For research use only. Not for use in diagnostic procedures.
After running a manual tune method to calibrate a mass spectrometer using one of the tuning methods located in the API Instrument folder, the results showed that the masses of the PPG ions were present and in the correct location along the m/z axis. However, when the end user inspected the data, the peaks did not have the correct appearance when compared to previous calibration data files that were generated by an engineer during the last preventative maintenance (PM) visit due to a high level of noise in the data.
This issue with the data set's appearance was due to an inadvertent parameter change made to the PPG tune and calibration method that was used. These tuning methods stored in the API Instrument project folder in the Analyst Data folder are prepared by the engineer during the instrument installation or during a PM visit and are used for tuning, calibration and/or diagnostic purposes. Because these methods are specific for each instrument, they should not be adjusted in any way except by properly trained personnel.
In this particular case, the declustering potential (DP) was changed to a non-optimal value, which caused chemical noise to become the predominant peak in the data file. Once the original DP value was restored in the method (can be instrument specific), the PPG spectrum regained its original appearance, with peaks showing in the correct locations and intensity without high levels of noise.