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1.
以柠檬醛为原料, 经环化、羟腈化、水解关环和脱水4步反应, 以40.24%的总产率合成了(±)-二氢猕猴桃内酯.  相似文献   

2.
建立液相色谱-串联质谱法(LC-MS/MS)测定氢氯噻嗪中三种氯苯胺的含量,色谱柱选用(CHIRALCEL??OJ-RH,150 mm×4.6 mm,5μm),离子源采用大气压化学电离源(APCI),使用正离子扫描模式;检测模式为选择反应监测(SRM)。结果显示,邻氯苯胺、间氯苯胺和对氯苯胺分别在0.76 ng·mL-1~30.55 ng·mL-1、0.76 ng·mL-1~30.26 ng·mL-1和0.76 ng·mL-1~30.44 ng·mL-1范围内线性良好,定量限均为0.76 ng·mL-1,检测限均为0.25 ng·mL-1;平均加标回收率分别为94.02%、93.27%和90.09%,RSD分别为2.69%、3.84%、3.19%,且稳定性良好。样品检测结果显示6批均未检出三种杂质,建立的分析方法重复性好、专属性强、灵敏度高,适用于氢氯噻嗪中三种氯苯胺的检测。  相似文献   

3.
烟草中β-胡萝卜素的热裂解产物的研究   总被引:22,自引:0,他引:22  
杨伟祖  谢刚  王保兴  侯英  杨勇  徐济仓  杨燕  王玉 《色谱》2006,24(6):611-614
为了研究烟草中β-胡萝卜素的高温裂解产物对卷烟抽吸品质的影响,利用热裂解气相色谱/质谱联用仪在不同裂解氛围(空气、氮气中含10%O2及N2)和不同温度(300,600和900 ℃)下对β-胡萝卜素进行裂解,裂解产物用固相微萃取装置进行吸附,然后将吸附到的裂解产物用气相色谱/质谱联用仪(GC/MS)进行分析。结果表明,β-胡萝卜素在不同裂解条件下主要的裂解产物是甲苯、对二甲苯、1,2,3,4-四氢-1,1,6-三甲基萘和2,7-二甲基萘等化合物,另外还生成异佛尔酮、β-环柠檬醛、β-紫罗兰酮、二氢猕猴桃内酯等香味化合物,这些物质随裂解温度和裂解氛围的不同其含量有所差异。  相似文献   

4.
采用高效液相色谱-串联质谱(HPLC-MS/MS)技术建立了塑料聚合物中9,10-二氢-9-氧-10-磷杂菲-10-氧化物(DOPO)迁移量的测定方法,并对不同浸泡模拟物、不同温度和时间下DOPO的迁移规律进行研究。样品采用欧盟(EU)2017/752法规中的食品模拟物浸泡。水基模拟物直接过滤,橄榄油模拟物用含38%甲醇的乙腈溶液萃取后,经C_(18)色谱柱分离,以甲醇-2 mmol/L醋酸铵水溶液(含0.1%甲酸)为流动相,采用多反应监测模式进行检测。水基模拟物(3%乙酸、10%乙醇、50%乙醇)中DOPO的定量下限为0.10 ng/mL,橄榄油模拟物中的定量下限为1.0 ng/g。样品加标回收率为85.3%~110%,相对标准偏差(RSD,n=6)不大于7.3%。该方法快速简便、灵敏度高、准确性好,适用于塑料聚合物中DOPO迁移量的测定。  相似文献   

5.
提出了气相色谱-串联质谱法测定无烟气烟草中N,N-二甲基亚硝胺的方法。无烟气烟草样品(0.500g)用二氯甲烷10mL超声萃取,上清液用硅固相萃取柱净化。在气相色谱分离中用DB-WAX石英毛细管色谱柱为固定相,在质谱分析中采用多反应监测模式。采用内标法定量。N,N-二甲基亚硝胺的线性范围为0.2~10μg·L~(-1),方法的检出限(3s)为0.018ng·g~(-1),测定下限(10s)为0.060ng·g~(-1)。在3,6,10ng等3个浓度水平进行加标回收试验,回收率为94.7%~101%,测定值的相对标准偏差(n=5)为2.8%~6.8%。  相似文献   

6.
本文构建了一种基于FLASH色谱技术的烟草烘丝尾气收集液的分级装置。该装置采用阳离子交换柱、阴离子交换柱和大孔吸附树脂柱串联的方法分级烟草烘丝尾气收集液,优化分离条件,结合气相色谱/质谱(GC/MS)分析对烟草烘丝尾气收集液分级装置进行评价。结果显示,烟碱吸附于732型的阳离子交换树脂中,而717型阴离子交换树脂和AB-8型大孔吸附树脂富集了乙酰基吡咯、二氢猕猴桃内酯、β-二氢大马酮等烟草中的多种致香成分。  相似文献   

