Application of DLLME‐SFO as a Green Analytical Tool for Determination of Trace Amounts of Cadmium and Lead in Vegetables and Fruits using FAAS: Optimization Using Box‐Behnken Design**

Abstract

In this study, dispersive liquid-liquid microextraction method based on solidification of floating organic drop (DLLME-SFO) was developed for the preconcentration of trace amount of Pb(II) and Cd(II) in vegetable and fruit extracts (DIW, Apple, Kiwi, Banana, Orange, Mint, Dill, Savory, and Thyme) and determination of these ions by flame atomic absorption spectroscopy (FAAS). The proposed method is based on the formation of an ion association Pb-4-(2-thiazolylazo) resorcinol (TAR) -zephiramine chloride (ZCl) and Cd-4-(2-thiazolylazo) resorcinol (TAR) -zephiramine chloride (ZCl) and then extraction of the resulting complex in micro-droplets of the extraction solvent. Response surface methodology (RSM) based on the Box-Behnken Design (BBD) was applied to optimize the experimental variables and evaluate the effect of factors. Optimal conditions were obtained with pH = 6, 0.6 mL of the ligand solution 4-(2-thiazolylazo) resorcinol 0.2 %, 221 μL of 0.2 % zephiramine chloride, 130 μL of 1-undecanol as solvent extraction, and 530 μL of acetonitrile. The linear range was 3.8-200 and 1.0-160.0 μg L À 1 with a coefficient of determination (R 2 ) of 0.9976 and 0.9985 for Pb (II) and Cd(II), respectively. The limit of detection (LOD) was found to be 1.2 and 0.3 μg L À 1 for Pb (II) and Cd(II), respectively. According to the results of market samples, the recovery (%) of the interday and intraday related to the Pb(II) were in the range of 94.67 % to 103.33 % and 95.33 % to 104.00 % for fruits and vegetables, respectively. Also, the relative standard deviation (RSD%) values of Pb(II) corresponding to the interday and intraday were found to be 1.52 % to 4.36 % and 2.15 % to 4.54 % for fruits and vegetables, respectively. In addition, the recoveries of Cd(II) were obtained 96.33 % to 104.00 % and 97.33 % to 103.33 % for fruits and vegetables, respectively. The RSD values of Cd(II) were 2.09 % to 4.19 % and 2.15 % to 4.54 % for fruits and vegetables, respectively. DLLME-SFO uses an extraction solvent with lower toxicity instead of highly toxic solvents in other methods and high extraction recovery within a short period of time is possible.

Taking a deeper look into the roles of amines in atomic absorption spectrometry

“…100 Alternatively, a similar study used a dispersive liquid–liquid microextraction involving the solidification of floating organic drop (DLLME-SFO) for the preconcentration of trace amounts of Pb (II) and Cd (II) in vegetable and fruit extracts and determination by FAAS. 101 The proposed method involves an ion association complex at pH 6.0, Pb-4-(2-thiazolylazo) resorcinol (TAR) – zephiramine chloride (ZCl) and Cd-4-(2-thiazolylazo) resorcinol (TAR) – zephiramine chloride (ZCl), extracted as micro-droplets and diluted with 1 M HNO 3 . The LOD was 1.2 and 0.3 μg L −1 for Pb (II) and Cd (II) , respectively.…”