Microwave-assisted high-throughput derivatization techniques utilizing silicon carbide microtiter platforms

Parallel microwave-assisted gas chromatography (GC) derivatization protocols utilizing a silicon carbide (SiC)based microtiter plate platform fitted with screw-capped GC vials were developed. For three selected standard derivatization protocols such as acetylation (exemplified for morphine), pentafluoropropionylation (for 6-monoacetylmorphine) and trimethylsilylation (for Delta(9)-tetrahydrocannabinol) complete derivatization was achieved within 5 min at 100 degrees C in a dedicated multimode microwave instrument using online temperature monitoring. Microwave irradiation leads to rapid and homogeneous heating of the strongly microwave-absorbing SiC plate, with minimal deviations in the temperature recorded at different positions of the plate. The current platform allows the simultaneous derivatization of 80 reaction mixtures under strictly controlled temperature conditions. Similar results can also be obtained using a standard hotplate as heating source, although heating to the target temperature of 100 degrees C is slightly slower. The results demonstrate that parallel microwave derivatization procedures can significantly reduce the overall analysis time and increase sample throughput for GC-MS-based analytical methods. (C) 2009 Elsevier B.V. All rights reserved.