7.
以不同配比的甲醇和水作洗脱液,对手性物质酒石酸和5-氰基-1,3-二苯基-4,5-二氢吡唑进行了手性色谱柱高效液相色谱分离。对于亲水性的酒石酸,以纯水作为洗脱液,手性异构体不能得到分离;洗脱液中甲醇的含量增加到50%,D-和L-异构体得到分离,但是内消旋异构体和D-异构体仍然混在一个峰中;以100%甲醇作洗脱液,酒石酸的内消旋及D-和L-三个异构体的色谱峰全部分开。对于憎水性的5-氰基-1,3-二苯基-4,5-二氢吡唑,以100%甲醇作为洗脱液;当洗脱液中水的含量增加到30%时,R-和S-手性异构体的色谱峰开始分离,但是两个峰大小不相等,分离效果不理想;当洗脱液中水的含量增加到35%时,R-和S-手性异构体的色谱峰分离为两个大致相等的色谱峰,但是两个色谱峰仍有部分交叠。保留时间加长,有利于对映异构体的分离,保留时间长的色谱峰变宽。  相似文献   

8.
工作场所空气中54种挥发性烃类物质的检测   总被引:2,自引:1,他引:1  
采用Tenax-TA吸附剂管采集工作场所空气中54种挥发性烃类化合物,经热脱附-气相色谱检测。结果显示,1,1-二氯乙烯、二氯甲烷、1,2-二氯乙烯(反式)、1,2-二氯乙烯(顺式)、2,2-二氯丙烷、溴氯甲烷、1,1,1-三氯乙烷、1,2-二氯乙烷、1,1-二氯丙烯的相关系数在0.9941~0.9986之间,溴氯甲烷、二溴甲烷、三氯甲烷、溴二氯甲烷、2,2-二氯丙烷、二溴氯甲烷、溴仿的检出限为5.4~10.3ng,最低检出浓度0.01~0.1mg/m3(采样体积0.5L)。其余38种挥发性烃类物质的相关系数均大于0.999,最低检出浓度0.001~0.01mg/m3;其中烯烃类检出限为0.4~2.7ng、烷烃类为1.4~3.7ng、芳香烃类为0.2~1.0ng、萘为2.2ng;54种挥发性烃类物质的热脱附效率92.1%~113.1%,RSD为0.6%~17.4%,除1,2-二氯乙烯(顺式)、1,1-二氯乙烷、1,1,1-三氯乙烷、1,1-二氯乙烯、2,2-二氯丙烷、三氯甲烷、1,2-二氯乙烯(反式)、二氯甲烷、溴氯甲烷的RSD值在5.1%~17.4%外,其余45种挥发性烃类物质的RSD均小于5%;9种化合物...  相似文献   

9.
建立了超高效液相色谱法快速测定辣椒制品中辣椒素、二氢辣椒素、降二氢辣椒素的方法.样品以四氢呋喃-甲醇(体积比1:1)提取,采用反相高效液相色谱分离.色谱柱为BEH C18,流动相乙腈-水进行梯度洗脱;二极管阵列检测器(DAD),检测波长为280 nm.各成分在1.0 -100.0 mL/L范围内线性良好.辣椒素、二氢辣...  相似文献   

10.
邵曼  余晓琴  黄丽娟  姚欢  李澍才 《色谱》2023,(5):426-433
研究在优化前处理条件及色谱分离的基础上,建立了同时测定巧克力、软糖、糕点、饼干、饮料、白酒等6种典型食品基质中8种大麻素类化合物的超高效液相色谱-串联质谱(UPLC-MS/MS)的测定方法。前处理方法中考察了不同的净化方式,采用增强型脂质去除净化剂(EMR-Lipid)解决了巧克力中复杂油脂及软糖中胶质难以去除的问题;同时净化溶液在氮吹前加入10%丙三醇甲醇溶液,解决了目前文献方法中直接氮吹对回收率影响很大的关键问题。样品以乙腈为提取溶剂,EMR-Lipid为净化剂进行净化,无水硫酸钠除水后,乙腈层加入10%丙三醇甲醇溶液100μL,氮吹至近干;采用Waters ACQUITY UPLC BEH Shield RP18色谱柱进行分离,电喷雾负离子扫描,多反应监测(MRM)模式检测,基质匹配外标法定量。方法学研究表明,四氢大麻酚、次大麻二酚、四氢大麻素、大麻萜酚在2~200 ng/mL范围内线性关系良好;大麻酚、大麻二酚、大麻二酚酸、四氢大麻酚酸A在0.4~40 ng/mL范围内线性关系良好,相关系数(r)均大于0.995;检出限和定量限分别为0.8~4μg/kg和2~10μg/kg。在...  相似文献   

11.
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%.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
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.  相似文献   

18.
19.
《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.  相似文献   

20.
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.  相似文献   

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