Total Organic Carbon (TOC) (TC ) will be an acceptable method for monitoring residues routinely and for cleaning validation. To make this test TOC to be functionally suitable, we should first establish with suitable study that a substantial amount of the contaminating material(s) is of organic origin which contains carbon that can be oxidized by conditions applied in TOC test. This is an important exercise because some organic compounds cannot be reliably detected using TOC.
Test for TOC may be used to for direct surface sample testing as well as indirect (rinse water) sample testing. In both cases. As TOC does not identify or distinguish between different compounds containing oxidizable carbon, any detected carbon is to be therefore attributed to the target compound(s) for comparing with the established limit. Thus, a pharmaceutical manufacturing firm should limit ‘background’ carbon (i.e., carbon from sources other than the contaminant being removed) as much as possible. If TOC samples are required to be stored for long periods of time before analysis, a pharmaceutical manufacturing firm should verify the impact of sample storage time on accuracy and limit of quantization.
What are the References for above discussion:
21 CFR 211.67: Equipment cleaning and maintenance.
21 CFR 211.160(b): General requirements (Laboratory Controls)
USP 643 Total Organic Carbon
Guide to Inspections of Cleaning Validation, 1993
Regulatory affairs in pharmaceutical industry
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