| Thin layer chromatography (TLC) plates were imaged onto a SIT vidicon camera to obtain both normal two-dimensional images and spectral images of components by emission and absorption.; The output of the camera is viewed in real time on a television monitor and stored on a hard disk. The instrument is controlled by a PDP 11/04 and analyzed either on the PDP 11/04 or the department VAX 11/780.; Fluorescent fingerprinting of components on thin layer plates is accomplished by imaging the spots on the entrance slit of a monochromator and removing the exit slit, preserving both the emission spectra and the retention profile of the components. The free base octaethyl porphyrin (H(,2)OEP) and tetraphenyl porphyrin (H(,2)TPP) were highly overlapping on the plate, yet both were clearly distinguishable by their emission spectra.; Absorption spectra are obtained by scanning the plate over the wavelength region of interest while simultaneously storing the images. 70 images over 300 nm may be obtained in 8.5 min. each for both the blank and developed plate. A spectrum may be obtained by plotting the absorption values for a selected pixel for a component. This was successful for the spectral analysis of H(,2)TPP, zinc tetraphenyl porphyrin, and palladium etioporphyrin.; The data is in the form a two-dimensional matrix (fluorescence), or a series of two-dimensional matrices (absorption), allowing the use of complex mathematical analysis methods to obtain qualitative and quantitative information of the compounds. This ability reduces the need for complete separation of the components on the plate. Rank analysis and rank annihilation were attempted on the data with moderate success.; In the normal image modes of both fluorescence and absorption, the instrument was found to be reproducible to within a half percent. Due to nonuniform distribution and stray light effects, the linearity is limited to narrow ranges. Sensitivity for fluorescence was 3 pg H(,2)TPP and 5 ng ZnTPP for absorbance, making it competitive with commercial instruments. |
