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1.
对土壤及玉米植株中均三氮苯类除草剂的残留分析   总被引:4,自引:0,他引:4  
刘峰  慕卫  王金信  于金凤 《色谱》1998,16(6):543-544
土壤或玉米植株样品用V(甲醇)∶V(乙腈)=1∶1提取,提取液用石油醚净化后,浓缩液过C18小柱净化,最后用Nova-PakC18柱进行HPLC分析。回收率:氰草津为82.4%~99.8%,莠去津为85.6%~102.3%,西草净为89.1%~108.4%。  相似文献   

2.
测定牛奶中5种青霉素残留量的高效液相色谱柱前衍生法   总被引:16,自引:1,他引:16  
样品采用乙腈直接提取,离心分离及固相(C18柱)净化方式,经衍生后,用液相色谱紫外检测器测定牛奶中5种青霉素残留,方法最小检测质量 度0.005mg/L,回收率范围在68.9%-101.3%之间,相对标准偏差为3.21%-6.18%。  相似文献   

3.
测定了LaX3-C18H16N3O2Cl-H2O(X=NO^3,Cl^-)三元体系在30℃时的溶度和饱和溶液的折光率。发现La(NO3)3=C18H16N3O2Cl-H2O体系有不一致溶化合物La(C18H16N3O2Cl)3(NO3)3生成,而LaCl3-C18H16N3O2Cl-H2O体系为简单共饱体系。  相似文献   

4.
直接测定钨产品中部分杂质元素的FAAS   总被引:1,自引:0,他引:1  
采用氨水-EDTA二铵盐作为钨产品的溶剂和干扰抑制剂,以空气乙炔火焰原子吸收法直接连续测定钨产品中Cd、Co、Cu、Fe、Mg、Mn、Ni元素。经三氧化钨标准样的验证,测定值与推荐值相符。实际样品的加标回收率为84.4~106%,RSD在1.18%~5.18%范围。  相似文献   

5.
极谱法测定地质样品中痕量氯   总被引:7,自引:2,他引:7  
提出了0.1%HCOOH-8×10^3%百时香酚兰,-0.4mol/LHClO4-0.4%TritonX-100极谱法痕量氯离子的新体系,检出限为0.18μg/g,RSD为7.6%,标准样品测定结果与推荐值相吻合。  相似文献   

6.
本文以工业应用为目的,采用内循环无梯度反应器,在573-673K,0.30-1.20MPa的条件下,原料气组成为H2 50-54%,CO11.7-20.7%,CH4 2.1-14.3%,CO2 6.4-11.5%,N2 12.2-18.1%范围内,研究了φ×3mmSDM-1型城市煤气耐硫甲烷化催化剂的宏观动力学方程选择 CO+3H2=CH4+H2O (1) CO+H2O=CO2+H2 (2)  相似文献   

7.
固相萃取技术-HPLC测定复方甘草片中吗啡的含量   总被引:9,自引:0,他引:9  
王勇  曾洁 《色谱》1998,16(3):229-231
报道了用SEP-PAKC18小预柱固相萃取技术和反相高效液相色谱法测定复方甘草片中微量吗啡含量的方法。对固相萃取条件进行了研究,最终选择10%甲醇溶液为清洗溶液,70%甲醇溶液为洗脱溶液,基本消除了干扰组分对测定的影响,色谱图背景吸收小,基线平稳。色谱柱为μ-BondapakC18柱,流动相为0.1mol/LNaH2PO4溶液-甲醇(51),检测波长为286nm。平均回收率为(101.2±1.5)%,RSD为1.5%。  相似文献   

8.
蜂蜜中四环素族抗生素残留量的薄层色谱测定法   总被引:8,自引:1,他引:8  
残留在蜂蜜中的四环素族抗生素在经Sep-PakC18小柱固相萃取处理后,用高效正相薄层色谱予以分离,喷雾显色后用紫外灯进行定性分析;使用双波长薄层扫描仪进行定量测定。在蜂蜜中的添加量为0050×10-3、010×10-3及020×10-3时,强力霉素(DC)、土霉素(OTC)和四环素(TC)的回收率分别为916%~1003%、845%~1031%和770%~1032%。该法的测定低限可达到10-3μg。  相似文献   

9.
18-冠-6修饰碳糊电极测定金的研究   总被引:2,自引:0,他引:2  
本文研究了18-冠-6修饰碳糊电极测定金的条件,金在0.5mol/LHC1-0.005mol/LKC1底液中富集,介质交换到0.01mol/LHC1中进行测定。金(Ⅲ)浓度在0.1~1.0μg/mL范围内呈线性关系,相对标准偏差为9.7%,检出限为20ng/mL。可不经预先分离直接测定矿样中的金,结果良好。并研究了Au(Ⅲ)在18-冠-6碳糊修饰电极上的还原机理。  相似文献   

10.
接枝共聚物氯化聚乙烯-苯乙烯对聚苯乙烯的共混改性   总被引:1,自引:0,他引:1  
用氯化聚乙烯接枝苯乙烯共聚物(CPE-g-St)和氯比聚乙烯(CPE)对聚苯乙烯(PS)进行共混改性.当CPE含量为25%时,用CPE-g-St改性的共混物的冲击强度为18.5kJ·m ̄(-2),是用CPE改性的共混物冲击强度的2.1倍;其拉伸强度不低于34MPa.  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.
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   

13.
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   

14.
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   

15.
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   

16.
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   

17.
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   

18.
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   

19.
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.  相似文献   

20.
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.  相似文献   

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