Analysis Of Natural Organic Matter Research Articles

Analysis of Natural Organic Matter in Water from Cold and Hot Mineral Springs in South Korea Using 15T FT-ICR-MS.

The natural organic matter (NOM) properties in water from cold and hot mineral springs in South Korea are not well documented. We analyzed the characteristics of NOM in water from 25 cold and hot mineral springs located across South Korea. The NOM of each sample was concentrated using solid-phase extraction and analyzed using 15T Fourier-transform ion cyclotron resonance mass spectrometry. The origin of NOM was identified using van Krevelen diagrams. This study suggests that an analytical method to evaluate the characteristics of water in each region of South Korea can be established and used as a baseline for further research.

A History of Molecular Level Analysis of Natural Organic Matter by FTICR Mass Spectrometry and The Paradigm Shift in Organic Geochemistry.

Natural organic matter (NOM) is a complex mixture of biogenic molecules resulting from the deposition and transformation of plant and animal matter. It has long been recognized that NOM plays an important role in many geological, geochemical, and environmental processes. Of particular concern is the fate of NOM in response to a warming climate in environments that have historically sequestered carbon (e.g., peatlands and swamps) but may transition to net carbon emitters. In this review, we will highlight developments in the application of high-field Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) in identifying the individual components of complex NOM mixtures, focusing primarily on the fraction that is dissolved in natural waters (dissolved organic matter or DOM). We will first provide some historical perspective on developments in FTICR technology that made molecular-level characterizations of DOM possible. A variety of applications of the technique will then be described, followed by our view of the future of high-field FTICR MS in carbon cycling research, including a particularly exciting metabolomic approach.

Application of Online Liquid Chromatography 7 T FT-ICR Mass Spectrometer Equipped with Quadrupolar Detection for Analysis of Natural Organic Matter

In this study, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), combined with quadrupolar detection (QPD), was applied for online liquid chromatography (LC) MS analysis of natural organic matter (NOM). Although FT-ICR MS has emerged as an important analytical technique to study NOM, there are few previous reports on online LC FT-ICR MS analysis of NOM due to the long acquisition time (2-8 s) required to obtain high-resolution mass spectra. The QPD technique provides a critical advantage over the conventional dipolar detection (DPD) technique for LC-MS analysis because a spectrum with the same resolving power can be obtained in approximately half the acquisition time. QPD FT-ICR MS provides resolving powers ( ) of ∼300000 and 170000 at m/ z 400 with acquisition times per scan of 1.2 and 0.8 s, respectively. The reduced acquisition time per scan allows increased number of acquisitions in a given LC analysis time, resulting in improved signal to noise ( S/ N) ratio and dynamic range in comparison to conventional methods. For example, 40% and 100% increases in the number of detected peaks were obtained with LC QPD FT-ICR MS, in comparison to conventional LC DPD FT-ICR MS and direct-injection FT-ICR MS. It is also possible to perform more quantitative comparison and molecular level investigation of NOMs with 2 μg of a NOM sample. The data presented herein demonstrate a proof of principle that QPD combined with LC FT-ICR MS is a sensitive analytical technique that can provide comprehensive information about NOM.

Optimization and Application of Paper-Based Spray Ionization Mass Spectrometry for Analysis of Natural Organic Matter.

In this study, paper-based ionization techniques-paper spray ionization (PSI) and paper spray chemical ionization (PSCI)-were evaluated and applied for high-resolution mass spectrometry (MS)-based analysis of natural organic matter (NOM). Methanol:isopropyl alcohol (50:50, v/v) and ethanol emerged as good spray solvents for PSI, and hexane:dichloromethane (50:50, v/v) was a good spray solvent for PSCI. PSI-MS spectra could be obtained with NOM samples on the microgram scale, which is a critical advantage over conventional electrospray ionization (ESI)-MS when the amount of available sample is limited. In addition, PSI is more tolerant to salt contamination than ESI for NOM analysis. PSCI preferentially ionized less polar compounds, which may not be ionized well using ESI. Therefore, PSCI can be used as a complementary method to ESI or PSI. Comparison of the numbers of peaks obtained with ESI-, PSI-, and PSCI-MS showed that employing PSI and PSCI can increase the number of compounds that can be detected by high-resolution MS. In conclusion, the data presented in this study showed that PSI and PSCI are suitable ionization techniques for NOM analysis. To the best of our knowledge, this is the first study evaluating and applying PSI and PSCI for NOM analysis.

