Gellan Gum Determination
1. Apparatus: glass filter; dryer (180mm).
2. Procedures
Weigh about 1.0g of pure diatomaceous earth chromatography, placed in a glass filter, even paved, 105℃ drying 5h, cooled in the dryer and accurate weighing. Weigh about 0.2g dry (105℃, 2.5h) of the gellan gum sample (accurate to 0.001g), add 50mL of water, at about 80℃ water bath pot stirring dissolved 30min. Adding 200mL pre-heated to 60℃ ~ 70℃ anhydrous ethanol, mixed evenly, standing 12h, with the glass filter with diatomaceous earth filtration, then washed with ethanol residue 5 times, each time before washing 3 times the amount of 20mL, each time after washing 2 times the amount of 10 mL. The residue at 105℃ drying 5h, cooled in the dryer and accurate weighing.
3. Calculation
Where: X1 - gellan gum content,%;
m1 - the quality of residue, in units of grams (g);
m0 - Specimen mass, in units of grams (g).
Results to three significant figures.
Gel Strength Determination
Apparatus:
Thermo-tank ( 5 ~ 50℃)
Electronic balance (accurate to 0.001g)
Gel Strength Meter
Water bath ( 10 ~100℃)
Procedure:
Weigh 0.6g sample ( accurate to 0.01g ), transfer to 250mL beaker and add 120mL distilled water, weigh the total weight of beaker and solution and note it. Put the beaker in water bath ( 80℃) and stir it by glass bar for three times, 30 seconds for each time, heat for 20 minutes to ensure that the gellan gum dissolved totally, then add 2.7% calcium chloride ( CaCl2 ) 2mL, then take the beaker out, swab up the outer wall of the beaker, add the water to make up a loss. Agitate to make the solution evenly, then pour the solution into the flat bottom container, the height of the liquid is 2cm, cool the solution to form the gel, then store the gel for 20h in Thermo-tank ( 20℃). Make three samples parallelly, determine their gel strength and take the average value.
Transparency Determination
Apparatus:
Electronic balance (accurate to 0.001g)
Spectrophotometer
Thermo-tank ( 5 ~ 50℃)
Water bath ( 10 ~100℃)
Procedure:
Weigh 0.6g sample ( accurate to 0.01g ), transfer to 250mL beaker and add 120mL distilled water, weigh the total weight of beaker and solution and note it. Put the beaker in water bath ( 80℃) and stir it by glass bar for three times, 30 seconds for each time, heat for 20 minutes to ensure that the gellan gum dissolved totally, then add 2.7% calcium chloride ( CaCl2 ) 2mL, then take the beaker out, swab up the outer wall of the beaker, add the water to make up a loss. Agitate to make the solution evenly, pour the solution into 10mm cuvette and put the cuvette in Thermo-tank immediately, stand it for 15 minutes, using Spectrophotometer to determine the transmittance at 497nm, against the blank. Make three samples parallelly, determine their transmittance and take the average value.
Determination Of Particle Size
1. Instrument: 60 mesh; electronic balance: a sense of the amount of 0.1g.
2. Operating procedures
Beaker with clean plastic sample weighed about 100.0g, tile in the mesh, the measure of its fineness, recorded interception.
3. Calculation
Particle size%= |
m1-m |
×100 |
———— |
m1 |
Where: m - interception, g;
m1 - the quality of the sample, g.
Results to three significant figures.
Loss on Drying
Mix and accurately weigh the substance to be tested, and, unless otherwise directed in the individual monograph, conduct the determination on 1 to 2 g. If the test specimen is in the form of large crystals, reduce the particle size to about 2 mm by quickly crushing. Tare a glass-stoppered, shallow weighing bottle that has been dried for 30 minutes under the same conditions to be employed in the determination. Put the test specimen in the bottle, replace the cover, and accurately weigh the bottle and the contents. By gentle, sidewise shaking, distribute the test specimen as evenly as practicable to a depth of about 5 mm generally, and not more than 10 mm in the case of bulky materials. Place the loaded bottle in the drying chamber, removing the stopper and leaving it also in the chamber. Dry the test specimen at the temperature of 105℃ and for 2.5 hours: it loses not more than 14.0%. [NOTE—The temperature to be regarded as being within the range of ±2℃ of the stated figure.] Upon opening the chamber, close the bottle promptly, and allow it to come to room temperature in a desiccator before weighing. |
