甲乙酮、丙酮、环己酮中水分含量检测方案(卡氏水分测定)

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Inspire the Next HITACHI HIRANUMAAPPLICATION DATA Karl Fischer Titrator Data No. KF14V Water contents Ketones and Aldehydes - KF Volumetry， Direct-Injection Methyl ethyl ketone，Acetone， and Cyclohexanone 1.Abstract Water contents of ketones and aldehydes could be determined by Karl Fischer volumetric titrator. In volumetric titration， titrant have a factor whichis the capacity to react with water per 1 mL of titrant. Factor is pre-determined before sample measurement and water content of sample is calculatedfrom consumed titrant volume by sample measurement. When the sample is liquid， generally sample is measured by direct injection into the titration cell. Dehydrated methanol is generally used for titrationsolvent. However， in the measurement of ketones and aldehydes， since these react with methanol to produce water， the measurement result tends to behigher than the true value (formula (1)). R2CO+2CH3OH→R2C(OCH3)2+H2O·.·(1) For above reason， Karl Fischer reagent without methanol should be used for water determination of ketones and aldehydes. There are commerciallyavailable reagents with a special composition for ketones and aldehydes. This chapter introduces an example for the water determination in methylethyl ketone， acetone and cyclohexanone with water added to them to 1%. These samples are often used as paint solvents， raw materials of adhesives，and synthetic resins. 2. Apparatus and Reagents (1)Apparatus (2)Reagents Titrator：Hiranuma Karl Fischer Volumetric titrator AQV-seriesTitration cell：Standard CellTitrant：HYDRANAL Composite 5KTitration solvent：HYDRANAL Working Medium K 3.Procedure (1) Fill 50 mL of titration solvent into the titration cell as shown in Fig.3.1. (2) Start blanking to attain stable background. (3) Wash the syringe with sample. (4) Draw the sample into syringe and then weigh the syringe. (5) Inject sample from rubber septum of titration cell as shown in Fig.3.2. (6) Start titration. Measurement parameter is shown in Table 4.1. (7) Weigh the syringe again and then set the difference of weight to sample size. Fig.3.1 Preparation of the reagents Fig.3.2 Injection of sample 4. Parameters and results Table 4.1. Parameter. Condition File Cal Mode O：Sample weight(net) X=(H-b)xFx1000/SIZE Interval Time 30 sec Max Volume 20 mL Min Feed Vol. 0.01 mL S.Timer 0 min KF Factor 5.4839 mg/mL KF Buret No. 1 KF Speed(OUT) 12 mL/min KF Speed(IN) 24 mL/min Back Ground OFF Sample Size Input Every Time Blank Value 0 mL Unit Mode AUTO E.P Detection uA Solvent S，O，CE C.P Level 150 pA E.P Level 200 pA Auto Interval 0 g Table 4.2 Results of water content measurement in ketones 5.Note When the side reaction cannot be suppressed even though you use reagent for ketones， phenomena such as unstable blanking or undetectable endpoint can be (1) obtained. In that case， it may be improved by reducing the amount of sample or replacing titration solvent with new one. (2) Sampling tools should be dried up well before use. (3) Purge and fill the titrant to fill it homogeneously into the buret. Science fora better tomorrow飞热线电话：立科学仪器(北京)有限公司 本实验通过容量法对酮和醛的水含量进行测试。样品为液体时，通常通过直接注入滴定池来测量样品。