Figure 2: Specificity-A: Mass Spectrogram of Carvedilol Drug Substance (Control sample). Specificity-B: Mass Spectrogram of Carvedilol Drug Substance spiked with all related Compounds without 4 -Oxiranylmethoxy-9HCarbazole at specification level. Specificity-C: Mass Spectrogram of Carvedilol Drug Substance spiked with all related. Compounds with 4 -Oxiranylmethoxy- 9H-Carbazole at specification level.