Simultaneous Determination and Enrichment of β-Sitosterol From Edible Oil Samples Using Poly(NMA-ST-co-TAIC-co-EDMA) Monolith as Sorbent with On-line SPE-HPLC

A poly(NMA-ST-co-TAIC-EDMA) monolithic column was prepared by redox initiation method using N-methylolacrylamide (NMA) and styrene (ST) as co-monomers. The composite monolith was characterized by scanning electron microscopy (SEM) and nitrogen adsorption-desorption isotherm and was used as a solid phase extraction (SPE) absorbent for enrichment of beta-sitosterol by high performance liquid chromatography (HPLC). Under the optimum conditions for extraction and determination, the calibration equation was y = 1.02247x + 0.1766; the linear range was 0.015-0.75 mg mL(-1) and the linear regression coefficient was 0.998. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.006 mg mL(-1) and 0.02 mg mL(-1), respectively. The spiked recoveries of beta-sitosterol in edible oil samples were 83.60-103.88%; precisions for intra-day and inter-day assays presented as relative standard deviations were less than 6.0% and 6.2%, respectively. The enrichment factor of beta-sitosterol was 60 and the results showed that the monolithic column had high selectivity and good permeability as an on-line SPE absorbent for the enrichment and determination of beta-sitosterol from edible oils.