Diffusive sampling of methyl isocyanate using 4-nitro-7-piperazinobenzo-2-oxa-1,3-diazole (NBDPZ) as derivatizing agent

Abstract

A diffusive sampling method for the determination of methyl isocyanate (MIC) in air is introduced. MIC is collected using a glass fiber filter impregnated with 4-nitro-7-piperazinobenzo-2-oxa-1,3-diazole (NBDPZ). The urea derivative formed is desorbed from the filter with acetonitrile and analyzed by means of high-performance liquid chromatography (HPLC) using fluorescence detection (FLD) with lambdaex = 471 nm and lambdaex = 540 nm. Additionally, a method was developed using tandem mass spectrometric (MS-MS) detection, which was performed as selected reaction monitoring (SRM) on the transition [MIC-NBDPZ + H]+ (m/z 307) to [NBDPZ + H]+ (m/z 250). The diffusive sampler was tested with MIC concentrations between 1 and 35 microg m(-3). The sampling periods varied from 15 min to 8 h, and the relative humidity (RH) was set from 20% up to 80%. The sampling rate for all 15 min experiments was determined to be 15.0 mL min(-1) (using HPLC-FLD) with a relative standard deviation of 9.9% for 56 experiments. At 80% RH, only 15 min sampling gave acceptable results. Further experiments revealed that humidity did not affect the MIC derivative but the reagent on the filter prior to and during sampling. The sampling rate for all experiments (including long term sampling) performed at 20% RH was found to be 15.0 mL min(-1) with a relative standard deviation of 6.3% (N = 42). The limit of quantification was 3 microg m(-3) (LC-MS-MS: 1.3 microg m(-3)) for 15 min sampling periods and 0.2 microg m(-3) (LC-MS-MS: 0.15 microg m(-3)) for 8 h sampling runs applying fluorescence detection.

Abstracts of Papers Presented at the 2007 Pittsburgh Conference

“…In recent years, passive sampling methods have proven great effectiveness and reliability for air monitoring applications for many airborne analytes. Regarding isocyanates, there are up to now only two fully validated passive methods for methyl isocyanate (MIC) known from the literature [ 1 , 2 ], as well as an early approach [ 3 ] reporting a passive dosimeter for toluene diisocyanate (TDI). Furthermore, a method for diffusion-controlled sampling of TDI and hexamethylene diisocyanate (HDI) using SPME devices has been reported.…”

HPLC-UV and HPLC-ESI+-MS/MS analysis of free monomeric methylene diphenyl diisocyanate in polyurethane foams and prepolymers after stabilization with NBMA a new derivatizating agent

“…Nowadays, the analyses of isocyanates, either from airborne samples, insulating and adhesive foams, sealing waxes, hardeners, primers or surface coatings, are based mainly on the derivatization of the isocyanates with different nucleophiles (secondary amines and alcohols), followed by chromatographic separation and quantication using a specic detector. Examples of amine-based derivatization agents are n-dibutylamine (DBA), 18,19 1-(anthracene-9-yl)-N-methylmethanamine (or 9-(methylaminomethyl)anthracene, MAMA), [20][21][22][23][24][25] 1-(2-pyridyl)piperazine (2-PP), [26][27][28] 1-(9-anthracenylmethyl)piperazine (MAP), 20,26 1-(2-methoxyphenyl)piperazine (2-MP), 20,26,[29][30][31][32][33] 4nitro-7-piperazino-2,1,3-benzoxadiazole (NBDPZ) [34][35][36] and Nbenzylmethylamine (NBMA, rst introduced in this paper). Alcohols used include methanol and ethanol.…”

“…Gel Permeation Chromatography (GPC) separates the isocyanates directly (without formation of derivatives). 40 The quantitation is done using different types of specic detection: ultraviolet absorption (UV), [20][21][22][23][24][25][26][28][29][30]33,34,[37][38][39]41 electrochemical (EC), 29,30,37,42,43 uorescence (Fl) 20,23,26,27,34,[44][45][46][47] or mass spectrometric (MS) 18,19,26,29,31,32,35,36,[48][49][50][51] detection.…”

The role of isocyanates in fire toxicity

“…Additionally, during prolonged sampling with an impinger, the solvent containing the derivatisation agent could evaporate. Denuder or dry sampling methods, such as the ISO-CHECK® three stage filter system, as well as passive sampling methods where the isocyanates are absorbed onto a filter without using any pumps or other assistance, have been developed for personal sampling and/or prolonged sampling times (Marand et al 2005;Gylestam et al 2014;Henneken et al 2006;Henneken et al 2003;von Zweigbergk et al 2002;Nordqvist et al 2005). Furthermore, these solvent-free, filter-based methods do not need any field preparation or fragile glassware, such as an impinger (Gylestam et al 2014).…”