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 x 1 cm) with a circular micro zone (6 mm in diameter and 25 mum 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 lambda (em) = 520 and lambda (exc) = 363 run. 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. (C) 2001 Elsevier Science B.V. All rights reserved.