Chemiluminescence optosensing implemented with multicommutation: Determination of salicylic acid

In this paper we have coupled, for the first time, chemiluminescent detection with multicommuted optosensing principles. This approach has been implemented with the use of a commercial flow cell of 1 mm optical path length filled with an appropriate anionic exchanger gel as chemiluminescence sensing phase. The cell was placed in front of the window of the photosensor module of a home-made luminometer developed in our laboratory and a flat mirror was stuck on the back of the cell. The suitability of using chemiluminescence as detection technique in multicommuted flow-through optosensors has been demonstrated: the determination of salicylic acid by simple oxidation with permanganate on the sensing solid phase was chosen as model reaction. The proposed system allows the determination of salicylic acid in pharmaceuticals, with a sample frequency as high as even 60 samples h−1 and showing a detection limit of 0.30 μg mL−1, the linear response range is 1-30 μg mL−1 and the R.S.D. is 3.1%. Satisfactory results have been obtained when applying the sensor to pharmaceuticals. The accuracy of the proposed methodology has been tested by using a reference method.