Identification of Trace Components in Sauce-Flavor Baijiu by High-Resolution Mass Spectrometry.

Sauce-flavor Baijiu is one of the most complex and typical types of traditional Chinese liquor, whose trace components have an important impact on its taste and quality. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) is one of the most favorable analytical tools to reveal trace molecular components in complex samples. This study analyzed the chemical diversity of several representative sauce-flavor Baijiu using the combination of electrospray ionization (ESI) and FT-ICR MS. The results showed that ESI+ and ESI- exhibited different chemical features characteristic of trace components. Overall, sauce-flavor Baijiu was dominated by CHO class compounds, and the main specific compound types were aliphatic, highly unsaturated with low oxygen, and peptide-like compounds. The mass spectral parameters resolved by FT-ICR MS of several well-known brands were relatively similar, whereas the greatest variability was observed from an internally supplied brand. This study provides a new perspective on the mass spectrometry characteristics of trace components of sauce-flavor Baijiu and offers a theoretical foundation for further optimization of the gradients in Baijiu.

An advanced LC-MS/MS protocol for simultaneous detection of pharmaceuticals and personal care products in the environment.

RATIONALE: The development of appropriate analytical screening techniques for pharmaceuticals and personal care products (PPCPs) is the basis for studying the distribution and environmental impact of emerging contaminants (ECs). Mass spectrometry-based screening methods vary with the complexity of the target compounds. It is challenging to balance both positive and negative ion quantification with a low detection limit. To establish a set of experimental methods including extraction, chromatography-separation and mass spectrometry screening is one of the most important topics in PPCP research. This paper describes a universal and efficient qualification and quantification protocol for the simultaneous detection of 34 PPCPs in different environmental samples in a single analytical data acquisition run. METHODS: Thirty-four representative PPCPs, which are widely distributed in the environment with high ecological toxicity and complex chemical structures, were selected as representative target ECs. The extraction of the target PPCPs was achieved using only one solid-phase extraction cartridge without the need to adjust the pH of samples. The enriched samples were detected by LC-MS/MS in both positive and negative ion modes simultaneously. The protocol was evaluated based on the accuracy, precision, detection limits and matrix effects. RESULTS: This method achieved simultaneous detection of PPCPs in both positive and negative ion modes, with a single analytical cycle of 12 min. The observed SPE recoveries were between 40% and 115%. The instrumental detection limits (IDL) varied from 0.01 to 1 pg, and the method detection limits (MDL) were between 0.002 and 3.323 ng/l in different matrices. Most of the PPCPs were subjected to matrix suppression below 30%. The method was successfully applied for quantitative analysis of the PPCPs in different environmental samples, including river samples, wastewater treatment plant (WWTP) samples and soil samples. CONCLUSIONS: This protocol developed a rapid and efficient detection method to simultaneous qualitative and quantitative 34 representative PPCPs in the environment. The IDL ranged from 0.01 to 1 pg and the MDL ranged from 0.002 to 3.323 ng/l in different matrices. The detection limit was one order of magnitude lower compared to previous studies. The protocol also provided a wide application range for different environmental matrices, which permitted the migration and transformation of PPCPs to be explored.

Fractionation and characterization of dissolved organic matter using solid-phase extraction followed by Fourier transform ion cyclotron resonance mass spectrometry with electrospray, atmospheric pressure photoionization, and laser desorption ionization.

