Capillary electrophoresis micro X-ray fluorescence: a tool for benchtop elemental analysis

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Separation Science

Background:

• Elemental analysis and chemical speciation are crucial in various scientific fields.
• Existing methods for elemental detection and speciation can be complex or require specialized equipment.
• The need for benchtop, non-destructive, and simultaneous analytical techniques is growing.

Purpose of the Study:

• To develop and demonstrate a novel hyphenated analytical system for separation and elemental detection.
• To investigate the capability of the system for chemical speciation applications.
• To evaluate the performance and detection limits of the prototype system.

Main Methods:

• Interfacing a capillary electrophoresis (CE) apparatus with a benchtop energy-dispersive micro X-ray fluorescence (MXRF) system.
• Utilizing an EDAX Eagle II micro X-ray fluorescence system with a polycapillary Rh target excitation source and SiLi detector for X-ray excitation and detection.
• Employing fused-silica capillaries for the separation of analytes.

Main Results:

• Successfully separated and detected species containing different metals, specifically copper (Cu) and cobalt (Co).
• Demonstrated the separation of free cobalt (Co) from cobalt bound to cyanocobalamin (vitamin B-12).
• Achieved separation of a large biological protein (ferritin) from a smaller organic molecule (cyanocobalamin) with preliminary detection limits around 10(-4) M.

Conclusions:

• The developed CE-MXRF system provides a viable benchtop solution for non-destructive, simultaneous, on-line elemental analysis.
• The system shows potential for various chemical speciation applications.
• Performance is comparable to more complex techniques like CE-synchrotron XRF.