title: Determination of ricin by nano liquid chromatography/mass spectrometry after extraction using lactose-immobilized monolithic silica spin column.
abstract: Ricin is a glycosylated proteinous toxin that is registered as toxic substance by Chemical Weapons convention. Current detection methods can result in false negatives and/or positives, and their criteria are not based on the identification of the protein amino acid sequences. In this study, lactose-immobilized monolithic silica extraction followed by tryptic digestion and liquid chromatography/mass spectrometry (LC/MS) was developed as a method for rapid and accurate determination of ricin. Lactose, which was immobilized on monolithic silica, was used as a capture ligand for ricin extraction from the sample solution, and the silica was supported in a disk-packed spin column. Recovery of ricin was more than 40%. After extraction, the extract was digested with trypsin and analyzed by LC/MS. The accurate masses of molecular ions and MS/MS spectra of the separated peptide peaks were measured by Fourier transform-MS and linear iontrap-MS, respectively. Six peptides, which were derived from the ricin A-(m/z 537.8, 448.8 and 586.8) and B-chains (m/z 701.3, 647.8 and 616.8), were chosen as marker peptides for the identification of ricin. Among these marker peptides, two peptides were ricin-specific. This method was applied to the determination of ricin from crude samples. The monolithic silica extraction removed most contaminant peaks from the total ion chromatogram of the sample, and the six marker peptides were clearly detected by LC/MS. It takes about 5 h for detection and identification of more than 8 ng/ml of ricin through the whole handling, and this procedure will be able to deal with the terrorism using chemical weapon.
authors.affiliation: Fourth Chemistry Section, National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882, Japan. kataoka@nrips.go.jp
authors.forename: Mieko
authors.initials: M
authors.lastname: Kanamori-Kataoka
authors.forename: Haruhito
authors.initials: H
authors.lastname: Kato
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Uzawa
authors.forename: Shigenori
authors.initials: S
authors.lastname: Ohta
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Takei
authors.forename: Masahiro
authors.initials: M
authors.lastname: Furuno
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Seto
mesh_terms: D000595:Amino Acid Sequence; D002853:Chromatography, Liquid / Q000379:methods*; D004591:Electrophoresis, Polyacrylamide Gel; D007785:Lactose / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods*; D008969:Molecular Sequence Data; D036103:Nanotechnology / Q000379:methods; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D012276:Ricin / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D020539:Sequence Analysis, Protein; D012822:Silicon Dioxide / Q000737:chemistry*; D014357:Trypsin / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D012822:Silicon Dioxide; D012276:Ricin; D014357:Trypsin; D007785:Lactose