Experimental design for optimizing MALDI-TOF-MS analysis of palladium complexes

This paper presents optimization of matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometer (MS) instrumental parameters for the analysis of chloro(2,2 , 2 -terpyridine) palladium(II) chloride dihydrate complex applying design of experiments methodology (DoE). This complex is of interest for potential use in the cancer therapy. DoE methodology was proved to succeed in optimization of many complex analytical problems. However, it has been poorly used for MALDI-TOF-MS optimization up to now. The theoretical mathematical relationships which explain the influence of important experimental factors (laser energy, grid voltage and number of laser shots) on the selected responses (signal to noise - S/N ratio and the resolution - R of the leading peak) is established. The optimal instrumental settings providing maximal S/N and R are identified and experimentally verified.