Application of three-dimensional liquid chromatography for quantification of 2-acetyl-4-(1,2,3,4-tetrahydroxybutyl)imidazole (THI) in caramel colours

Abstract

Multidimensional chromatography is a widely used technique to quantify specific compounds in complex samples. A three-dimensional liquid chromatography with UV detection was developed to separate 2-acetyl-4-(1,2,3,4-tetrahydroxybutyl)imidazole, an undesirable neoformed by-product found in class III caramel colours. The first column was a classical reversed-phase column (C18 column); the second one was a cation-exchange column operated with acidic mobile phase; the last column was a specific reversed-phase column (porous graphitic carbon). This method is validated to quantify this compound in caramel colours in 45 min in the 5–50 mg kg⁻¹ concentration range. The limit of quantification is found at 5 mg kg⁻¹. The total error is less than 20% at 5 mg kg⁻¹ and less than 10% between 10 and 50 mg kg⁻¹. This method is used routinely to quantify THI in class III caramel colours and to check compliance with caramel regulations.