A multi-wavelength HPLC fingerprint comparison method was proposed for the screening of oil-soluble
synthetic dyes in chilli products. The screening was based on the fingerprint differences of normal
unadulterated chilli sample with tested chilli samples. The samples were extracted with acetone and
fingerprinted by HPLC under four visible light wavelengths (450 nm, 490 nm, 520 nm, and 620 nm). It
was found that the fingerprints of different chilli product samples had a relatively fixed number of peaks
and stable retention time. When 16 kinds of known synthetic dyes were used as model analytes to assess
the screening efficiency, 14 of them could be screened using fingerprint comparison method, with LOD of
0.40–2.41 mg/kg. The new screening method was simple and had the possibility of finding existence of
the adulterated dyes which could not be identified using known standard analytes as control.