title: 4-Nitro-7-piperazino-2,1,3-benzoxadiazole as a reagent for monitoring of airborne isocyanates by liquid chromatography.
abstract: 4-Nitro-7-piperazino-2,1,3-benzoxadiazole (NBDPZ) is presented as a new reagent for the determination of mono- and diisocyanates in air samples. NBDPZ readily reacts with the airborne analytes, thus yielding the corresponding urea derivatives, which are subsequently separated by means of reversed-phase liquid chromatography. On a phenyl-modified stationary phase, excellent baseline separation for numerous mono- and diisocyanate derivatives is obtained. Both diode array and fluorescence detection are performed with limits of detection of 11-35 and 5-9 nmol/L for the individual derivatives, respectively. In contrast to established derivatizing agents for the analysis of isocyanates, NBDPZ provides for increased selectivity due to the favorable detection wavelengths in the visible range (UV/visible, absorption maximums approximately 480 nm; fluorescence, excitation maximums approximately 470 nm, emission maximums approximately 535 nm). In addition, the high molar absorptivities of the reagent and the derivatives provide excellent sensitivity that is superior to most literature-known methods. Finally, air sampling methods comprising both the use of impingers and test tubes are developed and successfully applied to the determination of isocyanates in gaseous samples. Excellent recovery reaching values of >90% is observed for each of the two techniques investigated.
authors.affiliation: Department of Chemical Analysis and MESA+ Research Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands. m.vogel@ct.utwente.nl
authors.forename: Martin
authors.initials: M
authors.lastname: Vogel
authors.forename: Uwe
authors.initials: U
authors.lastname: Karst
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D002853:Chromatography, Liquid / Q000379:methods*; D017953:Isocyanates / Q000032:analysis* / Q000737:chemistry; D015394:Molecular Structure; D009570:Nitriles / Q000032:analysis* / Q000737:chemistry; D010069:Oxadiazoles / Q000737:chemistry*; D010879:Piperazines / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis
chemical_list: C432126:4-nitro-7-piperazino-2,1,3-benzoxadiazole; D000393:Air Pollutants; D017953:Isocyanates; D009570:Nitriles; D010069:Oxadiazoles; D010879:Piperazines; C025319:phenyl isocyanate; C045766:propyl isocyanide