高效液相色谱法测定指甲油中甲醛、乙醛和丙酮

采用高效液相色谱法测定指甲油中甲醛、乙醛和丙酮的含量。样品用乙腈和水提取,2,4-二硝基苯肼为衍生剂,采用Kromasil-C18色谱柱为分离柱,以乙腈-水(65+35)溶液为流动相,在检测波长364nm处进行测定。甲醛、乙醛和丙酮的质量浓度均在0.01~20.0mg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.001 5~0.003 5mg·L-1之间。加标回收率在88.6%~110%之间,相对标准偏差(n=6)在1.2%~9.7%之间。     

在线衍生-高效液相色谱法测定化妆品中的游离甲醛

采用自动在线衍生-高效液相色谱法测定化妆品中游离甲醛的含量。样品经乙腈涡旋提取,以2,4-二硝基苯肼的乙腈-乙酸溶液为衍生液,在线衍生2min后,衍生物在Agilent C_(18)色谱柱上分离,以乙腈(65+35)溶液为流动相进行洗脱,用二极管阵列检测器测定,检测波长为355nm。甲醛线性范围为1.0~20.0mg·L~(-1),测定下限(10S/N)为50mg·kg~(-1)。加标回收率在83.0%~98.4%之间,测定值的相对标准偏差(n=6)在3.4%~7.8%之间。     

微波辅助衍生-离子液体分散液液微萃取-高效液相色谱法测定发酵酒和饮料中甲醛

提出了微波辅助衍生-离子液体分散液液微萃取-高效液相色谱法测定发酵酒和饮料中的甲醛。以2,4-二硝基苯肼为衍生试剂,1-辛基-3-甲基咪唑六氟磷酸盐为提取剂,乙腈为分散剂,样品溶液在300 W的微波功率下辐照60s后离心,甲醛衍生物被萃取到离子液体中,用乙腈定容。以SB-C18色谱柱为分离柱,以水-甲醇(2+8)溶液为流动相进行洗脱,检测波长355nm。甲醛的质量浓度在1.00~100μg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)为0.16μg·L-1,测定下限(10S/N)为0.53μg·L-1。对啤酒、葡萄酒、可乐和橙汁4个样品进行加标回收试验,回收率在92.5%~99.1%之间,测定值的相对标准偏差(n=5)在2.6%~7.8%之间。     

气相色谱法快速测定橡皮擦中的甲醛北大核心CSCD

采用柱前衍生-气相色谱法测定橡皮擦中的甲醛。样品经粉碎,过0.180mm筛后,称取2.000 0g,用20mL水于70℃浸提20min,冷却后再超声提取30min,离心。10.0mL提取液中加入2,4-二硝基苯肼0.5mL,于70℃衍生反应15min,冷却后用5mL甲苯萃取2次,萃取液经DB-5色谱柱分离,采用电子捕获检测器对甲醛衍生物进行检测。甲醛的线性范围为0.105~10.5mg·L^(-1),检出限(3S/N)为0.01mg·L^(-1),加标回收率在88.6%~92.4%之间。测定值的相对标准偏差(n=6)为2.1%。应用该方法测得32种橡皮擦样品中的甲醛的质量比在0.135~48.5mg·kg^(-1)之间。     

气相色谱法快速测定橡皮擦中的甲醛

采用柱前衍生-气相色谱法测定橡皮擦中的甲醛。样品经粉碎,过0.180mm筛后,称取2.000 0g,用20mL水于70℃浸提20min,冷却后再超声提取30min,离心。10.0mL提取液中加入2,4-二硝基苯肼0.5mL,于70℃衍生反应15min,冷却后用5mL甲苯萃取2次,萃取液经DB-5色谱柱分离,采用电子捕获检测器对甲醛衍生物进行检测。甲醛的线性范围为0.105~10.5mg·L~(-1),检出限(3S/N)为0.01mg·L~(-1),加标回收率在88.6%~92.4%之间。测定值的相对标准偏差(n=6)为2.1%。应用该方法测得32种橡皮擦样品中的甲醛的质量比在0.135~48.5mg·kg~(-1)之间。     

