Ag@SiO_2/ZnO@SiO_2的制备及其对水溶液中生物分子的分析检测

采用一种操作简单、反应条件温和的方法在室温下制备了Zn O@SiO2和Ag@SiO2/Zn O@SiO2,利用透射电子显微镜(TEM)、紫外吸收光谱(UV)、荧光光谱(FL)、纳米粒度和ZETA电位分析仪等技术对所制备纳米粒子的粒径大小、吸收光谱、发光性质进行表征。结果表明,Zn O@SiO2核壳量子点的平均粒径为3~8 nm,最大紫外吸收波长在330 nm左右,可发射510 nm的黄绿色荧光。而Ag@SiO2增强了Zn O@SiO2核壳量子点的荧光,未改变Zn O@SiO2核壳量子点的发射峰位置,同时Ag@SiO2显著增强了Zn O@SiO2核壳量子点的荧光稳定性。利用L-半胱氨酸和血红蛋白对量子点荧光不同程度的猝灭作用,建立了一种简单、快速、灵敏的检测分析方法。在最佳条件下,L-半胱氨酸和血红蛋白的浓度分别在0.068~10.10 mg/L和4.00×102~4.00×103mg/L范围内与溶液的荧光强度呈良好的线性关系,相关系数(r2)分别为0.993 8和0.995 1,以3.37 mg/L的L-半胱氨酸标准溶液进行11次平行实验,相对标准偏差(RSD)为1.3%,以3倍标准偏差计算检出限为6.92×10-3mg/L。以2.00×103mg/L的血红蛋白标准溶液进行11次平行实验,相对标准偏差为2.5%,以3倍标准偏差计算检出限为2.04 mg/L。     

三元缔合物以双波长共振瑞利散射测定药物中酒石酸美托洛尔

建立了一种快速、准确测定药物中酒石酸美托洛尔的双波长共振瑞利散射(DWORRS)新方法。在酸性Tris-盐酸介质中,刚果红与酒石酸美托洛尔及表面活性剂十六烷基三甲基溴化铵反应生成红色三元缔合物,使双波长共振瑞利散射显著增强并产生新的具有2个明显散射峰的共振瑞利散射(RRS)光谱,最大共振瑞利散射峰位于375 nm,另一共振瑞利散射峰位于515 nm,酒石酸美托洛尔在0.004~0.55 mg/L范围内与体系的RRS增强强度的绝对值(│△I_(RRS)│)呈线性关系,检出限为0.0032 mg/L(375 nm),0.0038 mg/L(515 nm)和0.0018 mg/L(DWO-RRS,375 nm+515 nm)。还探讨了RRS的光谱特征、适宜反应条件、反应机理及共存物质的影响。方法用于药物中酒石酸美托洛尔含量的测定,加标回收率为98.57%~102.1%,相对标准偏差为2.0%~2.5%。     

双波长叠加吸收光谱法测定药物中的酒石酸美托洛尔

建立了快速、准确测定药物中酒石酸美托洛尔的双波长叠加可见吸收光谱法。在pH 4.55的酸性Tris-盐酸介质及586~740 nm波长范围内,偶氮氯膦Ⅲ与酒石酸美托洛尔反应生成具有两个明显正吸收峰的离子缔合物,最大正吸收波长位于614 nm,次大正吸收波长位于664 nm,表观摩尔吸光系数(κ)分别为6.03×10~4L/(mol·cm)(614 nm)和5.37×10~4L/(mol·cm)(664 nm),酒石酸美托洛尔的质量浓度在0.2~8.6 mg/L范围内服从朗伯-比尔定律,检出限为0.13 mg/L(614 nm)和0.15 mg/L(664 nm)。当采用双波长叠加法测定时,其表观摩尔吸光系数(κ)可达1.14×10~5L/(mol·cm),检出限为0.072 mg/L。该文同时探讨了显色反应的适宜条件、共存物质的影响及吸收光谱特征。实验发现,该反应体系的单波长及双波长叠加吸收光谱法的表观摩尔吸光系数可达5.37×10~4~1.14×10~5L/(mol·cm),方法可用于市售药物中酒石酸美托洛尔含量的测定,加标回收率为98.0%~101%,相对标准偏差(n=6)为1.8%~2.3%。     

