| 摘要 |
Time-of-flight mass spectrometry techniques are simultaneously combined with path-bending spatial dispersion in magnetic- or electric-sector mass spectrometers to improve the mass resolution or, with an ion fragmentation region, to rapidly obtain the same multidimensional mass spectral data previously obtained by tandem mass spectrometry. The instrumentation generates data defining relationships between parent ions and daughter ions produced by fragmentation, metastable or induced, data to differentiate stable from metastable ion, and data to improve mass resolution. The subject time-resolved mass spectrometers are combined with chromatography apparatus and serve to obtain multidimensional MS/MS-type data during the relatively short duration of a single chromatographic peak. In exemplary apparatus, ions produced by sample ionization are accelerated and then fragmented to produce daughter ions. The daughter ions, together with any unfragmented (stable parent) ions, are mass analyzed in a magnetic or electric sector including a deflection field. A suitable detector system determines two parameters in addition to ion current for unfragmented ions and daughter ions: (1) deflection field strength required to produce a particular angular or spatial dispersion as a result of ion path bending, and (2) ion time-of-flight. Time-of-flight of any detected ion is inversely proportional to its velocity. Parent/daughter ion relationships are indicated by ions of different mass but equal velocities. Mass determinations for all ions, daughters and parents, are made from the measurements of flight time and momentum (independent of kinetic energy) or flight time and kinetic energy (independent of momentum). In time-resolved multi-sector instruments, grandparent/ granddaughter relationships can be determined. While the subject time-resolved mass spectrometry technique permits the rapid collection of complete MS/MS-type data using a transient recording detection system, various types of specialized scans are readily achieved using a simpler time slice detection system, such as parent ion scans, daughter ion scans, and neutral loss scans, stable ion scans and "total daughter" ion scans. |