衍生液提取-高效液相色谱法测定食品中甲醛

提出了高效液相色谱法测定了几种食品中甲醛含量。以衍生液2,4-二硝基苯肼乙腈溶液-pH 5的磷酸盐缓冲溶液(1+1)的混合溶液为提取剂对样品进行提取,以Agilent C18色谱柱(4.6 mm×250 mm,5μm)为固定相,以甲醇-水(70+30)溶液为流动相分离。甲醛的测定下限(10S/N)为5.0 mg.kg-1。以鲜香菇、鲜鱿鱼、奶粉和面粉样品为基体,分别添加5.0,10.0,20.0 mg.kg-1甲醛标准溶液,回收率在73.3%~97.7%之间,相对标准偏差(n=6)在1.4%~5.0%之间。     

高效液相色谱法测定粮食制品中甲醛残留量

研究建立了一种用HPLC测定粮食制品中甲醛残留量的分析方法。样品中甲醛经60℃水浴提取,与2,4 二硝基苯肼衍生后,生成的2,4 二硝基苯腙经石油醚萃取净化,用HPLC DAD分离测定,外标法定量。最小检出质量浓度为5×10-11g,对于5g样品,最低检出量为0.01mg kg,样品回收率>80%,相对标准偏差≤10%,能满足残留量分析的要求。     

高效液相色谱法测定染发剂中2-硝基-p-苯二胺

应用高效液相色谱法测定了染发剂中2-硝基-p-苯二胺的含量。样品用乙醇-水(1+1)混合溶液提取后,经水系C18色谱柱分离,以(A)10mol·L-1柠檬酸缓冲溶液-10mol·L-1辛烷磺酸钠溶液(pH 2.6)与(B)乙腈以体积比75比25组成的混合溶液为流动相进行等度洗脱,用二极管阵列检测器于410nm检测。2-硝基-p-苯二胺的线性范围为2.4～240mg·L-1,检出限(3S/N)为0.7mg·L-1。以染发剂样品为基体,进行加标回收试验,回收率在90.4%～99.4%之间,相对标准偏差(n=6)在0.35%～3.0%之间。     

离子色谱法测定水果和蔬菜中2,4-二氯苯氧乙酸的含量

采用离子色谱法测定水果和蔬菜中2,4-二氯苯氧乙酸的含量。水果或蔬菜样品10.0g经0.2mol·L-1硫酸溶液10.0 mL提取后,用二氯甲烷10.0 mL萃取,二氯甲烷层再用35mmol·L-1氢氧化钾溶液5.00mL反萃取,取水相,经AG-19保护柱及AS-19阴离子分离柱分离,以35mmol·L-1氢氧化钾溶液淋洗色谱柱,所得淋出液采用抑制电导检测器检测。2,4-二氯苯氧乙酸的质量浓度在5.0mg·L-1以内与其峰面积呈线性关系,检出限(3S/N)为0.05 mg·L-1。加标回收率在93.6%~105%之间,测定值的相对标准偏差(n=6)在2.1%~5.5%之间。     

衍生液提取-高效液相色谱法快速测定香菇中的游离甲醛

以2,4-二硝基苯肼乙腈溶液-pH 5磷酸盐缓冲液(体积比为1:1)为提取溶液,提取香菇中游离的甲醛,采用高效液相色谱法测定。结果表明,乙腈-pH 5磷酸盐缓冲液(体积比为1:1)能够有效地抑制香菇中酶反应释放甲醛,达到提取香菇中游离甲醛的目的。在提取液中加入衍生化试剂2,4-二硝基苯肼,将甲醛的提取和衍生化反应相结合,此衍生液提取方法有效地提高了检测效率。鲜香菇样品中分别添加5.0、10.0、20.0 mg/kg的甲醛,平均回收率分别为89.2%、91.7%和90.4%,相对标准偏差(n=6)＜5.0%。方法的定量限（S/N＞10）为5.0 mg/kg。该方法适用于香菇中游离甲醛的检测,且快速简便、重现性好,是确定香菇中甲醛天然本底值的有效方法。     

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.     

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.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.     

Copper-catalyzed multicomponent reactions of 2-iodoanilines,benzylamines, and elemental sulfur toward 2-arylbenzothiazoles

A relatively cheap copper salt-catalyzed, three-component approach providing 2-arylbenzothiazoles in good to excellent yields from readily available 2-iodoanilines, benzylamines, and sulfur powder is reported. This methodology allows preparation of various classes of 2-arylbenzothiazoles and provides a general, reliable approach.