YY/T 0719.8-2019Ophthalmic optics - Contact lens care products - Part 8: Test method for detergent (English PDF)

4.1 Poloxamer

4.1.1 Gel chromatography

4.1.1.1 Test principle

Poloxamer is a polyoxyethylene polyoxypropylene ether block copolymer. It is a class of polymer nonionic surfactants. The commonly used models in care products are poloxamer 188 and poloxamer 407. This method uses a

b) Column temperature: 30°C;

c) Refractive index detector, temperature is 30°C;

d) Mobile phase: sodium dihydrogen phosphate solution (0.02mol/L): acetonitrile=7:3;

e) Flow rate: 0.7mL/min;

f) Injection volume: 50µL.

4.1.1.7 Determination and result analysis

Respectively conduct analysis determination to standard solution and sample.

Establish standard working curve and regression equation. Calculate the content of poloxamer in the sample. See Annex A for typical chromatograms.

4.1.2 Ultraviolet-visible spectrophotometry

4.1.2.1 Test principle

According to the characteristic that hydroxypropyl methylcellulose has the ability to form a gel after heating in an aqueous solution, and then dissolve after cooling, pre-process the care solution to remove HPMC. Use ultraviolet-visible spectrophotometry that takes iodine-potassium iodide solution as the developer to determine the poloxamer content in nursing solution in the care solution.

4.1.2.2 Instruments and reagents

4.1.2.2.3 Instruments: UV-visible spectrophotometer, 1cm quartz cuvette; analytical balance with accuracy of 0.1mg.

4.1.2.2.1 Reagents: iodine, potassium iodide

4.1.2.2.2 Reference substance: poloxamer

4.1.2.3 Solution preparation

Poloxamer standard stock solution (0.1mg/mL): Accurately weigh 0.5g of poloxamer for reference that has been dried to constant weight, to the nearest of 0.1mg. Use pure water to conduct ultrasonic dissolution and set volume into a 50mL volumetric flask. Shake well. Then accurately pipette 1mLof the above solution to a 100mL volumetric flask. Use pure water to set volume to the scale. Shake well to obtain the solution.

Iodine-potassium iodide color developing solution: Weigh 2.0g of potassium iodide. Add an appropriate amount of water to make it dissolved. Then accurately add 1.0g of iodine to make it dissolved. Transfer to a 100mL analytical balance with accuracy of 0.1mg.

4.2.3 Solution preparation

Epoxyethylene hydrogenated castor oil standard stock solution (0.2mg/mL):

Weigh 0.1g of RH40 reference substance, to the nearest of 0.1mg. Use pure water to dissolve. Set volume to a 50mL volumetric flask. Shake well. Then accurately pipette 1mLof the above solution to a 10mL volumetric flask. Use pure water to set volume to the scale. Shake well to obtain 0.2mg/mL standard stock solution.

Iodine-potassium iodide color developing solution: Weigh 2.0g of potassium iodide. Add an appropriate amount of water to make it dissolved. Then accurately add 1.0g of iodine to make it dissolved. Transfer to a 100mL volumetric flask. Add water to dilute to the scale. Shake well to obtain the solution (this product shall be kept away from light).

4.2.4 Preparation of standard solution

Respectively pipette 1.0mL~3.0mL of epoxy ethylene hydrogenated castor oil standard stock solution to 10mL volumetric flasks. Set volume and shake well.

Add 0.25mL of mixed color developing solution. Shake well to obtain a series of standard solutions with a concentration of 20 x 10^-6~60 x 10^-6. At least 5 concentration points shall be selected. Use the same method and take pure water for blank.

4.2.5 Sample processing

Precisely pipette the right amount of sample. Dilute to a concentration about 40 x 10^-6. Then accurately add 0.25mL of iodine-potassium iodide color developing solution. Shake well.

4.2.6 Determination and result analysis

After standard and sample are placed for 2h, at 500nm, determine the absorbance. Perform parallel determination of 3 sets of data. Establish working standard curve and regression equation. Calculate the content of epoxy ethylene hydrogenated castor oil in the sample according to the standard curve.