A method of mass spectrometry comprising: providing a plurality of different parent ions; and performing at least one cycle comprising: (i) mass analysing said parent ions so as to obtain first mass spectral data; (ii) subjecting said parent ions to ECD and/or ETD to produce fragment and/or product ions; and mass analysing said fragment and/or product ions so as to obtain second mass spectral data; (iii) subjecting said parent ions to ECD and/or ETD, thereby producing intermediate ions, wherein the intermediate ions are non-dissociated parent ions held together by non-covalent interactions and/or are charge-reduced parent ions that have not fragmented after being exposed to the ECD and/or ETD conditions; and subjecting said intermediate ions to a fragmentation technique other than ETD and/or ECD such that said intermediate ions fragment to form fragment ions, wherein said fragmentation technique other than ECD and/or ETD is Collisionally Induced Dissociation fragmentation; and mass analysing these fragment ions so as to obtain third mass spectral data; and (iv) associating parent ions detected in said first mass spectral data with fragment and/or product ions detected in said second and/or third mass spectral data, wherein the method alternates between steps (ii) and (iii) by passing the parent ions through a Collisionally Induced Dissociation fragmentation device that is repeatedly switched between a low collision mode to perform step (ii) and a high collision mode to perform step (iii). providing a plurality of different parent ions; and performing at least one cycle comprising: (i) mass analysing said parent ions so as to obtain first mass spectral data; (ii) subjecting said parent ions to ECD and/or ETD to produce fragment and/or product ions; and mass analysing said fragment and/or product ions so as to obtain second mass spectral data; (iii) subjecting said parent ions to ECD and/or ETD, thereby producing intermediate ions, wherein the intermediate ions are non-dissociated parent ions held together by non-covalent interactions and/or are charge-reduced parent ions that have not fragmented after being exposed to the ECD and/or ETD conditions; and subjecting said intermediate ions to a fragmentation technique other than ETD and/or ECD such that said intermediate ions fragment to form fragment ions, wherein said fragmentation technique other than ECD and/or ETD is Collisionally Induced Dissociation fragmentation; and mass analysing these fragment ions so as to obtain third mass spectral data; and (iv) associating parent ions detected in said first mass spectral data with fragment and/or product ions detected in said second and/or third mass spectral data, (i) mass analysing said parent ions so as to obtain first mass spectral data; (ii) subjecting said parent ions to ECD and/or ETD to produce fragment and/or product ions; and mass analysing said fragment and/or product ions so as to obtain second mass spectral data; (iii) subjecting said parent ions to ECD and/or ETD, thereby producing intermediate ions, wherein the intermediate ions are non-dissociated parent ions held together by non-covalent interactions and/or are charge-reduced parent ions that have not fragmented after being exposed to the ECD and/or ETD conditions; and subjecting said intermediate ions to a fragmentation technique other than ETD and/or ECD such that said intermediate ions fragment to form fragment ions, wherein said fragmentation technique other than ECD and/or ETD is Collisionally Induced Dissociation fragmentation; and mass analysing these fragment ions so as to obtain third mass spectral data; and (iv) associating parent ions detected in said first mass spectral data with fragment and/or product ions detected in said second and/or third mass spectral data, wherein the method alternates between steps (ii) and (iii) by passing the parent ions through a Collisionally Induced Dissociation fragmentation device that is repeatedly switched between a low collision mode to perform step (ii) and a high collision mode to perform step (iii).