EFFECTS OF MATRIX VARIATIONS AND THE PRESENCE OF IRON ON MATRIX-ASSISTED LASER DESORPTION IONIZATION MASS-SPECTRA OF DNA/

Matrix-assisted laser desorption/ionization mass spectra of deoxyribon ucleic acid (DNA) homopolymers were recorded using three different mat rices under otherwise identical conditions. The matrices were 3-hydrox ypicolinic acid, 6-aza-2-thiothymine, and a mixture of 2,3,4- and 2,4, 6-trihydroxyacetophenone. Using a time-of-flight mass spectrometer wit h pulsed ion extraction, considerable fragmentation was observed. Pare nt-ion yields and fragment-ion identities were compared in the three c ases. The influence of iran on DNA mass spectra was also investigated and found to he matrix dependent.