Structural Elucidation of Agrochemicals and Related Derivatives Using Infrared Ion Spectroscopy.

Agrochemicals frequently undergo various chemical and metabolic transformation reactions in the environment that often result in a wide range of derivates that must be comprehensively characterized to understand their toxicity profiles and their persistence and outcome in the environment. In the development phase, this typically involves a major effort in qualitatively identifying the correct chemical isomer(s) of these derivatives from the many isomers that could potentially be formed. Liquid chromatography-mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy are often used in attempts to characterize such environment transformation products.

Combining Ultraviolet Photodissociation and Two-Dimensional Mass Spectrometry: A Contemporary Approach for Characterizing Singly Charged Agrochemicals.

Ultraviolet photodissociation (UVPD) has been shown to produce extensive structurally informative data for a variety of chemically diverse compounds. Herein, we demonstrate the performance of the 193 nm UVPD fragmentation technique on structural/moiety characterization of 14 singly charged agrochemicals. Two-dimensional mass spectrometry (2DMS) using infrared multiphoton dissociation (IRMPD) and electron-induced dissociation (EID) have previously been applied to a select range of singly charged pesticides.

Advantages of Two-Dimensional Electron-Induced Dissociation and Infrared Multiphoton Dissociation Mass Spectrometry for the Analysis of Agrochemicals.

Analysis of agrochemicals in an environmental matrix is challenging because these samples contain multiple agrochemicals, their metabolites, degradation products, and endogenous compounds. The analysis of such complex samples is achieved using chromatographic separation techniques coupled to mass spectrometry. Herein, we demonstrate a two-dimensional mass spectrometry (2DMS) technique on a 12 T Fourier transform ion cyclotron resonance mass spectrometer that can analyze a mixture of agrochemicals without using chromatography or quadrupole isolation in a single experiment.

Comparison of Fragmentation Techniques for the Structural Characterization of Singly Charged Agrochemicals.

Investigating the structure of active ingredients, such as agrochemicals and their associated metabolites, is a crucial requisite in the discovery and development of these molecules. In this study, structural characterization by electron-induced dissociation (EID) was compared to collisionally activated dissociation (CAD) on a series of agrochemicals. EID fragmentation produced a greater variety of fragment ions and complementary ion pairs leading to more complete functional group characterization compared to CAD.

Comparative metabolism of xenobiotic chemicals by cytochrome P450s in the nematode Caenorhabditis elegans.

We investigated the metabolic capabilities of C. elegans using compounds whose metabolism has been well characterised in mammalian systems. We find that similar metabolites are produced in C.

The nematode Caenorhabditis elegans as a tool to predict chemical activity on mammalian development and identify mechanisms influencing toxicological outcome.

To determine whether a C. elegans bioassay could predict mammalian developmental activity, we selected diverse compounds known and known not to elicit such activity and measured their effect on C. elegans egg viability.

A high-resolution accurate mass (HR/AM) approach to identification, profiling and characterization of in vitro nefazodone metabolites using a hybrid quadrupole Orbitrap (Q-Exactive).

Rationale: This paper describes a strategy for the profiling and identification of metabolites based on chemical group classification using high-resolution accurate mass (HR/AM) full scan mass spectrometry (MS) and All-Ion fragmentation (AIF) MS data.

Methods: The proposed strategy uses a hybrid quadrupole Orbitrap (Q-Exactive) employing stepped normalised collision energy (NCE) at 35% and 80% to produce key chemically diagnostic product ions from full coverage of the product ion spectrum. This approach allows filtering of high-resolution AIF MS data in order to identify parent-related compounds produced following incubation in rat liver microsomes (RLMs).