Simultaneous chemiluminescent determination of carbaryl and 1-naphthol in soils using a flow-injection system

Abstract

ABSTRACTA flow-injection method coupled with the luminol chemiluminescence (CL) detection was developed for the simultaneous determination of carbaryl and 1-naphthol in soils. The method is based on the inhibition of luminol oxidation by the presence of 1-naphthol with the consequent reduction in the CL intensity. The conversion of carbaryl into 1-naphthol was made by the alkaline hydrolysis with NaOH. Under the optimised conditions, the method permits the determination of carbaryl and 1-naphthol over the range 25–400 ng mL−1 with high determination coefficient using both peak area and height, and high sample throughput (40 h−1). The detection limits applying the International Unión of Pure and Applied Chemistry (IUPAC) criteria were 65 ng g−1 and 123.5 ng g−1 for peak height and area, respectively. A simple extraction procedure employing chloroform as the solvent and sonication was effective for the complete extraction of the analytes present in soils. The method was validated by the analysis of spiked samples, with recoveries between 88.7 and 103.1%. The Flow Injection-Chemiluminescence (FI-CL) method has proven to be simple, fast and accurate for the quantification of carbaryl and its main degradation product in soils.