Achieving Higher Signal Response Than Splitless GC Injection by High-Pressure Headspace Sampling and Full Evaporation Technique

This paper aims to improve the signal response in headspace (HS) analysis over than the GC analysis with a classical splitless injection mode, and this was achieved by the development of high-pressure headspace (HP-HS) analysis method. Based on the theoretical analysis on the sampling principle of HS, the HP-HS concept was proposed in section one, indicative of possibility to achieve excellent signal response. In the proposed HP-HS technology, the complete transfer of gas sample from HS to GC column is achieved in a very short purge-off time in the splitless injection of GC using the high-pressure carrier gas. The sampling size was increased by adopting high-pressure auxiliary gas. The dilution effect of venting process on detected substance was greatly reduced by controlling the terminal pressure of venting process at a high level. With the HP-HS analysis technology, the optimal equilibration temperature and signal response for analytes with high or medium volatility in ten common solvents was determined, and the results showed that the HP-HS-GC method can achieve very high signal response and very low solvent effect on GC. For aqueous samples, the signal response of HP-HS-GC can be up to three times than that of the splitless GC analysis. The present technology has a great potential, in particular, in high sensitivity analysis of complicated samples with serious substrate effect.