The combination of a magnetic sector and a TOF analyser has been shown to readily meet the requirements for structural determination studies by MS/MS [1]. The magnetic sector as MS-1 provides high transmission with unit mass resolution of precursor ions from both pulsed and continuous ion sources. The orthogonal TOF [2] as MS-2 enables fast acquisition of full product ion spectra with high sensitivity and reliable mass accuracy. A gas collision cell allows collisions at up to 800eV, for which the centre of mass collision energy may be adjusted from less than 5eV to over 50 eV. This enables acquisition of both low and high energy CID product ion spectra.
In addition, this hybrid-TOF instrument may be fitted with a "magnet by-pass" allowing the whole of the ion beam, without mass analysis, to be transported to the TOF analyser. This allows the same high sensitivity, fast acquisition characteristics of the TOF analyser to be used for MS as well as MS/MS. In this configuration the TOF analyser is capable of producing MS and MS/MS spectra within chromatography time scales, fast switchover between MS and MS/MS operation being achieved, quickly and simply, by turning the magnet by-pass on and off.
This paper describes a combined magnetic sector TOF instrument fitted with a magnet by-pass addition. The design includes provision for gas collision induced decomposition over a wide range of "centre of mass" collision energies and orthogonal acceleration of the product ions into the TOF analyser.
MS/MS data from singly and multiply charged protonated ions of a number of well documented peptides, produced under low and high energy CID conditions, using LSIMS, ESI, and MALDI ion sources will be presented. These spectra will be compared to CID spectra from four sector instruments, triple quadrupoles, and to post source decay (PSD) on MALDI TOF systems. In addition, the performance of the system, when used in conjunction with the "magnet by-pass" for MS acquisition, will be illustrated with the electrospray mass spectra of lysozyme.