毛细管电泳-电化学检测法测定淮山中8种必需氨基酸含量

将8种人体内必需氨基酸(苏氨酸、缬氨酸、蛋氨酸、异亮氨酸、亮氨酸、苯丙氨酸、赖氨酸、色氨酸)与邻苯二甲醛(OPA)发生衍生化反应,再采用毛细管电泳-电化学检测(CE-ED)方法对其含量进行测定。考察了衍生化时间、检测电位、运行缓冲液浓度和p H值、分离电压及进样时间等的影响。在优化条件下,8种氨基酸在12 min内实现了分离,线性范围为0.1~1 500μg/L;检出限为0.01~0.05μg/L,峰高的相对标准偏差(RSD)为1.3%~1.8%,迁移时间的RSD为0.6%~1.0%。该方法已用于淮山样品中8种必需氨基酸的测定,加标回收率为96.8%~102.0%,RSD均不大于2.4%。     

淮山中丙草胺和多抗霉素B的CE-ECL法同时检测

采用毛细管电泳-电化学发光法同时检测淮山中残留丙草胺和多抗霉素B的含量.考察了检测电位、缓冲液浓度及pH值、分离电压、进样电压和时间等实验参数对丙草胺和多抗霉素B测定的影响.在最优条件下,丙草胺和多抗霉素B同时得到较好的分离检测,其线性范围均为0.1~1 000μg/L(相关系数分别为0.999 7和0.999 5),检出限分别为0.01和0.05μg/L(S/N=3).该方法已用于淮山中残留丙草胺和多抗霉素B含量的同时测定,加标回收率在96.3%~98.7%之间,RSD≤2.3%.     

毛细管电泳-电化学发光法检测淮山中乐果的残留量

采用毛细管电泳-电化学发光(CE-ECL)法检测淮山中乐果的残留量。考察了检测电位、缓冲液浓度及其pH值、分离电压、进样电压和时间等实验参数对测定乐果的影响。在优化的实验条件下,乐果在0.50~10 000μg/L范围内与ECL强度呈良好线性,检出限为0.050μg/L。对0.500mg/L乐果溶液连续6次测定,峰高的相对标准偏差(RSD)为1.8%,迁移时间的RSD为1.0%。该方法用于淮山中乐果残留量的测定,加标回收率在98.3%~103.0%之间,RSD≤2.3%。     

加压毛细管电色谱-激光诱导荧光法检测4种黄曲霉毒素

建立了三氟乙酸( TFA)柱前衍生,加压毛细管电色谱-激光诱导荧光( pCEC-LIF)快速测定黄曲霉毒素B1、B2、G1、G2方法。使用粒径1.8μm的C18毛细管色谱柱,以甲醇-水(45：55, V/V,含0.05%甲酸)为流动相,泵流速为0.05 mL/min,分离电压为15 kV,激发波长为375 nm,发射波长为450 nm,黄曲霉毒素B1, B2, G1, G2达到基线分离。各组分的检出限(S/N=3)分别为0.02,0.016,0.008和0.01μg/L,在0.1~10μg/L,0.1~10μg/L,0.1~3.0μg/L,0.1~3.0μg/L 范围内分别呈线性相关,相关系数 R2分别为0.9999,1.0000,0.9995,0.9997。将本方法应用于花生酱的分析,加标回收率在90.0%~112.0%之间,RSD在0.5%~1.9%之间。     

超高效液相色谱-电雾式检测器测定福建产绞股蓝中绞股蓝皂苷XLVI和LVI北大核心CSCD

该研究利用超高效液相色谱-电雾式检测器(UHPLC-CAD)建立了福建产绞股蓝中绞股蓝皂苷XLVI和LVI含量的测定方法。首先利用超高效液相色谱-四极杆-飞行时间质谱(UHPLC-Q-TOF/MS)结合UHPLC-CAD鉴定了福建产绞股蓝的主要成分,其中绞股蓝皂苷XLVI、LVI以及二者相应的含丙二酰基酸性皂苷为其主成分,因此在含量测定时先进行碱水解预处理将酸性皂苷转化为对应的去丙二酰基中性皂苷,再利用UHPLC-CAD测定碱水解后绞股蓝皂苷XLVI和LVI的含量。将绞股蓝样品粉末在乙醇-水-氨水(50∶46∶4,v/v/v)和料液比1∶150(g∶mL)条件下超声提取30 min,静置24 h后,在Waters ACQUITY UPLC BEH C18色谱柱(100 mm×2.1 mm,1.7μm)上分离,采用0.1%(v/v)甲酸水溶液和乙腈作为流动相进行梯度洗脱,流速0.5 mL/min,柱温40℃,电雾式检测器检测。结果表明,绞股蓝皂苷XLVI和LVI分别在9.94~318.00μg/mL和12.78~409.00μg/mL范围内具有良好的线性关系,相关系数(r)分别为0.9993和0.9995。方法精密度、重复性和24 h稳定性试验的相对标准偏差(RSD)均小于2.0%(n=6),绞股蓝皂苷XLVI与LVI的加标回收率分别在100.2%~107.2%与97.9%~104.2%范围内,RSD值分别为2.4%与2.6%。16批绞股蓝样品含量测定结果显示:绞股蓝皂苷XLVI含量占0.57%~2.57%,绞股蓝皂苷LVI含量占0.66%~2.99%。该方法灵敏度高,重复性好,可用于福建产绞股蓝的质量研究和质量控制。     

