A High Resolution/Accurate Mass (HRAM) Data-Dependent MS³ Neutral Loss Screening, Classification, and Relative Quantitation Methodology for Carbonyl Compounds in Saliva

Abstract

Reactive carbonyl compounds (RCCs) are ubiquitous in the environment and are generated endogenously as a result of various physiological and pathological processes. These compounds can react with biological molecules inducing deleterious processes believed to be at the basis of their toxic effects. Several of these compounds are considered to be implicated in neurotoxic processes, aging disorders, and cancer. Therefore, a method characterizing exposures to these chemicals will provide insights into how they may influence overall health and contribute to disease pathogenesis. Here, we have developed a high resolution accurate mass (HRAM) screening strategy allowing simultaneous identification and relative quantitation of DNPH-derivatized carbonyls in human biological fluids. The screening strategy involves the diagnostic neutral loss of hydroxyl radical triggering MS3 fragmentation, which is only observed in positive ionization mode of DNPH-derivatized carbonyls. Unique fragmentation pathways were used to develop a classification scheme for characterizing known and unanticipated/unknown carbonyl compounds present in saliva. Furthermore, a relative quantitation strategy was implemented to assess variations in the levels of carbonyl compounds before and after exposure using deuterated d3-DNPH. This relative quantitation method was tested on human samples before and after exposure to specific amounts of alcohol. The nano-electrospray ionization (nano-ESI) in positive mode afforded excellent sensitivity with detection limits on-column in the high-attomole levels. To the best of our knowledge, this is the first report of a method using HRAM neutral loss screening of carbonyl compounds. In addition, the method allows simultaneous characterization and relative quantitation of DNPH-derivatized compounds using nano-ESI in positive mode.

Alcohol-Derived Acetaldehyde Exposure in the Oral Cavity

“…However, consistency in the measuring time may be an issue in these studies and a more standardized universal way for evaluating acetaldehyde naturally present vs. acetaldehyde derived from ethanol exposure should be implemented. For example, a quantitative assessment via gas or liquid chromatography/mass spectrometry [ 40 , 111 ] of the initial acetaldehyde levels in the beverages to be administered should always be performed prior to exposure to derive the portion of acetaldehyde naturally present vs. that of acetaldehyde derived from individual ethanol metabolism.…”

Identification of lignin oligomers in Kraft lignin using ultra-high-performance liquid chromatography/high-resolution multiple-stage tandem mass spectrometry (UHPLC/HRMSn)

“…Characteristic neutral losses for specific LO-linkages are known from studies by Morreel et al [14]. Recently, Dator et al developed a HR-data-dependent neutral loss-MS 3 approach for carbonyl compounds in salvia [24]. This approach can be adapted for LOs and used as a pre-selection tool.…”

Bioanalytical and Mass Spectrometric Methods for Aldehyde Profiling in Biological Fluids

“…Studies using negative ionization have described the MS and MS/MS behavior of DNPH-derivatized carbonyls [215,216,229]. Studies using positive electrospray ionization have characterized DNPH-derivatized malondialdehyde [198,199,217,230] and 4-HNE [199], and recently we characterized the positive ionization and fragmentation of a wide range of DNPH-derivatized carbonyls to establish consistent fragmentation rules applicable to this class of compounds, allowing for screening of unknown carbonyl compounds and comprehensive detection [218] (Table 3).…”

“…High-resolution mass spectrometry-based methods for metabolomics profiling provide accurate masses of both precursor and MS/MS fragment ions, and thus allow confident identification of detected metabolites in complex biological matrices. Recently, we have developed a high-resolution accurate mass data-dependent MS 3 neutral loss (NL) screening strategy to characterize DNPH-derivatized carbonyls in biological fluids, allowing for the simultaneous detection and quantitation of suspected and unknown/unanticipated carbonyl compounds [218]. Previous analyses of DNPH-derivatized carbonyls were mostly performed in negative ionization mode and at relatively high-flow rates, which limit the sensitivity of detection and quantitation of trace level analytes (Table 3).…”