Separation and determination of n-alkylamines and histamine by capillary zone electrophoresis using salicylaldehyde-5-sulfonate as a derivatizing reagent

Sodium salicylaldehyde-5-sulfonate (SAS) was investigated as a derivatizing reagent for the separation and determination of primary amines by capillar y zone electrophoresis (CZE). The amines were derivatized with SAS to the c orresponding Schiff bases before their determination. Optimal conditions fo r the formation reactions of the Schiff bases and the CZE analysis were inv estigated in details. The Schiff bases were formed almost completely within 9 min in 40% (v/v) ethanol solution at 40 degreesC. A migrating solution c ontaining 40%(v/v) ethanol and 20 mM phosphate buffer (pH 7.8) was found to be preferable for the stability of the Schiff bases. Eight kinds of n-alky lamines were derivatized with SAS under the optimal conditions and the deri vatives were successfully separated by a CZE analysis. The proposed method allows simultaneous, sensitive and sufficiently precise determination of th e n-alkylamines with the alkyl chain length from 3 to 12 of methylene group s. The derivatization process with SAS was successfully applied to the dete ction of histamine at a very low level. The detection limit was 2.5(.)10(-6 ) M, and it was improved in the order of 8 times compared with the CZE anal ysis without derivatization. (C) 2001 Elsevier Science B.V. All rights rese rved.