The aim of this work was to find the effect of temperature and manufacturing source of phenylmercuric nitrate (PMN) on PMN absorption on low-density polyethylene (LDPE) and polypropylene containers in chloramphenicol eye drops. Two factorial experiments were designed to study the effect of temperature on PMN assay in chloramphenicol eye drops stored in LDPE and prepared from two different PMN sources. PMN source had no effect on PMN assay at 2-8 °C, however at stress conditions (30 °C/75%RH) for 3 weeks, the effect of PMN source on PMN assay was found significant (p