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101.
102.
Ultrasound treatment acceleration of solvent extraction for fumigant residues from wheat 总被引:1,自引:0,他引:1
Concerns about consumer and worker safety and the fate of fumigants have fuelled strong efforts to determine their residues in foodstuffs. Fumigants are usually extracted from commodities with solvent at room temperature (25 degrees C). In this paper, solvent extraction of methyl bromide, phosphine, carbonyl sulfide, and carbon disulfide using ultrasonic acceleration or heating was evaluated. Wheat samples plus solvent, in gas-tight bottles, were placed in an ultrasonic chamber or an oven (50 degrees C), and fumigants were released into the headspace over the solvent. Completeness of extraction was demonstrated within 2 h for ultrasonic extraction, 7-20 h for 50 degrees C heating, and 8-35 h for room temperature extraction. The rapidity of extraction was mainly due to ultrasonic vibration rather than increased temperature. 相似文献
103.
双波长分光光度法同时测定岩石矿物中的微量金和钯 总被引:2,自引:0,他引:2
本文提出以硫代米蚩酮为显色剂,用双波长分光光度法同时测定岩石矿物中的微量金和钯的方法,消除了测定金钯的相互干扰,该方法简便,快速,选择性好,用于矿石样品中金和钯的测定,结果满意。 相似文献
104.
105.
壳聚糖衍生物的制备及其吸附性能 总被引:18,自引:2,他引:18
壳聚糖衍生物的制备及其吸附性能曲荣君,马千里,郑秀丽,孙言志(烟台师范学院化学系烟台264025)关键词壳聚精衍生物,制备,吸附壳聚糖(CTS)是重金瞩离子的吸附剂 ̄[1,2],由于壳聚精分子中的-NH_2在pH较低的水溶液易形成而使CTS溶于水,造... 相似文献
106.
The monodisperse, porous poly(chloromethylstyrene-co-divinylbenzene) beads of 7.9 microm were prepared by a single-step swelling and polymerization method. The seed particles prepared by dispersion polymerization exhibited good absorption of the monomer phase. Based on this media, a weak cation-exchange (WCX) stationary phase for HPLC was synthesized by a new chemically modified method. The prepared resin has advantages of biopolymer separation, high column efficiency, low column backpressure, high protein mass recovery, and good resolution for proteins. The dynamic protein-loading capacity of the synthesized WCX packings was 18.2 mg/g. Five proteins were separated in 3.0 min using the synthesized WCX stationary phase. The experimental results show that the obtained WCX resin has very weak hydrophobicity. The WCX resin was also used for the rapid separation and purification of lysozyme from egg white in 5.0 min with only one step. The purity and specific bioactivity of the purified lysozyme were found to be more than 93% and 70 245 U/mg, respectively. 相似文献
107.
108.
A simply fabricated microfluidic device using a green organic light emitting diode (OLED) and thin film interference filter as integrated excitation source is presented and applied to fluorescence detection of proteins. A layer-by-layer compact system consisting of glass/PDMS microchip, pinhole, excitation filter and OLED is designed and equipped with a coaxial optical fiber and for fluorescence detection a 300 microm thick excitation filter is employed for eliminating nearly 80% of the unwanted light emitted by OLEDs which has overlaped with the fluorescence spectrum of the dyes. The distance between OLED illuminant and microchannels is limited to approximately 1 mm for sensitive detection. The achieved fluorescence signal of 300 microM Rhodamine 6G is about 13 times as high as that without the excitation filter and 3.5 times the result of a perpendicular detection structure. This system has been used for fluorescence detection of Rhodamine 6G, Alexa 532 and BSA conjugates in 4% linear polyacrymide (LPA) buffer (in 1 x TBE, pH 8.3) and 1.4 fmol and 35 fmol mass detection limits at 0.7 nl injection volume for Alexa and Rhodamine dye have been obtained, respectively. 相似文献
109.
细胞色素C的电化学行为研究 总被引:7,自引:0,他引:7
本文评述了细胞色素C电化学研究的发展概况,重点介绍了细胞色素C在促进剂作用下的电化学行为,促进剂种类,影响促进作用的因素及促进机理。 相似文献
110.
蒙脱石修饰碳糊电极测定氨基酸的研究:Ⅱ.酪氨酸的测定 总被引:13,自引:1,他引:13
本文报道蒙脱石修饰碳糊电极测定酪氨酸,在0.001mol/L KCl-HCl(pH=2.0)溶液中开路富集,介质交换后微分脉冲阳极溶出伏安法测定,在0.5-2.5μg/ml范围内有线性,检测限为63ng/ml。可避免其他氨基酸,微量元素和常量金属元素的干扰,直接用于氨基酸药物样品的分析,获得了满意的结果,还对酪氨酸在电极上的反应机理进行了探讨。 相似文献