Determination of the pesticide morestan by means of a single-use phosphorimetric sensor

A new test procedure to determine the pesticide morestan based on solid phase room temperature phosphorescence using a disposable optical sensor is proposed. The device consists of a disposable polyester sheet ( 5 cm×1 cm) with a circular micro zone (6 mm in diameter and 25 μm in thickness), formed by polyvinylchloride and tributylphosphate as a plasticizer, on its surface. When the sensor was introduced for 2 h into a solution containing morestan, the pesticide was fixed in the sensing zone and its phosphorescence emission could be directly measured at λ em=520 and λ exc=363 nm. Construction and use of the sensor, and characterization of the fixation parameters have been studied. The applicable morestan concentration range was 1.0–200.0 ng ml −1 with a detection limit of 0.28 ng ml −1 and a precision (as relative standard deviation) of 2.9%. The method was applied to the determination of the pesticide in different water samples (natural, tap, sea, river and waste water) with recovery percentages ranging between 82.2 and 105.7%. A study of the interference produced by other pesticides and various organic and inorganic species frequently present in these waters showed the selectivity of the method. The method was validated chemometrically.