Study Of JCAMP-DX Access And Automatic Phase Correction In NMR Data Processing

As an advanced structure analysis tool, nuclear magnetic resonance (NMR) plays more and more important roles in fields of chemistry, biology and medicine, etc. In the past decades, great progress has been achieved in NMR hardware and software. However, many aspects are still needed to improve. In this thesis, two problems in NMR data processing are discussed. One is the access of NMR data, the other is the automatic phase correction of NMR spectra.Since different data storage formats are adopted in NMR spectrometers from different manufacturers, and even a variety of formats are used in the NMR spectrometers from a same manufacturer. Specialized NMR softwares are required for the exchange of NMR data in different formats. This hinders the development of NMR. JCAMP-DX was designed to solve this kind of problem. JCAMP-DX is an international standard for exchanging spectral data in different formats. JCAMP-DX5.00 has been successfully applied in NMR. However, with the development of NMR technique. JCAMP-DX5.00 can no longer meet the needs. Therefore, it is necessary to define new standard. Based on the JCAMP-DX6.00 protocol and some IUPAC recommendations for NMR, we discussed some problems existing in JCAMP-DX6.00 protocol, such as the description of pulse sequence, the storage of multidimensional NMR data. A software scheme of JCAMP-DX6.00 was proposed and implemented using Java JDK1.6 on Windows platform.Because of the phase misadjustment, the lineshapes of an NMR spectrum from the fast Fourier transform of free induction decay (FID) signal are generally not pure absorptive. Phase correction is the process that corrects the spectral phase via computing the phase misadjustment. It is a necessary step in NMR data processing. In this paper, several common automatic phase correction methods such as dispersion-absorption lineshape analysis (DISPA), extended dispersion absorption approach (eDISPA), phase correction based on minimized entropy, were discussed. Two novel phase correction methods were proposed and implemented based on new data point selection scheme and new objective function for correction evaluation. One was directional speedup automatic phase correction method. This method optimizes the objective function by using the Powell directional speedup approach and corrects the phase misadjustment of NMR spectra automatically. The other one was automatic pivot phase correction. The phase distortion of NMR spectra was computed by using the Brent method without derivative. The phase of NMR spectra can be corrected successfully by the directional speedup automatic phase correction method and the pivot automatic phase correction method.