Application of partial least squares multivariate calibration for the determination of mixtures of carbaryl and thiabendazole in waters by transmitted solid phase spectrophosphorimetry

Abstract

Mixtures of the pesticides carbaryl and thiabendazole were studied using solid phase spectrophosphorimetry at room temperature with Whatman No. 4 filter-paper as solid support and Pb(II) as enhancer of the phosphorescence. The transmitted phosphorescence was used as an analytical signal and its measurement was performed by placing the paper containing the sample between two quartz plates. In this way, the use of a dry inert gas flow to avoid the quenching of atmospheric agents (oxygen and moisture) is not needed. The influence of several experimental parameters (e.g., pH, nature of the enhancers and solid supports, gate and delay times) on the phosphorescent emission of both chemicals was also studied. As a result, a new method for the simultaneous determination of these pesticides is proposed, using partial least squares (PLS-1) multivariate calibration. The statistical parameters of the optimised matrix, are included as a table. The applicable concentration ranges were from 0.16 to 1.20 mg l^–1 for thiabendazole and from 0.50 to 4.00 mg l^–1 for carbaryl. The method was applied to the determination of both pesticides in water, with recoveries between 93.4 and 105.6% for carbaryl and between 90.0 and 105.0% for thiabendazole. HPLC was used as a reference method.