1. Department of Chemistry, Zhejiang University, Hangzhou 310028, China;
2. Zhejiang Provincial Key Laboratory of Health Risk Appraisal for Trace Toxic Chemicals, Zhejiang University, Hangzhou 310028, China;
3. School of Pharmaceutical and Chemical Engineering, Taizhou University, Taizhou 317000, Zhejiang Province, China
Abstract:The ion chromatography with on-line sample pretreatment using column-switching technique is applied to the simultaneous analysis of the conventional inorganic anions and organic acids in edible oils and illegal cooking oils. In this work, a polymer-based reversed-phase column was used as the pretreatment column. Via column-switching technique, sample solution with target ions were eluted from a collection loop to the analytical columns with matrix eliminated on-line. A series of standard solutions consisting of target ions of various concentrations from 0.05 to 10 mg·L-1 are analyzed, with a correlation coefficient r≥0.9990 and a satisfactory repeatability (RSD≤2.34%, n=6). The limits of detection are in the range from 4 to 41 μg·L-1 based on S/N of 3 and the 25 μL injection volume. The average spiked recovery rates are between 75.6% and 87.7%. The result shows that the concentration of acetate and formate are significantly higher in the illegal cooking oils than edible oils. The on-line sample pretreatment IC system is convenient and practical for the determination of conventional inorganic anions and organic acids in edible and illegal cooking oil samples.
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