高效液相色谱法测定红霉素、甲红霉素和罗红霉素的研究

建立了高效液相色谱-荧光法同时测定红霉素、甲红霉素、罗红霉素的方法。该方法以9-芴代甲氧苯酰氯(FMOC-CL)为衍生试剂,以V(乙腈)∶V(磷酸二氢钾)=3∶1为反应体系,于50℃反应1 h。液相色谱分析条件为:Extend-C18柱(4.6 mm i.d.×150 mm),乙腈-25 mmoL磷酸二氢胺(pH 7)为流动相,梯度淋洗;柱温30℃,流速1.5 mL/min,激发波长255 nm、发射波长315 nm。线性范围分别为红霉素0.5~100μg、甲红霉素0.5~100μg、罗红素0.1~150μg。检出限为红霉素1μg/mL、甲红霉素1μg/mL、罗红霉素0.25μg/mL。加标回收率为90%~97%,相对标准偏差为3.5%~7.9%。     

柱前衍生-高效液相色谱法测定蔬菜中甲醛含量

建立了蔬菜中甲醛含量的高效液相色谱分析方法。样品用水提取、2,4-二硝基苯肼衍生及二氯甲烷萃取、浓缩后,采用Waters Sunfire C18色谱柱(250×4.6 mm,5μm)分离,流动相为乙腈-水(1∶1,V/V),在355nm波长处紫外检测。甲醛在0.1~2.0μg/mL浓度范围内呈线性关系,相关系数0.9989,方法检出限为1.0 mg/kg,在2~10mg/kg添加浓度范围内,甲醛平均回收率为78.1%~114.2%,相对标准偏差在0.8%~9.5%之间。     

涂料中甲醛的分光光度测定新方法

在FeCl3存在的盐酸介质中,甲醛与蛋白胨反应生成紫色化合物,最大吸收波长555 nm,甲醛浓度在1~25μg/10 mL范围内,吸光度与浓度成线性关系,线性相关系数r2=0.9997,检出限0.05μg/mL。用本法测定经活性炭脱色的水溶性涂料中的甲醛含量,回收率为96.46%~103.32%,相对标准偏差(n=6)为1.36%~2.09%。     

柱前衍生高效液相色谱法测定注射液中白消安的研究

建立了一种以二乙基二硫代氨基甲酸钠(DEDC)为柱前衍生化试剂测定白消安的反相高效液相色谱分析方法。采用C18色谱柱(250 mm×4.6 mm,5μm),以V(乙腈)∶V(水)∶V(四氢呋喃)=55∶25∶20为流动相,流速为1.0mL/min,检测波长为278 nm。白消安在119.0~892.5μg/mL范围内呈良好的线性关系,r=0.9988,回收率99.81%~99.89%。     

衍生化法测定蓝莓果汁饮料中花色苷含量

柱前衍生,高效液相色谱法测定蓝莓果汁饮料中花色苷的含量。在温度为353K条件下,蓝莓果汁饮料与25%盐酸/甲醇溶液(V∶V=1∶1)反应1h,经过0.45μm微孔滤膜过滤后,采用高效液相色谱配二极管阵列检测器检测,以氯化矢车菊素为参照,外标法计算含量。采用Agilent HC-C18柱(250mm×4.6 mm,5μm),流动相A:0.4%三氟乙酸(TFA)水溶液,流动相B:0.4%TFA/乙腈溶液,梯度洗脱,流速1m L·min-1,进样体积20μL,柱温35℃,检测波长为190~800 nm,定量波长520nm。平均加标回收率为94.8%~98.0%,RSD为2.83%,检出限为0.008μg·m L-1。该方法简单、快速、成本低,适用于蓝莓果汁饮料中花色苷含量的测定。     

纺织品中游离甲醛含量的高效液相色谱法测定

建立了纺织品中游离甲醛的高效液相色谱检测法,采用SinoChrom ODS-BP色谱柱(250×4.6 mm i.d.,5μm),流动相为甲醇-水(70∶30,V/V),流速1.0 mL/min,检测波长360 nm。通过正交试验优化了甲醛衍生条件,应用F检验和t检验证实了本方法的准确性。方法相对标准偏差(RSD)为2.53%,回收率在95.0%~102.7%范围。     

