| Research was conducted on a custom built quadrupole ion trap laser microprobe instrument (constructed at the University of Florida). Initial studies with the instrument showed that it was capable of detection of pharmaceutical compounds in intact tissue masses at trace levels by use of matrix-assisted laser desorption ionization (MALDI); however, determining the exact spatial location of those compounds within the tissue mass was not possible by simple application of the MALDI matrix solution onto the surface of the tissue (the MALDI-drop method).; An X,Y-micro-manipulation stage was constructed so that spatial information about the location of drug compounds in intact tissue masses could be obtained. The studies showed that, within half the diameter of the probe tip (2 mm), all spatial information about the location of a drug compound was lost during the MALDI-drop method. In order to preserve the spatial distribution of drug compounds in intact tissue samples, two alternative methods were investigated.; The first alternative method investigated to preserve the spatial distribution of the drug compounds within intact tissue samples was laser desorption coupled to chemical ionization (LD/Cl). Studies demonstrated that the spatial distribution of drug compounds is maintained during LD/Cl and that drug compounds could be detected at trace levels by LD/Cl in intact tissue masses.; The second method investigated was the electrospraying of the MALDI matrix solution onto the surface of the tissue. An apparatus was constructed to perform the electrospraying of the MALDI matrix solution. Experiments showed that by electrospraying the matrix solution, the MALDI matrix solvent evaporated quickly enough to prevent significant migration of pharmaceutical compounds (within the resolution of the instrument---approximately 150 mum).; Samples of tissue with a distribution of a pharmaceutical compound were prepared and the ability of the instrument to map the location of a compound within intact tissue masses was demonstrated. The drug spiperone, at a level of 25 ng/mg of tissue, was mapped with a lateral resolution of 150 gm in a tissue sample by both LD/Cl and the electrospray method. An experimental drug in animal tissue, at a level of 59 ng/mg, was mapped with a resolution of 150 mum in an intact tissue sample by both methods. |
