Pda Technical Report: 39

TR 39 conceptualizes shipping as a system—not just a box and a logger. This includes:

First published in 1998 and revised in 2008, PDA TR 39 was developed by a consortium of industry experts, filter manufacturers, and regulatory scientists. Its primary objective was to standardize the approach to sterilizing grade filtration.

The cornerstone of TR 39 is its definition of a sterilizing grade filter. The report clarifies that a filter is defined not merely by its pore size rating (commonly 0.2 µm or 0.22 µm), but by its performance.

: Using stability data to determine how long a product can safely withstand excursions.

TR 39 emphasizes that the validation is specific to the filter type and the process conditions. If a manufacturer changes the filter vendor or alters the process parameters (temperature, pressure, time), the validation data must be re-evaluated.

This definition shifted the industry focus from "pore size" to "retention capability," a critical distinction that TR 39 cemented into industry practice.