title: Analysis of ustiloxins in rice using polymer cation exchange cleanup followed by liquid chromatography-tandem mass spectrometry.
abstract: Ustiloxins are cyclopeptide mycotoxins produced by the pathogenic fungus Ustilaginoidea virens of rice false smut. Quantification of ustiloxins is essential to assess the food safety of rice infected by rice false smut disease. This paper describes a sensitive method for the simultaneous quantification of ustiloxins A, B, C, D and F in rice grains using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Since notable matrix enhancement effects (21%-78%) occurred for all of the target analytes (except for ustiloxin A), several solid phase extraction materials were tested for their ability to retain ustiloxins from aqueous solutions prior to the LC-MS/MS analysis, including C18 sorbents, polymer anion exchange sorbents resin (PAX), and polymer cation exchange resin (PCX). The PCX resin was adopted due to its higher extraction capability and selectivity for all targets compared to others, and in this case, almost no matrix effects (-5% to 8%) were observed for all of the ustiloxins monitored. The developed method reached limits of quantification of 0.2-2ngg-1, and linearity was statistically verified over two orders of magnitude with regression coefficients (R2)>0.991. The mean recoveries were from 85% to 109%, and the inter-day precisions (n=11) were less than 16%, with intra-day precisions (n=6) within 12%. Analysis of samples showed that ustiloxin A was the dominant species, with the content ranging from 5.5 to 273.8ngg-1, followed by ustiloxin B (≤88.7ngg-1), while concentrations of ustiloxins C, D and F were slightly lower (≤43.2ngg-1). To our knowledge, this is the first report on the determination and analysis of five ustiloxins simultaneously in a single analysis.
authors.affiliation: Rice Product Quality Inspection and Supervision Center of Ministry of Agriculture, China National Rice Research Institute, Hangzhou 310006, China.
authors.forename: Zhao-Yun
authors.initials: ZY
authors.lastname: Cao
authors.affiliation: Institute of Health Food, Zhejiang Academy of Medical Sciences, Hangzhou 310007, China.
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Sun
authors.affiliation: Rice Product Quality Inspection and Supervision Center of Ministry of Agriculture, China National Rice Research Institute, Hangzhou 310006, China.
authors.forename: Ren-Xiang
authors.initials: RX
authors.lastname: Mou
authors.affiliation: Rice Product Quality Inspection and Supervision Center of Ministry of Agriculture, China National Rice Research Institute, Hangzhou 310006, China.
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Lin
authors.affiliation: Rice Product Quality Inspection and Supervision Center of Ministry of Agriculture, China National Rice Research Institute, Hangzhou 310006, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Zhou
authors.affiliation: Rice Product Quality Inspection and Supervision Center of Ministry of Agriculture, China National Rice Research Institute, Hangzhou 310006, China.
authors.forename: You-Ning
authors.initials: YN
authors.lastname: Ma
authors.affiliation: Rice Product Quality Inspection and Supervision Center of Ministry of Agriculture, China National Rice Research Institute, Hangzhou 310006, China. Electronic address: cmingxue@live.com.
authors.forename: Ming-Xue
authors.initials: MX
authors.lastname: Chen
mesh_terms: D002411:Cation Exchange Resins; D002851:Chromatography, High Pressure Liquid; D006999:Hypocreales / Q000737:chemistry; D009183:Mycotoxins / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D012275:Oryza / Q000382:microbiology*; D010456:Peptides, Cyclic / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D011108:Polymers; D052616:Solid Phase Extraction / Q000379:methods*; D053719:Tandem Mass Spectrometry
chemical_list: D002411:Cation Exchange Resins; D009183:Mycotoxins; D010456:Peptides, Cyclic; D011108:Polymers; C089077:ustiloxin B; C087237:ustiloxin A; C089078:ustiloxin C
keywords: LC–MS/MS; PCX cartridge cleanup; Rice grain; Ustiloxins