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β-环糊精增敏荧光猝灭法测定水中微量银离子 总被引：1，自引：0，他引：1
银离子和盐酸萘乙二胺(NNE)的活性氨基有很好的配位络合作用,在pH=5.80的乙酸-乙酸钠缓冲溶液中可形成金属配合物NNE-Ag导致荧光强度发生猝灭,因其降低NNE分子的极性,有利于分子中的萘环进入β-环糊精的疏水空腔中,使体系的荧光强度猝灭更加明显。据此建立β-环糊精增敏NNE荧光猝灭测定银离子的方法。考察了pH值、反应介质、反应时间和β-环糊精用量等条件对体系的荧光强度影响。结果表明,在β-环糊精存在条件下,银离子可以使NNE的荧光强度发生较明显的猝灭,荧光猝灭程度与Ag离子的浓度在0-28μmol/L范围内呈良好线性,回归方程为I0/I=0.99363+0.01108C(C的单位为μmol/L),r=0.9985,检出限为2.35×10-4mol/L。将该方法用于水样中银离子的测定,得到较满意的结果。 相似文献
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基于亚硝酸根与碘化钾反应生成单质碘,碘可使异硫氰酸荧光素发生荧光猝灭的原理,采用流动注射连续可更新液滴荧光法测定亚硝酸根.体系的激发和发射波长分别为492nm和516nm,亚硝酸根含量在25~100μg/L范围内有良好的线性关系,检测限为3.9μg/L.本方法灵敏度高,选择性好,操作简单.用于环境水样中痕量亚硝酸根的测定,结果满意. 相似文献
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离子交换树脂光度法测定三种茶叶中的微量铜 总被引：1，自引：0，他引：1
在pH8.20时,吸附负载有铜试剂(二乙基二硫代氨基甲酸钠,DDTC)的717#强碱性阴离子交换树脂能与Cu2 形成稳定的树脂络合物,Cu2 -DDTC树脂络合物的最大吸收波长为442nm.以此建立了测定3种市售茶叶中微量Cu2 的新方法.Cu2 含量在0.08~3.2μg/mL范围内遵守Beer定律,较溶液光度法的灵敏度提高了近7倍.信噪比等于3(S/N=3)时,方法的检测限(LOD)为0.033μg/mL.此方法用于3种茶叶中的微量Cu2 的测定,相对标准偏差(RSD)小于3.0%,回收率97.3%~101.6%. 相似文献
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维生素C(抗坏血酸)经Cu2+氧化为脱氢抗坏血酸,在一定条件下与邻苯二胺反应生成具有荧光的物质.基于此,建立了一种新的测定维生素C的荧光分析法.实验中对氧化剂Cu2+及邻苯二胺的用量、缓冲液介质等进行了优化,在优化条件下,维生素C的浓度在0.05～5.00 μg/mL与其对应荧光强度呈良好的线性关系,相关系数R2=0.998 7;检出限为0.03 μg/mL;对3个不同浓度的样品进行加标回收实验,其回收率为88.91％ ～92.25％;对1.0μg/mL的样品测定3次,测定结果的相对标准偏差为1.98％.将该法用于西红柿、青椒等水果及蔬菜中维生素C含量的测定,结果令人满意. 相似文献
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用荧光光谱法研究嗪草酮与牛血清白蛋白的结合反应,显示嗪草酮能强烈的猝灭牛血清白蛋白的荧光强度。当嗪草酮的浓度为2×10-5～3.2×10-4mol/L时,荧光猝灭程度与嗪草酮浓度呈线性关系,其线性方程为I=3.44167+0.8885C,相关系数r=0.9926,检出限为6.26×10-7mol/l。用该方法对嗪草酮进行了实际样品中其含量测定。并且测定了该反应的结合常数和结合位点数。给出了在实际生产中对农药嗪草酮使用的指导意见。 相似文献
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《南阳师范学院学报》2017,(3):18-21
在表面活性剂Triton X-114存在下,利用Cu(Ⅱ)与2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚(5-Br-PADAP)反应生成疏水性配合物,建立了浊点萃取分光光度法测定痕量铜的方法.在pH=7的磷酸体系缓冲液中,该配合物的最大吸收波长λ_(max)=560nm,ε=2.7×105 L·mol5 L·mol(-1)·cm(-1)·cm(-1),测定铜的线性范围是0.01(-1),测定铜的线性范围是0.010.4μg/mL,相对标准偏差(RSD)为3.5%,加标回收率在95%0.4μg/mL,相对标准偏差(RSD)为3.5%,加标回收率在95%102%之间.此法用于实际水样中铜含量的测定,结果令人满意. 相似文献
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基于R(HFinCl4I4)在滤纸同体基质上能发射强而稳定的室温燐光,KBrO3氧化R发生室温燐光猝灭,HCHO与KBrO3反应生成Br2进一步氧化R,导致室温燐光剧烈猝灭,HCHO含量△Ip值呈良好线性关系,据此建立了HFinCl4I4-KBrO3-Tween-80体系同体基质室温燐光猝灭测定痕量甲醛的新方法.加比不加Tween-80时,△Ip增大9.1倍.本方法的线性范围为0.016～1.6(fg/spot)(对应浓度为0.040～4.0pg/mL,0.40pL/spot),工作曲线回归方程△Ip=136.6+28.28mHCHO(fg/spot),n=6,相关系数r=0.9935,检出限为4.5ag/spot(对应浓度1.1x10-44g/mL),灵敏、简便、快速,用于实际样品中痕量甲醛的测定,结果满意.同时探讨了HFinCI4I4-KBrOy-Tween-80体系固体基质室温燐光猝灭法测定甲醛的反应机理. 相似文献
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研究了新试剂5-H-酸偶氮若丹宁(HAR)与铜的显色反应.在pH7.0NH4Ac缓冲介质中,CTMAB存在下,HAR与Cu2 生成2∶1紫色稳定络合物,λm ax=590 nm,κ=1.02×104,质量在0-30μg/25 mL范围内符合比尔定律.该方法用于面粉、头发、指甲、滇池湖水中微量铜的测定,结果令人满意. 相似文献
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痕量铜的新催化光度法测定 总被引：1，自引：0，他引：1
研究了铜(Ⅱ)催化双氧水氧化溴百里酚兰褪色的催化效应及动力学条件,建立了测定痕量铜的新催化光度法.该法标准曲线的线性范围为铜(Ⅱ)浓度0～0.5μg/25mL,检出限为0.009μg/25mL,方法简便、快速、准确,用于铝合金中痕量铜的测定,回收率为96.0%～98.3%. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献