MIP OES Quantification of Cd, Co, Cr, Pb and Zn Preconcentrated on Multiwalled Carbon Nanotubes Using Multifunctional Ultrasonic Sampler

Abstract

The new ultrasonic sampler (USS) system for simultaneous multielement determination of Cd, Co, Cr, Pb and Zn enriched on carbon nanomaterial together with on–line calibration and internal standardization (IS) to microwave induced plasma optical emission spectrometry (MIP OES) has been proposed. The dispersive micro solid–phase extraction (DMSPE) procedure was applied for analytes pre–concentration on oxidized multi-walled carbon nanotubes (MWCNTs) in the liquid samples. The USS ensures that the suspension and liquids are introduced through separate capillaries and adequately mixed directly into the aerosol generation area. The new assembly is easy to use and enables different settings of continuous solution flow rates to perform on-line calibration (both standard and diluent), continuous flow rate of yttrium solution for IS and suspension injection in discontinuous mode. The DMSPE-USS-MIP OES technique allows microvolume (15 µL) injection of nanomaterial suspensions using a peristaltic pump, while two syringe pumps were used for on-line calibration and IS. The analytical parameters of the proposed method were evaluated by determining the limits of detection (LODs), absolute limits of detection and precision (RSDs) for all elements tested. The LODs obtained were 0.4, 1.0, 0.5, 0.1 and 0.7 ng mL-1 for Cd, Co, Cr, Pb and Zn, respectively, and the precision ranged from 4% to 8%. The method was validated using certified reference materials and successfully use for simultaneous determination of metals in water real samples.