A freeze method for deproteinization coupling with the chitosan purification process was developed for
the determination of 8 synthetic food colorants in protein-rich samples.
The solvents for extraction and different methods for deproteinization were examined and selected.
Chitosan was employed for the purification after deproteinization, and further compared with the traditional polyamine purification method.
Determination of the purified extract was conducted through the separation using high perfor-mance liquid chromatography and detection by multi-wavelength mode.
Under the optimum conditions,the method showed good linearity between 0.6 and 10 mg/kg, for the 8 synthetic colorants, and the limit of detection was between 0.1 and 0.4 mg/kg as was defined when the ratio of signal to noise was three.
The recoveries of the spiked samples were found to be between 83% and 91%.
The intra-day precision and
inter-day precision was estimated to be 3–10% and 6–12%, respectively.
The developed method could be applied to deproteinization and clean-up for pretreatment of protein-rich samples.