Online Flow-Batch Dispersive Liquid-Liquid Microextraction System for ET AAS Determination of Molybdenum in Water and Complex Matrices

This work presents a novel on-line flow-batch dispersive liquid-liquid microextraction system for the determination of molybdenum in water, meat, and vegetable material with electrothermal atomic absorption spectroscopy (ET AAS) as detection technique. After optimizing the experimental conditions, the analytical performance of the new methodology was determined. A limit of detection of 0.03 µg/L for water and 0.02 µg/kg for the other matrices, as well as an enrichment factor of 130 were obtained employing this methodology. Standard reference materials were used for accuracy and precision evaluation. No significant differences were found at the 95% confidence level between the certified and obtained values, and precision expressed as repeatability (RSD) was better than 5% in all cases. The developed automated methodology offers great advantages when compared to manual dispersive liquid-liquid microextraction, such as low risk of contamination while working in closed systems, minimal handling, reduced exposure of the analyst to the chemical products, greater security, improvement in repeatability and the elimination of the laborious and time-consuming procedure of phase separation by centrifugation. The method was successfully applied for the determination of molybdenum in natural groundwater, bovine and sheep meat, and pasture samples.