A new sample deposition device for off-line SFC-MALDI combination of supercritical fluid chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was assembled. This device was successfully applied to the detailed characterization of synthetic silicone oils. SFC was used to separate samples of silicone oils on micropacked capillary columns and to determine their molecular mass distribution. The separated fractions for the identification studies were obtained from SFC runs at defined time intervals. Using the constructed deposition device, these fractions were sprayed directly from the restrictor on the target probe covered with a proper matrix. MALDI-TOF MS was used for the identification of individual oligomers in the separated fractions and also in the unfractionated sample. The determined molecular mass distributions based on supercritical fluid chromatography with flame ionization detector, MALDI-TOF MS, and combined SFC-MALDI measurements were compared and the results were in a good agreement. The sample deposition device is based on a common plotter unit, complemented by a microcontroller PIC16C84. The unit is connected by an RS-232 interface to a PC with the main control software running under MS Windows. The new sample deposition device made the off-line combination SFC-MALDI simpler, faster, and more sensitive.

Institute of Analytical Chemistry Academy of Sciences of the Czech Republic Brno

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