微波条件下双酚A向食品模拟物的迁移研究

采用气相色谱-质谱联用法研究了微波条件对食品接触材料中双酚A在水、乙酸（3%,体积分数）、乙醇（10%,体积分数）、橄榄油4种食品模拟物中迁移行为的影响。在微波加热下,食品快速升温并能将热量传递给外部包装,从而加速包装材料中双酚A向食品的迁移。研究了不同微波温度、时间和功率下双酚A在4种食品模拟物中的迁移规律,结果表明：微波对双酚A迁移有显著影响,迁移量随着微波温度、时间和功率的增加而增加。在相同加热温度和时间条件下,微波加热方式中双酚A在4种食品模拟物种的迁移量均高于水浴加热。     

超高效液相色谱－串联质谱法测定食品接触用纸和纸制品中乙烯亚胺的迁移量

采用超高效液相色谱－串联质谱（UPLC－MS/MS）建立了食品接触用纸和纸制品中乙烯亚胺迁移量的测定方法。以0.1%（体积分数）甲酸水溶液和甲醇作为流动相,使用电喷雾离子源对目标物进行电离,采用多反应监测模式进行测定。结果表明,乙烯亚胺在4%乙酸、10%乙醇、95%乙醇与异辛烷模拟物中的线性范围为0.003 ~ 0.05 mg/L,检出限为1 μg/L;在橄榄油模拟物中的线性范围为0.003 ~ 0.05 mg/kg,检出限为1 μg/kg。各食品模拟物中,乙烯亚胺的加标回收率为96.0% ~ 102%,相对标准偏差（RSD）为1.6% ~ 5.9%。采用该方法对20批次实际样品进行检测,有2批次检出乙烯亚胺。该方法简单快速,具有较高的准确性、灵敏度,适用于食品接触用纸和纸制品中乙烯亚胺迁移量的检测。     

食品接触材料中19种紫外光吸收剂迁移量的测定及迁移规律研究

建立了食品接触材料中19种紫外光吸收剂迁移量测定的高效液相色谱法。研究了不同食品模拟物及浸泡时间对紫外光吸收剂迁移量的影响。实验结果表明,紫外光吸收剂在水、3%乙酸、低浓度的乙醇中迁移量低,在95%乙醇和异辛烷模拟物中迁移量高,迁移规律性与紫外光吸收剂的分子结构密切相关。食品接触材料中紫外光吸收剂在80℃浸泡6 h的迁移量与40℃浸泡10 d相当。所建立液相色谱法的定量下限为0.1~0.5 mg/kg,在95%乙醇和异辛烷模拟物中,3个加标水平下的回收率为83.8%~98.0%。方法的灵敏度与回收率高,选择性好,能满足实际工作的要求。     

聚酯类食品包装材料中二氧化钛在食品模拟物中的迁移规律

采用电感耦合等离子体质谱法(ICP–MS),在不同的模拟迁移条件(模拟物、盛放温度、接触时间、乙酸浓度、使用次数等)下,研究聚酯类食品包装材料中二氧化钛在6种食品模拟物(水、4%乙酸、10%乙醇、65%乙醇、正己烷和异辛烷)中的迁移规律。结果显示:食品模拟物的属性对迁移行为有显著影响,迁移量随温度的升高及时间的延长而增加,食品的酸性越强,二氧化钛的迁移量越大。因此需适量控制聚酯类食品包装材料的反复使用次数、盛放食品时的温度和时间以降低二氧化钛迁出风险。     

聚乳酸生物降解复合膜向食品模拟物的总迁移及钙的迁移研究

研究了5种不同碳酸钙含量的PLA/PBAT/CaCO3复合膜中的钙在40 ℃和70 ℃下向3%乙酸食品模拟物的迁移及向3种食品模拟物（3%乙酸、10%乙醇、95%乙醇）的总迁移,探究了复合膜中碳酸钙含量与总迁移的关系,并研究了紫外老化处理对迁移的影响。结果表明,5种复合膜向3%乙酸中的总迁移量均超过总迁移限值（OML）,且总迁移主要受复合膜中碳酸钙含量的影响,钙浓度与总迁移量呈线性关系。同时,随着复合膜中碳酸钙含量的增加,钙的迁移量增加,且不同碳酸钙含量的复合膜均在短时间内达到迁移平衡（40 ℃,4 h）。将复合膜紫外老化处理较长时间（24 h以上）会导致钙的迁移量减少,可能的原因是紫外照射引起聚己二酸/对苯二甲酸丁二酯（PBAT）的交联反应,从而抑制了钙的迁移。此类生物降解复合膜作为食品接触材料的安全性值得进一步关注和研究。     

