凝胶渗透色谱-气相色谱法测定豆瓣酱中6种防腐剂

提出了气相色谱法测定豆瓣酱中山梨酸、苯甲酸、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯、对羟基苯甲酸丁酯共6种防腐剂含量的方法。豆瓣酱样品用乙醚提取,所得提取液须经凝胶色谱净化大分子干扰物质。方法中采用Biobeads S-X3凝胶渗透色谱净化柱和乙酸乙酯-环己烷(1+1)混合溶液作流动相,采用Rxi(-17(0.25 mm×30 m,0.25μm)毛细管柱分离后,用氢火焰离子化检测器检测。6种防腐剂的质量浓度均在10.0~400 mg.L-1范围内与峰面积呈线性关系,方法的检出限(3S/N)在0.56~0.74 mg.kg-1之间。在3个浓度水平下对方法的回收率和精密度进行了试验,测定回收率在91.4%~98.8%之间,相对标准偏差(n=5)在2.9%~5.3%之间。     

气相色谱法测定修正类产品中10种苯类溶剂残留量

采用气相色谱法测定修正类产品中10种苯类溶剂的残留量。修正类产品样品用乙酸乙酯超声提取30min,用DB-WAX毛细管色谱柱(30m×0.32mm,0.25μm)分离,火焰离子化检测器检测。10种化合物的质量浓度均在0.20~100.0mg·L-1范围内与其信号强度呈线性关系,方法的测定下限(10S/N)在1.8~2.1mg·kg-1之间。以空白样品为基体进行加标回收试验,所得回收率在90.3%~113%之间,测定值的相对标准偏差(n=6)在1.8%~6.1%之间。     

超声萃取-气相色谱-质谱法测定卷烟主流烟气中的6种挥发酚

采用气相色谱-质谱法测定卷烟主流烟气中的苯酚、对甲酚、间甲酚、邻甲酚、对苯二酚和间苯二酚等6种挥发酚的含量。用剑桥滤片在标准抽吸条件下采集5支卷烟烟气粒相物,用甲醇超声萃取10min。所得萃取液用DB-624毛细管色谱柱(30m×0.25mm,1.4μm)为固定相进行分离,在质谱分析中采用全扫描和选择离子监测模式。以苯酚-D_5为内标物。方法的检出限(3S/N)在10~16ng·支~(-1)之间,测定下限(10S/N)在28~40ng·支~(-1)之间。加标回收率在84.6%~99.1%之间,测定值的相对标准偏差(n=6)在2.1%~6.4%之间。     

高效液相色谱法测定化妆品中5种季铵盐类防腐剂

建立了高效液相色谱法(HPLC)同时测定化妆品中5种季铵盐类防腐剂(西曲溴铵、西他氯铵、米他氯铵、劳拉氯铵和苄索氯铵)的检测方法。这5种季铵盐类防腐剂在15 min内能达到有效分离,在10~200μg/m L范围内线性良好,检出限在1.11~1.97μg/m L范围内,平均回收率为77.1%~110.2%。     

毛细管气相色谱法测定沉香中20种有机氯农药残留量

应用毛细管气相色谱法测定沉香中20种有机氯农药的残留量。样品以乙酸乙酯提取,提取液用凝胶色谱-固相萃取(GPC-SEP)进行净化。采用DB-1701P石英毛细管色谱柱(30m×0.25mm,0.25μm)分离样品,电子捕获检测器进行检测。20种有机氯农药的线性范围均为1~50μg·L-1,检出限均为0.1μg·kg-1。方法用于沉香样品分析,加标回收率在95.8%~114%之间,测定值的相对标准偏差(n=6)在0.3%~3.8%之间。     

气相色谱-质谱法测定化妆品中13种防晒剂

防晒剂广泛应用于化妆品中,是目前化妆品监管的重点。建立了同时测定化妆品中13种防晒剂的气相色谱-质谱(GC-MS)方法。化妆品样品经二氯甲烷提取后,涡旋超声后稀释。采用程序升温模式,经HP-5ms毛细管色谱柱(30 m×250 μm×0.25 μm)在30 min内对13种防晒剂实现分离,经电子轰击(EI)源电离后采用选择离子监测模式(SIM)扫描测定,外标法定量。比较了6种常用有机溶剂的基质效应和平均回收率,二氯甲烷的基质效应弱,平均回收率较高。13种防晒剂在相应的线性范围内线性关系良好,相关系数均大于0.998,检出限(LOD, S/N=3)为0.04~0.63 mg/g,定量限(LOQ, S/N=10)为0.12~2.10 mg/g。实验选取了两种基质,在3个水平下验证方法的回收率和精密度,13种防晒剂在霜类基质中的加标回收率为88.7%~103.6%,相对标准偏差(RSD, n=6)为1.7%~4.9%,在乳类基质中的加标回收率为88.4%~102.3%, RSD(n=6)为1.2%~3.9%。美白类化妆品常添加防晒剂成分,为监管盲区,采用该方法检测了5批含有防晒剂的美白类化妆品,其所含5种防晒剂的含量为0.8%~5.2%,符合相关要求。该方法操作简单,灵敏度高,回收率好,测定的13种防晒剂均为我国《化妆品安全技术规范》2015版规定的常用的限用组分,可以用于各类化妆品中13种防晒剂的定性定量测定,为市场监管和实验室检测提供新的技术支持。     

