The Study Of On-line Solid-phase Extraction With Hydrophobic Monolithic Column For Sudan Dyes In Chili Pepper Powder

Objectives In order to overcome the problems of conventional solid-phase extraction(SPE) sorbents in packing and reusing, the porous hydrophobic poly(butyl methacrylate-co-ethyleneglycol dimethacrylate) monolithic column was fabricated and explored as anovel SPE material. A methodology was developed using the prepared monolith as on-lineclean-up and extraction sorbent, followed by liquid chromatography-tandem massspectrometry (HPLC-MS/MS) for the analysis of Sudan I~IV in chili pepper powder.Methods The hydrophobic monolithic column was prepared in a stainless steel column(50mm×4.6mm i.d.) via in-situ copolymerization of butyl methacrylate (BMA) asmonomer and ethylene dimethacrylate (EDMA) as crosslinking agent. The amount ofmonomer BMA, the variety and ratios of porogens were varied to investigate their effectson the performance of the monoliths. The prepared columns were characterized byscanning electron microscope, nitrogen adsorption-desorption and pressure dropmeasurements. On-line SPE was performed on the synthesized poly (BMA-co-EDMA)monolith and the parameters were optimized such as the eluting solution, the flow rate foreluting and the composition of the mobile phase for separation. Finally, the specificity,linearity range, accuracy and precision, the limit of detection (LOD) and the limit ofquantification (LOQ) of the proposed method were investigated.Results The scanning electron microscope image displayed the porous and uniformmorphology of the monolith. The surface area was found to be121.45m2g-1. On-linesolid-phase extraction was performed on the synthesized monolithic column using10mmol L-1ammonium acetate solution as loading solution with the aid of an on-line clean-up chromatograph system. The desorption of Sudan I-IV was achieved with acetonitrileas the eluting solution at the flow rate of0.5mL min-1. The extracted analytes weresubsequently eluted into a C18analytical column for chromatographic separation using amixture of10%acetonitrile-90%formic acid (0.5%) solution as the mobile phase. Theproposed method was linear over the range of1.0~50.0μg kg-1for Sudan I~IV. The LODfor Sudan I~IV was0.3μg kg-1and the LOQ was1.0μg kg-1, respectively. The intra-dayand inter-day recoveries of Sudan I~IV in chili pepper powder samples ranged from94.8%to100.9%(RSDs ranged from3.37%to7.01%) and94.9%to99.4%(RSDsranged from5.01%to7.68%), respectively.Conclusions Compared with the results had reported, it had been demonstrated that theproposed method can be used for routine determination of Sudan dyes in chili pepperpowder with wide linear range, acceptable recovery and low detection limit. Moreover,the novel sorbent had the remarkable advantages of easy preparation, high extractionefficiency and satisfactory reusability.