Development of an interface for directly coupled solid-phase extraction and GC-MS analysis

Solid-phase extraction (SPE) is widely used as a sample preparation technique in numerous application areas of chromatography. Large-volume injection is an attractive technique for coupling SPE to gas chromatography (GC) because it provides improved detection limits and circumvents the need for miniaturization of the SPE instrumentation. In this article, the authors describe how they linked an SPE system with a GC-mass spectroscopy (MS) instrument using an interface consisting of a switching valve, a short length of capillary tubing, and a restrictor. They applied large-volume programmed temperature vaporization injection to transfer the SPE eluate into the gas chromatograph. They tested the performance of the SPE-GC-MS system by analyzing two real-world samples: caffeine in urine and triazines in drinking water. Both automated large-volume injections and on-line SPE-GC-MS experiments showed good repeatability at the desired concentration levels.