Dissolve 80.25g Gu-HCl in 100mL Autoclaved dH2O.
Add 17.67g potassium acetate (if mixing yourself: 0.18mol = 10.09g KOH dissolved in water + 10.809mL glacial acetic acid).
Adjust the pH to 4.8 with glacial acetic acid.
Make up to 200mL with autoclaved dH2O.
Don’t need to sterilise.