LC–MS Analytical Method for Biomonitoring of Aliphatic and Aromatic Low-Molecular-Mass Aldehydes in Human Urine

[Recent advances in chemical derivatization-based chromatography-mass spectrometry methods for analysis of aldehyde biomarkers]

Human exposure to chemical pollutants in the environment can cause a variety of diseases, including cancer, diabetes, cardiovascular disease, and neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, etc.). Exogenous and environmental pollutant exposure-induced endogenous aldehydes are highly reactive electrophilic compounds that can form covalently modified products with a variety of important biological molecules in the human body, thus inducing toxic effects. Exposome research has become a hotspot since it was first proposed in 2005. Exposure studies can map the complex relationships between biomarkers and disease risk. Therefore, the measurable and characteristic changes of all biomarkers together constitute a key basis for exposome research. Aldehydes are among the main components of chemical exposure. Because of the physical and chemical properties of aldehydes and the existence of multiple matrix interferences in the samples, it is particularly difficult to analyze and characterize them. The analysis and detection methods for aldehydes mainly include sensing analysis, electrochemical methods, fluorescence imaging, chromatography, mass spectrometry (MS), and chromatography-MS. Analytical techniques based on gas chromatography-MS (GC-MS) and liquid chromatography-MS (LC-MS) have emerged as the main methods for chemical exposome research. Chemical derivatization, especially stable isotope labeling derivatization (also known as chemical isotope labeling) combined with LC-MS analytical techniques, can help circumvent the problems encountered in targeted and non-targeted metabolome and exposome analysis. The combination of chemical derivatization with chromatography-MS is one of the most important solutions for the accurate analysis of aldehydes in complex samples. Over the past five years, the development and application of chromatography-MS analytical methods based on chemical derivatization have become key topics in aldehyde analysis. This paper summarizes and reviews the latest progress in GC-MS and LC-MS methods based on chemical derivatization (2015-2020). The review focuses on analytical method development for aldehyde exposure biomarkers in bio-matrices (blood, urine, saliva, biological tissue, etc.). Various derivatization reagents for labeling small-molecule aldehydes, qualitative/quantitative analytical methods and their application value, advantages/disadvantages of different analytical methods for aldehyde exposure biomarkers, and future development trends are also included. The manuscript contents may aid the integrated development of exposome, metabolomics, and lipidomics, as well as research on the environment, ecology, and health. To clarify the complex actions of exogenous and endogenous aldehydes in physiological and pathological events, it is necessary to improve the analysis and characterization techniques and tools for studying the "aldehydome." With the development and application of sophisticated mass spectrometers, advances in high-performance chromatographic separation and bioinformatics, and advent of single-cell analysis and MS imaging, future aldehyde exposome analytical methods will have higher sensitivity and throughput. This in turn would be more useful for screening and identifying unknown aldehyde compounds and discovering new exposome biomarkers.

Determination of ketones and ethyl acetate-a preliminary study for the discrimination of patients with lung cancer

In this work, ten possible volatile biomarkers of lung cancer (acetone, 2-butanone, ethyl acetate, 2-pentanone, 4-methyl-2-pentanone, 2-hexanone, 3-heptanone, 2-heptanone, 3-octanone, and 2-nonanone) have been analyzed to evaluate their different concentration levels in urine samples from lung cancer patients (n = 12) and healthy controls (n = 12). The volatile compounds were generated with a headspace autosampler and analyzed with a gas chromatograph equipped with a programmed temperature vaporizer and mass spectrometry detector (HS-PTV-GC-MS). With the aim of evaluating the aforementioned differences, a Mann-Whitney U test and box-plots were obtained. Very good discrimination between cancer and control groups was achieved for three (ethyl acetate, 3-heptanone, and 3-octanone) of the ten analytes studied. With a view to assigning samples to the group of healthy or ill individuals, the Wilcoxon signed-rank test has been used. In spite of the small number of urine samples assayed, the results may suggest that the studied compounds could be considered useful tools in order to discern samples and they could be employed as a complementary test in a diagnosis. Graphical abstract Classification of samples (lung cancer patients and controls) with the Wilcoxon signed rank test.