We have been working trying to analyze N-nitroso Ciprofloxacin. This impurity has a very poor solubility and the only way we have found to perform testing is dissolving it with NaOH 1N. But we face a lot of reproducibility problems and loss of sensibility in HPLC/MS (triple quad). Have anyone found a more friendly solving media?
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Try with Acetonitrile: Methanol in ratio of 100:900 v/v
@Rubenlalu, the addition of NaOH increases solubility; however, when dealing with analytes like N-nitroso ciprofloxacin, it hinders the ionization process and, consequently, sensitivity. In other words, do not use NaOH.
To address this issue, I recommend initially dissolving the N-nitroso ciprofloxacin in water. Ultrasonication (20 to 30 min., approx.) can aid in achieving a homogeneous solution. Subsequently, the addition of an organic solvent (methanol or acetonitrile), may be considered based on the requirements of the mobile phase and the MS ionization process. My suggestion: 50:50 (aqueous:organic).
Please provide feedback on the results obtained with this modified procedure for further evaluation and refinement.
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Yeah I have experience with this Nitrosamine earlier, please dissolve 5 mg in 200 ml acetonitrile and need to sonicate until it dissolves (might takes 15 to 20 minutes).
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Thank you all for your willingness to help with the challenge. This is community practices at its best, exactly what we planned this community to be! Thanks
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Thank you all for your willingness to help with the challenge. This is community practices at its best, exactly what we planned this community to be! Thanks
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You can also try to disolve it initiatially in DMF like 20mg in 50mL and afterwards made dilutions with the solvents that you need (water, methanol, whatever…)
Thank you all for the suggestions.
We have tried to dissolve 5.3 mg of N-nitroso ciprofloxacin with water/ACN (50:50) in a 200 mL volumetric flask but some particles remain undissolved.
We have tried to dissolve 5.8 mg of N-nitroso ciprofloxacin with ACN in a 200 mL volumetric flask and although it is difficult to be completely sure with this small amount it seems fully dissolved.
Now we are making trials to evaluate which concentration of Ciprofloxacin HCl would be required to achieve the limit established. The concentration we were using when dissolving with the aid of NaoH was 120 mg/mL. We have achieved 60 mg/mL when using water/ACN (50:50) but the sample is not dissolved at 60 mg/mL with ACN.
We recently had a case of analysing N-Nitroso-Ofloxacin (structural similar) and our approach was the following:
HPLC-MS (gradient)
Mobile phase A: 0.2% formic acid in water
Mobile phase B: 0.2% formic acid in acetonitrile
Solvent mixture: 0.2% Formic acid aqueous solution/Methyl alcohol (80:20)