Introduction
There are many types of sugars, and most of the sugars are insoluble in methanol, so a methanol/formamide ratio solvent is needed to dissolve, and some sugars need to be heated to 50 ° C to dissolve well. Below we will introduce you to the solvent ratio and heating temperature of different types of sugar.
2. Instrument
1, s300 Karl Fischer moisture analyzer (capacity method)
2, one in ten analysis balance
3, volumetric flasks, measuring cylinders and other glass instruments
3. Reagents
1, pyridine-free volumetric Karl Fischer reagent
2, anhydrous methanol, formamide
4. Experimental steps
1 , instrument calibration:
10 μL of pure water was taken with a 10 μL syringe, and the Karl Fischer reagent was calibrated in the calibration function of the instrument. Repeated 3-5 times, the instrument automatically calculated the average value of the calibration.
2 , sample processing:
The pulverizer sample was pulverized to a powder.
3 , the type of sugar, solvent ratio, temperature setting and sample size:
Fructose: 30ml methanol / formamide 2:1, room temperature 2g
Mannitol: 30ml methanol / formamide 2: 1, 50 ° C 2g
Galactose: 30ml methanol / formamide 2: 1, 50 ° C 3g
Glucose monohydrate: 30 ml methanol, 50 ° C 3 g
Lactose: 0ml methanol / formamide 2:1, room temperature 0.2g
Sucrose attached water: 25ml methanol / chloroform 1:4 room temperature 0.5g
Total water content of sucrose: 30ml methanol / formamide 2:1, 50 ° C 1g
4 , measurement and calculation of results:
1. Compare the above solvents according to the different types of sugars, and add the corresponding amount to the reaction cup. Use the “Blank†function in the instrument to react the water in the solvent.
2. Take 10 μL of pure water with a 10 μL syringe and perform calibration of Karl Fischer reagent in the “calibration†function of the instrument. Repeat 3-5 times and the instrument will automatically calculate the average value of the calibration.
3. Enter the “measurement†function of the instrument. According to the above list, take the sample weight of the corresponding weight, add it to the reaction cup, input the sample weight and start the measurement. The measurement can be completed in about 2 minutes. The measurement will automatically calculate the result and end. Save, the process repeats 3-5 times;
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