A novel poly (NMA-co-DEA-co-EDMA) monolithic column as a sorbent for online solid-phase extraction and its application in the determination of β-sitosterol in plant oil samples.

A novel monolithic column was prepared by in-situ free radical polymerization using N-methylolacrylamide (NMA) and N,N-diethylacrylamide (DEA) as co-monomers. The monolith was characterized by scanning electron microscopy (SEM) and its nitrogen adsorption-desorption isotherm, and it was used as a solid phase extraction (SPE) absorbent for the online enrichment of β-sitosterol by high performance liquid chromatography. The optimized method had good linearity, and the linear regression coefficient was 0.998. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.006 mg/mL and 0.02 mg/mL, respectively. The interday and intraday accuracies were less than 7.28%. The spiked recoveries of β-sitosterol in the six plant oil were 90.96-103.56%. The maximum amount of β-sitosterol adsorbed on the monolithic column was 12.69 mg/g, and the enrichment factor of β-sitosterol was 78. The results showed that the monolith could be used as an online SPE absorbent for the determination of β-sitosterol in plant oil samples.