Publication details

Combined Contactless Conductometric, Photometric and Fluorimetric Single Point Detector for Capillary Separation Methods



Year of publication 2010
Type Article in Periodical
Magazine / Source Analytical Chemistry
MU Faculty or unit

Faculty of Science

Field Analytic chemistry
Keywords detection; capillary separation methods; combined detector; photometric detection; fluorimetric detection; C4D
Description This work for the first time combines three on-capillary detection methods, namely capacitively coupled contactless conductometric (C4D), photometric (PD) and fluorimetric (FD), in a single (identical) point of detection cell, allowing concurrent measurements at a single point of detection for use in capillary electrophoresis, capillary electrochromatography and capillary/nano-liquid chromatography. The novel design is based on a standard 6.3 mm i.d. fiber-optic SMA adapter with a drilled opening for the separation capillary to go through, to which two concentrically positioned C4D detection electrodes with a detection gap of 7 mm were added on its each side acting simultaneously as capillary guides. The optical fibers in the SMA adapter were used for the photometric signal (absorbance) and another optical fiber at a 45 degree angle to the capillary was applied to collect the emitted light for FD. Light emitting diodes (255 nm and 470 nm) were used as light sources for the PD and FD detection modes. LOD values were determined under flow-injection conditions to exclude any stacking effects: For the 470 nm LED LODs for FD and PD were for fluorescein (1x10-8 mol/L) and tartrazine (6x10-6 mol/L), respectively and LOD for the C4D was for magnesium chloride (5x10-7 mol/L). The advantage of the three different detection signals in a single point is demonstrated in capillary electrophoresis using model mixtures and samples including a mixture of fluorescent and non fluorescent dyes and common ions, underivatized amino acids, and a fluorescently labeled digest of bovine serum albumin.
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