RATIONALE: Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) combined with different ionization techniques provides a powerful means to characterize dissolved organic matter (DOM) at the molecular level. Solid-phase extraction (SPE) is currently the most widely utilized method for extracting the DOM, but one-step elution using methanol does not provide a comprehensive picture of DOM. The development of efficient extraction and enrichment methods as well as characterization techniques from water samples remains a priority for DOM research, which is investigated in this study. METHODS: The DOM was extracted from lake water by SPE using one-step elution (methanol or dichloromethane) and multistep elution (water, methanol, acetone, and dichloromethane). A combination of electrospray ionization (ESI), atmospheric pressure photoionization (APPI), and matrix-free laser desorption ionization (LDI) was utilized for FT-ICR MS analysis in both positive (+) and negative (-) ion modes. RESULTS: The total recovery of the multistep elution was 23.5% higher as compared to the investigated one-step elution procedure (85% vs. 61.6%); however, a comparison of the observed molecular species and the range of diversity under different ionization techniques along with the statistical analyses showed that proper selection of solvent and ionization method was required to explore specific compounds from the sample. CONCLUSIONS: For DOM species containing different heteroatoms, a combination of ESI, APPI, and LDI can offer a comprehensive profile of DOM in aquatic ecosystems. The specific molecular formulae of each ionization technique are characterized as follows: ESI- mode exhibited strong selectivity for lignin-like and tannins-like species with high oxygen content, as well as organosulfates. ESI+ favored lipid species and peptide/protein compounds. Unsaturated and condensed aromatic hydrocarbons with low oxygen were preferably ionized by both APPI and LDI.

Fluorescence and molecular signatures of dissolved organic matter to monitor and assess its multiple sources from a polluted river in the farming-pastoral ecotone of northern China.

The sources and composition of dissolved organic matter (DOM) in rivers are critical to water quality and aquatic ecosystems. Studies on detailed composition of organic matter in rivers in the farming-pastoral ecotone are relatively limited in the research community. To better understand the characteristics and dynamics of DOM, Yang River in North China was selected as the study area because of its profound influences on the farming-pastoral ecotone nearby. A combination of fluorescence spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) techniques revealed that the DOM composition of Yang River is driven by land use. DOM in Yang River is predominantly imported from allochthonous inputs, together with agricultural runoff, pastureland, and urban sewage, causing a comprehensive impact on DOM. In detail, DOM associated with cropland inputs was dominated by lignin-like species, with higher nitrogen content. In comparison, DOM related to grassland is more diverse and susceptible to degradation. An increase in urban areas led to an increase in sulfur-containing compounds, while their oxygen, nitrogen, and aromaticity contents were significantly lower than those in cropland. Interestingly, urban-influenced lignin-like compounds may be associated with the effluents from the pulp and paper mill. Additionally, synthetic surfactants from the lower section of the river were also structurally identified by tandem mass spectrometry. Overall, this study could provide valuable insights into the DOM sources and their transformation dynamics at a molecular level, which could be an indicator for riverine water quality management and be applied to other farming-pastoral ecotones straightforward.

Characterization of Lignin Compounds at the Molecular Level: Mass Spectrometry Analysis and Raw Data Processing.

Lignin is the second most abundant natural biopolymer, which is a potential alternative to conventional fossil fuels. It is also a promising material for the recovery of valuable chemicals such as aromatic compounds as well as an important biomarker for terrestrial organic matter. Lignin is currently produced in large quantities as a by-product of chemical pulping and cellulosic ethanol processes. Consequently, analytical methods are required to assess the content of valuable chemicals contained in these complex lignin wastes. This review is devoted to the application of mass spectrometry, including data analysis strategies, for the elemental and structural elucidation of lignin products. We describe and critically evaluate how these methods have contributed to progress and trends in the utilization of lignin in chemical synthesis, materials, energy, and geochemistry.

Quadrupole detection FT-ICR mass spectrometry offers deep profiling of residue oil: A systematic comparison of 2ω 7 Tesla versus 15 Tesla instruments.

Mass resolving power is one of the key features of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), which enables the molecular characterization of complex mixtures. Quadrupole (2ω) detection provides a significant step forward in FT-ICR MS performance, as it doubles the resolving power for a given signal acquisition time. Whether this 2ω detection technique truly substitutes for a higher magnetic field remains unknown however. In this study, a residue oil sample was characterized using both a 2ω 7 Tesla FT-ICR and a 15 Tesla FT-ICR instrument, and analytical figures of merit were systematically compared. It was shown that 2ω 7T FT-ICR MS provided comparable performance in the deep profiling of the complex oil sample, with better signal intensities and reproducibilities for absorption-mode processing. The 15T FT-ICR MS gave more precise measurements with better estimates of the sample's elemental compositions. To the best of our knowledge, this is the first published study, which thoroughly compared the performance of 2ω detection on a low magnetic field instrument with that of a high magnetic field FT-ICR-MS.