Enrichment and Separation of Fe(III), Mn(II), Ni(II), and Zn(II) as Their Congo Red Chelates on Multiwalled Carbon Nanotube (MWCNT) Disk in Food and Water Samples

In this study, a novel method of using multiwalled carbon nanotube disk-solid phase extraction (MWCNT disk-SPE) of iron, manganese, nickel, and zinc in food and water samples is described. Congo Red (CR) was used as the chelating agent. The analytical parameters of the MWCNT disk-SPE system, including pH, amount of CR, sample volume, type of eluent, and sample flow rates, were investigated. Detection limits of 4.2, 1.2, 2.1, and 1.8 ng/mL for iron, manganese, nickel, and zinc, respectively, were obtained and a preconcentration factor of 25 was achieved. The SPE technique was applied to the determination of analyte elements in certified reference materials, water and food samples with satisfactory results