Determination of codeine in process streams using flow-injection analysis with chemiluminescence detection

A flow-injection (FI) methodology using tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence was developed and evaluated for the determination of codeine in process streams. For the samples analysed codeine exhibited high sensitivity and selectivity over various other similar Papaver alkaloids, especially morphine (104 times more sensitive). A simple, computer controlled FI manifold incorporating a heterogenous lead dioxide/silica reactor was utilised to analyse an artificial sample and two process samples. The results were compared with those obtained by an established ion-pair liquid chromatography (LC) method. Calibration was linear between 1.0 x 10-8 to 1.0 x 10-6 M with a 3σ detection limit of 5 x 10-9 M. The internal calibration method compared most favourably with the LC determinations which highlighted complicated matrix effects observed at differing process sample points. The efficacy of the solid phase reactor and the suitability of the methodology for application to continuous on-line analysis of codeine process streams was assessed.