title: Direct infusion electrospray ionization-ion mobility-mass spectrometry for comparative profiling of fatty acids based on stable isotope labeling.
abstract: A rapid method for fatty acids (FAs) comparative profiling based on carboxyl-specific stable isotope labeling (SIL) and direct infusion electrospray ionization-ion mobility-mass spectrometry (ESI-IM-MS) is established. The design of the method takes advantage of the three-dimensional characteristics of IM-MS including drift time, m/z and ion intensity, for comparison of d0-/d6-2,4-dimethoxy-6-piperazin-1-yl pyrimidine (DMPP)-labeled FAs. In particular, without chromatographic separation, the method allowed direct FAs profiling in complex samples due to the advantageous priority of DMPP in signal enhancement as well as the extra resolution that IM-MS offered. Additionally, the d0-/d6-DMPP-labeled FAs showed expected features, including very similar drift times, 6 Da mass deviations, specific reporter ions, similar MS responses, and adherence to the drift time rule regarding the influence of carbon chain length and unsaturation on relative drift times. Therefore, the introduction of isotope analogs minimized the matrix effect and variations in quantification and ensured accurate identification of non-targeted FAs by those typical features. Peak intensity ratios between d0-/d6-DMPP-labeled ions were subsequently used in relative quantification for the detected FAs. The established strategy has been applied successfully in the rapid profiling of trace free FAs between normal and cancerous human thyroid tissues. Sixteen free FAs were found with the increased level with a statistically significant difference (p < 0.05) compared to the normal tissue samples. The integrated SIL technique and ESI-IM-MS are expected to serve as an alternative tool for high-throughput analysis of FAs in complex samples.
authors: Department of Chemical Engineering, North University of China, Taiyuan 030051, China. Electronic address: jpleng@126.com.
authors: Jiapeng
authors: J
authors: Leng
authors: Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center (FUSCC), Shanghai 200032, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China.
authors: Qing
authors: Q
authors: Guan
authors: Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center (FUSCC), Shanghai 200032, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China. Electronic address: tuanqisun@163.com.
authors: Tuanqi
authors: T
authors: Sun
authors: National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China.
authors: Haoyang
authors: H
authors: Wang
authors: Department of Chemical Engineering, North University of China, Taiyuan 030051, China.
authors: Jianlan
authors: J
authors: Cui
authors: Department of Chemical Engineering, North University of China, Taiyuan 030051, China.
authors: Qinghao
authors: Q
authors: Liu
authors: Agilent Technologies (China) Co., Ltd, Shanghai 200080, China.
authors: Zhixu
authors: Z
authors: Zhang
authors: Agilent Technologies (China) Co., Ltd, Shanghai 200080, China.
authors: Manyu
authors: M
authors: Zhang
authors: National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China. Electronic address: ylguo@sioc.ac.cn.
authors: Yinlong
authors: Y
authors: Guo
mesh_terms: D005227:Fatty Acids / Q000032:analysis*; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D057230:Limit of Detection; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013961:Thyroid Gland / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000473:pathology*
chemical_list: D005227:Fatty Acids
keywords: Electrospray ionization; Fatty acids; Ion mobility–mass spectrometry; Stable isotope labeling