We have qTOF 6546. Is there abybody who tried to analised nitrosoamines on qTOF. According to the Agilent application "Determination of Nitrosoamines Using the High Resolution Agilent 6546 LC/Q_TOF"  (link below) it is possible to reach the sensitivity up to
0,1 ppb. I have tried to do this but for e.g NDMA  the sensitivity about 100 ppb is maximum i could reach.For other nitrosamines it is hard to get 10 ppb. 

I did some online reaserch and  found the article: "Nitrosamine Impurities Testing by LC-MS Methods from the United States Pharmacopeia General Chapter <1469>" (link below) where I found that information:

"Our laboratory experienced sensitivity issues with an ultra-modern HRMS detector (Agilent 6546 Q-TOF), and to verify the results different HPLC columns, solvents, and reagents were tested. Chromatographic system suitability criteria could be met, but it was not possible to meet system suitability for overall identification and sensitivity.


Do you have any experience with nitrosoamines on qTOF and you could give me some hints about e.g MS tuning? Do tou know how can I contatct with the authors of that aplication to ask for more information?

Thank you for nay help,

Best regards, 

Piotr Kujawski

  • Thank you for your answer it was really helpful.

    I used water and methanol from Fisher (Gold ones).

    I have other questions.

    You wrote that you used High resolution mode while doing tuning and High sensitivity mode while doing calibration.

    In qTOF  (help F1) it its written "For the 6546, never use the High Sensitivity slicer position." 

    That information also appeared on Agilents webminar "Eliminate the ferar of using LC QTOF" "provided by David Weil.

    Do you have any idea why we should not use it?

    Have you observed some fluctuations if you use it? 

    During that webminar the following procedure of tuning was presented:

    1. System tune 3200 m/z (High resolution) AJS

    2. Swich to 1700 m/z

    3. Tansmision Tune for TOF e.g (50-250 Fragile ions) High resolution

    4. Note the Quad AMU Value form the report

    5. Tansmision Tune for Quad (only avaliable option 50-1700)

    6. Check if Quad AMU value has been changed - if  it has been changed , manually changed to value form Transmision Tune  for TOF report 

    7. Save tune

    8. Swich to APCI

    9. Start TOF Mass Calibration.

    Have you ever  used procedure described above ?

    You wrote that I can do TOF Transmission TUNE (1700 m/z) or   TOF Transmission Calibration as well ( 250m/z range) - by TOF Transmission Calibration do you mean TOF Mass Calibration?

    Do you use the Agilent HPH C18 2.1 x 100mm x 1.9 um (p/n 695675-702) for nitrosoamines application?

     If you remember it - Could you write me the  approximate value of abundance one ion eg 121 thta you observe for ACPI calibrat after the transmision TOF 50-250 (I would like to compare it with my value  after i do the transmision tune in the range 50-250)

    In ma case for transmision tune 1700m/z   the 922 ion in APCI calibrant  has  app. 2,000,000  - I know that value is ion source cleanliness highly dependent.

    Thanku you for your help,

    Best Regards 

    Piotr Kujawski

  • Hi Piotr,

    I observed that using "High Sensitivity" mode during Mass Calibration helps in achieving better abundance and that is important in quantitaive workflow. like we need in nitrosamine. By TOF transmission Calibration I mean " TOF Mass Calibration".

    Agilent HPH C18 2.1 x 100mm x 1.9 um (p/n 695675-702) column was used for demonstrating nitrosamine standards although when some drug substance/drug product is involved I recommend using longer length column like the one I used in Ranitidine app note (5994-1626EN).

    I don't remember exactly the m/z 121 abundance, but I was always comfortable when it is > 900K.

    I would always make sure that Ion source is clean, Mobile phase is freshly prepared, Nitrogen quality is at best by using fresh RMSN-4 and Activated Carbon Tower, LCMS grade water, methanol and formic acid, ensure that 121 abundance is > 900K and we are good to go.

    Keep in mind that my 1000ppm standard stock is in refrigerator in amber color test tubes and I would prepare the calibration standards freshly before starting the batch.


    Chander Mani

  • Hi Chander,

    Thank you for your help I will try to achieve abundance of 121 m/z > 900 K, and then face nitrosoamines once again.  

    Regards, Marry Christamas and happy 2024 :)

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