Ion clustering in electrospray mass spectrometry of brine and other electrolyte solutions

Electrospray ionization is suggested as a complementary technique for the investigation of the solution chemistry of metal salts, which allows us to achieve direct insight into the molecular entities present in solution. While the transfer of the metal ions from solution to the gas phase in the course of the electrospray process is associated with significant changes in concentration, pH, and also composition in the case of mixed solvents, systematic studies of concentration series can provide criteria to assess the extent to which the gas-phase data correlate with the situation in solution. While there does not exist a 1 ∶ 1 correlation between mass spectrometric measurements and solution properties, very useful qualitative molecular insights can be achieved and quantitative analysis can be made once the specific circumstances of the ionization process are taken into account.