title: Application of the stochastic resonance algorithm to the simultaneous quantitative determination of multiple weak peaks of ultra-performance liquid chromatography coupled to time-of-flight mass spectrometry.
abstract: The stochastic resonance algorithm (SRA) has been developed as a potential tool for amplifying and determining weak chromatographic peaks in recent years. However, the conventional SRA cannot be applied directly to ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC/TOFMS). The obstacle lies in the fact that the narrow peaks generated by UPLC contain high-frequency components which fall beyond the restrictions of the theory of stochastic resonance. Although there already exists an algorithm that allows a high-frequency weak signal to be detected, the sampling frequency of TOFMS is not fast enough to meet the requirement of the algorithm. Another problem is the depression of the weak peak of the compound with low concentration or weak detection response, which prevents the simultaneous determination of multi-component UPLC/TOFMS peaks. In order to lower the frequencies of the peaks, an interpolation and re-scaling frequency stochastic resonance (IRSR) is proposed, which re-scales the peak frequencies via linear interpolating sample points numerically. The re-scaled UPLC/TOFMS peaks could then be amplified significantly. By introducing an external energy field upon the UPLC/TOFMS signals, the method of energy gain was developed to simultaneously amplify and determine weak peaks from multi-components. Subsequently, a multi-component stochastic resonance algorithm was constructed for the simultaneous quantitative determination of multiple weak UPLC/TOFMS peaks based on the two methods. The optimization of parameters was discussed in detail with simulated data sets, and the applicability of the algorithm was evaluated by quantitative analysis of three alkaloids in human plasma using UPLC/TOFMS. The new algorithm behaved well in the improvement of signal-to-noise (S/N) compared to several normally used peak enhancement methods, including the Savitzky-Golay filter, Whittaker-Eilers smoother and matched filtration.
authors.affiliation: Jiangsu Key Laboratory for TCM Formulae Research, College of Pharmacy, Nanjing University of Chinese Medicine, China. hs_deng@njutcm.edu.cn
authors.forename: Haishan
authors.initials: H
authors.lastname: Deng
authors.forename: Erxin
authors.initials: E
authors.lastname: Shang
authors.forename: Bingren
authors.initials: B
authors.lastname: Xiang
authors.forename: Shaofei
authors.initials: S
authors.lastname: Xie
authors.forename: Yuping
authors.initials: Y
authors.lastname: Tang
authors.forename: Jin-ao
authors.initials: JA
authors.lastname: Duan
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhan
authors.forename: Yumei
authors.initials: Y
authors.lastname: Chi
authors.forename: Defei
authors.initials: D
authors.lastname: Tan
mesh_terms: D000465:Algorithms; D000470:Alkaloids / Q000097:blood; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003198:Computer Simulation; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D008962:Models, Theoretical; D013269:Stochastic Processes
chemical_list: D000470:Alkaloids