丙酮中水分含量的检测 应用资料

丙酮中水分含量的检测 应用资料(英文版)丙酮是油漆、药物、偶联剂的溶剂、指甲油去除剂、测试设备的清洁剂，甚至在食品领域用作制造糖和淀粉的沉淀剂。在这些应用中，如果丙酮中的水分影响产品的质量，则必须对其进行控制。本应用资料使用库仑法卡尔费休水分仪测量丙酮中水分含量的示例。APKF-0164en Application Note Measuring the moisture in acetone IndustryChemicals InstrumentKarl Fischer Moisture Titrator Measurement methodCoulometric Titration/Direct method StandardsGB/T 6324.8 1. Scope Acetone is a solvent for paints, a pharmaceutical, a coupling agent, a nail polish remover, a cleaner for testing equipment, and is even used in the food products field as a precipitant in the manufacture of sugar and starch. In such applications, if the moisture in the acetone influences the quality of products, it must be controlled. This Application Note describes an example of measuring the moisture in acetone using the Karl Fischer method. In the Karl Fischer method, acetone and other ketones react with methanol, as shown below, producing water, which interferes with the results. Therefore, general purpose anolytes that contain methanol cannot be used. It is necessary to use anolytes for ketones containing low reactivity alcohols as a substitute for methanol. 2. Precautions Organic solvents are used, so place the Karl Fischer moisture titrator inside a fume hood. Note: The interference is not completely avoided by using an anolyte for ketones. If the titration does not finish or it takes time for the drift value to drop, assume that the capacity of the anolyte to control the interference has been reached, and replace the anolyte. 3. Post-measurement procedure Drain the anolyte and catholyte. Then clean the titration flask, the twin platinum electrode, and the inner burette with toluene. If alcohol is used as the cleaning liquid, when the acetone is measured at the next step, residual alcohol on the partition of the electrolytic electrode might interfere with the measurement. 4. Apparatus Main unit Karl Fischer moisture titrator(Coulometric titration) Electrode Twin platinum electrode, two component inner burette 5. Reagents Anolyte KEM AQUA AKE Catholyte KEM AQUA CGE 6. Procedure —Preparation— 1) Fill the titration flask with approximately 100 mL of the anolyte. 2) Fill the electrolytic electrode with approximately 5 mL of the catholyte. 3) Perform a preliminary titration and dehydrate the inside of the titration cell. —Measurement— 1) Using a syringe, collect the sample and weigh it. 2) Inject the sample using the side plug for the syringe and measure the moisture. 3) After injecting the sample, weigh the syringe. 4) The difference in the weight of the syringe before and after sample injection corresponds to the amount collected. 5) The measurement finishes when the moisture content per unit time(μg/s) falls below the initial drift value(μg/s)+ the relative drift value(μg/s). . 7. Formula Moisture(ppm)=((Data- Drift × t- Blank)/(Wt1- Wt2)) × F × 1 Data Total moisture content(μg) Drift Initial drift value(μg/s) Blank Blank test value(0 μg) t Measurement time(s) Wt1 Weight of the syringe before injecting the sample(g) Wt2 Weight of the syringe after injecting the sample(g) F Factor value(1.0) 8. Example of measurement We were able to measure commercial beer in GV/ P+ AIR mode. ― Titration parameter ― ＜Titr.Para＞ ＜Ctrl.Para＞ Titration mode H2O Cell type 2-comp. t(stir) 0s Stable 0.1μg/min t(wait) 30s Ctrl. gain 5.0 t(max) 0s E. speed Standard Drift stop Rel End level 200mV Drift 0.1μg/s Start mode Auto Sample time 5s Stirrer speed 3 (The above condition is an example. The setting condition depends on the model.) ― Example of Titration curve ― Time(h:m:s) Table 1 Moisture of Acetone Sample(g) Moisture(μg) Concentration(ppm) 1 1.5886 1177.6 741.3 2 1.6844 1252.4 743.5 3 1.4774 1099.3 744.1 Mean - - 743.0 SD - - 1.5 RSD(%) - - 0.2