气相色谱-质谱法同时测定化妆品中18种氯代烃类有机溶剂

建立了同时测定化妆品中18种氯代烃类有机溶剂的气相色谱-质谱(GC-MS)检测方法。样品在饱和氯化钠溶液中由正十四烷振荡提取后,以Agilent J&W DB-624超高惰性毛细管柱(30 m×0.25 mm×1.4 μm)为分离色谱柱进行分析,以电子轰击(EI)源、SIM模式进行质谱监测,外标法定量。结果表明,18种化合物在19 min内完成色谱分离分析,检出限(LOD, S/N=3)和定量限(LOQ, S/N=10)分别为0.033~0.049 mg/L和0.10~0.15 mg/L, 18种氯代烃类有机溶剂在0.2~100 mg/L线性范围内线性关系良好,相关系数(R²)均不小于0.9992。以阴性样品口红(固体)和漱口水(液体)为样品基质,在不同添加水平下,18种氯代烃类有机溶剂的平均回收率分别为92.4%~103.1%和93.3%~102.4%,相对标准偏差(RSD, n=6)分别为3.1%~5.3%和2.8%~5.4%。采用该方法对115个化妆品样品进行测定,3个指甲油样品均检测出四氯乙烯,测定值为11.4~42.0 g/kg。研究建立的方法采用高沸点溶剂作为进样溶剂,取消溶剂延迟时间,使只能在溶剂延迟时间出峰的化合物得到有效色谱分离,分析时间短,且重复性好,灵敏度高,可同时检测各种化妆品中多种氯代烃类有机溶剂。该方法的建立为我国化妆品中氯代烃类有机溶剂检测标准的制订和质量安全监控提供了参考。     

稳定同位素稀释气相色谱-质谱联用测定化妆品中5种磷酸三酯类化合物

根据不同化妆品的基质特性探讨优化不同的提取净化方法,建立了稳定同位素稀释气相色谱-质谱联用测定化妆品中5种磷酸三酯类化合物(OPEs)的方法。膏霜乳液类和蜡基类化妆品经溶剂提取后,采用ENVI-Carb固相萃取柱净化;粉剂类和水剂类化妆品经溶剂提取、浓缩后直接检测。样液经DB-5MS(30 m×0.25 mm×0.25μm)色谱柱分离,GC-MS的选择离子监测(SIM)模式检测,以保留时间和特征离子丰度比定性,稳定同位素稀释内标法定量。在优化的实验条件下,5种磷酸三酯类化合物在各自的线性范围内相关系数大于0.9995,方法检出限为1.0~30μg/kg,平均回收率为89.5%~105%,相对标准偏差(n=6)为2.9%~9.1%。本方法净化效果好,可有效消除基质效应,且有较好的回收率,可用于不同类型的化妆品基质中磷酸三酯类化合物的测定。     

气相色谱法测定溶剂型涂料中环己酮含量

建立测定溶剂型涂料中环己酮含量的气相色谱(GC)检测方法。样品在乙酸乙酯中超声提取,以ZB–WAX毛细管柱(30 m×0.25 mm,0.25 μm)为分离色谱柱,加入十四烷作为内标物,氢火焰离子化检测器(FID)检测,内标法定量。结果表明,环己酮的质量浓度在10~250 mg/L范围内呈良好的线性关系,相关系数r=0.999 9。以阴性涂料样品为样品基质,加标平均回收率在92.5%~97.8%之间,测定结果的相对标准偏差在0.87%~1.77%(n=7)之间,方法检出限为13 mg/kg。采用该方法对15种溶剂型涂料样品进行测定,其中11种检出环己酮。该方法能使目标化合物得到有效分离,分析时间短,重复性好,灵敏度高,适用于溶剂型涂料中环己酮含量的快速测定。     

气相色谱-质谱法测定有机建筑粘合剂中3种苯胺类化合物含量

提出了气相色谱-质谱法测定有机建筑粘合剂中3种苯胺类化合物含量的方法。样品中3种苯胺类化合物用乙醇超声提取,离心分离后,所得提取液过0.22μm有机滤膜,滤液供气相色谱-质谱分析。在气相色谱分离中用DB-WAX毛细管色谱柱(30m×0.25mm,0.25μm)为固定相,在质谱分析中采用全扫描和选择离子监测模式。3种苯胺类化合物在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.3~0.6mg·kg-1之间。在3个浓度水平上做回收试验,加标回收率在91.1%~97.3%之间,相对标准偏差(n=6)在1.7%~4.0%之间。     

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.     

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 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.