS光谱特征,确定1584 cm~(-1)作为鸭肉中TMS残留快速检测的SERS分析特征峰。研究了含TMS的鸭肉提取液加入量、吸附时间分别对鸭肉中TMS在1584 cm~(-1)处的SERS信号强度的影响,确定了含TMS的鸭肉提取液的加入量和吸附时间分别为20μL和1 min。建立了TMS水溶液检测的标准曲线,在质量浓度0.5~40.0 mg/L范围内呈良好的线性关系,相关系数(R2)为0.9725,检测限为0.5 mg/L,预测样本的平均回收率介于87%~105%之间。建立了鸭肉中TM S残留检测的标准曲线,在质量浓度2.0~50.0 mg/L范围内呈现出良好的线性关系,R2为0.9839,检测限可达2.0 mg/L,预测样本的平均回收率介于75%~103%之间。基于SERS的鸭肉中TM S残留的快速检测方法是可行的。     

离子抑制剂对苯甲酸等9种食品添加剂的反相液相色谱行为的影响

研究了反相高效液相色谱(RP-HPLC)流动相中酸性离子抑制剂三氟乙酸(TFA)与缓冲盐离子抑制剂TFA-乙酸铵(AmAc)对安赛蜜、糖精、咖啡因、阿斯巴甜、苯甲酸、山梨酸、甜菊糖苷、脱氢乙酸和纽甜等9种食品添加剂色谱保留行为的影响。着重探讨了TFA与TFA-AmAc作为离子抑制剂的有机调节剂作用,考察了乙腈-TFA水溶液和乙腈-TFA-AmAc水溶液流动相体系中溶质的保留因子与离子抑制剂体积分数之间的关系。在最佳流动相组成(乙腈-TFA (0.01%, v/v)-AmAc (2.5 mmol/L)水溶液)条件下梯度洗脱,苯甲酸等9种食品添加剂实现了基线分离。9种食品添加剂在10.0～100.0 mg/L内具有良好的线性关系(r2＞0.9991);检出限为0.33～2.36 mg/L,定量限为1.11～7.80 mg/L;9种食品添加剂在空白干红葡萄酒中的添加回收率为87.61%～108.4%,其相对标准偏差为2.2%～9.4%。本实验结果对于食品中多组分食品添加剂的RP-HPLC分离分析方法的建立和优化具有较好的指导意义。     

Au@SiO2核壳结构-表面增强拉曼光谱原位检测食品中的酸性橙Ⅱ

以具有核壳结构的Au@SiO2纳米颗粒为基底,建立了一种以表面增强拉曼(SERS)原位、快速检测食品中非法添加剂酸性橙Ⅱ的新方法.研究了活性硅加入量对所形成的Au@SiO2纳米颗粒的SERS活性的影响,制备了具有最佳SERS活性的Au@SiO2,并以此为SERS基底建立了酸性橙Ⅱ的分析方法,可实现0.17 mg/L酸性橙Ⅱ的SERS检测.将合成的Au@SiO2滴加到瓜子表面后,可以实现对瓜子表面酸性橙Ⅱ浓度为0.01 mg/g时的SERS检测,能够满足食品中酸性橙Ⅱ的测定要求,有望用于瓜子及其它可能被非法添加该物质的食品的现场、快速检测.     

构筑内标化表面增强拉曼散射基底用于梨汁中福美双的检测

本文基于表面增强拉曼光谱(SERS)技术，以内嵌有4-巯基苯甲腈(4-MBN)的银包金核壳纳米粒子(Au@4-MBN@AgNPs)为SERS基底，结合高通量疏水纸基，建立了一种免标记、高灵敏的福美双检测方法。内标探针4-MBN的引入显著提高了SERS基底的重现性；疏水纸基的使用进一步提高了检测的灵敏度。结果表明：福美双与内标探针的SERS信号强度比值(I_R=I₁₃₈₁/I₁₅₈₂)与不同浓度福美双之间具有较好的线性关系，相关系数R²为0.9990,检出限(LOD)为2.70×10^-10 mol/L。梨汁中加标回收率为85.36%～89.15%,与高效液相色谱-串联质谱法的检测结果(86.21%～91.68%)具有较好的一致性。本文提出的福美双检测方法操作简单、成本低、普适性强，为农残的快速、准确定量检测提供了新的可能。     

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.     

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.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.