HPLC法快速测定熟肉制品中10种食品添加剂

建立了熟肉制品中10种食品添加剂的高效液相色谱分析方法。以乙醇–氨水溶液为提取溶剂,样品经超声波辅助溶剂萃取法萃取后,以Atlantis d C18(250 mm×4.6 mm,5μm)色谱柱为分离柱,20 mmol/L乙酸铵–甲醇为流动相进行分离测定。10种目标化合物的质量浓度在1.0~200.0 mg/L范围内与其峰面积线性关系良好(r0.999),在20.0,500.0,1 000.0 mg/kg的添加水平下,10种目标化合物的平均加标回收率为82%~104%,测定结果的相对标准偏差小于4.0%(n=6),方法的检出限为1.0~5.0 mg/kg(S/N=3)。该方法简单、快速、准确,适合于熟肉制品中食品添加剂的检测。     

固相萃取-高效液相色谱法测定水产品中喹乙醇

建立了固相萃取-高效液相色谱法测定水产品中喹乙醇的方法。匀浆后的水产品试样经甲醇溶液提取、正己烷除脂、固相萃取小柱直接净化浓缩后,以体积分数15%的甲醇溶液作为流动相,流速:1.0 m L/min,采用Symmetryshield TM RP18色谱柱进行分离,紫外检测器检测,外标法定量。方法的检出限和定量限分别为0.02 mg/kg和0.05 mg/kg,浓度在0.05~1.00 mg/L范围内,线性良好(r=0.9999)。添加浓度在0.05~1.00 mg/kg时,不同品种水产品的回收率在78%~99.6%之间,相对标准偏差小于7.7%。方法适合于水产品样品的成批定量检测。     

气相色谱法测定溶剂型木器涂料中异佛尔酮含量

建立一种快速测定溶剂型木器涂料中异佛尔酮含量的气相色谱法。样品经乙酸乙酯提取,采用Rtx–1701毛细管色谱柱分离后,以十四烷作内标物,内标法定量。该方法中异佛尔酮质量浓度在10~200 mg/L范围内呈良好的线性关系,相关系数r=0.999 98,方法检出限为10 mg/kg。样品平均加标回收率为92.2%~97.1%,测定结果的相对标准偏差为0.13%~1.25%(n=6)。该方法能有效地对溶剂型木器涂料中异佛尔酮进行定性、定量分析,而且具有简单、快速、准确、检出限低等特点,能满足实验要求。     

气相色谱-质谱法检测豆制品中的二甲基黄

建立气相色谱–质谱法测定豆制品中二甲基黄的方法。考察了不同样品前处理方法对回收率的影响。试样用d SPE纯化管超声净化后,以10 mL乙腈提取。样品溶液经毛细管气相色谱柱HP–5MS分离,以质谱检测器(MSD)测定其中的二甲基黄含量。二甲基黄的质量浓度在0.05~1.5 ng/mL范围内与响应值呈良好的线性关系,相关系数r=0.999 1,检出限为0.005 mg/kg。加标水平为0.005~1.0 mg/kg时的平均回收率为70%~88%,测定结果的相对标准偏差为2.5%~8.0%(n=6)。该方法净化效果好,灵敏度高,适合于豆制品中二甲基黄的检测。     

高效液相色谱法测定面粉及面粉制品中乙二胺四乙酸二钠的含量

在未使用离子对试剂和高盐缓冲液条件下,采用亲水性C_(18)反相液相色谱柱,以甲醇-水体系为流动相,建立了面粉及面粉制品中乙二胺四乙酸二钠含量的高效液相色谱测定方法。样品采用水溶液提取,在超声辅助下与三氯化铁反应生成稳定的衍生产物,用三氯甲烷净化衍生产物。采用高效液相色谱法以pH 4.0甲醇-水溶液(10∶90,体积比)为流动相,亲水性C_(18)反相液相色谱柱为固定相,260 nm波长下测定面粉及面粉制品中乙二胺四乙酸二钠含量。乙二胺四乙酸二钠的质量浓度在1.0~50.0 mg/L范围内呈良好的线性关系,其相关系数为0.999 6,检出限为3.0 mg/kg,定量下限为10.0 mg/kg。面粉样品添加浓度在10.0~200 mg/kg范围内,加标回收率为95.0%~103%,相对标准偏差为4.0%~6.3%,可满足面粉及面制品中乙二胺四乙酸二钠的快速检测和定量分析要求。     

