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91.
Yi-Liang Lin Po-Yen Wang Ling-Ling Hsieh Kuan-Hsuan Ku Yun-Tai Yeh Chien-Hou Wu 《Journal of chromatography. A》2009,1216(36):6377-6381
A simple and sensitive method is described for the determination of picomolar amounts of C1–C9 linear aliphatic aldehydes in waters containing heavy metal ions. In this method, aldehydes were first derivatized with 2,4-dinitrophenylhydrazine (DNPH) at optimized pH 1.8 for 30 min and analyzed by HPLC with UV detector at 365 nm. Factors affecting the derivatization reaction of aldehydes and DNPH were investigated. Cupric ion, an example of heavy metals, is a common oxidative reagent, which may oxidize DNPH and greatly interfere with the determination of aldehydes. EDTA was used to effectively mask the interferences by heavy metal ions. The method detection limits for direct injection of derivatized most aldehydes except formaldehyde were of the order of 7–28 nM. The detection limit can be further lowered by using off-line C18 adsorption cartridge enrichment. The recoveries of C1–C9 aldehydes were 93–115% with a relative standard deviation of 3.6–8.1% at the 0.1 μM level for aldehydes. The HPLC–DNPH method has been applied for determining aldehyde photoproducts from Cu(II)–amino acid complex systems. 相似文献
92.
WANG Ping WANG Lei WANG Li-cheng LI Chun-yuan WANG Ren MIAO Qing-hua YANG Ming WANG Zhi .Key Laboratory for Molecular Enzymology Engineering of Ministry of Education .College of Life Science Jilin University Changchun P.R.China 《高等学校化学研究》2009,25(1)
A simple method for rapid estimation of the enantioselectivity of lipase in resolution of chiral esters is described. The enantioselectivity of lipase can be estimated rapidly through comparing the dif-ference of hydrolysis rates for the racemic ester and its slow reacting enantiomer under the same condition because the difference mainly depends on the enantioselective ratio(E values). The higher the enantiose-lectivity of enzyme, the larger the difference of hydrolysis rate. The bromothymol blue(BTB) can be used as pH indicator for microplate reader to monitor the formation of acid in lipase-catalyzed hydrolysis ofesters. This method has been successfully used to rapidly estimate the enantioselectivity of several lipases in the resolution of glycidyl butyrate. 相似文献
93.
94.
硫酸铈(Ⅳ)催化合成丁酸丁酯 总被引:5,自引:2,他引:5
丁酸丁酯被广泛应用于食品、医药、烟草、日用化学工业 ,目前工业生产方法以浓硫酸催化丁酸和丁醇反应为主[1] 。由于浓硫酸的脱水、氧化作用 ,使得产物色泽深 ,产率低 ;而且硫酸易腐蚀设备 ,产品后处理产生的酸性废水严重污染环境。因此人们在努力寻找浓硫酸催化法的替代方法。用对甲苯磺酸、杂多酸为催化剂[2 4 ] 对合成丁酸丁酯具有很好的催化效果 ,但存在反应时间长、原料用量大等问题。本文以结晶硫酸高铈为催化剂合成了丁酸丁酯。1 实验部分1 .1 仪器与试剂岛津GC 1 6A气相色谱仪 ,FTS 2 1 0 0型红外光谱仪(美国Bio Ra… 相似文献
95.
《Thermochimica Acta》2003,405(1):147-154
This paper reports measurements on excess thermodynamic properties for the ternary system: butyl butyrate+1-octanol+decane at the temperature 308.15 K and atmospheric pressure.The binary and ternary experimental data were correlated using the Redlich-Kister and Cibulka equation, respectively. Experimental values were compared with the predictions obtained by several contribution models and several empirical equations. 相似文献
96.
97.
Poly‐3‐hydroxy butyrate has been etched and studied under scanning and transmission electron microscopes. It displays three of the following unusual features: (1) spherulites develop in a loose spiral rather than radial structure, which appears to reflect the chiral nature of the polymer; (2) in the banded spherulitic structure, lamellae oriented flat‐on to the surface are etched more deeply in relation to edge‐on lamellae; and (3) material crystallized at high temperature is less resistant to etching than that crystallized at low temperature, whereas the most rapid rate of etching appears to be where growth occurred at an intermediate temperature where the growth rate was at its maximum. The second and third phenomena are contrary to what is found in polymers such as polyethylene and polyethylene terephthalate and are attributed to excess free volume in the material located between the main lamellar bundles. Polyoxymethylene also displays the same unusual relationship of etching rate with crystallization temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 124–133, 2002 相似文献
98.
99.
用循环伏安法研究了2,2’-联喹啉推动Cu~(2+)在水/硝基苯界面的转移,提出了配合转移机理,并研究了配合反应过程的动力学,测定了Cu~(2+)和2,2’-联喹啉形成的1:2配合物的界面热力学参数和配合物的形成速率常数k. 相似文献
100.
分别以罗丹明B和罗丹明6G为荧光信号报告基团,以增强水溶性为目的的羟乙基肼为修饰基团,合成了反应型的Cu_(2+)离子选择性荧光探针分子L1和L2.紫外光谱和荧光光谱等分析结果表明,探针分子L1和L2对Cu_(2+)离子具有高灵敏度、高选择性的光谱识别行为.探针分子对Cu_(2+)离子的识别过程是通过Cu_(2+)离子催化水解控制氧杂蒽荧光信号的螺环酰肼基团实现荧光信号的开启,从而达到识别检测Cu_(2+)离子的目的,对Cu_(2+)离子的检出限均可达到10-8mol/L量级.同时,探针分子对常见金属离子和铵离子均具有较强的抗干扰能力.由于羟乙基肼的引入增强了探针的水溶性,使得探针L1和L2具有良好的细胞通透性和低毒性,实现了其对β-胰岛细胞(INS-1细胞)中Cu_(2+)离子的荧光成像检测. 相似文献