Feasibility of Dispersive Liquid–Liquid Microextraction for Molybdenum Determination in Lamb Meat by MIP OES

Abstract

The dispersive liquid–liquid microextraction (DLLME) was evaluated as a strategy to improve the MIP OES sensitivity for molybdenum determination in lamb meat. Initially, the dispersive (methanol) and extracting (tetrachloromethane) solvents were selected based on a mixture design. The best results were achieved with methanol and carbon tetrachloride as dispersive and extracting solvent, respectively. The operational parameters, such as pH, volume of dispersive and extractant solvents, and complexing agent concentration (8-hydroxyquinoline) were optimized using a Box-Behnken design. The optimal conditions were established as pH 3.8, 90 μL of carbon tetrachloride, 480 μL of methanol, and 1.09 mmol L-1 of 8-hydroxyquinoline. Besides, the use of external gas module control (EGCM) was explored to minimize the matrix effects caused by the organic solvent introduction. The accuracy of the proposed method was estimated employing a certificate reference material (bovine liver, NIST 1577c) and the obtained recovery was 92%. The limit of detection was found to be 0.20 μg g-1, and the enrichment factor was 4.5. The DLLME-MIP OES was applied for six samples of lamb meat, and the results compared to ICP-MS presented no statistical difference. Therefore, the proposed method showed satisfactory accuracy and suitable sensitivity.