Offline gas chromatography has long been the reference method for photocatalytic gas analysis, and it is precise. Its constraint is throughput: each data point costs a manual sampling step and a chromatographic run, so kinetic information between points is simply lost. Online detection trades some of that single-point precision for continuous coverage, and for most modern catalyst work the trade is worth it.
GC separates and confirms product identity, resolves complex mixtures, and provides the certified-calibration precision needed for absolute quantification. It remains the right tool for final confirmation and for products an online sensor cannot resolve.
Continuous curves reveal induction periods, deactivation, plateaus and oscillations, features invisible at a few points per run. Time resolution improves from hours to minutes without operator burden, enabling long unattended stability runs that manual sampling cannot practically support.
Anchor the online system with periodic GC confirmation: sample the same stream to GC at defined times and compare integrated online amounts with GC values. This validates the online calibration in the real matrix and preserves the audit trail. Report the anchoring protocol when publishing online data.
Keep the reactor and sampling geometry unchanged between methods; run both in parallel for a validation campaign; and document detection limits for each. Once online data track GC within your tolerance, the online curve becomes the primary record and GC the periodic check.
Perfectlight's Ugas online systems and complete photocatalysis solutions are designed for exactly this migration; see gas detection products for configurations.
