A novel determination method for diuron in seaweed samples: Combination of quadruple isotope dilution strategy with liquid chromatography - quadrupole time of flight - tandem mass spectrometry for superior accuracy and precision.

This paper proposed an accurate and sensitive analytical method based on the combination of Liquid Chromatography-Quadrupole Time of Flight-Tandem Mass Spectrometry (LC-QTOF-MS/MS) system with Quadruple Isotope Dilution-Mass Spectrometry (ID4MS) strategy for the determination of diuron at trace levels. In order to achieve accurate and reliable determination of the analyte, ID4MS strategy that uses stable isotopically labelled analogues was employed. Diuron-d6 was synthesized in the laboratory using a novel strategy and employed in ID4MS for the preparation of three calibration blends and seaweed sample blend. The analytical performance of the LC-QTOF-MS/MS method was evaluated and the respective detection and quantification limits obtained were 14.6 µg kg-1 and 46.5 µg kg-1. Good linearity was obtained with a correlation coefficient of 0.9995 over the dynamic range from 50 to 1000 µg kg-1. The validity of the method was successfully tested by carrying out spiking experiments in seaweed samples. The percent recovery value showed superior enhancement for ID4MS strategy (99.97 ± 0.41%) confirming the applicability of the method to complex matrices with great accuracy and precision.