title: A robust automatic phase correction method for signal dense spectra.
abstract: A robust automatic phase correction method for Nuclear Magnetic Resonance (NMR) spectra is presented. In this work, a new strategy combining 'coarse tuning' with 'fine tuning' is introduced to correct various spectra accurately. In the 'coarse tuning' procedure, a new robust baseline recognition method is proposed for determining the positions of the tail ends of the peaks, and then the preliminary phased spectra are obtained by minimizing the objective function based on the height difference of these tail ends. After the 'coarse tuning', the peaks in the preliminary corrected spectra can be categorized into three classes: positive, negative, and distorted. Based on the classification result, a new custom negative penalty function used in the step of 'fine tuning' is constructed to avoid the negative peak points in the spectra excluded in the negative peaks and distorted peaks. Finally, the fine phased spectra can be obtained by minimizing the custom negative penalty function. This method is proven to be very robust for it is tolerant to low signal-to-noise ratio, large baseline distortion and independent of the starting search points of phasing parameters. The experimental results on both 1D metabonomics spectra with over-crowded peaks and 2D spectra demonstrate the high efficiency of this automatic method.
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China.
authors.forename: Qingjia
authors.initials: Q
authors.lastname: Bao
authors.forename: Jiwen
authors.initials: J
authors.lastname: Feng
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.forename: Fang
authors.initials: F
authors.lastname: Chen
authors.forename: Zao
authors.initials: Z
authors.lastname: Liu
authors.forename: Bin
authors.initials: B
authors.lastname: Jiang
authors.forename: Chaoyang
authors.initials: C
authors.lastname: Liu
mesh_terms: D000465:Algorithms; D002788:Cholesterol Esters / Q000737:chemistry; D004574:Electromagnetic Fields; D006801:Humans; D008239:Lysine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D055432:Metabolomics / Q000379:methods*; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D012984:Software; D058067:Wavelet Analysis
chemical_list: D002788:Cholesterol Esters; D008239:Lysine; C060123:cholesterol acetate
keywords: Automatic phase correction; Coarse tuning; Fine tuning; Metabonomics study; NMR; Negative penalty