Utility of solid phase extraction for colorimetric determination of lead in waters, vegetables, biological and soil samples

A highly sensitive, selective and rapid method for the determination of lead based on the reaction of lead (II) with 5-(4'-chlorophenylazo)-6-hydroxypyrimidine-2,4-dione (CPAHPD) and the solid phase extraction of the Pb(II)-CPAHPD complex with Amberlite XAD-2000 was developed, in the presence of pH 5.6 buffer solution and Triton X-114 medium. CPAHPD reacts with lead to form a violet complex with a molar ratio of 2:1 (CPAHPD to lead). This complex was enriched by the solid phase extraction with Amberlite XAD-2000. An enrichment factor of 500 was obtained by elution of the complex from the resin with a minimal amount of isopentyl alcohol (0.2 mL). In isopentyl alcohol medium, the molar absorptivity of the complex is 1.13 x 10(6) Lmol(-1) cm(-1) at 647 nm. Beer's law is obeyed in the range of 5.0-160 ng mL(-1) in the measured solution. The relative standard deviation for 10 replicate samples of 50 ng mL(-1) level is 1.26%. The detection and quantification limits reaches 1.5 and 4.7 ng mL(-1) in the original samples. The presented procedure was successfully applied for determination of lead content in real samples such as vegetables, waters, biological and soil samples with satisfactory results. (C) 2018 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.