MALDI MASS-SPECTROMETRY OF BIOMOLECULES AND SYNTHETIC-POLYMERS USING ALKALI HEXACYANOFERRATE(II) COMPLEXES AND GLYCEROL AS MATRIX

K-4[Fe(CN)(6)]/glycerol and Na-4[Fe(CN)(6)]/glycerol have been investi gated as liquid matrix systems for UV-MALDI MS applying a N-2 laser. A nalyte molecules were detected as sodium or potassium adduct ions and, in the case of proteins, as well as protonated molecular ions. Mass a ccuracies were comparable to those found with standard solid matrix sy stems with -0.06 to +0.05% deviation in the reflectron mode and with - 0.24 to +0.13% in the linear mode. Useful results could be obtained wi thin a mass range of 15 000 Da for single-charged proteins and 8000 Da for potassium cationized polyethylene glycols. Detection limits were found for hydrophilic compounds in the low picomol range and for lipop hilic compounds as triacylglycerols or peracetylated and partially ben zylated carbohydrates in the low femtomol range. As shown by scanning electron microscopic investigations, the generation of a thin homogeno us matrix layer was essential for a successful mass spectrometric expe riment. A very careful cleaning of the target surface with glacial aci d prior to matrix deposition improved the formation of such a matrix f ilm that maximum sensitivity as well as good reproducibility of the ex periments could be achieved. (C) 1997 Elsevier Science B.V.