TOC Analyzers & Bioburden Analyzers

METTLER TOLEDO total organic carbon analyzers use UV oxidation and differential conductivity measurement to determine organic contamination. High performance digital conductivity sensors take a conductivity measurement before and after a sample of the water is exposed to 185 nanometer UV light. The UV exposure breaks down the bonds in the non-ionic, organic compounds (oxidation) which creates carbon dioxide and water. This further forms carbonic acid, which dissociates into ionic conductive species. The increase in conductivity after oxidation is directly proportional to TOC measurement.

Conductivity measurements are great for identifying ionic contamination, but generally organic contaminants are non-ionic. Therefore, they cannot be detected with standard conductivity measurements and require a TOC analyzer to provide an adequate measurement of organic contamination.

TOC analyzers are typically used for measurement throughout the water purification process and at specific points in the water usage process. Key applications where a TOC analyzer can provide benefit include:

• Monitoring membrane efficiency after reverse osmosis
• Monitoring resin life and efficiency after deionization
• Ensuring low organic levels are maintained after storage in pure water tanks after final polish
• Ensuring low organic levels prior to water return during recycle and reclaim processes
• Monitoring UV light efficiency after TOC destruction in water purification
• Ensuring final water quality before the point of use distribution lines

Compared with the on-line measurements available for other parameters required by pharmacopeia regulations, bioburden analysis by plate counting can delay your process significantly. These laboratory-based methods have been around for over a century, and the procedure hasn't changed much. A water sample is left on an agar plate for five days or longer, and then the number of colony forming units (CFUs) is counted. Not only is the method slow, but it only provides a snapshot of the system's water quality at the time the sample was taken. 

With an online water bioburden analyzer, in-line detection is quicker than lab methods; therefore, you can more quickly make a change to your process when there is an unexpected increase to the bioburden in the water. This provides continuous data in real time to provide a complete picture of the bioburden load in water systems.

METTLER TOLEDO recommends using a bioburden analyzer in conjunction with plate counting, not as a replacement for place counting.

There are several different types of water that are used in pharmaceutical production. In each of these, the TOC of water and bioburden in the water system should be properly monitored. Each is used at different steps in the process and has different specifications for purity. Purified Water (PW) is water that has been processed to remove impurities to low levels. Water for Injection (WFI) is water used as an excipient in the production of parenteral medications. Ultrapure Water (UPW) is water that has been purified to extremely low levels of impurities that must meet very strict specifications.