Role of the sample supports in the LDI mass spectrometric studies of silver clusters

One of the basic parameters of the LDI TOF MS (laser desorption ionization time of flight mass spectrometry) method is its sensitivity. It depends on many factors such as the proper sample preparation. Within the sample preparation various steps are taken to achieve the greatest sensitivity of the LDI method. One of them is the application of so-called sample supports on the stainless steel sample holder surface, on which the sample is loaded. The aim of this study was to examine the influence of sample supports selected by the author on the outcome of the experiment. In this respect, silver benzoate was studied. The apparatus used was a linear time of flight mass spectrometer and the method of ionization was LD (laser desorption). Mass spectra obtained for the sample support materials (glass, mica, floppy disc foil, copper, aluminium foil) were compared to those obtained with the stainless steel. All of these were recorded under identical experimental conditions. Mass spectra were characterized in terms of mass peaks registered. It was noted that the processes of silver clustering for each sample support and the stainless steel ran with different intensity. The largest registered ion cluster Agn was the biggest for floppy disc foil (n = 92), the smallest for copper (n = 59). The FWHM parameter in the case of Ag+ and Ag− ion mass peaks was the smallest for stainless steel. Metallic sample supports (copper, aluminum foil) appeared to be advantageous for the studies of negative ion mass spectra - negative ion current corresponding to particular ion mass peaks was then more intensive than positive ion current. The mica was the exception.