A new thin gold film-assisted (TGFA) laser desorption/ionization (LDI)
technique has been combined with Fourier transform ion cyclotron reso
nance (FT-ICR) high-resolution mass analysis. A thermally labile organ
ic sample is coated onto a thin gold film deposited on a glass plate a
nd desorbed and ionized by Nd:YAG laser irradiation. The wavelength fo
r maximum light absorption may be tuned by varying the thickness of th
e metal film; e.g., a 10-nm-thick gold film absorbs maximally near the
Nd:YAG fundamental wavelength (1064 nm). A key advantage of the metho
d is the stability of the gold film, which facilitates deposition of s
amples from any of a variety of solvent systems. Coupled with recently
introduced quadrupolar excitation and collisional cooling for ion axi
alization, TGFA-LDI FT-ICR mass spectra provide high sensitivity (e.g.
, 100-fmol single-shot detection limit and mass resolving power, m/DEL
TAm almost-equal-to 113 000, for (M + K)+ ions from gramicidin S at m/
z 1180).