A New Separation and Enrichment Method of Heavy Metals in Water and Food Samples Using 2-(2'-Benzothiazolylazo)-6-Aminophenol Impregnated Multi-Walled Carbon Nanotubes

Objective: This study uses a novel complexing agent of 2-(2'-benzothiazolylazo)-6- aminophenol impregnated adsorbent multi-walled carbon nanotubes to enrich and separate trace levels of Cd (II), Cu (II), Co (II), Ni (II) and Pb (II) from various samples of food and water collected in Saudi Arabia. Method: Identification of the analyte ions was confirmed by flame atomic absorption spectrometry. The analytical parameters and matrix ions of the solid phase extraction technique were varied to explore optimal analyte recovery. Validation of the procedure was verified by using certified reference materials. Results: The pre-concentration factor was determined to be 100. The following detection limits (LODs) were calculated: Cd (II) 0.6 μg L-1, Cu (II) 0.7 μg L-1, Co (II) 1.0 μg L-1, Ni (II) 0.5 μg L-1 and Pb (II) 1.2 μg L-1. Analyte recovery values ranged from 95-102%, indicating methodological accuracy. Furthermore, precision was demonstrated by the low relative standard deviation (RSD < 2%). Results were consistent with the validating reference materials attesting to the reliability of the method. Conclusion: The method demonstrates high selectivity as it does not experience significant interference from matrix ions. It is also a sensitive method, able to detect ions present in very low quantities. The pre-concentration factor and limit of detection of the proposed method are superior to the other previous solid phase extraction methods.