Hr. Padley et al., QUANTIFICATION OF BIOMOLECULES BY EXTERNAL ELECTROSPRAY-IONIZATION FOURIER-TRANSFORM MASS-SPECTROMETRY, Analytical chemistry, 69(15), 1997, pp. 2914-2918
Fourier transform mass spectrometry (FTMS) is well-known for its capab
ilities in structural characterization of molecules, Recent developmen
ts in radio frequency excitation, linearized trapping, and accumulatio
n of ions generated from external sources have improved the potential
of FTMS for quantitative analysis, Here, a commercial external electro
spray ionization ETMS, employing a linearized ion trap (the Infinity C
ell) and an ion accumulation procedure in which ions are deflected off
-axis and injected into the trap, is evaluated as an analytical method
for quantifying amino acids, peptides, and proteins. Linear response
over similar to 2-3 orders of magnitude is observed for singly-charged
ions with low coefficients of variation (generally <10%), and the cal
ibration curves generated can be used to quantify structurally similar
analytes with <4% relative error, as shown here for quantification of
leucine enkephalin from curves generated by methionine enkephalin, Si
milar precision is obtained for multiply-charged lysozyme, but over on
ly 1.5 orders of magnitude, Some mit discrimination is observed as a f
unction of trap accumulation potential for a two-component cytochrome
c/lysozyme mixture, The results are promising because they suggest tha
t quantification using liquid chromatography coupled to electrospray F
TMS is possible.