Optimization and modeling of preconcentration of lead in rice samples by organic gas steam–liquid extraction

Organic gas steam–liquid extraction by using a special home-made extraction cell followed by graphite furnace atomic absorption spectrometry was proposed for the preconcentration and determination of ultra-trace amounts of lead in rice samples. The variables influencing the organic gas steam–liquid extraction procedure including extraction solvent volume, sample solution pH, extractant agent concentration, and the extraction chamber temperature were optimized. The optimization process has been performed by employing response surface methodology based on the central composite design. The linear dynamic range was obtained 0.5–10 μgL −1 (with R 2 > 0.99). The average recovery for the extraction of lead was > 90%. The developed method was validated by determining Pb 2+ in a certified reference material and successfully applied to the preconcentration and determination of lead in various rice samples. The obtained results revealed that in most of the analyzed rice samples, the lead content was lower than the limit values established by INS and WHO. The proposed method bears advantages with respect to the other conventional liquid–liquid preconcentration methods. These advantages included minimal organic solvent consumption, simplicity, low cost, and high extraction recovery.