New! Rxi®-5Sil MS Capillary GC Columns

Significance of the Topic

Analysis of semivolatile compounds is critical in environmental monitoring and food safety. These analytes often require sensitive and inert gas chromatography mass spectrometry systems to achieve low detection limits and robust quantification of complex mixtures.

Study Objectives and Overview

This work evaluates the performance of a new silarylene phase capillary column referred to as Rxi-5Sil MS. The aim was to demonstrate improved inertness, reduced bleed and enhanced peak shape for active and late eluting semivolatile analytes compared with conventional diphenyl dimethyl polysiloxane phases.

Materials and Methods

Sample mixtures based on regulatory method 8270D containing a range of acids, bases and neutral compounds were injected under splitless pulsed conditions. Temperature programs were optimized between 40 and 330 degrees Celsius using constant helium flow. Calibration levels ranged down to single nanogram on column for challenging analytes.

Used Instrumentation

• Capillary columns The Rxi-5Sil MS fused silica columns with dimensions of 20m x 0.18mm id x 0.18um film and 30m x 0.25mm id x 0.25um film
• Inlet Pulsed splitless inlet with drilled uniliner liner operated at 250 degrees Celsius
• Carrier gas Helium at constant flow rates from 1.0 to 1.2 ml per minute
• Oven programming from 40 degrees Celsius hold to 260 degrees at 20 degrees per minute then ramp to 330 degrees
• Detector Mass spectrometer in electron ionization mode scanning from m z 35 to 550

Results and Discussion

Low bleed from the silarylene phase resulted in rapid baseline stabilization and consistent column to column reproducibility. Separation of critical PAH isomers benzo b and benzo k fluoranthene was achieved with clear resolution. Active compounds such as pyridine and 2 4 dinitrophenol exhibited excellent peak symmetry and response at low nanogram levels. Narrower bore columns allowed faster temperature ramps without compromising key separations.

Benefits and Practical Applications

• Enhanced sensitivity for late eluting semivolatiles enables reliable quantification of trace level contaminants
• Improved inertness reduces peak tailing for acidic and basic analytes
• Low bleed profiles extend MS source maintenance intervals and speed up analysis cycles
• Column dimensions can be chosen to balance throughput, capacity and lifetime for diverse laboratory needs

Future Trends and Opportunities

Advances in column phase chemistry and narrow bore formats will continue to drive faster semivolatile analyses. Integration with high throughput MS platforms and automated sample introduction promises to meet growing demands in environmental and food safety testing. Further reductions in bleed and enhanced chemical resistance will open new applications in pharmaceutical impurity profiling and forensic toxicology.

Conclusion

The Rxi-5Sil MS column demonstrates a significant step forward for semivolatile analysis achieving low bleed, high inertness and robust separations. These improvements enable laboratories to achieve lower detection limits and higher throughput with reliable reproducibility.

References

• US EPA Method 8270D Semivolatile Organic Compounds by Gas Chromatography Mass Spectrometry