title: New urea-modified paper substrate for enhanced analytical performance of negative ion mode paper spray mass spectrometry.
abstract: Electrospray ionization mass spectrometry (ESI-MS) analysis in the negative ion mode is adversely affected by ionization suppression caused by electrical discharge and the presence of salts. Paper spray mass spectrometry (PS-MS) also suffers from the above phenomenon, being built on principles similar to those of ESI. Herein, we report the use of a paper substrate modified by 1-[3-(trimethoxysilyl)propyl]urea to improve the sensitivity of quantitative PS-MS analysis in the negative ion mode. The obtained results demonstrated that the urea modified paper substrate can effectively bind anions and highly polar compounds in the sample solution, decreasing competitive ionization in the negative ion mode of PS-MS and significantly reducing the signal intensity of Cl-adducts. In addition, the analyte responses were also significantly improved owing to the decreased electrical discharge observed for the less polar surface to decrease electrical discharge. Compared to non-modified PS-MS, urea-modified PS-MS exhibits a much higher sensitivity, showing 2-109 times improved signal-to-noise ratio (S/N). In real sample analysis, the limits of detection (LODs) of salicylic acid in urine and terpene lactones in Ginkgo biloba extract (EGb) were improved 10-fold and 2-40-fold, respectively, compared to that of non-modified PS-MS.
authors.affiliation: Key Laboratory of Phytochemical R&D of Hunan Province and Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Hunan Normal University, Changsha 410081, China; College of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of Phytochemical R&D of Hunan Province and Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Hunan Normal University, Changsha 410081, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: He
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Chen
authors.affiliation: Key Laboratory of Phytochemical R&D of Hunan Province and Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Hunan Normal University, Changsha 410081, China. Electronic address: mingma@hunnu.edu.cn.
authors.forename: Ming
authors.initials: M
authors.lastname: Ma
authors.affiliation: Key Laboratory of Phytochemical R&D of Hunan Province and Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Hunan Normal University, Changsha 410081, China.
authors.forename: Shouzuo
authors.initials: S
authors.lastname: Yao
authors.affiliation: Key Laboratory of Phytochemical R&D of Hunan Province and Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Hunan Normal University, Changsha 410081, China. Electronic address: dr-chenpo@vip.sina.com.
authors.forename: Bo
authors.initials: B
authors.lastname: Chen
mesh_terms: D003517:Cyclopentanes / Q000032:analysis; D005663:Furans / Q000032:analysis; D020441:Ginkgo biloba / Q000737:chemistry; D046934:Ginkgolides / Q000032:analysis; D013058:Mass Spectrometry / Q000379:methods*; D010209:Paper; D020156:Salicylic Acid / Q000652:urine; D012821:Silanes / Q000737:chemistry; D014508:Urea / Q000737:chemistry*
chemical_list: D003517:Cyclopentanes; D005663:Furans; D046934:Ginkgolides; D012821:Silanes; D014508:Urea; C073710:bilobalide; D020156:Salicylic Acid
keywords: Negative ion mode analysis; Paper spray mass spectrometry; Salicylic acid; Terpene lactones; Urea modified paper substrate