Choice of Substrate in Determining Peroxidase Activity in the Amniotic Fluid

. Peroxidase activity in the amniotic fluid has been measured with two different chromogens, O‐dianisidine and p‐phenylenediamine. No activity was demonstrable with the former substrate but was present with the latter. These results show that choice of substrate is important in determining peroxidase activity, especially in the amniotic fluid.