Application of quadrupole ion trap for the accurate mass determination of submicron size charged particles

Abstract

An optical method is developed for the precise mass determination of submicron size charged particles. The measurement is carried out in a hyperbolic quadrupole ion trap electrode system in vacuum by adjusting particle trajectory star shape patterns. This method does not involve gravity so this may be suitable to use in space applications in weightlessness. Due to the imperfect electrode alignment of the ion trap the mass/charge ratio can now be calculated by means of the corresponding electrical parameters with a relative accuracy of 103. Since the measured parameter is frequency the relative accuracy of the mass measurement could later be increased to 106. Combined with stepwise electron loss events induced by UV radiation it is possible to determine the mass of a single particle in the 109–1012 amu range with similar precision. These findings would seem to indicate the feasibility of a novel optical method for high precision mass determination of a single particle in the submicron diameter range.

Optical detection methods for mass spectrometry of macroions

“…On a longer time scale, the 10 À6 range is accessible (Schlemmer et al, 2001). Similar conclusion was also reached by Hars & Tass (1995), who proposed to use a star branch counting method for high precision m/z measurements.…”

Calibration of an audio-frequency ion trap mass spectrometer

“…Since then, the device has been frequently utilized as an electrodynamic balance for single aerosol analysis [12]. A mass accuracy of the order of 10 −3 or better for particles weighing 10 −16 kg can readily be attained [13][14][15][16][17]. The accuracy is comparable to that (0.1%) provided by the commercial RF QITMS [5], suggesting a possibility of utilizing this AF ion trap as a mass spectrometer.…”

“…The value is about four times greater than that of Hars and Tass [16], who ignored the large size difference between the submicron-sized particle and the buffer gas molecules in their analysis.…”

Measuring Masses of Single Bacterial Whole Cells with a Quadrupole Ion Trap

“…This work demonstrates that it is possible to measure the absolute masses of single Escherichia coli macroions within the QIT using MALDI as the ion source 14 and ELS for particle detection. Partial success of the measurement has been previously reported for bacillus spore clusters, 15 and complete measurements have been accomplished for SiO 2 particles in the same mass range. 16 The E. coli K-12 whole cells were obtained from Sigma and used without further purification.…”