Sensitive absorption-based wave-mixing detector for anthracycline drugs separated by capillary electrophoresis

Abstract

Sensitive absorption-based detection of anthracycline antibiotics, daunorubicin and doxorubicin is demonstrated using a capillary electrophoresis system interfaced to a nonlinear wave-mixing detection system. Unlike conventional absorption methods, this nonlinear absorption method can detect very thin analytes (50 μm) efficiently. At the same peak height, the wave-mixing CE peak is narrower than a conventional CE peak, and hence, compared to other laser-based or non-laserbased CE on-column detection methods, our wave-mixing detection method offers intrinsically enhanced separation resolution even when using identical CE separation conditions. In this unusually sensitive "absorbance" detection method, two input laser beams interact to produce a thermally induced grating from which coherent laser-like wave-mixing signal beams are created. Using our sensitive "absorbance" on-column CE detector, we report a preliminary concentration detection limit of 9.9 × 10 −10 M using a 50 μm i.d. capillary column. The corresponding "injected" mass detection limit is 9.1 × 10 −18 mol using an injection volume of 9.2 nL. The corresponding preliminary "detected" mass detection limit inside the 12-pL detector probe volume is 1.2 × 10 −20 M.

Recent advances in the analysis of antibiotics by CE and CEC

“…Berniolles et al 76 developed a CZE method coupled to a forward‐scattering wave mixing laser detector for the separation of doxorubicin and daunorubicin. This detector offers excellent sensitivity for small absorbance measurements and the CE peaks obtained with this detector are narrower than the conventional peaks obtained with laser based or nonlaser‐based detection methods.…”