[Historical study on spectrometry innovation for the structural analysis of organic compounds (part 2)]

Third spectrometry innovation (1970s) Pulse Fourier transformation NMR spectrometry (PFT-NMR) (at 100 MHz) was presented. Therefore the H-1 and C-13 NMR spectra of organic compounds can be measured with a small amount of the samples. Proton-proton spin decoupling methods in NMR spectrometry are helpful for the structural analysis of organic compounds. The Stereostructures of organic compounds were elucidated by new techniques, the nuclear Overhauser effect (NOE), and the application of NMR chift reagents. Double-focus MS spectrometers were introduced in the 1970s. The MS instruments related to computer-aided data processor systems were also introduced. The molecular weight and the formula were directly obtained by the use of the on-line MS system. Several ionizing techniques of mass spectrometry were also introduced, such as electron ionization (EI), chemical ionization (CI), and in-Beam methods. Fourth spectrometry innovation (1980s). In the 1980s, NMR spectrometers had super conductivity magnets (200-500 MHz) introduced. Some new NMR spectral techniques, such as 2D (H-H, H,-C) and 3D (H-H,H,C-H) NMR spectral methods, were introduced. The structures of complex organic compounds could then be elucidated by the above methods. Gaschromatography (GC) and liquid chromatography (LC) were connected to MS spectrometers. Several instruments were introduced, including GC-MS and LC-MS, which were applied to organic medicines and their metabolites. Many new ionizing techniques (such as FD, API, PD, SIMS, TSP, FAB, and ESP) were then applied. Bio-organic mass-spectrometry (BMS) was developed in a new research field. The structural determination method by the X-ray single-crystal analysis method is also described.