HPLC法检测丁二酸发酵液中的有机酸和水溶性维生素

采用高效液相色谱法(HPLC)同时检测丁二酸发酵液中的有机酸和水溶性维生素。以RP-HPLC为分离模式,选用Hedera ODS-2色谱柱(5μm,4.6×250 mm),20 mmol/L的磷酸盐缓冲溶液(pH2.9)和乙腈为流动相,梯度洗脱,检测波长为210 nm,建立了同时测定分析8种水溶性维生素和3种有机酸的方法,15 min内所有组分都洗脱完全。8种水溶性维生素和3种有机酸在线性范围内峰面积与浓度呈良好的线性关系,相关系数为0.9989~0.9997;加标回收率在92.5%~100.3%之间;RSD(n=5):0.9%~1.9%。本方法采用同一种流动相既可以测定发酵液中的有机酸又可以测定水溶性维生素的含量。     

反相高效液相色谱法测定山楂中的有机酸

采用Hypersil ODS2(4.6 mm×250 mm,5μm)色谱柱,以磷酸盐缓冲溶液(pH=2.6)为流动相,流速0.8 mL/m in,检测波长210 nm,建立了山楂中柠檬酸、苹果酸等有机酸的高效液相色谱分析方法。其中柠檬酸和苹果酸的线性范围分别为0.50~50.04μg、0.10~10.00μg;3个浓度水平的回收率分别为95.5%~96.6%、100.2%~103.7%,RSD分别为0.11%~0.38%、0.41%~2.53%;检出限分别为0.04μg、0.03μg(S/N=3)。测定了5种不同产地山楂果肉及山楂核中的柠檬酸、苹果酸的含量。所建立的方法快速、灵敏度高、重复性好,可用于山楂中有机酸的测定。     

高效液相色谱-串联质谱法测定地表水样品中5种有机磷酸酯代谢物

将固相萃取(SPE)和高效液相色谱-串联质谱(LC-MS/MS)结合,建立了河水样品中5种有机磷酸酯(OPEs)代谢物的分析方法。样品过滤后,使用HLB固相萃取小柱进行富集净化,采用6 m L甲醇洗脱后氮吹定容。以Luna Phenyl-Hexyl色谱柱为分离柱,甲醇和50 mmol·L-1乙酸铵水溶液为流动相梯度洗脱,在电喷雾负离子模式下,采用多反应监测模式(MRM)进行测定。优化条件下,仪器测定限(IDL)为0.002~1.15μg·L~(-1),方法检出限(MDL)为0.15~4.48 ng·L~(-1),实际水样加标浓度为10 ng·L~(-1)和50 ng·L~(-1)时回收率分别为54.1%~83.6%和57.8%~102%,相对标准偏差(RSD)分别为5.3%~19.5%和2.8%~15.7%。考察了基质效应对5种化合物分析的影响,同时应用该方法对武汉7个湖水样品进行分析,除DEHP外其它4种OPEs代谢物均有检出。该方法具有良好的精密度和准确度,可用于有机磷酸酯代谢物的环境行为研究。     

高效液相色谱法测定植物根系分泌物中的有机酸

以小麦为例,建立了植物根系分泌物中有机酸的提取和测定方法。小麦根系分泌物由培根法培育收集,先后经阳离子和阴离子交换树脂提取,旋转蒸发至干后用pH 2.1的稀HClO4溶液溶解、定容,以5 mmol/L H2SO4水溶液为流动相,经Bio-Rad Aminex HPX-87H阳离子交换树脂柱分离,在波长210 nm处紫外检测。在小麦根系分泌物中,有机酸的检测限为1~120 μg/L,日内检测精密度为1.2%~4.7%,日间检测精密度为3.3%~10.6%,不同剂量的加标回收率为82.0%~96.2%,相对标准偏差为0.67%~3.31%。该方法简便快速,灵敏可靠,适用于介质复杂的环境样品中有机酸的测定。     

