An improved selected ion recording system for precise isotope ratio determination

Area of Science:

• Analytical Chemistry
• Biomedical Assays
• Isotope Ratio Mass Spectrometry

Background:

• Selected ion recording (SIR) systems are crucial for quantitative analysis in mass spectrometry.
• Traditional SIR systems face limitations in dwell time and mass cycling error, impacting precision.
• Accurate determination of isotopic enrichment is vital for biomedical research and diagnostics.

Purpose of the Study:

• To describe an improved analog four-channel selected ion recording (SIR) system.
• To enhance the precision and dynamic range of isotopic enrichment measurements.
• To enable accurate analysis of low-level isotopic enrichment in biomedical applications.

Main Methods:

• Modification of an analog four-channel SIR system to decrease dwell time to 33 ms per channel.
• Synchronization of the system with a sinusoidal sweep voltage for real-time monitoring.
• Application of the improved system to analyze palmitate turnover in canine models using [1--13C] palmitic acid.

Main Results:

• Achieved a dwell time of 33 ms per channel, significantly reducing mass cycling error.
• Enabled simultaneous real-time monitoring of two channels and continuous mass recording.
• Demonstrated high precision (0.2%) in ion current ratio measurements over a wide dynamic range.
• Successfully detected 0.04% excess [1--13C] palmitate in canine palmitate turnover analysis.

Conclusions:

• The improved SIR system offers enhanced precision and accuracy for isotopic enrichment determination.
• This technology is suitable for sensitive biomedical assays, including those with single isotopic labels.
• The system's capabilities were validated through a practical application in metabolic research.