Help on: Peak Purity Assessment

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Question:
“While performing peak purity assessment (or doing force degradation studies), if any unknown impurity with similar spectra co-elutes with the peak of interest, then software will show that the peak is pure. But is there any trick or any method to get correct results...?”

Answer:
“Peak purity assessment software can only interpret the information that is collected from the UV diode array. Unfortunately organic impurities often produce very similar spectra to analytes of interest because the difference in the molecules does not relate to the functional groups which are producing the UV response. Although software may report that a peak is pure you can never reach this conclusion when investigating peak purity by this method. All you can conclude is that you have not found any impurities co-eluting with the peak of interest. To differentiate between analytes of interest and their impurities where the structure is very similar is not within the capability of this UV technique so there are no tricks or methods to make it possible. Mass spectrometry may also be used for peak purity assessment but it also suffers from some limitations.”