气相色谱-串联质谱法同时测定烟用水基胶中15种邻苯二甲酸酯类化合物

采用气相色谱-串联质谱法同时测定烟用水基胶中15种邻苯二甲酸酯类化合物的含量。烟用水基胶样品0.300g经2mL水分散,用10mL正己烷萃取5min。在气相色谱分离中用DB-35MS色谱柱为固定相,在质谱分析中采用多反应监测模式。15种邻苯二甲酸酯类化合物的质量浓度均在0.05~5.0 mg·L~(-1)内与其对应的峰面积呈线性关系,方法的检出限(3S/N)为0.006~0.027μg·g~(-1)。在4,20,100μg·g~(-1)等3个浓度水平进行加标回收试验,回收率为87.8%~104%,测定值的相对标准偏差(n=6)为1.3%~6.1%。     

磁性石墨烯分散固相萃取结合液相色谱-串联质谱法测定水基胶中的双酚A和烷基酚

建立了超高效液相色谱-串联质谱(UPLC-MS/MS)与磁性石墨烯相结合测定水基胶中双酚A、壬基酚和辛基酚的方法。样品提取后,以磁性石墨烯分散固相萃取净化,经BEH C18色谱柱分离。分析物的回收率在81.5%～97.9%之间,日间相对标准偏差(RSDs)小于8.0%。所有化合物均获得了良好的线性系数(r≥0.9996),检出限(LOD)和定量限(LOQ)范围分别为3～8μg/kg和10～26μg/kg。采用该方法对20个水基胶实际样品进行检测,仅有1个样品检出4-正壬基酚。该方法可用于测定水基胶中双酚A和4种烷基酚的含量。     

超高效液相色谱-串联质谱法测定纺织品中19种邻苯二甲酸酯

采用超高效液相色谱-串联质谱法(UPLC-MS/MS)测定纺织品中19种邻苯二甲酸酯(PAEs)类化合物。实验采用Waters C_(18)色谱柱(50×2.1 mm,1.7μm),以甲醇-0.1%甲酸溶液为流动相,流速为0.4μL/min,采用梯度模式洗脱;质谱采用正离子电离模式(ESI+),多反应监测模式(MRM)检测。19种PAEs在其线性范围内线性良好(r20.994),定量限(S/N=10)为0.1~0.5mg/kg,回收率为88.8%~112.6%,相对标准偏差(RSDs,n=6)为1.1%~10.9%。实验表明该方法检测速度快,灵敏度高,适合纺织品中增塑剂的检测。     

固相萃取-超高效液相色谱法测定烟用水基胶中丙烯酰胺

建立了采用固相萃取-超高液相色谱/紫外检测测定烟用水基胶中丙烯酰胺的分析方法。样品经超纯水进行超声提取,固相萃取柱进行富集净化后,经HSS T3色谱柱分离,以甲醇和水为流动相等度洗脱,紫外检测,外标法定量。结果显示,丙烯酰胺在浓度0.01~20.0μg·mL-1范围内有良好的线性关系,相关系数为0.9999。丙烯酰胺三个不同浓度的加标回收率为91.7%~105.1%;相对标准偏差为1.3%~4.7%(n=6);检出限为3.5μg·L-1。该方法分析时间短、结果准确可靠,满足烟用水基胶中丙烯酰胺的测定。     

气相色谱-质谱联用同时测定蔬菜中16种邻苯二甲酸酯残留

研究了蔬菜中16种邻苯二甲酸酯(PAEs)环境激素残留的气相色谱-电子轰击离子源质谱(GC-EI/MS)分析方法。优化了样品的前处理条件,以苯甲酸苄酯(BB)为内标物,采用GC-EI/MS的选择离子检测方式(SIM)进行定性和定量分析。当蔬菜样品的加标浓度水平分别为100和200μg/kg时,加标回收率为70.9%~123.0%,相对标准偏差为1.6%~15%。除邻苯二甲酸二甲氧基已酯(DMEP)外,其它15种PAEs的方法检测限(MDL)均为0.11~2.77μg/kg。在50.0~800.0μg/kg浓度范围内16种PAEs都呈现良好的线性关系,r为0.99623~0.99998。方法已用于5种蔬菜中16种痕量PAEs残留的分析。     

