An Alternative Microbiological Validation for an Online Water Bioburden Analyzer

Abstract

Background. The Mettler-Toledo 7000RMS analyzer is a bio-fluorescent particle counter (BFPC) used to monitor real-time bioburden results from purified water (PW). Objective. Validation of the analyzer using 13 microorganisms and a low-intensity, fluorescent, polystyrene bead. Methods. During the execution of the validation, a laboratory water system that met PW quality standards was connected to the 7000RMS, and a syringe pump was used to introduce various concentrations of microorganisms and fluorescent polystyrene beads to the analyzer. Samples were collected and tested via the traditional membrane filtration (MF) method and the colony-forming unit (CFU) plate count results were compared to the auto-fluorescent unit (AFU) of the 7000RMS analyzer. The validation study was designed to follow the guidance in United States Pharmacopeia (USP) Chapter 1223, European Pharmacopeia (EP) Chapter 5.1.6, and parenteral drug association (PDA) Technical Report 33. Concepts and strategies were adapted from EP Chapter 2.6.12 Microbiological Examination of Non-Sterile Products: Microbial Enumeration Tests, EP Chapter 10.2, EP Chapter 2.6.1 Sterility, USP Chapter 61 Microbiological Examination of Non-Sterile Products: Microbial Enumeration Tests, USP Chapter 71 Sterility Tests, and Japanese Pharmacopoeia (JP) General Information Chapter G8 Water: Quality Control of Water for Pharmaceutical Use. Results. All pre-determined validation acceptance criteria for accuracy, specificity, precision, LOD, LOQ, linearity, and range were met. Conclusions. The 7000RMS demonstrated performance equivalence to the MF method per USP 1223 but characteristically lacked correlation to the CFU. Highlights. This validation approach highlights the superior capabilities of the 7000RMS when compared against the traditional compendial MF testing method for PW.