Chromatography Forum

Hello,

I'm approaching an untargeted UHPLC-HRMS analysis using ESI source in positive ionization. I am tracing the area intensity of about 20 molecules, of which we do not yet have sufficient structural information and which may be very different from each other. I am having difficulty choosing the internal standard to use in order to normalize the areas. In theory, would any molecule capable of responding adequately in the positive be suitable for normalization activity?

Thank you so much,
Francesco

Until you know more about your analytes, choose internal standards that work predictably in your analysis. As an example, in semi-volatile GCMS analysis PAH internal standards are used to quantitate non-aromatic molecules and even estimate concentrations of tentatively identified compounds.