How do you incorporate a buffer in a biology experiment to stop a change in pH?

I'm doing an experiment in class on how an enzymes activity is changed by temperature and I don't want anything else to affect it as the results may be inaccurate.How do you incorporate a buffer in a biology experiment to stop a change in pH?
Enzymes have a very narrow optimal pH (outside this range their tertiary structure changes) so it really depends upon the enzyme. For a neutral phosphate buffer (pH 7); -



make stock solutions of



0.1 molar Sodium hydroxide (NaOH)



Comes as white pellets (Molecular weight 40.0)

Dissolve 4g in 1 ltr of deionized, or preferably molecular grade

water (i.e. MilliQ)



0.1M potassium dihydrogen phosphate (KH2PO4).



Comes as white powder (Molecular weight 136.09)

Dissolve 13.609g in 1 ltr of deionized water





Add 29.1 ml of 0.1 molar NaOH to 50 ml 0.1 molar potassium dihydrogen phosphate (KH2PO4)



Make sure its pH 7 with a pH meter



This is your working solution, make more or less as required but make enough for the entire experiment for consistency. Too much is better than running out halfway through!



Hope this helps, double check this coz i don't want to be responsible for messing up your work!