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determination of fluorine
相关语句
  测定氟
     Based on the linear range of fluorine ion-selective electrode,a new method with four point calibrating and linear regression is described for determination of fluorine content,within the fluorine content of 0.02%~5.00%,the recovery of 94%~100.2% and the relative standard deviation(RSD)of 0.4%~2.1%,which is a better determination than that of traditional method.
     研究一种基于氟离子选择电极的线性范围,提出了用四点校正法和线性回归方法计算测定氟含量的方法,w(F)在0.02%~5.00%,回收率94%~100.2%,相对标准偏差(RSD)0.4%~2.1%。 该方法具有准确、简便、快速、灵敏、选择性好的特点,明显优于传统的测定计算方法。
短句来源
     Determination of Fluorine with Ion Selective Electrode by Sample Addition
     试样加入-离子选择性电极法测定氟
短句来源
     Spectrophotometric Determination of Fluorine with Alizarin Complexone by 8-Hydroxylquinoline Extraction
     8-羟基喹啉萃取-氟试剂分光光度法测定氟
短句来源
     Determination of Fluorine in Solution of Containing Calcium with Fluorine Ion Selective Electrode
     用离子选择性电极在含钙溶液中测定氟
短句来源
     Determination of Fluorine With Ion Selevtive Electrode by Sample Addition
     试样加入法—离子选择性电极测定氟
短句来源
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  氟测定
     The problem of the effect of temperature in the determination of fluorine can be solved by this method.
     该模型较好地解决了温度对氟测定的影响 ,且适用范围较广
短句来源
  氟的测定
     The Method of Determination of Fluorine Content in Air
     空气总氟的测定方法
短句来源
     It has been applied to the determination of fluorine in various vegetables with satisfactory results.
     应用于各种蔬菜中氟的测定,结果满意。
短句来源
     Determination of Fluorine in Organic Compounds
     有机化合物中氟的测定
短句来源
     The method controlls the pH value of solution to remove the disturbing ions for the determination of fluorine concentration in sediments, and uses two time added method and a small procedure ( with PC-1500) for the analyses of sea water and pore water, which effectively avoid the error in slope and the complicated calculation in conventional methods.
     该法在沉积物的分析中用控制溶液的pH值来排除干扰离子,在海水和间隙水中对氟的测定用两次加入法及使用微型计算机,从而避免了斜率误差与传统方法的烦琐计算。
短句来源
     Study on Determination of Fluorine Content in Feedstuff
     饲料中氟的测定研究
短句来源
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  “determination of fluorine”译为未确定词的双语例句
     DETERMINATION OF FLUORINE IN CeO_2 WITH LOW PRESSURE ION CHROMATOGRAPHY
     低压离子色谱法测定CeO_2产品中微量氟的研究
短句来源
     The determination of fluorine in barytes ores by 14 MeV neutron activation analysis
     14MeV中子活化分析法测定重晶石矿样中氟
短句来源
     Determination of Fluorine in Salt by Electrode Method
     电极法测定食盐氟
短句来源
     A method for the determination of fluorine in vegetables by ion selective electrode is described.
     本文介绍了一种用氟离子选择性电极测定蔬菜中微量氟的方法。
短句来源
     Determination of Fluorine in Pazufloxacin Mesilate Sample by ~(19)F Nuclear Magnetic Resonance
     ~(19)F-NMR测定甲磺酸帕珠沙星样品中的氟
短句来源
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  determination of fluorine
The volumetric thoriometric determination of fluorine in organic compounds after their fusion with KOH is made easier by using a cationite.
      
Use of cationite in the determination of fluorine in fluoroorganosilicon compounds by thoriometric titration
      
1.It was shown that silicic acid interferes in the colorimetric determination of fluorine by the zirconia-alizarin method by combining with zirconium and reducing the red component of the color.
      
