Increased analytical precision in the hollow cathode discharge emission source by improved discharge current control

Area of Science:

• Analytical Chemistry
• Atomic Spectroscopy

Background:

• Hollow cathode discharge is a common emission source in atomic spectroscopy.
• Achieving high precision and long-term stability in hollow cathode sources has been a challenge, particularly for microsample analysis.

Purpose of the Study:

• To report significant improvements in the precision and stability of a hollow cathode emission source.
• To introduce and characterize a new current-controlled switch for hollow cathode discharges.
• To demonstrate the analytical performance of the improved hollow cathode source for microsample analysis.

Main Methods:

• Implementation of electronics to maintain constant discharge current.
• Shielding of wiring to the hollow cathode source.
• Development and utilization of a current-controlled switch for DC and pulsed modes.
• Characterization of pulse generation and temporal current stability.
• Analysis of microsamples (less than 50 nL) deposited in AI and stainless steel hollow cathodes.

Main Results:

• Achieved precision of 1% or less over several hours.
• Reported average long-term stability of 4.3% for Li and 6.0% for Na emission signals.
• Demonstrated improved discharge stability and repeatability at turn-on using the new switch.
• Presented temporal current plots comparing new instrumentation with conventional power supplies.

Conclusions:

• The developed instrumentation significantly enhances the precision and stability of the hollow cathode emission source.
• The novel current-controlled switch improves discharge characteristics in both DC and pulsed modes.
• The improved hollow cathode source is suitable for precise and stable analysis of microsamples.