A high‐sensitivity LIF detector with silver mirror coating detection window and small‐angle optical deflection from collinear system for CE

Abstract

An LIF detector was integrated into a CE system based on silver mirror coating detection window and small-angle optical deflection from collinear configuration. For this detection scheme, the incident light beam was focused on capillary through the edge of a lens, resulting in a small deflection angle that deviated 18° from the collinear configuration. Meanwhile, the excitation light and emitted fluorescence were effectively reflected by silver mirror coating at the detection window. The fluorescence was collected through the center of the same lens and delivered to a PMT in the vertical direction. In contrast to conventional collinear LIF detection systems, the fluorescence intensity was greatly enhanced and the background level was significantly eliminated. FITC and FITC-labeled amino acids were used as model analytes to evaluate the performance with respect to design factors of this system. The limit LOD was estimated to be 0.5 pM for FITC (S/N = 3), which is comparable to that of optimized confocal LIF systems. All the results indicate that the proposed detection scheme will be promising for development of sensitive and low-cost CE system.

Sensitive determination of sulfonamides in environmental water by capillary electrophoresis coupled with both silvering detection window and in‐capillary optical fiber light‐emitting diode‐induced fluorescence detector

“…The method of coating detection window with silver has been depicted in our previous work . Briefly, a detection window was made on the capillary by removing a 0.5 cm section of polyimide coating, which was then rinsed by deionized water and ethanol.…”

Recent advances in amino acid analysis by capillary electromigration methods, 2013–2015

“…By using a colinear optical arrangement proposed 20 years ago , Li et al. have increased the sensitivity of LIF detection of a 16 factor using an Ag mirror around the capillary window and a small 18° deflection angle prior to the normal of the capillary . Ag nanorods (ND) has showed high metal enhanced fluorescence used in microfluidic systems, with a multilayer of SiO 2 Ag‐NDs.…”

Research of Laser Induced Fluorescence Detection Techniques Based on Microfluidic Devices

“…The LOD of FITC was estimated to be 2 pM (S/N = 3). Li et al [26] reported a similar LIF detection system with a small-angle (18°) optical deflection from collinear configuration with silver mirror coating detection window, which greatly enhanced fluorescence intensity. The LOD of 0.5 pM FITC (S/N=3) was obtained.…”