Calibration for Trace Oxygenates in CO2

KIN-TEK’s new FlexStream™ Automated Gas Standards Generating System dynamically blends calibration standards for acetaldehyde and other oxygenate contaminants in nitrogen or food grade carbon dioxide matrix.  Trace Source™ permeation tubes are used in the FlexStream™ to add known concentrations of the various oxygenate species to a flow of purified food grade CO2.  Since concentration specifications are in the ppb range, the diluent CO2 may contain unknown and variable residual contamination. To eliminate that uncertainty the FlexStream™ system creates ‘standard additions’ of the various contaminants.  Calibration is based on the known difference in oxygenate concentration due to the addition. A secondary dilution feature gives low ppb and ppt concentrations adjustable over a 400:1 range. Mixture concentrations are traceable to NIST through physical standards.

Trace oxygenates and other naturally occurring impurities in carbon dioxide used for beverage carbonation and pharmaceutical processing can create “off taste” and “off odor” in products, so the CO2 purity must be monitored. Effective calibration of the monitoring systems requires traceable reference standards at multiple concentrations for each of the potential contaminants. Typically, static mixtures containing trace concentrations of these very reactive compounds are not stable in storage.