气相色谱-负化学电离质谱法测定塑料中十七种邻苯二甲酸酯

建立了气相色谱-负化学电离质谱法(GC-NCI/MS)同时测定塑料中17种邻苯二甲酸酯(PAEs)的分析方法。塑料样品经二氯甲烷超声提取并过滤后进行检测。采用HP-5 MS毛细管色谱柱在程序升温条件下对滤液进行色谱分离,质谱采用负化学电离(NCI)模式,反应气采用氨气。17种PAEs在0.05~3.5 mg/L范围内线性关系良好,相关系数(r)均大于0.995;检出限为0.018~2.162 mg/kg;在100,500,1000,5000 mg/kg 4个添加水平下,17种PAEs的平均加标回收率为95.8%~106.5%,RSD(n=6)为2.6%~7.9%。方法可用于塑料产品中17种邻苯二甲酸酯的检测。     

顶空-气相色谱法测定烟用水基胶中乙酸乙烯酯的残留量

采用顶空-气相色谱法测定烟用水基胶中乙酸乙烯酯的残留量。以N,N-二甲基甲酰胺为基质校正剂、正丙醇为内标,通过顶空进样后,采用HP-VOC色谱柱分离,火焰离子化检测器(FID)检测。乙酸乙烯酯的质量浓度在0.51~50mg·L-1范围内呈线性,方法的检出限(3S/N)为0.82μg·g-1。方法用于不同烟用水基胶中乙酸乙烯酯残留量的测定,加标回收率在96.2%~101%之间,测定值的相对标准偏差(n=6)小于3%。     

超高效液相色谱-串联质谱法快速测定口服液中非法添加的25种激素

建立了快速检测延缓衰老口服液中9种孕激素、7种雄激素、7种糖皮质激素及2种雌激素的超高效液相色谱-串联质谱(UPLC-MS/MS)方法。样品经1%乙酸-乙腈溶液、甲醇分步提取,浓缩至干后,用甲醇-水(1∶1)溶解残渣,Shim-pack XR-ODSⅡ色谱柱梯度分离,采用电喷雾正离子模式电离,基质匹配标准曲线定量。结果表明:25种化合物在0.5~50μg/L范围内呈良好的线性关系,相关系数均大于0.99,定量下限为0.099~0.492μg/kg,检出限为0.029~0.147μg/kg。在0.5,1.0,5.0μg/kg 3个加标水平下,各化合物的平均回收率为73.3%~122.2%,相对标准偏差(RSD)为5.1%~14.9%。该方法简便、快速、准确,适用于延缓衰老口服液中多种激素的同时、快速测定。     

畜肉中10种镇静剂残留的超高效液相色谱-串联质谱测定方法

建立了一种灵敏的超高效液相色谱-串联四极杆质谱(UHPLC-MS/MS)方法,并用于动物肌肉组织(猪肉、牛肉、羊肉)中10种兽药镇静剂的同时测定。样品酶解后,经乙腈提取,MCX固相萃取净化,以ACQUITY UPLC CSH C18色谱柱分离,UPLC-MS/MS的多反应监测(MRM)模式,用同位素稀释内标法(安眠酮采用基质匹配外标法)进行分析。10种镇静剂在0.5~100μg/L范围内显示良好线性(r2≥0.993 6),其检出限(LOD)不高于0.5μg/kg,定量下限(LOQ)不高于1.0μg/kg。在1.0,5.0,50.0μg/kg加标水平下,10种镇静剂的平均回收率为82.0%~116.0%,相对标准偏差(RSDs)为0.6%~12.8%。该方法准确可靠,适用于畜肉中镇静剂多残留的分析。     

超高效液相色谱-串联质谱法同时检测植物叶片中吲哚-3-乙酸及其3种氧化产物

以玉米叶片为供试材料,建立了同时测定植物体内吲哚-3-乙酸(IAA)及其3种氧化产物吲哚-3-甲醇(ICI)、吲哚-3-甲醛(ICA)、吲哚-3-羧酸(IFA)含量的超高效液相色谱-串联质谱(UPLC-MS/MS)方法。结果表明,该方法对IAA及其3种氧化产物检测的线性、精密度和重复性较好,灵敏度较高,4种化合物的检出限为0.002~1.63μg/kg,定量下限为0.007~5.43μg/kg;方法的加标回收率为89.5%~95.3%,相对标准偏差为2.3%~5.1%。玉米叶片的实际测定结果表明,IAA,ICI,ICA和IFA的含量分别为(196.25±7.10),(26.21±2.13),(18.65±2.02),(13.62±2.06)μg/kg。该方法已成功应用于小麦、豌豆、硬毛刺苞菊叶片的测定,通用性较好。     

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.