Improvement of m/z accuracy for linear MALDI‐TOF MS

RATIONALE Linear MALDI-TOF MS is a widely used in analytical and biomedical applications. The use of delayed extraction increases the resolution, but the roughness of the matrix crystals and the target plate misalignment in order of a few mum cause substantial spread in the ion time-of-flight values and decrease mass accuracy. METHODS: The method of mass spectra correction based on the correlation of matrix fragments peaks in MALDI mass spectra was used. The experiments were performed with the MALDI-TOF instrument CMI-1600 built by Guangzhou Hexin Instrument Co., Ltd. SIMION 8.1 and MATLAB were used for ion motion simulations. Data analysis was done using the home built custom developed software and MATLAB. RESULTS: It was shown that the drift of peak position in the MALDI-TOF MS mass spectra depends linearly on the time-of-flight in a wide mass range. While using the linear correction of the time-of-flight scale, an increase in m/z accuracy of more than 10 times was achieved. The mass accuracy is limited by the resolution of the fast ADC used. CONSLUSION It is expected that the proposed method will significantly increase the dynamic range, since it becomes possible to sum up corrected individual mass spectra without significant loss of resolution. The time scale adjusting can be used both for the linear time-of-flight instruments and for the reflector systems of various configurations.