Possibility of the application of molecular bands for the determination of fluorine in tungsten
      
Determination of fluorine in glass crystallite using complexometric back titration
      
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In view of the necessity of a rapid and accurate process for the deter-mination of fluorine applicable in the analysis of sodium fluoride and otherfluorine compounds,the author has established a new volumetric processconsisting in the titration in aqueous-alcoholic medium with ferric nitrate asstandard solution and sodium salicylate as indicator.All of the methods,published by Guyot,Greeff,Fairchild andVisintin proposed for the determination of fluorine using ferric solutionas standard,are based on the...

In view of the necessity of a rapid and accurate process for the deter-mination of fluorine applicable in the analysis of sodium fluoride and otherfluorine compounds,the author has established a new volumetric processconsisting in the titration in aqueous-alcoholic medium with ferric nitrate asstandard solution and sodium salicylate as indicator.All of the methods,published by Guyot,Greeff,Fairchild andVisintin proposed for the determination of fluorine using ferric solutionas standard,are based on the reaction:6NaF+FeCl_3→Na_3FeF_6+3NaCl. But the sodium ferric fluoride thus formed is fairly soluble in water and makesthe end-point unclear,therefore the titration can not be performed accurately.This seems to be due to the fact that the following two reactions advancesimultaneously,and accordingly the formation of sodium ferric fluoride is in-complete in aque(?)us medium:3NaF+Fe(NO_3)_3→FeF_3+3N_aNO_33NaF+FeF_3→Na_3FeF_6Nevertheless,these reactions,according to the author's experiments;proceedalmost quantitatively in meda.containing at least 50% by volume of alcohol.This paper reports the xperimental results obtained in the fundamentalstudies on the various factors influencing the accuracy of the volumetry,namely,the sensitivity and the necessary amount of sodium salicylate used asindicator,the pH value,the alcoholic concentration of the titration medium,the concentration of the fluoride taken for the determination and the timewhen alcohol should be added in the course of titration.Furthermore,a rapidvolumetric process with high accuracy is proposed together with its applicationsin ordinary analyses of sodium fluoride and other fluorine compounds.The proposed method is characteristic in using sodium salicylate asindicator,which shows sharp violet color with minute amount of ferric ion inmedium of pH 3 controlled with buffer solution,then titrating with standardferric nitrate,and adding proper amount of alcohol(the alcoholic concentra-tion at the end-point should be above 50%)during the titration,when themedium becomes orange yellow in color.The method may be summarized as follows:Take 5 ml of neutral sodiumfluoride solution of about 0.3 N in a small Erlenmeyer flask,add 2.5 mlof Walpole's buffer solution of pH 3(formed by dissolving 34.0 g ofcrystalline sodium acetate and 20 ml of 38% HCl in water,and making upto 250 ml)and 1 ml of 0.1 M sodium salicylate dissolved in 50% alcohol.After sufficient stirring,titrate with standard 0.3 N(0.05 M)ferric nitratesolution,using micro-burette until the medium becomes orange yellow,thisstep being reached after addition of about 4 ml of titrant.Then decolorizethe solution by adding 12.5 ml of absolute alcohol(or 13 ml of 95% alcohol),previously purified by redistillation with lime;stirring is necessary during theaddition.Further continue the titration until the light pink color formeddoes not fade after stirring for 30 seconds when observed over a white surface. In the analyses of sodium fluoride and other fluorine compounds con-taining interfering substances,such as divalent and polyvalent metallic ions,phosphate,silicate,borate,carbonate,sulfide ions and reductants acting on ferricion,it is necessary to separate fluorine from these interfering substances bythe distillation with sulfuric acid according to the method of Willard andWinter(20).Then the distillate is neutralized with dilute sodium hydroxideand adjusted to the proper pH with hydrochloric acid using p-nitrophenol asindicator.The solution is ready for titration as described.But in the caseof absence of these interfering substances except carbonate,for example,inthe determination of the concentration of sodium fluorde solution obtained bythe extraction of the crude product,produced industrially by fusing fluorsparwith sodium carbonate and silica,the above separation of fluorine by dis-tillation is dispensable.The anaIytical results obtained by the proposed method are in goodagreement with those obtained by the lead chlorofluoride process(8),whichis recognized as official method for the determination of fluorine in agriculturalproducts.

