Automation of the photodegradation spectrophotometric method for the determination of diethylstilbestrol by flow injection

An spectrophotometric determination of diethylstilbestrol is proposed on the basis of on-line photo-degradation and measurement at 330 nm. The procedure is accomplished by means of flow-injection assembly including a photo-reactor formed by a PTFE 168 cm long coil around a low-pressure mercury lamp 6 w; this photo-reactor was nested between the injection valve and the spectrophotometric flow-cell. The sample solution was injected into a carrier stream of aqueous di-potassium hydrogen ortophosphate flowing at 5.0 ml min(-1). Influence of the physic-chemical and hydrodynamic parameters was studied and optimised. The calibration graph was linear up to 65 mg l(-1), and the procedure presented a reproducibility (rsd of the calibration slope) 1.4%, and a sample throughput of 52 h(-1). The influence of foreign compounds was tested.