丹磺酰肼衍生-高效液相色谱-荧光检测法测定包装纸中的甲醛和乙醛

建立了丹磺酰肼(DNSH)衍生-高效液相色谱-荧光检测测定包装纸中甲醛和乙醛的分析方法,并与2,4-二硝基苯肼(DNPH)衍生法进行了比较。纸张样品经衍生化试剂振荡萃取30 min,衍生化反应24 h,萃取液经PSA/C18净化管净化处理后,以Diamonsil~ C18(2)色谱柱(150 mm×4.6 mm,5μm)为固定相,用醋酸水溶液(pH2.55)-乙腈为流动相进行梯度洗脱。采用荧光检测器检测,激发波长为330 nm,发射波长为484 nm。结果表明,衍生剂、甲醛-DNSH和乙醛-DNSH在20 min内可完全分离,方法的加标回收率为81.64%~106.78%,相对标准偏差(RSD)为2.02%~5.53%(n=5),甲醛和乙醛的检出限分别为19.2μg/kg和20.7μg/kg,定量限分别为63.9μg/kg和69.1μg/kg。该法操作简单,灵敏度高,比常规方法具有更低的检出限,能很好地应用到实际样品检测中,为低含量醛类化合物的检测提供了一种新思路。     

4-二甲胺偶氮苯磺酰氯柱前衍生高效液相色谱法测定人体尿液中肌氨酸

建立了以4-二甲胺偶氮苯磺酰氯为柱前衍生试剂的高效液相色谱法测定人体尿液中肌氨酸的含量。通过优化衍生反应的条件,确定了最佳衍生条件为:反应时间20min,反应温度75℃,衍生反应pH为9.8,衍生试剂与肌氨酸比例为4∶1。采用Agilent TC-C18柱(250×4.6mm,5μm),以pH=7.0的9mmol/L磷酸盐缓冲溶液-乙腈(60∶40,V/V)为流动相,流速1.0mL/min,检测波长465nm。结果表明,肌氨酸在0.002~4.00mmol/L范围内呈良好的线性关系,相关系数为0.9998;检测限(S/N=3)为0.70nmol/L;定量限(S/N=10)为2.33nmol/L;加标回收率为95.69%~107.79%。该方法简单、灵敏度高、稳定性好,可用于测定尿液中肌氨酸含量。     

偏二甲肼衍生-高效液相色谱法测定水产品中甲醛

在高效液相色谱法(HPLC)测定水产品中甲醛时采用偏二甲肼作为衍生化试剂对甲醛进行预衍生化.经在中性溶液中反应10 min后定量生成衍生化产物偏二甲腙,偏二甲腙在紫外光区呈现强吸收,其吸收峰在237 nm波长处,可不经任何富集处理直接进行HPLC测定.偏二甲腙(方法中以甲醛表示)的质量浓度与其吸光度之间在0.12～1 200 mg·L-1范围内呈线性关系.测得方法的检出限(3S/N)为0.5μg.·g-1.对3种水产品样品进行了分析并对方法的精密度做了检测,求得其相对标准偏差均小于6%,以3种不同的水产品样品作为基体,加入不同浓度的标准甲醛进行了回收试验,测得结果在88%～110%之间.     

高效液相色谱法测定化妆品中甲醛

建立了柱前衍生化、高效液相色谱法(HPLC)测定化妆品中甲醛的方法。样品用乙腈溶解,加水稀释后于旋盖离心管中振荡提取2 h,离心后分取部分提取液与2,4-二硝基苯肼在弱酸条件下衍生反应,衍生物直接HPLC测定。以乙腈-水(65+35)为流动相,流速为1.0 mL.min-1,Supelco Discovery(C18柱(4.6 mm×250 mm,5μm)为分离柱,365 nm紫外波长下检测,在5.0,50.0及100.0μg.g-1甲醛的浓度水平作了精密度及回收率试验,回收率为70%~102%,相对标准偏差<5.0%,检出限为5.0μg.g-1。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.