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 capillary zone electrophoresis (CZE). The amines were derivatized with SAS to the corresponding Schiff bases before their determination. Optimal conditions for the formation reactions of the Schiff bases and the CZE analysis were investigated in details. The Schiff bases were formed almost completely within 9 min in 40%(v/v) ethanol solution at 40 degrrees C. A migrating solution containing 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-alkylamines were derivatized with SAS under the optimal conditions and the derivatives were successfully separated by a CZE analysis. The proposed method allows simultaneous, sensitive and sufficiently precise determination of the n-alkylamines with the alkyl chain length from 3 to 12 of methylene groups. The derivatization process with SAS was successfully applied to the detection 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 analysis without derivatization.

Separation and determination of haloperidol, parabens and some of their degradation products by micellar electrokinetic chromatography.

A micellar solution containing phosphate buffer, anionic surfactant, and water-miscible organic solvent was employed as a migration solution for the separation and the quantification of eleven analytes by micellar electrokinetic chromatography (MEKC): the analytes examined were haloperidol, methylparaben, ethylparaben, n-propylparaben, iso-propylparaben, n-butylparaben, iso-butylparaben, sec-butylparaben, 4-(4-chlorophenyl)-4-hydroxypiperidine, 4-fluorobenzoic acid and 4-hydroxybenzoic acid. In order to provide good separation between micelle and haloperidol, which showed strongest interaction with the micelle among the analytes, surfactant concentrations and organic modifier percentages were studied with phosphate buffer at pH 7.0. All the analytes were successfully resolved when 10 mM sodium dodecylsulfate and 15% ethanol were contained in the migration solution; the time window was very wide in the range from 14.8 to 65.5 min. Optimized applied voltage at 30 kV and capillary temperature at 45 degrees C enable analyze all compounds in less than 17 min with the best resolution, the shorter migration time window, the highest precision and lowest detection limit.