Detection of trans-fatty acids by high performance liquid chromatography coupled with in-tube solid-phase microextraction using hydrophobic polymeric monolith

Based on in-tube solid-phase microextraction (in-tube SPME) using a hydrophobic poly (octadecyl methacrylate-co-ethylene dimethacrylate) [poly (OMA-co-EDMA)] monolith, a simple high performance liquid chromatography (HPLC) method has been developed for detection of trans-fatty acids (TFAs) as their fatty acid methyl esters (FAMEs). The poly (OMA-co-EDMA) monolithic column with high hydrophobicity was specially prepared for simultaneous microextraction, pre-separation and purification for the analytes. The pre-separation selectivity, the extraction efficiency, and the purification effect for FAMEs were investigated respectively. Furthermore, some operation parameters have been optimized in detail with respect to satisfactory extraction efficiency of the target compounds. Under the optimized conditions, the enrichment factors for model FAMEs were ranged from 58.3 to 70.9, wide linear range (0.01-1.00 mg/kg) and low detection limits (LODs) (3.0-7.1 μg/kg) were achieved, respectively. In addition, recoveries of the method were in the range from 83.0 to 106.4% with low relative standard deviations (RSDs) of 3.2-4.7% (n = 4) at spiking levels of 0.05, 0.25 and 0.5 mg/kg, respectively. Finally, the proposed method was successfully applied for detection of TFAs in practical samples, which possesses short time-consuming, low disturbance and high detection sensitivity.