title: Active single-drop microextraction for the determination of gaseous diisocyanates.
abstract: This paper presents a novel application of active single-drop microextraction (SDME) for the determination of mixtures of four gaseous diisocyanates: 2,4- and 2,6-toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI) and methylene diphenyl diisocyanate (MDI). The optimised simultaneous extraction, preconcentration and derivatization method utilizes a 2.3-microL Milli-Q water drop containing dibutylamine (DBA) as a derivatization reagent and phenylisocyanate (PHI) as an injection standard. A type III screening design, combined with Box-Behnken surface modelling and Simplex optimisation was applied to optimise the method. Several SDME approaches--standard SDME, automatic organic solvent film (OSF) and use of a supported-drop (SD) device--were compared with solid-phase microextraction (SPME) in terms of sensitivity and robustness under varied conditions. Of these SDME alternatives, SD proved to be the most suitable for diisocyanate sampling. The detection limits using SDME followed by UPLC-MS-MS analysis were 0.9 and 0.8 microg m(-3) for 2,4- and 2,6-TDI, respectively, 1.0 microg m(-3) for HDI and 0.2 microg m(-3) for MDI.
authors.affiliation: Department of Analytical Chemistry, Aragón Institute of Engineering Research (I3A), CPS-University of Zaragoza, 50018 Zaragoza, Spain. r13bat@unizar.es
authors.forename: Ramón
authors.initials: R
authors.lastname: Batlle
authors.forename: Patricia
authors.initials: P
authors.lastname: López
authors.forename: Cristina
authors.initials: C
authors.lastname: Nerín
authors.forename: Carlo
authors.initials: C
authors.lastname: Crescenzi
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003485:Cyanates / Q000032:analysis* / Q000302:isolation & purification; D017953:Isocyanates / Q000032:analysis* / Q000302:isolation & purification; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D014051:Toluene 2,4-Diisocyanate / Q000032:analysis* / Q000302:isolation & purification; D014867:Water; D001559:Benzhydryl Compounds
chemical_list: D003485:Cyanates; D017953:Isocyanates; D014051:Toluene 2,4-Diisocyanate; D014867:Water; C015262:1,6-hexamethylene diisocyanate; C005969:4,4'-diphenylmethane diisocyanate; D001559:Benzhydryl Compounds