Preparing hydrogels for pH analysis
- Add 1.5ml of water in to a epitest tube with 2mg hydrogel.
- Centrifuge sample containing hydrogels and crystal violet indicator 3 times for 5 minutes at 13200 rpm.
- By using UV-Vis, measure the absorbance of each supernatant to find the amount of crytal violet in the supernatent. Use the data to find out the amount of crystal violet absorbed by the hydrogels.(Initial amount of indicator added to the epi test tube is 20uL)
- Prepare 2 more hydrogel solutions (with 1.5 water and 2mg hydrogel) with 55 μL methyl red and 30μL bromophenol blue.
Info on indicators
methyl violet 0-2
methyl red- 4.4-6.2
bromocresol purple- 5.2-6.8
bromophenol blue 6.0-7.6
cresol red 7.2-8.8