Derivatization, stabilization and detection of biogenic amines by cyclodextrin-modified capillary electrophoresis–laser-induced fluorescence detection

Abstract

o-Phthalaldehyde (OPA) derivatives of eight biogenic amines were stabilized at 5°C by forming inclusion complexes with methyl-β-cyclodextrin (MBCD). The derivatives were separated and detected by cyclodextrin-modified capillary electrophoresis (CE) with UV or laser-induced fluorescence (LIF) detection. Using a borate buffer, pH 9.0 consisting of ethanol and a mixture of negatively charged sulfobutylether-β-cyclodextrin and neutral MBCD, baseline separation of the eight OPA derivatives was achieved within 25 min with high separation efficiencies. The detection limits ( S/ N=3) obtained by UV and LIF detection were determined to be 10 μ M and 0.250 μ M, respectively. Glutamic acid was added after the initial derivatization step to neutralize residual OPA which otherwise caused a significant interference, particularly when analysis was performed around the detection limit of the OPA derivatives. Important biogenic amines in fish, wine and urine were then derivatized and determined by CE–LIF. In the case of sole and rainbow trout, the results obtained were validated by an enzymatic assay using putrescine oxidase.