Matrix Solid-Phase Dispersion Extraction and UPLC Determination of Sudan Dyes in Chili Powder

A new method involving matrix solid-phase dispersion (MSPD) extraction and UPLC in conjunction with photodiode array detection was developed for the rapid and simple determination of Sudan dyes in chili powder. Separation of Sudan I, Sudan II, Sudan III, and Sudan IV was achieved within 2 min on the 1.7 mu m Acquity UPLC BEH C18 column by using gradient elution with a mobile phase consisting of acetonitrile-water at a flow rate of 0.5 mL min(-1). Optimization of MSPD extraction parameters, such as type of solid sorbent and elution solvent were carried out. Optimal conditions selected for MSPD extraction were 0.25 g of sample, 0.5 g of silica gel as solid sorbent, and 7 mL of acetonitrile-methanol (9:1, v/v) as eluting solvent. Limits of detection ranged between 0.25 and 0.30 mg kg(-1) depending on the dye involved. All analytes provided average recoveries from spiked (at 1, 1.5, and 2 mg kg(-1)) chili powder samples ranging from 81 to 106%. The method was applied to the analysis of chili powder samples obtained from different countries.