Legg E F, Spencer A M
Clin Chim Acta. 1975 Dec 1;65(2):175-9. doi: 10.1016/0009-8981(75)90105-9.
The effects of storage pH and temperature on pancreatic amylase, lipase and trypsin in duodenal fluid were studied. All the enzymes were most stable when stored at --20 degrees C, while the optimum storage pH was found to depend on the particular enzyme under investigation.