Get More From Your GMP Part Washer: On-line TOC Monitoring

TOC (total organic carbon) analysis is one of the most common analytical methods used for cleaning validation in the pharmaceutical industry. This nonspecific method is typically used to detect the presence of organic residues on cleaned product contact surfaces. In conventional automated cleaning systems such as COP (clean out-of-place) parts washers, a sample of the final rinse water is analyzed for TOC off-line. This approach requires that a sample be manually taken from the washer and transferred to a laboratory for TOC analysis. A new technology is now available that allows this analysis to be performed by the washer itself.

With the recent regulatory developments in the pharmaceutical industry driven by ICH guidelines Q8, Q9, and Q10, and the new FDA process validation guidance document released in January 2010, the emphasis on continued process verification has increased. This article describes a TOC monitoring system integrated into a COP parts washer. This system can provide increased productivity, meet PAT and QbD goals, and provide ongoing assurance over the lifecycle of the process.

Operation (Figure 1):
The conductivity of the rinse water is first measured after the final rinse using a conductivity probe that is located in the sump of the washer and interfaced with Conductivity Analyzer. Rinses are automatically repeated until the conductivity has reached the level that is within the operation range of the TOC analyzer. A controlled amount of final rinse water is then directed to the TOC sensor assembly through an isolation valve. The TOC sensor uses ultraviolet oxidation with differential conductivity as the method to determine TOC concentrations in the final rinse water sample. Built-in conductivity sensors provide continuous conductivity measurement before and after sample oxidation. The measured TOC value is then transmitted to the washer PLC, which will generate an alarm if the value is higher than the set point.

Benefits:
The system offers several benefits for users and the validation team. It gives quick analysis results with reduced labor while reducing risk of contaminating rinse water samples. Since results are readily available, components can be released more quickly thus reducing manufacturing equipment downtime. It measures a critical quality attribute (CQA), allowing process trending and analysis ensuring robustness.

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