Abstract:

A method was presented for determining six Sudan reds and Para red in pepper oil using solid-phase extraction (SPE) and HPLC. Samples were extracted with acetonitrile and cleaned up on a C18 SPE column using n-hexane as the eluant, and the eluate was evaporated to dryness and dissolved in methanol prior to HPLC analysis. The analytes were detected at 510 nm, and quantified using an external calibration method. The detection limits were 7.0－7.2 μg/kg for six Sudan reds and Para red in pepper oil. At three spiked levels of 25－250 μg/kg, the average recoveries for six Sudan reds and Para red in pepper oil were 78.3% －93.5%, and the intra and inter CVs were 3.3%－9.2% and 4.6%－10.6%, respectively. There was a good linear correlation (r ＞ 0. 9997) between the peak area and the concentrations of Sudan reds and Para red in the range of 15 to 2000 μg/L.

Key words: HPLC, solid phase extraction (SPE), Sudan red, Para red