Electrospray ionization tandem mass spectrometry of mixtures: Deconvolution by parent‐ion scans

Electrospray ionization (ESI) mass spectra equine myoglobin and a mixture of bovine insulin, melittin and bovine growth hormone releasing factor (GHRF) were obtained on a tandem quadrupole mass spectrometer. The parent‐ion mass spectrum of m/z 171 for equine myoglobin contained all of the multiply charged molecular ions present in the conventional ESI mass spectrum. Similar results were obtained with the parent‐ion scans of selected ions for the insulin, melittin and GHRF mixture. This technique was able to differentiate between the multiply charged molecular ions produced from each of the three componenets in the mixture.