Preparation of ionic clusters of amino acids in the copper sulfate presence under the field ionization of their water-acetonitrile solutions conditions

Abstract

A systematic study of ionization of amino acids by the method of electrospray ionization (ESI-MS) in the name of salt was carried out. The influence of the composition of the mobile phase on the quality and composition of the mass spectra was studied. The composition of the acetonitrile-water mixture varied from 5 to 95% water. It is established that the change in the composition of the mobile phase does not significantly affect the composition of the mass spectrum. The best ratio for work was 70% water and 30% acetonitrile. The quality of the mass spectrum significantly depends on the purity of the acetonitrile used, which in large quantities increases the chemical noise and makes identification difficult. It is shown that for aromatic amino acids (tyrosine, tryptophan), the processes of amino acid molecule fragmentation, such as decarboxylation, deamination, dehydration are most characteristic. The processes of cluster formation in freedom are sup

pressed. Using proline as an example, it was shown that cluster formation occurs most often in simple non-aromatic amino acids.

It is seen that cluster formation in such cases proceeds in three different directions: the formation of molecular associates of amino acids with a charge carrying a proton, the formation of molecular associates of amino acids with a charge-carrying copper atom and the formation of polymolecular coordinated structures coordinated by two copper ions. It is shown that the results obtained in the study can be used for a more sen-sitive and informative search for amino acids in solutions of complex mixtures with chromatographic separa-tion and when using direct input.