Study On Novel Solid-Phase Microextraction Techniques

Solid-phase microextraction (SPME) is a simple and effective adsorption and desorption technique, which eliminates the need for solvents. As a new type of SPME, stir bar sorptive extraction (SBSE) has about 50-250 times more extraction phase than that of conventional SPME, resulting increase of enrichment factor up to 102. The stir bar coated with extraction phase is also used to stir samples during extraction. The SBSE technique is suitable for extraction of trace amount of organic compounds in food and environmental samples.A thermal desorption system (TDS), consist of a quartz liner and heaters, gas flow controllers, temperature control units, and a sample transfer line to the GC, was designed and evaluated. A 90 mm long stainless steel cylinder of 6.7mm I.D. and 12mm O.D. was used to hold the desorption liner and the transfer line. The transfer line was inserted directly through the injector septum into the GC pre-column about 20 cm deep. Desorption is complete and no carry-over is found. The device is compatible to all GC, and is robust and low cost.A sol-gel coating method for the preparation of bars used in sorptive microextraction was described. The extraction phase poly(dimethysiloane) (PDMS) was partially crosslinked with the sol-gel network, and the most part was entangled within the network. The thickness of coating layer is about 30μm by one coating process. Thicker coating layer can be realized by multi-coating process. The improved coating technology shows good thermal stability up to 300°C.Organophosphorus pesticides (OPPs) in vegetables were determined by stir...