A new algorithm is suggested for estn. of peak positions in FTMS spectra. Theor. and exptl. the new technique yields superior results compared to the currently applied techniques, when the noise level is high and/or the peaks are located close to each other. Cases are presented where the deviation from the true mass could be mistaken for space charge effect, while the shift is in fact solely due to the shortcomings of the current techniques and can be cor. by applying the shifted-basis technique. In 2 out of 3 cases, this technique gave more accurate (>5 times) result compared to the conventional anal. In the 3rd case, where the signal was high compared to the noise, the results were comparable. The new technique can be used to achieve better mass accuracy for noisy and not well resolved spectra, and to further study the features of the space charge effect. [on SciFinder (R)]