Determination of the migration of 8 benzophenones in food contact materials and products by HPLC-MS / MSEI北大核心CSCD

建立了高效液相色谱-串联质谱法测定食品接触材料及制品中8种二苯甲酮类物质迁移量的方法。样品经过食品模拟物浸泡后，水、4%乙酸、10%乙醇、20%乙醇、50%乙醇模拟物直接进样，95%乙醇模拟物用水按照1:4比例稀释后进样，橄榄油和异辛烷模拟物用甲醇-水混合溶液萃取后进样。采用C₁₈柱分离，用甲醇-0.1%甲酸水溶液为流动相梯度洗脱，质谱采用正离子多反应监测（MRM）模式运行。本方法在8种食品模拟物中的定量限为0.01～0.20 mg/kg;在0.04～0.80 mg/kg, 0.2～2.0 mg/kg, 0.6～3.0 mg/kg线性范围内相关系数良好（R≥0.9958）;加标实验结果显示相对标准偏差（RSD）为0.61%～7.8%。该方法可用于食品接触材料及制品中二苯甲酮类物质迁移量的测定。     

食品包装材料中双酚A在食品模拟物中迁移规律的研究

食品塑料包装材料的安全是保障食品安全的重要一环,包装材料中的双酚A潜在迁移性对人体健康的危害已引起社会的关注. 分别选取蒸馏水、3%乙酸(体积分数)和10%乙醇(体积分数)3种食品模拟物,浸泡已知双酚A含量的食品包装材料,在一定的时间点测试浸泡液中双酚A含量,研究迁移量与模拟物之间的关系. 结果表明,在不同食品模拟物下包装材料中双酚A的迁移量不同,其特定迁移量顺序为10%乙醇溶液>3 %乙酸溶液>蒸馏水. 并研究了温度、时间及微波作用影响食品包装材料中双酚A向食品中的迁移量,结果表明,双酚A向食品中迁移量随接触时间的延长、温度的升高而增加,微波作用能显著提高包装材料中双酚A向食品中的迁移量.     

HPLC同时检测食品接触材料中三聚氰胺与三聚氰酸单体迁移量

建立了一种用液相色谱技术检测分析食品接触材料中三聚氰胺与三聚氰酸单体迁移量的方法.样品采用水、4%乙酸和10%乙醇3种模拟物进行浸泡.色谱分离采用Phenomenex Luna NH2柱,柱温:30 ℃,流动相为乙腈-5 mmol/L,pH=6.5 PBS缓冲溶液(75∶25,V/V),流速1.0 mL/min,DAD...     

高效液相色谱法测定食品接触材料中苯酚和4-叔丁基苯酚迁移量

提出了食品接触材料在水、3％(质量分数)乙酸溶液、乙醇(1+9)溶液、异辛烷4种食品模拟物中苯酚、4-叔丁基苯酚迁移量的高效液相色谱测定方法.不同种类的食品模拟物采用不同的样品前处理方法提取后,用Diamonsil C18色谱柱为固定相,甲醇-水为流动相梯度洗脱,以激发波长220 nm、发射波长312nm的荧光检测器进...     

高效液相色谱-紫外法快速测定塑料类食品接触材料及制品中7种对苯二甲酸酯或苯甲酸酯的特定迁移量

建立了高效液相色谱-紫外检测（HPLC-UV）法快速测定从塑料类食品接触材料及制品迁移至10%（v/v）乙醇、3%（m/v,即3 g/100 mL）乙酸、4%（v/v）乙酸、20%（v/v）乙醇、50%（v/v）乙醇、95%（v/v）乙醇和橄榄油7种食品模拟物中对苯二甲酸二甲酯、对苯二甲酸二辛酯、苯甲酸甲酯、苯甲酸乙酯、苯甲酸丙酯、苯甲酸丁酯和新戊二醇二苯甲酸酯的特定迁移量。考察了多种提取溶剂、QuEChERS dSPE EMR-Lipid试剂盒和Captiva EMR-Lipid试剂盒对橄榄油食品模拟物中7种对苯二甲酸酯或苯甲酸酯的提取或净化效果。以甲醇和水为流动相进行梯度洗脱,7种对苯二甲酸酯或苯甲酸酯在苯基柱上于17 min内达到基线分离。检测波长为237 nm,进样量为10 μL。7种对苯二甲酸酯或苯甲酸酯在7种食品模拟物中的定量限为0.2~8.1 mg/kg、1~80 mg/L或8~160 mg/kg,相关系数r≥0.9998。在2或8、60、80或160 mg/kg 3个加标水平的回收率为91.7%~106%,相对标准偏差为0.1%~3.1%。该方法样品前处理简便,色谱分离和线性关系好,回收率和重复性较好,已应用于实际样品的检测。     

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.