A tandem-flow assembly for the chemiluminometric determination of hydroquinone.

A direct chemiluminescent procedure for determination of hydroquinone based on the emergent flow methodology known as multicommutation or tandem-flow is presented for first time. The manifold was based on a set of three channels and three solenoid valves; and, the determination was performed at 60 degrees C and at flow-rate of 7.5mlmin(-1). The complete cycle lasted 35s, which resulted in a sample flow trough of 103h(-1). The chemical process was the hydroquinone oxidation with the system sulphuric acid-potassium permanganate; and the light emission was clearly enhanced by the presence of quinine sulphate and benzalkonium chloride reaching a detection limit of 30mugl(-1). The dynamic interval was over the range 0.1-15.0mgl(-1) and a large list of interferents were assayed; the chemical robustness was also tested. The method was applied to different type of samples: namely, pharmaceutical formulations, a photographic solution and irrigation and residual superficial waters.