本文介绍一容量分析氟的新方法和在工业制品上的应用,并分析了一种工业制备的氟化钠液,所得的结果和氟氯化铅法所得的极为一致。对于影响该分析法准确度的各种因素:指示剂的灵敏度和滴定时适宜的用量、溶液的 pH 值、应加的乙醇量、操作中加乙醇的次序、以及氟离子的适宜浓度,均加以研究并找出适宜的情况。本法用硝酸铁为标准液,水杨酸钠作指示剂,在 pH=3左右作滴定;当溶液呈橙黄色时,加入适量的乙醇,使其浓度在终点时仍不低于50%。如有干扰物质如二价及多价金属离子、磷酸根、矽酸根、硼酸根、碳酸根、硫化物和还原物质可能与三价铁起作用者,均应分离之。

Procedures are developed for the determination of fluorine in organic compounds by titration with La (NO_3)_3-EDTA after decomposing the sample by Sch(?)niger's oxygen flask method. Five to fifteen mg of the sample are decomposed in an oxygen flask. The absorbing liquid is washed out, an excess of 0.01M La(NO_3)_3 regent is added, and the mixture is boiled for 10 minutes. After being allowed to cool, about 0.2g. hexamethylenetetramine and 2~3 drops of xylenol orange indicator are added, and the solution...

Procedures are developed for the determination of fluorine in organic compounds by titration with La (NO_3)_3-EDTA after decomposing the sample by Sch(?)niger's oxygen flask method. Five to fifteen mg of the sample are decomposed in an oxygen flask. The absorbing liquid is washed out, an excess of 0.01M La(NO_3)_3 regent is added, and the mixture is boiled for 10 minutes. After being allowed to cool, about 0.2g. hexamethylenetetramine and 2~3 drops of xylenol orange indicator are added, and the solution is titrated with 0.01M EDTA. *When Pr(NO_3)_3 (0.01M) regent is used in place of La(NO_3)_3, heating to boiling is sufficient; Otherwise, the procedure is the same as described above. *Direct titration with Pr (NO_3)_3 is less satisfactory.

本文提出了用两个简便、准确并且终点明显的络合滴定来测定有机氟化合物中氟的含量之新方法。硝酸镧试剂测定氟化物中含氟量的适用范围是0.45~7.00毫克;硝酸镨试剂测定氟化物中含氟量的适用范围是0.25~3.50毫克。Cl~-、Br~-、I~-、Mg~(2+)、Sn~(4+)、BO_3~-、BrO_3~-等离子对氟化物中含氟量的测定无干扰;PO_4~(3-)、AsO_4~(3-)离子和H_2O_2使测定结果偏高;Cu~(2+)可用硫脲作掩蔽剂,Al~(3+)可用乙酰丙酮作掩蔽剂。滴定前加入2~3滴乙酰丙酮有很大的好处。本法能适用于有机硅氟化合物中氟的测定,而用于有机硼氟化合物中氟的测定则不能得出满意的结果。

This article presents a study on the extent to which the rare-earth elements interfere with the determination of fluorine,and the elimination of this interference by treatment with ammonium oxalate.A procedure of the determination of fluorine with the fluoride-selec-tive electrode is suggested and its application to slags containing rare-earth elements for determining fluorine has been found to give satisfactory results.

本文研究了某些稀土元素对氟测定的干扰程度,及用草酸铵排除稀土干扰的情况,提出了用氟离子选择性电极测定氟的操作方法,并用此方法测定了各种炉渣中(含稀土)的氟,获得了令人满意的结果。

 
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