GC-MS/SIM法同时测定食品中的苏丹红Ⅰ~Ⅳ

采用气相色谱-质谱(GC-MS)选择离子检测法(SIM),建立了准确可靠、灵敏度高、快速简便的同时测定食品中苏丹红Ⅰ~Ⅳ的新方法。色谱柱为PR-SR石英毛细管柱(20m×0.25mm),进样口温度280℃,柱温200℃,以15℃/min升至280℃;柱前压130kPa,载气He;EI离子源,选择m/z77,105,115,143,176,247,248,261,352,380用于SIM检测,并按不同的采样时间分成4组,每组4个离子,分别对应于每种苏丹红进行定性分析确证;选择苏丹红Ⅰ~Ⅳ各自的分子离子峰m/z248,276,352,380作抽出离子图进行定量分析。苏丹红Ⅰ、Ⅱ的线性范围为0.01~10.0mg/L,苏丹红Ⅲ、Ⅳ的线性范围为0.1~10.0mg/L;检出限苏丹红Ⅰ、Ⅱ为1μg/kg,苏丹红Ⅲ为5μg/kg,苏丹红Ⅳ为10μg/kg;回收率86%~95%。本法与欧洲健康与消费者保护委员会的方法(HPLC法)相比灵敏度高1~2个数量级,分析时间缩短,用色谱保留时间、质谱同时定性,消除了食品中杂质的干扰,结果准确可靠,选择性和重复性好,适用于所有食品成品及原料的检验。     

串级质谱法鉴定食品中苏丹红一号

利用气相色谱串级质谱(GC/MS/MS)法定性定量鉴定食品中染料苏丹红一号,建立了离子阱气相色谱-质谱联用仪分析食品中苏丹红一号染料的方法。结果表明,苏丹红一号在0.045~0.90 mg.L-1浓度范围内呈线性关系,相关系数为0.999 0,检测下限为0.004 5 mg.kg-1,回收率在83.1%~103.2%之间。方法具有样品预处理简单、灵敏度高、检出限低于现行国家标准水平,确证能力强等特点,满足食品中苏丹红一号的定性定量监测。     

气相色谱-质谱法测定奶粉及奶制品中的三聚氰胺

摘采用气相色谱-质谱（GC-MS）分析技术,选择离子检测法（SIM）,开发出一种准确可靠、灵敏度高的测定奶粉及奶制品中三聚氰胺的新方法。色谱柱为DB-1 Ms石英毛细管柱,进样口温度280℃,柱温75℃,保持1min,再以30℃／min升至290℃。载气He,流量1．0mL／min。EI离子源,选择m／z 171、285、327、342用于SIM检测,根据这4个离子的抽出离子色谱图的峰面积比进行目标物确证,以基峰m／z 327做定量分析。三聚氰胺的线性范围为0．01～50mg／L,平均回收率为90％～98％,检出限为1μg／kg,定量下限为5μg/kg。该法与现有方法相比灵敏度提高了2个数量级,用色谱保留时间、质谱同时定性,消除了奶粉及奶制品中杂质的干扰,避免了可能产生的假阳性,结果准确可靠,选择性和重复性好,适用于奶粉及奶制品的检验。     

高效液相色谱-串联质谱法同时检测化妆品中6种禁用着色剂

建立了高效液相色谱-串联质谱(HPLC-MS/MS)同时测定膏状和粉状化妆品中苏丹红IV、酸性紫49、苏丹蓝2、溶剂红49、碱性紫1和颜料橙5等6种禁用着色剂的检测方法。样品经乙醇-乙腈(3:2, v/v)超声振荡提取20 min、离心净化及氮吹浓缩后,在Luna C18色谱柱(150 mm×2.1 mm, 5 μm)上进行反相液相色谱分离,以甲醇和10 mmol/L乙酸铵溶液为流动相进行梯度洗脱,采用多反应监测(MRM)模式进行质谱测定。根据保留时间及质谱图上特征离子的相对丰度比进行定性,外标法定量。结果表明: 6种着色剂的定量限(信噪比为10计)为0.1～10 μg/kg,回收率为86.67%～98.22%,相对标准偏差(RSD)为4.01%～7.01%。该方法简便、快速、灵敏度高且重现性好,适合于化妆品中禁用着色剂的定性与定量。     

高分辨热裂解气相色谱/质谱法快速定性检测农产品中的单增李斯特菌

要在高分辨率热裂解气相色谱/质谱(HRPGC/MS)系统中采用选择离子检测法(SIM),建立了准确可靠、灵敏度高、快速简便的检测农产品中单增李斯特菌的方法.裂解条件:起始温度50℃;升温速率20℃/min,裂解室温度230℃;裂解温度650℃;裂解时间为10 s.气相色谱条件:载气为氦气;恒定流速0.9 mL/min;DB-WAXTER毛细管色谱柱;起始温度45℃;保持4min,以6℃/min的速率上升到100℃,然后以10℃/min上升到200℃,接着以12℃/min上升至250℃,并保持25 min.分流比为50∶1.EI离子源.选择色谱保留时间19.056 min,鉴别离子m/z 54,98,用于SIM检测.通过对单增李斯特菌、2种空白农产品和2种不同农产品污染单增李斯特菌的样品检测结果表明,HRPGC/MS方法检测不同黄瓜、牛肉农产品中单增李斯特菌,均能得到很好的反映.本方法分析时间缩短,用保留时间、质谱同时定性,消除了不同种类农产品杂质的干扰,结果准确可靠,选择性和重复性好,适于快速检测农产品中的单增李斯特菌.     

