4 Replies Latest reply on Apr 25, 2018 5:27 AM by dannymobbs

    Method/ Column Help for Quantifying Dicyandiamide

    gmartinetti01

      Hello,

      I am trying to quantify Dicyandiamide in a fertilizer, but am having trouble with getting everything to elute from the column in a reasonable amount of time. I am using a reverse phase C-18 column (2.7 micron, 4.6x150mm) and ACN/water as solvent. I've tried all kinds of ACN/water ratios and also 100 ACN, but can't seem to get everything to leave the column quick enough. The DCD elutes right away (1-2 minutes) but it seems no matter what I try with this set up I still end up getting peaks eluding 40+ minutes in and have to wash out the column for much too long as a result.

       

      Any recommendations on how to get those peaks at 30, 40 minutes to elute faster? My only other solvent option at the moment is Methanol, but can buy more if needed.

      Otherwise I am thinking I will need to get a new column. I have found a few studies on quantifying DCD online and all seem to use normal phase columns or a couple specifically used HILIC (Hydrophilic Interaction Chromatography) amide columns. Are there any recommendations for what else I could do/ columns I could buy?

        • Re: Method/ Column Help for Quantifying Dicyandiamide
          dannymobbs

          Hello,

          You could try a C8 column since the non-polar hydrophobic material you are trying to wash off the column are likely to elute much faster than with the C18 phase you are using. There is a danger that your target analyte – dicyandiamide - will not retain sufficiently, but you can modify the starting conditions if this is the case.

           

          I would not recommend moving to methanol since water:methanol mixtures ‘typically’ have lower eluting strength than water:acetonitrile mixtures and you will beflushing for even longer....

           

          This compound seems to crop up in HPLC and LCMS methods analysing melamine (where there is a lot of literature and app notes). Some of the methods employ HILIC columns – we have a number of phases including HILIC-Z and HILIC-OH5 in the Poroshell 120 range you are currently using. HILIC requires starting with high acetonitrile composition (low water) and running a gradient to low acetonitrile (high water). The non-polar material will elute first and the dicyandiamide will elute later (apologies if this is stating what you already knew).

          • Re: Method/ Column Help for Quantifying Dicyandiamide
            gmartinetti01

            Unfortunately the only column option we have here right now are C-18 so C8 isnt an option. I think I will go with an HILIC column. Any recommendation on which one for a compound like this? HILIC-Z versus HILIC-OH5?