Sugars – KF Volumetry, Powder Sample Glucose, fructose, and sucrose | Karl Fischer titrator AQV-300/MOIVO-A19 - JM Science
HIRANUMA APPLICATION DATA Karl Fischer Titrator Data No. KF17 Apr. 19, 2018
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 the capacity to react with water per 1 mL of titrant. Factor is pre-determined before sample measurement and water content of sample is calculated from consumed titrant volume by sample measurement.
 This application introduces an example for the water determination in glucose, fructose, and sucrose. Sugars have tendency to dissolve in formamide. 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 or MOIVO-A19
    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 (S₁ [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 (S₂ [g]). The difference of (S₁-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 µA
E.P Level 200 µA
Auto Interval 0 g

 

Table 4.2 Results of water content measurement in sugars

Sample Sample
size (g)
Titer
volume(mL)
Water
(mg)
Water
content (ppm)
Statistics result
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

(1) The blanking might become unstable when time has passed since the solvents of methanol and formamide were mixed. The cause could be due to the ammonia generated by mixing solvents. Adding 3 g of benzoic acid to 50 mL of the titration solvent improves the unstable state of blanking.
(2) AQV series released after 2009 have the current detection method which is added as the endpoint detection method in addition to the conventional potential detection method. The current detection method doesn’t need the adjustment of the end point parameter “EP level” for each titration solvent type. In this application, it is set to the current detection method. When performing with the potential detection method, set “E.P. Detection” to “mV”, and set “E.P. level” to “3” for proper parameter of the titrant solvent (methanol/formamide).

Keywords: Karl Fischer, Volumetric titration, Sugar
Hiranuma aquacounter aqv-300 volumetric karl fischer titratorHiranuma aquacounter volumetric karl fischer titrator moivo-a19Water contents

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