| 摘要 |
In a quadrupole mass spectrometer, background noise is statistically computed during data acquisition by determining the distribution of the digitized background noise values around an average noise level in the mass spectrometer output signal. The noise distribution maximum and width is computed and used to set a threshold to recognize true ion currents above the noise. The determined noise levels are subtracted from the signal output values separately for each measurement period. An average ion current may be calculated by subtracting the noise level from all measurement values above the threshold, adding the corrected measurement values to give an integrated ion current and dividing the integrated ion current by the integration time. If noise distribution cannot be computed, then the noise distribution from another ion mass or another time period may alternatively be used to correct ion current measurements. The noise distribution may be Gaussian. |