毛细管电泳-电致化学发光法测定淮山药中胆碱和尿囊素

基于胆碱和尿囊素均能增强联吡啶钌的电致化学发光信号,建立了毛细管电泳-电化学发光法(CE-ECL)分离检测淮山药中胆碱和尿囊素的方法。在优化实验条件下,胆碱和尿囊素均在0.5～1000μg/L范围内与发光强度呈良好线性,检出限分别为0.02μg/L和0.04μg/L。对0.5 mg/L胆碱和0.5 mg/L尿囊素混合溶液连续6次测定,胆碱和尿囊素峰高的RSD分别为1.8%和2.0%,迁移时间的RSD分别为0.98%和1.1%。该方法已用于样品中胆碱和尿囊素测定,加标回收率在95.6%～101.1%之间,RSD≤2.5%。     

毛细管电泳检测大鼠大脑皮质中三磷酸腺苷二钠含量的动态变化

本文建立了大鼠大脑皮质中三磷酸腺苷二钠(ATP)检测的毛细管电泳方法。以89 mmol/L Tris,89 mmol/L硼酸,2 mmol/L EDTA组成的缓冲液(1×TBE,pH8.0)为分离电解质,在聚丙烯酰胺涂层毛细管上,ATP能与样品中的其它组分高效分离。ATP的浓度在0.5~10μg/mL范围内其峰面积和浓度有良好的线性关系。方法的检出限为0.04μg/mL。ATP迁移时间和峰面积的相对标准偏差分别为0.8%和5.7%(n=5)。探讨了脑缺血再灌流后ATP含量的变化规律,结果表明短暂脑缺血再灌流后存在着继发性能量衰竭的现象。     

HPLC测定中药渣中人参皂苷Rg_1、Re与Rb_1含量

建立了一种利用反相高效液相色谱检测中药渣中人参皂苷Rg_1、Re和Rb_1含量的分析方法。考察了提取试剂、提取温度、提取溶剂倍量、提取时间对提取效果的影响,最终将样品以10倍体积的70%甲醇于40℃水浴中超声提取0.5 h。采用Zorbax SB-C_(18)(4.6 mm×150 mm,5μm)柱分离,以乙腈和水为流动相进行梯度洗脱,流速为1.0 m L/min,进样量为20μL,柱温为20℃,检测波长为203 nm,采用外标法定量。在该条件下,人参皂苷Rg_1、Re、Rb_1分别在18.74~257.61、37.48~468.54、3.88~96.93 mg/L范围内线性关系良好(r~20.999)。人参皂苷Rg_1、Re和Rb_1的定量下限(S/N=10)分别为17.69、13.94、1.14 mg/L。3个不同浓度的加标回收率为89.1%~107%,相对标准偏差(RSD,n=3)为0.6%~4.1%。该方法具有操作简便快捷、检测灵敏度高等特点。     

超高效液相色谱/高分辨质谱法测定木质素氧化降解产物中单酚类化合物

建立了木质素氧化降解产物中单酚类产物的超高效液相色谱/高分辨质谱联用(UPLC/HRMS)检测方法。采用反相C18色谱柱,柱温30℃,0.1%(V/V)甲酸溶液-10%(V/V)甲醇乙腈溶液为流动相二元梯度洗脱,流速为0.2 mL/min,280 nm波长下紫外检测,可实现木质素氧化降解获得的9种单酚类化合物的有效分离,结合电喷雾离子源超高分辨飞行时间质谱(ESI-Q-TOF)正离子模式进行检测,对单酚类降解产物进行准确定性分析;通过高分辨质谱精确离子流抽提,面积外标法定量分析。本方法的线性范围为5.0~10000μg/L,线性相关系数大于0.9998,相对标准偏差(RSD)小于1.7%,检出限(LOD)和定量限(LOQ)分别为0.1~0.3μg/L和0.3~0.5μg/L,平均加标回收率为98.9%~105.1%。结果表明,酸性流动相体系下的正离子模式进行单酚类产物的质谱分析,具有较好的色谱分离效果和较高灵敏度。     

双波长UPLC同时测定桃金娘根中没食子酸和鞣花酸

建立了超高效液相色谱(UPLC)结合二极管阵列检测器(PDA)同时测定桃金娘根中没食子酸和鞣花酸的方法。样品经过甲醇超声提取,过滤,蒸干甲醇,残渣用二甲基亚砜定容。采用Waters BEH C18色谱柱(2.1×100 mm1.7μm),以乙腈-0.2%H2PO4溶液为流动相进行梯度洗脱,流速0.25 m L/min,检测波长为271 nm和253 nm。没食子酸在0.686~68.600μg/m L,鞣花酸在0.504~50.373μg/m L浓度范围内呈良好线性关系,相关系数分别为0.9999,0.9999;样品加标平均回收率分别为97.2%~99.0%、96.2%~98.9%;没食子酸和鞣花酸峰面积的RSD分别为1.1%和1.9%,迁移时间RSD为0.9%和1.3%;检出限分别为0.45和0.23 ng/m L。     

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.