The characteristics of laser ionization in low pressure background gas have been investigated through the measurement of temporal and kinetic energy distributions of Al+, Mn+, Nb+, In+, Ta+, and Bi+ produced from a disk comprised of these metallic elements. A Q-switched Nd:YAG laser was utilized with a laser beam at 532 nm of wavelength and 1.0 × 1010 W/cm2 of laser irradiance. The kinetic energy was found to be the same for all ablated species at the given pressure, regardless of the atomic mass. The plume propagation translates from a free expansion at 0.5 Pa to a collisional and shockwave-like hydrodynamic expansion at 50 Pa. A plume splitting exists at 500–1500 Pa where only the fast component can be observed with a grounded nozzle voltage. As the nozzle voltage grows up, the thermalized component with increased kinetic energy is found depending on the nozzle voltage.Highlights► We have measured kinetic energy distributions of different elements. ► Two approaches were used for measurement: temporal profile and deflecting voltage. ► Kinetic energy distributions are the same for different species, independent of mass. ► Kinetic energy loss of ions is much smaller than the theoretical value. ► Kinetic energy of the slow component increases proportionally with nozzle voltage.

A coated capillary modified with a coupled chitosan (COCH) was developed by using a simple and fast (60 min) process that could be easily automated in capillary electrophoresis instrument. The COCH coating was achieved by first attaching chitosan to the capillary inner wall, and then coupling with glutaraldehyde, and rinsing chitosan again to react with glutaraldehyde. The COCH coating was stable and showed amphoteric character over the pH range of 1.8–12.0. When the pH value was lower than 4.5, the capillary surface possessed positive charges, which caused a reversal in the direction of the electroosmotic flow (EOF). The normal EOF direction could be obtained when the pH value was higher than 4.5. The COCH coating showed strong stability against 0.1 mol/L HCl, 0.1 mol/L NaOH and other solvents compared with conventional chitosan coating. The relative standard deviation of the run-to-run, day-to-day and capillary-to-capillary coating was all below 2% for the determination of EOF. The COCH-modified capillary was applied to acidic and basic proteins analyses and high efficiency could be attained. The comparison between unmodified capillary, chitosan-modified and COCH-modified capillary for the separation of real sample, extract from Elaphglossum yoshinagae with water, was also studied. Better results could be obtained on COCH-modified capillary than the other two capillaries.