Determination of Copper,Cobalt, Lead,and Iron in Table Salt by FAAS After Separation Using Violuric Acid and Multiwalled Carbon Nanotubes

A separation–enrichment technique for the determination of trace amounts of copper(II), cobalt(II), lead(II), and iron(III) as violuric acid chelates on multiwalled carbon nanotubes at pH 6.0 was established. Analytes were determined by flame atomic absorption spectrometry. The effects of some analytical parameters like pH, amounts of violuric acid, flow rates, eluent type, and sample volume were investigated. The influences of the matrix ions were also investigated. The relative standard deviations for analyte elements were below 10%. The quantification limits of the analyte ions were found as 0.36 μg g⁻¹ for copper, 0.43 μg g⁻¹ for lead, 0.15 μg g⁻¹ for cobalt, and 0.38 μg g⁻¹ for iron. The accuracy of presented method was checked by the analysis of TMDA 54.4 fortified lake water, NIST SRM 1515 apple leave, and HR-1 Humber river sediment certified reference materials. The method was applied to analyte contents of table salt samples from different origin. The levels of iron in the analyzed table salt samples were found in the range of 1.6–6.4 μg g⁻¹, while lead was found in only one sample as 5.0 μg g⁻¹. In all other samples, cobalt, lead, and copper were found below the quantification limits of the analytes.