SPME/HPLC Interface Combines Fast Sample Extraction with Efficient Analysis for Explosives

Importance of the Topic

Solid phase microextraction (SPME) reduces solvent consumption and sample preparation time while enabling analysis of weakly volatile or thermally labile compounds by HPLC. The integration of an SPME/HPLC interface overcomes previous barriers in introducing microextracted analytes into liquid chromatography and supports efficient trace analysis of environmental and forensic targets such as explosives.

Goals and Overview of the Study

This application note describes the design and practical evaluation of a six-port SPME/HPLC interface for direct desorption of analytes from a coated fiber into an HPLC system. The primary demonstration focuses on extracting and separating fourteen common explosive residues from aqueous samples.

Methodology and Instrumentation

Explosive compounds were extracted from 4 mL of water containing 27% sodium chloride (pH 9.5) using a 65 µm polydimethylsiloxane/divinylbenzene SPME fiber under rapid stirring for 20 minutes. Two desorption approaches were tested: static desorption by soaking the fiber in 200 µL acetonitrile:water (50:50) for 1 minute, and dynamic desorption by continuous mobile phase flow. The interface consists of a stainless steel desorption chamber with a PEEK needle guide, VESPEL ferrule and compression clamp, coupled to a six-port Valco® or Rheodyne® injection valve. Separation was achieved on a 15 cm × 4.6 mm ID SUPELCOSIL LC-8 column (3 µm), using isopropyl alcohol:water (18:82) at 1.5 mL/min and UV detection at 254 nm.

Main Results and Discussion

All fourteen explosives at 50 ppb produced sharp, symmetric peaks, indicating efficient transfer from fiber to column. Static desorption provided complete analyte release without fiber deterioration, and interface pressures up to 5400 psi maintained seal integrity. These results confirm the interface’s suitability for sensitive, reproducible analysis of trace explosives.

Benefits and Practical Applications

• Reduced solvent use and faster sample preparation
• Improved detection limits for non-volatile and labile analytes
• Simplified workflow for environmental, forensic and pharmaceutical testing
• Reusable SPME fibers and rapid interface setup support high throughput

Future Trends and Potential Applications

Further developments may include automated SPME/HPLC modules, advanced fiber coatings for broader selectivity, coupling with mass spectrometry for confirmatory analyses, and portable systems for on-site environmental and security monitoring.

Conclusion

The SPME/HPLC interface offers a robust, solvent-saving solution for introducing microextraction samples into HPLC, delivering efficient, reproducible detection of explosive residues. This technology is poised for expansion into diverse analytical fields requiring trace-level precision.

Reference

1. Chen J. and Pawliszyn J. Anal. Chem. 67:2530-2533 (1995)
2. Boyd-Boland A.A. and Pawliszyn J. HPLC-SPME analysis of nonylphenol ethoxylate surfactants in water