Effect of pH on amylase
Method overview
Equilibrate amylase, starch and buffer at constant temperature. Mix amylase with buffer, add starch and start timing. Every 30 s place a sample onto iodine. Record when iodine remains orange-brown, repeat across pH values and calculate rate.
Apparatus set-up
Diagramamylase; starch; buffer solutions; iodine; spotting tile; pipettes; water bath; timer
Independent variable
pH
Dependent variable
time for starch to disappear or rate = 1/time
Control variables
amylase and starch concentration/volume; temperature; sampling interval; total volume
Apparatus
amylase; starch; buffer solutions; iodine; spotting tile; pipettes; water bath; timer
Safety
Wear eye protection; iodine is an irritant and stains; use a water bath rather than direct flame.
Scientific rationale
Buffer keeps pH constant; iodine detects remaining starch; constant temperature prevents it becoming a confounding variable.