HPLC法快速筛查抗风湿类中成药或保健食品中21种非法添加化学成分

基于亚3μm核壳填料色谱柱技术建立了高效液相色谱法快速筛查21种抗风湿类化合物。供试品以1%乙酸-甲醇为提取溶剂,经ACCHROM C18100A(4.6 mm×100 mm,2.8μm)分离,以磷酸水溶液(pH3.0)-甲醇-乙腈溶液为流动相,梯度洗脱,检测波长为230 nm,流速1.0 m L/min,柱温35℃。该方法在20 min内可分离21种成分,各化合物的线性范围为5~100μg/m L(萘普生为1.5~30μg/m L),回收率为91.0%~109.1%。萘普生的检出限(S/N=3)为0.8 mg/kg,其余化合物的检出限为2.0 mg/kg。按上述方法对抽检样品进行检测,发现18批阳性样品,并采用液相色谱-质谱联用法进一步确证。该方法快速、准确,适用于抗风湿类中成药或保健食品中非法添加化学成分的快速筛查,具有广阔的应用前景。     

瑞利光散射技术快速测定鲜苹果中的苹果酸

在碱性Tris-HCl缓冲介质中,苹果酸与维多利亚蓝B反应生成蓝色二元离子缔合物,使瑞利光散射明显增强,在368nm波长处,瑞利散射增强程度(ΔIRLS)与苹果酸的质量浓度在0.002~0.27mg/L范围内呈线性关系,检出限为0.0018mg/L。实验探讨了适宜的反应条件及主要分析化学性质。该方法简便、快速,用于市售鲜苹果中苹果酸含量的测定,回收率为98.4%~101%,相对标准偏差(RSD,n=5)为1.8%~2.2%。     

柱前衍生/高效液相色谱-荧光检测器测定面粉制品中的偶氮甲酰胺

建立了面粉制品中偶氮甲酰胺(ADA)残留量的丹磺酰氯柱前衍生结合高效液相色谱-荧光检测器的分析方法。面粉制品中的ADA经湿热处理后,转变成氨基脲(SEM),加入丹磺酰氯(DNS-Cl)进行衍生。采用Aglient TC C18(250 mm×4.6 mm,5μm)对衍生产物进行分离,流动相为乙腈-水(65∶35),流速1.0m L/min,柱温30℃,激发波长330 nm,发射波长530 nm,高效液相色谱-荧光检测器检测,外标法定量。偶氮甲酰胺在0.1~50 mg/L范围内具有良好的线性关系,相关系数(r)大于0.998,检出限(LOD)和定量下限(LOQ)分别为0.03 mg/L和0.10 mg/L。在0.1,0.3,1.0 mg/kg 3个加标水平下的平均回收率为78.4%~96.6%,相对标准偏差(RSD,n=6)为7.1%~9.4%。该方法具有简便、快速、灵敏等特点,可用于面粉制品中偶氮甲酰胺的检测。     

高灵敏共振瑞利散射法测定药物中的乌拉地尔

建立了一种快速测定药物中乌拉地尔的高灵敏共振瑞利散射(RRS)法,研究了RRS的光谱特征、反应条件及共存物质的影响。在p H 3.38的Tris-盐酸介质中,乌拉地尔与溴代十六烷基吡啶-偶氮氯膦Ⅲ反应生成三元离子缔合物,导致共振瑞利散射显著增强并产生新的RRS光谱。在最大共振瑞利散射峰374 nm波长处,乌拉地尔在0.002~0.37 mg/L范围内与缔合物的RRS增强强度的绝对值(│△IRRS│)呈线性关系,检出限为0.0016 mg/L。该法用于药物中乌拉地尔含量的测定,加标回收率为99.0%~99.7%,相对标准偏差(n=5)为1.6%~2.0%。     

