Conductivity / TOC
Conductivity / Total Organic Carbon
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A definition is SPEQ’s plain-language decode of how a term is used in practice, cited to the documents that define it. It is a practitioner reference, not legal or regulatory advice, it does not replace the definition in the source, and where a regulator’s wording differs the regulator’s wording governs.
Conductivity and Total Organic Carbon (TOC) are the two core chemical purity attributes of pharmaceutical water. Conductivity measures ionic (inorganic) contamination, while TOC measures organic contamination; together they replace the older wet-chemistry tests and are typically monitored online in real time.
Pharmacopeial conductivity is assessed in staged limits that account for temperature and dissolved CO₂, allowing an online reading to pass or triggering further stages. TOC has a defined pass limit and both attributes are commonly measured continuously on the loop return with periodic verification against grab samples.
Online monitoring lets excursions be caught immediately and the affected water quarantined, rather than discovering a failure days later from a lab sample — which is why real-time conductivity and TOC are central to water-system control and, where justified, to real-time release of water.
- —Conductivity = ionic purity; TOC = organic purity.
- —TOC limit commonly not more than 500 ppb in the pharmacopeial water monograph.
- —Conductivity assessed in temperature-compensated staged limits.
- —Typically monitored online/real-time on the loop.
Pharmacopeial water chapters (USP <643> Total Organic Carbon, USP <645> Water Conductivity; Ph. Eur. equivalents).
Frequently asked questions
What does Conductivity / TOC stand for?
Conductivity / TOC stands for Conductivity / Total Organic Carbon.
What is Conductivity / TOC?
Conductivity and Total Organic Carbon (TOC) are the two core chemical purity attributes of pharmaceutical water. Conductivity measures ionic (inorganic) contamination, while TOC measures organic contamination; together they replace the older wet-chemistry tests and are typically monitored online in real time.
Which regulations cover Conductivity / TOC?
Pharmacopeial water chapters (USP <643> Total Organic Carbon, USP <645> Water Conductivity; Ph. Eur. equivalents).