US EPA

1049782 

Journal Article 

Salt tolerance of desorption electrospray ionization (DESI) 

Jackson, AU; Talaty, N; Cooks, RG; Van Berkel, GJ 

2007 

1 

Journal of the American Society for Mass Spectrometry
ISSN: 1044-0305
EISSN: 1879-1123 

18 

12 

2218-2225 

English 

17977744 

10.1016/j.jasms.2007.09.018 

WOS:000251589100015 

The salt tolerance of desorption electrospray ionization (DESI) was systematically investigated by examining three different drug mixtures in the presence of 0, 0.2, 2, 5, 10, and 20% NaCl:KCl (1:1) from different surfaces. At physiological salt concentrations, the individual drugs in each mixture were observed in each experiment. Even at salt concentrations significantly above physiological levels, particular surfaces were effective in providing spectra that allowed the ready identification of the compounds of interest in low nanogram amounts. Salt adducts, which are observed even in the absence of added salt, could be eliminated by adding 0.1% 7 M ammonium acetate to the standard methanol:water (1:1) spray solvent. Comparison of the salt tolerance of DESI with that of electrospray ionization (ESI) demonstrated better signal/noise characteristics for DESI. The already high salt tolerance of DESI can be optimized further by appropriate choices of surface and spray solution.