超高效合相色谱法测定尼龙6食品接触材料中己内酰胺迁移量

建立了超高效合相色谱法测定尼龙6食品接触材料中己内酰胺迁移量的方法。样品经水、4%乙酸(V/V)、50%乙醇(V/V)、正己烷等4种食品模拟物浸泡后,50%乙醇、正己烷浸泡液直接进样,水、4%乙酸经乙醇稀释后进样,采用超临界CO2-甲醇(含2%水)为流动相进行梯度洗脱,经C18色谱柱(3.0 mm×100 mm,1.8μm)分离,通过PDA检测器对目标化合物在210 nm波长下进行分析,外标法定量。在优化条件下,己内酰胺在水、4%乙酸、50%乙醇、正己烷4种食品模拟物中,质量浓度范围分别在5.0~50.0 mg/L,5.0~50.0 mg/L,2.0~50.0 mg/L,5.0~50.0 mg/L线性良好,方法检出限分别为2.0,2.0,1.0,2.0 mg/L。进行添加回收实验,己内酰胺回收率为91.4%~98.4%,相对标准偏差为1.9%~3.2%。方法可用于食品接触材料中己内酰胺迁移量的快速测定。     

阴离子交换色谱-荧光检测法测定人体血清中酪氨酸及其代谢产物

建立了阴离子交换色谱-荧光检测法(AEC-FLD)同时测定人体血清中的酪氨酸(Tyr)、对羟苯基乳酸(PHPLA)和对羟苯基丙酸(PHPA)的分析新方法。样品经乙腈处理沉淀蛋白,离心后取上清液直接进样检测。采用IonPac AG21保护柱(50×2mm)、IonPac AS21分析柱(250×2mm),流动相为4mmol/L NaOH溶液,流速为0.45mL/min,荧光检测器的激发波长和发射波长分别为277nm和340nm。优化条件下三种物质能得到良好的分离和检测。Tyr、PHPLA和PHPA的线性范围分别为0.30~25mg/L、0.025~2mg/L和0.025~2mg/L,相关系数在0.9998~0.9999之间,检出限(S/N=3)分别为0.024mg/L、0.020mg/L和0.019mg/L。三个水平的加标回收率在72.6%~99.1%之间,其相对标准偏差均小于6.62%。该方法简单、快速、准确,可用于实际样品的测定。     

高效液相色谱法同时分离检测食品添加剂

建立了一种同时分离检测没食子酸丙酯(PG)、特丁基对苯二酚(TBHQ)、二丁基羟基甲苯(BHT)和苯甲酸等食品添加剂的高效液相色谱(HPLC)分析方法.通过对流动相、流速、柱温、检测波长等色谱条件的优化,确定了最佳的分离检测条件:甲醇(B)和水(A)(0.1%的乙酸溶液)作为流动相,梯度洗脱:0~6 min,60%B,流速0.3 m L/min;6~9 min,60%~100%B,流速0.6 m L/min,柱温维持在25℃,检测波长280 nm(PG、TBHQ、BHT),230 nm(苯甲酸).在最佳的色谱条件下,方法的线性范围分别为1~200、2~400、2~400、0.5~400 mg/L,检出限(LOD)为0.02~0.06 mg/L,相关系数(R2)均大于0.999 4,加标回收率在77.76%~106.27%之间.该方法还成功应用于话梅、薯片、方便面实际样品中食品添加剂的分析检测.     

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.     

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.     

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.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Studies of Photoionization of CF3 I by Femtosecond Time-resolved Mass Spectrometry

The multi-photon dissociative photoionization dynamics of CF3I has been studied with femtosecond two-color pump-probe time of flight mass spectra at a pump pulse of 265 nm and a probe pulse of 398 nm. The life constants of CF3I+ and its fragment ions CF3+ and I+ are obtained as (96±7), (198±130) and (167±6)fs, respectively. The multi-photon dynamics leading to these ions differ. CF3I+ corresponds to a (1+2′) transition with one-photon pump excitation to the A band of CF3I. CF3+ are mainly formed by a tow-photon probe excitation to the CF3+ with subsequent dissociation of parent ions. I+ are produced in (2+2′) combined with (1+1′+2′) process. The results provide information on the multi-photon pathways involved.