Search

Abstract: Separation and determination of dopamine and epinephrine with end-channel electrochemical (EC) detection integrated on a native printed microchip capillary electrophoresis (CE) system was investigated. Factors influencing the separation and detection were investigated and optimized. Results show manipulating EOF, which can be easily achieved by adjusting buffer pH, is a simple and effective way to achieve the baseline separation of dopamine and epinephrine in native polymeric microchips. Without surface modification of microchannel, printed microchips with advantages of low cost and easy preparation can achieve high performance like other microfluidic devices. [Copyright &y& Elsevier]

A two-dimensional layered inorganic-organic hybrid metal hydrogenophosphate (1) was treated with 0.1 M NaOH-ethanol solution, which resulted in a Na + -ion substitution product that exhibits excellent thermal and aqueous stability with 1, as well as much higher proton conductivity (σ = 10 -2 S·cm -1 ) even at low temperature (283 K). This is because Na + ions in aqueous solution make a more dense and extensive H-bonding network of water molecules, which enables protons to more easily transfer along the network.

Aim: To establish a method for separation and identification of alkaloids in Stephania tetrandra S. Moore methanol extracts by using non-aqueous capillary electrophoresis interfaced with electrospray ionization ion trap mass spectrometry., Methods: The molecular ions or adducts of alkaloids and fragments of specific parent ions were used for the identification. An uncoated capillary (86 cm x 75 microm ID, on-line UV detection occurred at 21 cm from the inlet of the capillary) was used. Ammonium acetate (50 mmol x L(-1)) containing 4% HAc in methanol was used as the running buffer; separation voltage was 25 kV. A coaxial sheath flow interface was used as the CE-MS interface; the electrospray voltage was 4.5 kV; the temperature of aluminium capillary was 170 degrees C; 60% isopropanol-39% water-1% HAc was used as the sheath liquid with the flow rate of 5 microL x min(-1); the collision energy of MS-MS was set at 30% and the least ion counts was 1 x 10(5)., Results and Conclusion: The alkaloids in Stephania tetrandra S. Moore methanol extracts were separated and identified by CE-ESI-MS/MS. The proposed method is of high accuracy and can be used for the investigation of traditional Chinese medicine.