葡萄糖、果糖、蔗糖中水分含量检测方案(卡氏水分测定)

HITACHI曰立Inspire the Next HIRANUMA APPLICATIONDATA Karl Fischer Titrator Data No. KF17 Water contents Sugars - KF Volumetry， Powder Sample Glucose， fructose， and sucrose 1.Abstract Water contents of sugars could be determined by Karl Fischer volumetric titrator. In volumetric titration， titrant have a factor which means thecapacity to react with water per 1 mL of titrant. Factor is pre-determined before sample measurement and water content of sample is calculated fromconsumed titrant volume by sample measurement. This application introduces an example for the water determination in glucose， fructose，and sucrose. Sugars have tendency to dissolve informamide. Therefore a mixed solvent of formamide and methanol was chosen as the titration solvent. 2. Apparatus and Reagents (1)Apparatus Titrator ：Hiranuma Karl Fischer Volumetric titrator AQV-series Titration cell ：Standard Cell， without drain valve P/N D327511-1 Powder funnel ：less than 13 mm outer diameter of leg (2)Reagents Titrant ：HYDRANAL Composite 1 (Honeywell) Methanol ：HYDRANAL Methanol (Honeywell) Formamide ：HYDRANAL Formamide dry (Honeywell) Titration solvent ：Mixed solvent of methanol and formamide at a volume ratio of 1： 2 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) Put a sample container， powder funnel and spoon on the balance. Record its read (Si[g]). (4) Open the glass stopper of titration cell lid to introduce the sample with powder funnel as shown in Fig.3.2. (5) Start titration. Measurement parameter is shown in Table 4.1. (6) Weigh the sample container， powder funnel and spoon again and record its read (Sz [g]). The difference of (Si-S2[g]) is set as sample size. Fig.3.1 Preparation of the reagents Fig.3.2 Introduction of sample with powder funnel 4. Parameters and results Table 4.1 Parameters Condition File Cal Mode 0：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 1.0868 mg/mL KF Buret No. 1 KF Speed(OUT) 12 mL/min KF Speed(IN) 12 mL/min Back Ground OFF Sample Size Input Every Time Blank Value 0 mL Unit Mode AUTO E.P Detection uA Solvent FM C.P Level 150 uA E.P Level 200 uA Auto Interval 0 g Table 4.2 Results of water content measurement in sugars Sample Sample Titer Water Water Statistics result size (g) volume(mL) (mg) content (ppm) Glucose 0.7383 1.41 1.532 2075.0 Avg. 2076.3 ppm 0.6805 1.27 1.380 2028.0 SD 49.0 ppm 0.4549 0.89 0.967 2126.0 RSD 2.4 % Fructose 0.6485 0.35 0.380 586.0 Avg. 585.1 ppm 0.7050 0.38 0.413 585.8 SD 1.4 ppm 0.5965 0.32 0.348 583.4 RSD 0.2% Sucrose 0.4116 0.29 0.315 765.3 Avg. 762.5 ppm 0.6171 0.43 0.467 756.8 SD 4.9 ppm 0.7238 0.51 0.554 765.4 RSD 0.6% 5. Note The blanking might become unstable when time has passed since the solvents of methanol and formamide were mixed. The cause could be dueto the ammonia generated by mixing solvents. Adding 3 g of benzoic acid to 50 mL of the titration solvent improves the unstable state of(1) blanking. AQV series released after 2009 have the current detection method which is added as the endpoint detection method in addition to theconventional potential detection method. The current detection method doesn’t need the adjustment of the end point parameter “EP level" foreach titration solvent type. In this application， it is set to the current detection method. When performing with the potential detection method， set (2)“E.P. Detection”to“mV”， and set“E.P. level" to “3”for proper parameter of the titrant solvent (methanol/formamide). KeywordsS：：Karl Fischer， Volumetric titration， Sugar Science fora better tomorrow日立科学仪器(北京)有限公司热线电话： Science fora better tomorrow热线电话：立科学仪器(北京)有限公司 本实验采用平沼卡尔费休库伦法测定仪对糖类样品中的水含量进行测试。在容量法滴定中，卡尔费休试剂有不同的滴定度，表示每1mL卡尔费休试剂与水反应的能力。滴定度根据实际情况预先确定，样品的水含量由样品测量消耗的滴定剂体积计算。