SINOCMC can provide highest purified grade(99.8%) Sodium CMC which can be used in pharmaceutical, cosmetic and food industries well. It can meet USP38, EP and JP() request well. You may be interested in the purity testing method and we are willing to share that.
1. Purity Test
Purity Calculation Equation=100%-W2%(Chloride)-W1%(Sodium Glycolate)
1.1 Determination of chloride(W2%)
1.1 Test method summary
The sample is dissolved in water, titrated with silver nitrate standard titration solution, and the end point is indicated by a potentiometer. Hydrogen peroxide is added to the solution to degrade the solution viscosity.
1.2 Reagents and materials
1) Nitric acid
2) Hydrogen peroxide
3) Silver nitrate standard titration solution: c(AgNO₃) = 0.1 mol/L
1.3 Testing equipment
1) Potentiometric titrator: With silver electrode and saturated calomel electrode (double salt bridge)
2) Micro burette: 10mL
1.4 Step
Weigh 2g samples dried at 105℃± 2℃ for 2h, accurate to 0.0002g, placed in 250mL beaker, add 100mL water and 5mL hydrogen peroxide. The beaker is placed in a steam bath and heated with intermittent stirring to obtain a non-viscous solution. If the solution viscosity after 20min has not yet fully degraded, plus 5mL of hydrogen peroxide and heated until the degradation is complete. Cool the beaker, add 100 mL of water and 10 mL of nitric acid on the magnetic stirrer of the potentiometric titrator, titrate the silver nitrate standard titration solution to the end of the potential with a microtiter tube.
1.5 Testing result calculating:
Chloride content(count by Nacl)mass fraction w2, according to A.5 calculating:
w₂ = c×V×Mmmc×V×M × 100% ………….. (A.5)
c-Silver nitrate standard solution concentration , unit is moles per liter (mol / L)
V-Silver nitrate standard titration solution volume, unit is milliliters (mL)
M–The molar mass of sodium chloride , unit is milligrams per mole (g / mmol) (M = 0.05845);
m -The weight of the sample, unit is grams (g)
The result of the calculation indicates one after the decimal point. The arithmetic mean of the results of two parallel measurements is taken as the determination result.
The absolute difference between the value of not more than 0.06%.
1.2 Determination of Sodium Glycolate(W1%)
1.2.1Reagents
H2SO4, Glycolic Acid, Acetone, NaCl, Glacial Acetic Acid, Aluminum Foil Paper
2, 7-dihydroxy naphthalene solution:weigh 0.1g 2, 7-dihydroxy naphthalene solution dissolved in concentrated sulfuric acid solution, let the solution stand until the yellow color disappears.The solution is stored in a brown reagent bottle and is valid for 1 month.
1.2.2 Instruments and Equipment
Spectrophotometer, Electronic Balance, accuracy 0.0001g, Water bath, Volumetric bottle: 25ml,100ml.
1.2.3 Analysis Steps
1) Sample treatment
Accurately weigh 0.5g sample and pour into 100ml beaker, thoroughly soak with 5ml glacial acetic acid, then add 5ml water, using a glass rod stir until completely dissolved (generally 15min), add 50ml acetone slowly during the stirring process, then add 1g Sodium Chloride, stir quickly for a few minutes to ensure that Sodium Carboxymethyl Cellulose precipitates completely appeared. Filter with a quantitative filter paper, and the filter paper is moistened with a small amount of acetone, and collect the filtrate into 100ml volumetric bottle.
In addition, 30ml acetone is used to speed up the transfer of solids and wash the cake, and then the acetone is fixed and shaken.
2) Preparation of Glycolic Acid standard solution
Accurately weigh 0.100g of glycolic acid (accurate to 1mg) dried in a dryer at room temperature for 24h and place it in a 100ml volumetric bottle
The water is dissolved and diluted to the scale, and this solution is valid for 1 month.
Take 0ml, 1.0ml, 2.0ml, 3.0ml and 4.0ml of the solution and add them into five 100ml volumetric bottles. Add water to the total volume of 5ml, then add 5mL glacial acetic acid, and use acetone to determine the volume, marked as number 1-5.
Take 2.0ml sample solution and 1-5 standard solution and add them into 25ml volumetric bottle respectively, and put the unsealed volumetric bottle to boiling water.
Remove acetone in water bath for 20min, then remove from boiling water bath and cool. Add 5ml 2, 7-dihydroxy naphthalene to each volumetric bottle and mix well.
Then, add 15ml 2, 7-dihydroxy naphthalene and mix well.
Seal each capacity bottle with aluminum foil paper. Place each volumetric bottle in a boiling water bath for 20min and then cool, then shake well with sulfuric acid.
3) Making standard curve
The light absorption of standard series solution is measured at 540nm by spectrophotometer with No. 1 solution as blank control and 1cm cupola
Degree and absorbance of sample solution, formulate standard curve.
4) Result Calculation
The mass fraction of sodium glycolate, w1%, is calculated according to equation(A.4):
w₁ = 12.9×m1(100−b)×m0(100−b)×m012.9×m1 ………….. (A.4)
Marks:
12.9—(molar mass of sodium glycolate/molar mass of glycolate)×10;
m1—the mass of glycolic acid found in the standard curve in milligrams (mg);
b—mass fraction of drying reduction,%;
m0—Sample mass, in grams (g).
SINOCMC Team