Extraction and Preconcentration of Trace Malondialdehyde from Lipid-Rich Foods Using Ion Pair–Based Solvent Bar Liquid-Phase Microextraction

In this research, for the first time, a new strategy based on ion pair–based solvent bar liquid-phase microextraction (IP-SB-LPME) in combination with GC instrument was introduced for sensitive determination of malondialdehyde (MDA) in lipid-rich foods. In this three-phase process, a cationic surfactant was added initially into alkaline donor solution to form hydrophobic ion pair with the anionic analyte. Then, the ion pair formed was enriched into organic solvent immobilized in the pores of the HF and finally back extracted into an acidified acceptor phase in the lumen of the fiber. Significant parameters affecting the proposed method were optimized to obtain the maximum preconcentration factor. Under the optimized conditions, the method provided good linearity in the range of 3–600 μg L−1 in pure water, 65.0–6875.0 μg kg−1 in infant powder milk, and 52.5–6875.0 μg kg−1 in vegetable oils. Acceptable repeatability and reproducibility (CV < 4%) with preconcentration factors in the range of 82–100 times were obtained. Methodological validation was accomplished by using the conventional spectrophotometric TBA (2-thiobarbituric acid) test. Finally, this procedure was applied to monitor trace amounts of MDA in the lipid-rich foods with satisfactory results.