气相色谱-质谱法测定聚醚砜奶瓶中二苯砜的含量及迁移量

采用气相色谱-质谱联用仪(GC-MS)对聚醚砜(PES)奶瓶中的二苯砜进行定性确证和定量分析。样品粉碎并用三氯甲烷超声溶解后,用乙腈沉淀树脂。选用HP-5MS色谱柱并使用选择离子扫描(SIM)模式进行定性和定量分析。定性离子为m/z77、97、125和218,定量离子为m/z125。二苯砜的线性范围为0.1～100mg/L,仪器的定量检出限为0.004mg/L。奶瓶样品中二苯砜的加标回收率为91%～113%,相对标准偏差(RSD)小于7.7%。将奶瓶进行迁移实验后,水、酸性和油性食品模拟物分析的加标回收率分别为88%～102%、96%～111%和89%～110%,RSD分别为5.2%、5.4%和8.7%。     

高效液相色谱-质谱法对饲料及食品添加剂中三聚氰胺的测定

建立了饲料中三聚氰胺的高效液相色谱-质谱测定方法.色谱条件:Kromasil C18柱(4.6 mm×250mm,5 μm),流动相:乙腈-0.1%(体积分数)甲酸(体积比5:95),流速0.4 mL/min.采用正离子模式的电喷雾质谱检测,以一级质谱得到的准分子离子m/z 127作为母离子,进行碰撞诱导解离(CID)二级质谱(MS2)分析,选择母离子和MS2的碎片离子m/z 85、109定性确证,提取m/z 85、109、127三个离子质量色谱峰面积定量.实验优化了质谱条件.线性范围为0.01～0.5 mg/L,检出限0.01 mg/L(S/N=3),回收率为80%～99%.     

超声波提取-气相色谱-质谱联用法测定苏丹红Ⅰ残留量

研究了苏丹红Ⅰ的气-质联用检测方法。样品中的苏丹红Ⅰ用超声波提取,采用选择离子(SIM)方式,据保留时间和特征离子丰度比对其进行确证。此方法可以在13 min之内定性和定量地快速检测苏丹红Ⅰ残留,通过多次试验验证,添加量为0.01~1.00μg,回收率在82%~97%之间,相对标准偏差小于5%,检出限为6.0×10-4μg/g。     

超高效液相色谱-串联质谱快速筛查葡萄酒中的14种禁用食品添加剂

建立了同时测定葡萄酒中14种禁用食品添加剂的超高效液相色谱-电喷雾电离串联质谱(UPLC-ESI-MS/MS)分析方法。采用UPLC BEH C18(100 mm×2.1 mm×1.7 mm)色谱柱,对流动相的组成、缓冲液离子强度及质谱的各种参数进行了优化。结果表明,流动相的离子强度对食品添加剂的质谱检测有重要影响,以含1 mmol/L甲酸铵-甲酸缓冲液(pH 3.9)-乙腈为流动相,梯度洗脱,柱温35℃,可以在6 min内完成14种食品添加剂的分离和检测。在ESI负离子模式下,采用选择离子监测方法进行测定时,除三氯蔗糖、日落黄和酸性红13的检出限分别为10,2和2 mg/L外,其它11种的检出限在0.01~1.0 mg/L之间。回收率为93.8%~106%,相对标准偏差小于3.1%。本方法快速、准确、灵敏度高,可用于葡萄酒及其它复杂基质食品中的低剂量、多种禁用食品添加剂的同时筛查。     

液相色谱-离子阱质谱联用分析食品中的对位红

用液相色谱/电喷雾-离子阱质谱联用建立准确测定食品中对位红染料的方法。样品中的对位红用乙腈提取,浓缩后直接进行分析。色谱柱为Agilent C18(4.0×125 mm,5μm),流动相为乙腈-0.5%乙酸溶液(体积比70∶30),等梯度洗脱,流速为0.5 mL.m in-1,外标法定量。质谱采用正离子电离方式,选择m/z156和277碎片离子作为定性离子,以丰度最高的碎片离子m/z277作为定量离子。对位红染料的检出限(LOD)为1.03 ng.g-1,定量下限(LOQ)为3.08 ng.g-1;回收率为86%~112%,重复性好。本法操作简便、灵敏准确,且分析时间较短,分析周期仅需9 m in,适合大批样品的快速分析检测。     

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.     

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.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.