高效液相色谱-串联质谱法测定水果中残留的烯唑醇

建立了水果中烯唑醇残留量的高效液相色谱-串联质谱（LC-MS/MS）测定方法。样品采用丙酮-正己烷液液振荡提取,经分散固相萃取（DSPE）净化后,采用ODS-C18柱为分离柱,以乙腈-0.1％甲酸溶液为流动相,采用液相色谱-串联质谱(ESI)多反应监测（MRM）正离子模式测定,外标法定量。烯唑醇在0.002～0.2 mg//L质量浓度范围内线性关系良好,方法定量下限（LOQ）为0.001 mg/kg。在0.005～0.1 mg/kg之间的3个添加浓度水平下,添加回收率为78.8 %~108.0 %,相对标     

液相色谱-串联质谱法测定饲料中的游离棉酚

建立了高效液相色谱-串联质谱法(LC-MS/MS)定量测定饲料中棉酚残留的分析方法。待测物经丙酮-水(7∶3)混合溶液振荡提取,C18色谱柱(100 mm×2.1 mm,3.5μm)分离,以乙腈和0.1%甲酸为流动相进行梯度洗脱,串联质谱测定,外标法定量。方法的定量下限(S/N10)为1 mg/kg;棉酚在10~100μg/L质量浓度范围内,线性相关系数为0.993。以1、20、40 mg/kg浓度进行加标后测得平均回收率为83.8%~97.5%,相对标准偏差为1.3%~5.2%。该方法操作简单、回收率稳定,可用于饲料中棉酚残留的快速确证及定量分析。     

RP-HPLC法测定中药材蚂蟥中蚂蟥多肽的含量

建立了一种测定蚂蟥药材中抗凝血活性多肽类化合物蚂蟥多肽含量的反相高效液相色谱(RP-HPLC)新方法。色谱柱采用Hypersil-C18柱(200×4.6mm,5μm),流动相为乙腈和水(体积比为2:98),加入质量分数0.03%KH2PO4,再用体积分数36%HAc调至pH 3.80,检测波长280 nm,流速1.0 mL/min,柱温35℃。当蚂蟥多肽的质量浓度为186~942 mg/L时,其峰面积与质量浓度的线性关系良好(r=0.9996);平均回收率为99.8%,RSD<2%。方法可作为蚂蟥药材或含有蚂蟥药材的中成药的质控方法。     

固相萃取-超高效液相色谱-电喷雾串联质谱法同时测定食品中13种抗氧化剂

建立了固相萃取-超高效液相色谱-电喷雾串联三重四极杆质谱联用技术分析食品中13种抗氧化剂的方法。样品经固相萃取后,以Agilent Eclipse Plus C18色谱柱为分离柱,以乙腈和水为流动相进行梯度洗脱,电喷雾离子源电离、正负离子多反应监测模式质谱进行定性和定量分析。13种抗氧化剂质量浓度在0.1~5 mg/L范围内线性良好,相关系数为0.9936~0.9993,方法的定量限为0.5 mg/kg;在不同种类食品中3个添加水平的平均回收率为80.5%~118.8%,相对标准偏差为0.8%~9.1%。应用本方法检测食品中的抗氧化剂,分别检测出4种食品中含有抗氧化剂。     

微波辅助萃取-分散固相萃取-气相色谱质谱法测定茶叶中23种农药残留

建立了微波辅助萃取-分散固相萃取净化-气相色谱质谱法（GC-MS）快速测定茶叶中23种农药残留量的方法. 茶叶样品用乙腈进行微波辅助萃取（MAE）,提取液经分散固相萃取（DSPE）净化处理. 采用DB-17MS毛细管色谱柱分离后,选择离子监测模式下（SIM）质谱法进行测定. 23种农药组分在0.01~0.50 mg/mL质量浓度范围内呈线性关系,相关系数r2大于0.995,方法测定低限（10S/N）为0.005~0.01 mg/kg. 以空白绿茶为基体,在4个标准添加水平0.01、0.05、0.10、0.25 mg/kg进行加标回收试验,加标平均回收率为70%~105%,相对标准偏差为3.0%~8.2%.     

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.     

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%).     

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.     

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.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

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.