THERMOOPTICAL ABSORBENCY DETECTION OF NATIVE PROTEINS SEPARATED BY CAPILLARY ELECTROPHORESIS IN 10-MU-M ID TUBES

Thermo-optical absorption (TOA) detection of native proteins separated by capillary electrophoresis is demonstrated in 10 mu m I.D. tubes. The eluents were on-column pumped at 257 nm and probed by a hologram-based refractive index detector. The use of 10 mu m capillaries allowed fast 2-min separations. Slower separations in wider tubes fed to limits of detection (LODs) of 7 . 10(-9) M for bovine serum albumin. These LODs are comparable to those obtained with laser induced fluorescence and two orders of magnitude lower than in absorbance detection. Since native fluorescence of proteins is rare, TOA detection appears as a more universal detection scheme and thus suitable for other proteins having smaller amounts of fluorescent amino acids.