A miniaturized spatial temperature gradient capillary electrophoresis system with radiative heating and automated...

A miniaturized spatial temperature gradient CE system with automated sample introduction for DNA mutation detection was established. Continuous electrokinetic sample injection was achieved by combining an automated slotted-vial array sample introduction device to the spatial temperature gradient CE system. The temperature gradient was produced by a radiative heating system with a single graphite block heater, and the stability of the temperature gradient was investigated. The temperature variation of each measure point was 0.12-0.21% RSD (n=7) within 6 h. A 14-cm Teflon AF-coated silica capillary was used both as the separation channel and as the liquid-core waveguide tube of fluorescence signal. Under a temperature gradient from 54.8 to 59.5°C, a low range control mutation standard (209 bp) was separated within 4 min with only 5.6 nL sample consumption. Automated continuous sample introducing and changing were realized with a carryover of 3.3%. Utility of the system was further demonstrated by detecting K-ras gene mutations in paraffin tissue sections from two colorectal cancer patients.