Determination of 2-acetyl-4(5)-(tetrahydroxybutyl)imidazole in ammonia caramel color by HPLC

A new approach for the determination of 2-acetyl-4(5)-(tetrahydroxbutyl)imidazole (THI) in ammonia caramel color has been developed. THI was extracted from samples by cation-exchange solid-phase extraction (SPE). After the cation exchange column extraction, a phenyl boronate agarose (PBA-30) affinity column was used for further cleanup. In the boronate extractor, a cyclic boronate ester was formed between the tetrahedral boronate anion and the cis-diol groups of THI. THI was isolated from most remaining matrix interferences and was recover by cleaving the formed ester with acetic acid. The collected samples were then determined by HPLC-UV, using a diol bonded phase column. The optimum HPLC conditions for the separation of THI from ammonia caramel color matrices were also investigated. The minimum detection limit of THI by this approach was at the 1 ppm level in ammonia caramel color.