COMMENT ON THE CYLINDRICAL CAPACITOR ELECTROSPRAY INTERFACE

Wang and Hackett have recently proposed (Anal. Chem. 1998, 70, 205-212 ) a new electrospray interface described as a ''concentric cylindrical capacitor''. Excellent spectra were obtained, especially in the negat ive ion mode, with lipid A, a 15-mer oligonucleotide, and a series of proteins. We find that similar results can be obtained merely by ensur ing a direct electrical contact between the analyte inside a fused-sil ica capillary and the high-voltage supply. No capacitor effect need be invoked.