1. Organic and Biological Mass Spectrometry Group, Chemical Sciences Division; Oak Ridge National Laboratory; Oak Ridge TN 37831-6131 USA
2. Department of Chemistry; University of Tennessee; Knoxville Tennessee 37996-1600 USA
3. Thin-Layer Chromatography Laboratory; Merck Millipore - Lab Essentials, Merck KGaA; 64293 Darmstadt Germany