PAHs analysis by UPLC- tubing easily got clogged

<p>Hi everyone,</p><p>I have a problem when switching the method from Waters HPLC system to UPLC system for PAH analysis. When analysing the sample (dissolved in 100% acetonitrile and filtered thru 0.2um filter) using the UPLC system (with initial gradient of 50/50 ACN/water), the tubing is clogged easily, probably because of the precipitation of some matrices in the sample (in ACN) when mixed with the mobile phase (50% ACN/water). However, I couldn't dissolve my sample in 50/50 ACN/Water at the start because some PAHs may not dissolve well in this solvent. Is there any solution for this? Please advice.</p><p></p><p>Uberto</p>

Comments

  • >> However, I  couldn't dissolve my sample in 50/50 ACN/Water at the start because some  PAHs may not dissolve well in this solvent. Is there any solution for  this? Please advice.

    Sounds like the PAHs are crashing out in the tubing, and potentially eating the tubing as the deposits grow. If the analytes won't stay in your mobile phase solution on the bench, they probably won't stay in solution on the LC.

    Are you using an H-Class or I-Class system?


    If you have a binary pump: mix a liter of 50/50 IPA-ACN, And place that on your solvent line, then on your aqueous line, use whatever you were using before.

    The mixture should run about 60%-70% Solvent and 30-40% Aqueous. May be worth testing solubility (once at 60-40, and again at 70-30) on the bench first.

    If you have a quaternary pump: Start at 30% IPA / 30% ACN / 40% H2O and make adjustments as necessary from there. Again, testing your mobile phase ratios with sample solubility on the bench is a good idea.

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