Capillary electrophoretic fingerprint investigation of gel pen inks.

In this study, two capillary electrophoresis modes, capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC), were employed for the examination of gel ink fingerprints. The optimized CZE conditions were as follows: running buffer, 0.2M boric acid and 0.05M sodium tetraborate; pH, 6.47; detection, 214 nm; separation voltage, 20 kV MEKC conditions were as follows: 20 mM sodium tetraborate-20 mM sodium dodecyl sulphate; detection, 214 nm; separation voltage, 20 kV. The CZE and MEKC fingerprints of 18 el pen inks from Beijing markets were analyzed and the inks were classified according to the fingerprints of the two CE modes.