Moving interaction boundary electrophoresis and its selective focusing of target guest molecule norfloxacin in urine by a cyclodextrin host

In this paper, a moving interaction boundary (MIB) method was developed using a guest compound and a host molecule of cyclodextrin (CD) in capillary electrophoresis (CE). With norfloxacin (Nor) as the model guest compound, experiments were carried out and the results revealed that (1) the MIB method can be designed as a tool for focusing target guest molecules in complex biological samples (e.g., urine); (2) the focusing is highly selective; (3) compared with capillary zone electrophoresis (CZE), a 143-fold sensitivity increase, in terms of the peak height, can be achieved and (4) moreover, the actual application of this MIB-based focusing method for the analysis of a complex biological sample (e.g. urine spiked with Nor), containing numerous metabolites, was carried out. The concept of MIB and its selective focusing has potential significance toward host–guest interaction and separation science.