Lead extraction from food samples by combined cloud point-micro solid phase extraction

Abstract

An economic strategy was investigated for extraction of Pb(II) by merging cloud point extraction (CPE) and micro solid phase extraction (μSPE) using montmorillonite (MMT) as a natural sorbent. In this context, Pb(II) was adsorbed onto MMT as 4-(pyridyl-2-azo)-resorcinol (PAR) complex and transferred into micellar phase of Triton X-114. Subsequently, Pb(II) were eluted from MMT by 0.5 mol L−1 of HNO3 and quantified by graphite furnace atomic absorption spectrometry (GFAAS). The central composite design of response surface methodology was used to study the effects of some experimental parameters such as pH, MMT amount, surfactant concentration, and temperature while the desirability function approach was utilized to define the best conditions for Pb(II) extraction. The calibration curve was linear from 0.02 to 10.0 µg L−1 of and an enrichment factor of 95.6 was obtained for 50.0 mL sample. The limit of detection for was 0.006 µg L−1 and the relative standard deviations for five replicate analysis of 1.0 µg L−1 and 5.0 µg L−1 of Pb(II) were 2.8% and 1.5%, respectively. The method was assessed for its environmental friendliness using the analytical AGREEnness calculator. The applicability of the method were evaluated by determination of Pb(II) in certified reference materials and food samples.