p-Tolyl isocyanate derivatization for analysis of CWC-related polar degradation products by mass spectrometry

Abstract

Most of the precursors and/or degradation products related to the Chemical Weapons Convention (CWC) are polar. Identification of these molecules in environmental samples provides clues regarding the alleged usage and/or synthesis of the parent toxic chemicals. Such polar compounds need to be derivatized in order to analyze them by gas chromatography-mass spectrometry (GC-MS). In this study, we developed a new derivatizing reagent, para-tolyl isocyanate (PTI), for derivatization of polar CWC-related compounds. The PTI reagent selectively derivatizes the -OH and/or-SH functional groups with high efficiency, but does not react with carboxylic acid (-COOH) or phosphonic acid (-(O)P(OH)2) groups. The PTI derivatives of dialkyl aminoethanols, dialkyl aminoethanol-N-oxides, and 3-quinuclidinol were successfully eluted through GC, and their electron ionization (EI) mass spectra were distinct and provided the structure information by which the isomeric compounds can be easily distinguished. We also calculated the GC-retention index values that can be used for further confirmation of the target compounds. All the studied PTI derivatives can be analyzed by EI-MS with direct insertion probe and/or by direct electrospray ionization mass spectrometry (ESI-MS) together with the MS-MS data; both sets of data provide full structure information. The PTI reagent was found to be better in some respects than the conventional bistrimethylsilyl trifluoroacetamide (BSTFA), a trimethyl silylating reagent. The PTI reagent is commercially available, and the PTI derivatives are highly stable for months and are not sensitive to moisture. The applicability of the PTI derivatization for trace-level determination of the target CWC-related polar compounds in environmental matrices and in human plasma samples is also evaluated.

Rapid and mild silylation of β‐amino alcohols at room temperature mediated by N‐methylimidazole for enhanced detectability by gas chromatography/electron ionization mass spectrometry

“…It is important to notice that this is a common fragmentation pattern observed for plain, underivatized β-aminoethyl alcohols [21] as well as other derivatives of these such as their carbamates. [22] The molecular ion peak was observed for all derivatives as well, albeit present in very low abundance. Thus, the base peaks (Fig.…”

Use of carbonyldiimidazole as a derivatization agent for the detection of pinacolyl alcohol, a forensic marker for Soman, by EI‐GC–MS and LC‐HRMS in official OPCW proficiency test matrices

“…Through derivatization, the molecular weight of PA is significantly increased, and this results in an increased retention time in the GC column [6], although this is not accomplished with trimethylsilylation [11] as it was found that the retention time for the PA-TMS derivative was even shorter than PA itself (i.e., ~2.68 min vs. 5.32 min for PA). Another useful result that can be attained after a derivatization reaction is the generation of a product that exhibits sharper peaks relative to the starting, unmodified material as it is in the case of ethanolamines and phosphonic acids [31][32][33][34]. Our work is based on the use of 1,1′-carbonyldiimidazole (CDI), a versatile reagent that reacts with alcohols and amines to yield carbonates [35,36] and ureas, respectively [37][38][39][40], as well as carbamates when both species are used in a sequential fashion [41][42][43].…”

Gas chromatography/mass spectrometry analysis of reaction products of Chemical Weapons Convention–related 2‐(N,N‐dialkylamino)ethylchlorides with 2‐(N,N‐dialkylamino)ethanols

“…The non‐scheduled precursors/reaction products are one reaction step away from scheduled 1 and 2 chemicals of the CWC, in which phosphorus‐, sulfur‐, nitrogen‐, and/or arsenic‐containing moiety is still present. Detection of degradation/reaction products of some of the CWC‐scheduled chemicals has been reported previously 11–18 . In this comprehensive study, we have examined the reaction products of 2‐( N , N ‐dialkylamino)ethylchlorides with 2‐( N , N ‐dialkylamino)ethanols, which are the known precursors/degradation products of VX‐type compounds (VX compounds are potent nerve agents and the most lethal CWAs).…”