Capillary electrophoretic separation enhanced by a macrocyclic dioxopolyamine additive

Macrocyclic polyamines, or in particular dioxopolyamines, are strong recept ors for analytes such as metal ions, catechol and catecholamine derivatives . in this paper, based on their interaction with a dioxopolyamine compound: 1,4,7,10-tetraazacyclotridecane- 11,13-dione (or dioxo[13]aneN(4)), we rep ort its use as an additive in capillary electrophoresis (CE) to improve the separation resolution and selectivity of various model analytes. Using an imidazole-acetic acid electrolyte with dioxo[13]aneN(4) as the only additiv e, alkali metal, alkaline earth metal and NH4- ions can be effectively sepa rated and detected by using CE with indirect UV detection, as opposed to th e use of crown ether in which another additive, such as alpha-hydroxyisobut yric acid, is needed. The host-guest interaction between dioxo[13]aneN(4) a nd metal and NH4+ ions can modify their electrophoretic mobilities, and the refore can be used to differentiate the various cations, especially between K+ and NH4+, and between Sr2+ and Ca2+. We have also found that dioxo[13]a neN(4) is an effective additive in CE to resolve nitrophenols and, in parti cular, dihydroxybenzenes. Moreover, unlike previous reports, the separation of various biogenic monoamine neurotransmitters can be achieved at neutral or physiological pH. This work demonstrates that one of the macrocyclic di oxopolyamine derivatives: dioxo[13]aneN(4) is a promising additive in CE se parations for any chemical species: cationic, anionic and neutral. (C) 1999 Elsevier Science B.V. All rights reserved.