Purified Water Microbial Testing: False OOS Due to TNTC vs Filtration Volume
Complimentary
Learning Level: Advanced
Time: 1100 - 1200 EST
Session Length: 1 hour
Due to filtering 100 ml of purified water through 47mm membrane filter there is a potential risk of overloafing the filter with TNTC and false OOS.
eg. If purified water has microbial contamination of 5cfu/ml,
Scenario 1: filter 100ml for TAMC testing, will recover 500cfu on a 47 mm membrane which cannot be counted will result in false OOS due to TNTC.
Scenario 2: filter 5ml for TAMC testing will recover 25cfu on a 47 mm membrane which can be counted.
Therefore, it is very important to determine the filtration volume to recover the countable colonies instead of false OOS due to test method, where as the actual microbial contamination level is well within Pharmacopoeial action limit of 100cfu/ml.
Learning Objectives
- Provide clarification on filtration volume of purified water to avoid false OOS due to the test method, while Purified water is meeting the Pharmacopoeia specification.
- Approaches on determination of filtration volume for Purified Water.
