Peak splitting

Peak splitting

What you Expect                                   What you Got

Disease	Medicine
Contamination of column or guard	Remove guard column. If the problem is solved replace it. If not go next
Plugged column	Use adequate recovery procedure. If the problem persists go next
Plugged inlet frit	Replace. If the problem persists discard column

Retention times are not constant

Retention times are not constant

What you Expect                                 What you Got                                         

Disease	Medicine
Leak	Check for loose fittings Check pump for leaks, salts and noise Check seals
Change in mobile phase composition	Check. Make new
Air trapped in pump	Check flow Prime pump. Check and change seals. Be sure the mobile phase is degasse
Temperature fluctuations	Stabilise column temperature. Use column oven
Overloading	Dilute sample
Sample dissolved in a solvent that is incompatible with the mobile phase	Dissolve sample in the mobile phase whenever possible. Adjust

Reference: 

Prof. Dr. H.J. Chaves das Neves

Universidade Nova de Lisboa 

No Pressure or Pressure Lower than anticipated

No Pressure or Pressure Lower than anticipated

                     

What you Expect.                                 What you got

Disease	Medicine
Leak	Check for loose fittings Check pump for leaks, salts and noise Check seals
Mobile phase interrupted	Check reservoirs. Check position of the inlet tubing Check loop for obstruction or air Check degasing of mobile phase Check compatibility of the mobile phase components
Air trapped in pump	Check flow disconnect column and prime pump Flush system with 100% methanol or iso propanol Contact servicing if necessary
Worn pump seals	Replace seals Check pistons and replace if necessary

Higher Pressure than anticipated

  What you Expect.                                 What you got

Disease	Medicine
Pump, injector, tubing	Disconnect column, run pump at 25 mL/min: Is the pressure minimal? Go to next step If pressure still high check systematically from detector to pump for obstruction
Obstructed column or guard	If guard column is obstructed, replace it If the analytical column is obstructed reverse it and flush disconnected from the detector. Use adequate restoration procedures Change inlet frit Replace de column

            

reference: 

Prof. Dr. H.J. Chaves das Neves

Universidade Nova de Lisboa 

No Peaks or view Small Peaks in HPLC

No Peaks or view Small Peaks in HPLC

What You Expect                                    What You got

Disease	Medicine
Detector off	Check Detector
Broken connections to recorder	Check connections
No flow	Check flow
No sample/Wrong sample	Check sample. Be sure it is not deteriorated. Check for bubbles in the vials
Wrong settings on recorder or detector	Check attenuation. Check gain

No Flow

Disease	Medicine
Pump off	Start pump
Flow interrupted	Check reservoirs. Check position of the inlet tubing Check loop for obstruction or air Check degasing of mobile phase Check compatibility of the mobile phase components
Leak	Check fittings Check pump for leaks and precipitates Check pump seals
Air trapped in the system	Disconnect column and prime pump Flush system with 100% methanol or isopropanol Contact servicing if necessary

Reference:
Prof. Dr. H.J. Chaves das Neves
Universidade Nova de Lisboa 

Operating Procedure of BRUKER AUTOFLEX MALDI-TOF Mass Spectrometer

Operating Procedure of BRUKER AUTOFLEX MALDI-TOF Mass Spectrometer

 

    1.  Press Ctrl-Alt-Del and enter your name and password to log into the computer. Allow
        time (30-60 s) for background processes to start.

    2.  Exit the WinTV application by clicking a cross in the right top corner of the window.

    3.  Double click on the FLEX Control icon on the desktop to launch the instrument control
        software. A dialog will appear. Click OK. An information window will open as the
        computer establishes communication with the mass spectrometer. The FLEX Control
        main window will then open.

    4.  Select the method to use by clicking on the appropriate method file and OK. The files are
        named according to detection mode, polarity and mass range. For example, the method
        “LP_0-2kDa” is linear mode method in which negative ions are detected in the mass
        range of 0-2000 Dalton. You can change the parameters to suit you particular needs.
        These files cannot be changed; you will need to save a modified method file under a
        different name in your directory.
        L=linear mode, R=reflector mode, P=Positive ions, N=negative ions


    5.  Place your target plate with prepared samples on the frame. Make sure the plate fits
        snugly, hits the three contact points of the frame and there are no gaps between the frame
        and the plate. The frame is located in the top right desk drawer and must be returned
        when finished for the next user.

    6.  Push the green Eject/Load button on the side of mass spectrometer. The door will open
        and the tray for the target will come out.
        CAUTION: The tray and loading mechanism are very fragile. Do not bump or apply any
        force on the tray. Always keep the area around the sample tray clear.

    7.  Place the frame with attached target on the tray so the beveled edges are pointing toward
        the mass spectrometer. Press the green Eject/Load button again to load the tray into the
        mass spectrometer. It will take several minutes for the target to load and the system to
        reach proper vacuum.

    8.  Click on the Sample Carrier tab and select a spot with your calibration sample. Click on
        a crystal in the camera screen to point the laser beam on it.

    9.  Adjust the number of shots (default=30) by changing the value in a small window below
        the camera screen. Use a slide bar to the right of the camera screen to adjust the laser
        power. A good starting point is 30%.

    10. Click the Start button to fire the laser. There may be a slight delay as the laser warms up.
        The spectrum will be displayed in the main screen. The laser power can be adjusted while
        a spectrum is being acquired if needed.
  11. Examine the spectrum for quality. Is the calibrant peak(s) present? Is signal intensity too
        high or too weak? If so, adjustments to the laser power may be needed, or a different
        crystal/sample spot selected, and a new spectrum acquired.

    12. Click on Calibration tab. Select the calibrant from the pull-down menus. Users can
        manually enter calibrant(s) by entering appropriate values into the boxes bellow the
        calibrant list. A red line will appear on the spectrum at the expected m/z for the calibrant.

    13. Select the calibrant on the spectrum by left-clicking to the left of the calibrant peak. The
        system will select the peak. The red line will turn green and a small white arrow will
        indicate the selected peak. Click the Accept button to calibrate the spectrum.

    14. Select another calibrant and repeat the calibration procedure for other calibrant peaks as
        necessary. Click the Accept button to calibrate the spectrum. The instrument is now
        calibrated. This calibration will apply to all spectra until another method file is opened or
        the target is removed or the FLEXControl program is closed.

    15. Click on the Sample Carrier tab and select a spot containing sample to be analyzed.

    16. Click the Start button to start acquiring data. Adjust the laser power and spot location to
        achieve the best possible quality.

    17. Choose Save Buffers As item in the File menu. Change the directory to
        D:\your_directory, enter the dataset name and click OK.

    18. A region of interest in the spectrum  can be enlarged using the mouse. Peaks are labeled
        by clicking the PeakLabel button on the main toolbar. The sensitivity of the peak picking
        machinery can be adjusted by choosing Tools and then On-line processing.

    19. The spectrum can be printed out of FLEXControl program by clicking the printer button
        on the toolbar.

    20. When finished, press the green Eject/Load button on side of the mass spectrometer. The
        door will open and the tray with the target will be ejected. Remove the target. Press the
        Eject/Load button again to retract the tray and close the door.

    21. Exit the FLEXControl program. Log out from the computer by going Start/Shutdown and
        choosing “Log Off” from the shutdown menu.