Ultraviolet native fluorescence detection in capillary electrophoresis using a metal vapor NeCu laser

Ultraviolet (UV) excitation for laser-induced native fluorescence (LINF) de tection in capillary electrophoresis (CE) offers impressive performance fig ures of merit when assaying peptides containing tyrosine or tryptophan resi dues, catecholamines, indolamines, and a number of other classes of analyte s with appreciable fluorescence when excited by UV radiation. One of the la rgest drawbacks of native fluorescence detection schemes in CE-LINF systems has been the expense and the complexity of the lasers required for excitat ion in the deep UV wavelength range of 200-300 nm. An improved "turn-key" N eCu laser operating at 248.6 nm interfaced to a sheath flow-based CE system obtains a performance similar to that of large frame frequency-doubled Ar ion lasers. The detection limits for serotonin and dopamine (27 nM and 8 mu M, respectively, for similar to3-nL injection) are similar to those obtaine d using a frequency-doubled Ar ion laser at 257 mn (21 nM and 8 muM, respec tively). An example of the detection of serotonin-related analytes from a s ingle-cell electropherogram demonstrates the performance of such a system f or mass-limited measurements.