QuEChERS-四极杆/静电场轨道阱高分辨质谱测定动物性食品中氟虫腈及其代谢物残留

基于低温处理和QuEChERS方法,采用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱建立了动物性食品中氟虫腈及其代谢物残留的分析检测方法。样品采用乙腈提取,经低温处理,N-丙基乙二胺(PSA)和C18粉分散固相萃取(d-SPE)净化,以BEH C18色谱柱为分析柱,乙腈-0.1%乙酸溶液为流动相进行梯度洗脱分离,外标法定量。采用高分辨质谱平行反应监测(PRM)扫描模式,以负离子采集进行定性筛查和定量分析。氟虫腈及其代谢物在0.02~2μg/L和0.2~20μg/L质量浓度范围内均呈良好的线性关系,相关系数(r2)大于0.992。对液体或半液体样品(如牛奶和鸡蛋)和固体样品(如鸡肉),方法的定量下限分别为0.1μg/kg和0.2μg/kg。在不同浓度的加标水平下,氟虫腈及其代谢物在鸡蛋中的平均回收率为81.6%~96.9%,相对标准偏差(RSD)为1.3%~11.5%;在鸡肉中的平均回收率为81.2%~96.0%,RSD为3.4%~11.4%;在牛奶中的平均回收率为79.1%~100.1%,RSD为1.5%~10.7%。该方法简单、灵敏、准确,适用于动物性食品中氟虫腈及其代谢物的快速筛查和定量检测,方法的灵敏度满足欧盟的残留限量要求。     

超高效液相色谱-三重四极杆质谱法同时检测人尿中12种单羟基多环芳烃代谢物

建立了高效、准确的同时测定人体尿样中多种多环芳烃代谢物的方法。取10.0 mL尿液,酶解,经固相萃取净化浓缩、0.2 μm滤膜过滤后,以Acquity UPLC^®HSS T3（100 mm×2.1 mm,1.8 μm）为分析柱,甲醇和水为流动相,采用负离子电喷雾多反应监测模式检测样品中多环芳烃代谢物的含量。12种多环芳烃代谢物在0.04~20.0 μg/L范围内线性关系良好,相关系数>0.99,方法检出限为0.01~0.41 μg/L,平均回收率为80.0%~105%,批内RSD为1.21%~9.12%,批间RSD为4.43%~19.7%。应用该方法对淮河流域某区域的100份人体尿样进行了检测,多环芳烃代谢物的检出率为98%。该方法操作简单,灵敏度高,选择性好,可同时检测尿中12种羟基多环芳烃代谢物。     

高效液相色谱法测定柠檬酸发酵液中有机酸

采用高效液相色谱法测定柠檬酸发酵液中7种有机酸(草酸、苹果酸、α-酮戊二酸、柠檬酸、富马酸、乌头酸和柠康酸)的含量。采用Atlantis C18色谱柱(4.6 mm×150 mm,5μm),以pH2.8的0.05 mol.L-1磷酸氢二钠溶液作流动相,流量为0.8 mL.min-1,在210 nm波长处用紫外检测器检测。在优化的色谱条件下,7种有机酸达到完全分离,且均在一定的质量浓度范围内呈线性。方法用于柠檬酸发酵液的分析,7种有机酸的加标回收率在97.1%~107.6%之间,相对标准偏差(n=6)均小于1.5%。     

高压离子色谱法快速测定PM2.5中的阴离子和有机酸

建立一种快速检测PM2.5中阴离子和有机酸的离子色谱方法。以Thermo Fisher Ion Pac AS18–4μm为分析柱,AG18–4μm为保护柱,以氢氧化钾溶液为流动相,等度洗脱,5 min内进行分离。被测组分的质量浓度与色谱峰面积具有良好的线性,相关系数在0.998 5~0.999 9之间,各色谱峰面积的精密度在0.98%~1.9%(n=7)之间,各组分加标回收率为92.1%~107.4%,检出限为0.04~2.00μg/L。该方法可应用于评价区域大气的质量。     

高效液相色谱法检测底泥中孔雀石绿及其代谢物

以乙腈、二氯甲烷、对甲苯磺酸和Mcilvain缓冲液等提取底泥中孔雀石绿和隐色孔雀石绿,以乙腈-甲醇-乙酸钠缓冲液为流动相,用DAD检测器在618nm处进行检测,建立了底泥中孔雀石绿及其代谢物的HPLC检测方法。孔雀石绿的回收率为75.2%~79.1%,隐色孔雀石绿的回收率为81.1%~84.2%,检测限均为5μg/kg。     

液相色谱-串联质谱法测定猪肉中咪唑类药物及其代谢物

建立了高效液相色谱-串联质谱同时测定猪肉中29种咪唑类药物及其代谢物残留的检测方法。样品采用乙酸乙酯提取,浓缩复溶后加入乙腈饱和正己烷净化除脂,以0.3%(体积分数)甲酸水溶液和乙腈为流动相,反相C_(18)色谱柱梯度洗脱分离,采用电喷雾正离子(ESI+)源多反应监测(MRM)模式进行检测。29种化合物在0.05~20.0μg/L范围内线性关系良好,相关系数r~20.99。在1.0~5.0μg/kg添加范围内,平均回收率为65.4%~103%,相对标准偏差(RSD)为1.3%~6.8%。方法检出限为0.02~0.3μg/kg,定量限为0.1~1μg/kg。该方法简便、快速、灵敏,适用于猪肉中咪唑类及其代谢物残留的检测。     

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.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.