System Suitability TOC monitoring can be done on-line or in the lab with a TOC analyzer of better then 50 ppb detection. All analyzers must be periodically challenged with a system suitability solution of 500 ppb USP 1.4 benzoquinone RS. In both cases the analyzers efficiency must be no lower then 85% and not higher then 115%. USP 27 Conductivity Method Compliance System verification is allowed within the USP specified 0.1 uS/cm, using a special NIST traceable resistor that plugs into an end-panel receptacle. Similarly, a pre-packaged, NIST traceable calibration standard confirms / calibrates the cell constant to within the specified 2%. Conductivity is reported as non-temperature compensated, and alarm outputs are based on the Stage 1 parameters established in the USP conductivity method.