System Suitability Testing: Simplifying A Critical Element In The TOC Monitoring Process

In the Pharmaceutical Water production process, System Suitability Testing (SST) is an essential activity to verify the performance of a Total Organic Carbon monitoring system and to ensure its adequacy for TOC analysis.

USP and EP Requirements
In the requirements for TOC measurement, The United States Pharmacopoeia and European Pharmacopoeia have established specific Total Organic Carbon (TOC) tests as described in USP General Chapter ‹643› and EP Chapter 2.2.44, respectively. These chapters provide:

1. Guidance on the methodology for TOC testing,
2. Criteria for establishing instrument acceptance, and
3. TOC limits for the sample to be tested.

The types of water subject to TOC testing are:

• USP Purified Water
• USP Water for Injection
• EP Aqua Purificata (Purified Water) – TOC may be performed in lieu of oxidizable substances test
• EP Valde Aqua Purificata (Highly Purified Water)
• EP Aqua ad Injectabilia (Water for Injections).
• JP Water for Injection, effective April, 2006

Challenges of System Suitability Testing
Because organic carbon appears in various forms in nature and subsequently in water treatment processes, a wide variety of oxidation states and chemical forms are found in these systems. The goal of System Suitability Testing is to challenge the TOC measurement technique by verifying that two chemicals of very different chemical properties respond equally. In this case, the two chemicals specified in the pharmacopoeial chapters are sucrose and 1,4- benzoquinone. Because of their unique and different chemical structure, sucrose and 1,4-benzoquinone challenge the bond-breaking and oxidation capability of the TOC measurement technology. These solutions are commonly referred to as easy to oxidize and hard to oxidize chemicals, respectively. In addition to sucrose and 1,4 benzoquinone, reagent water (the water used to manufacture the sucrose and 1,4 benzoquinone solutions) is analyzed during the suitability testing.