Comparison of UV and ELS detectors in HSPEC analysis of natural organic matter in dam water

This project arose out the need for a simple method to analyse natural organic matter (NOM) on a routine basis. Water samples were obtained from the Vaal Dam. Analysis was preceded by separating the NOM into the humic and non-humic fractions. The humic portion was separated further into two fractions by employing a non-ionic DAX-8 resin to separate humic acid from fulvic acid. High-performance size-exclusion chromatography (HPSEC), equipped with a UV detector and an evaporative light scattering detector (ELSD) was used to obtain information on the molecular weight distribution and concentration levels of the two acids. Mixed standards of polyethylene oxide/glycol were employed for calibration. The molecular weight distributions (MWDs) of the isolated fractions of humic and fulvic acids were determined with ELSD detection as weight-average (Mw), number-average (Mn) and polydispersity (ρ) of individual NOM fractions. The Mw/Mn ratio was found to be less than 1.5 in all fractions, indicating that they have a low and narrow size fraction. It is noted that the ELSD detector proved to be far more capable than the UV detector. A finding of interest is that 40% of the total organic carbon in the dam water samples could be attributed to humic substances. The developed method successfully separated the humic substances from water and further separated the humic substances into the component acids, namely, humic and fulvic acids. Molecular weight distribution of these compounds is a powerful indication of how much DOM was present in the dam water. Even though the UV method was useful in characterizing these substances, the ELS detector is recommended because it detects all the organic species present. Keywords: Natural organic matter, dam water, determination, ELSD

Characteristics of natural organic matter extracted from the waters of Medjerda dam (Tunisia)

The analysis of Natural organic matter (NOM) extracted from the waters of Medjerda dam (Tunisia) by ultraviolet–visible spectrophotometry (UV/Vis), nuclear magnetic resonance (NMR) and Fourier-transform infrared (FT-IR), has showed the heterogeneous nature of NOM and confirmed the importance of the extraction and characterization of the various subcomponents. CHNO/S elemental analysis of NOM has brought out a low content of carbon but a high amount of oxygen or oxygen-containing species, such as carbohydrate-OH and carboxylic groups. The relatively low fluorescence intensity measured for NOM can be ascribed to the aliphatic structure of its constituents and the high degree of non-fluorescent carbohydrates. Polluting solvents such as toluene, benzene, ethyl benzene were also identified in the NOM extracted by GC/MS. The characterization using qualitative speciation has contributed to source recognition of this aquatic NOM.

Targeted and Non-Targeted Boron Complex Formation followed by Electrospray Fourier Transform Ion Cyclotron Mass Spectrometry: A Novel Approach for Identifying Boron Esters with Natural Organic Matter

The formation of boron esters was investigated in peat-soluble humified materials with a detailed molecular-level description of boron-organic interactions. Thousands of individually baseline separated signals were obtained from the analysis of natural organic matter of peat samples, using Fourier transform ion cyclotron resonance mass spectrometry. This technique offers unsurpassed isotope-specific mass resolution that can lead to precise molecular formula assignments by means of mathematical data analysis and visualisation techniques, such as mass defect (Kendrick) or elemental ratio (van Krevelen) plots. The analysis of potential boron binding structures within the sample of natural organic matter was described based on prior results. Herein, we describe an algorithm that can be used to effectively distinguish and filter complexes through data obtained from boron-enriched systems with highly intricate mass spectra, such as natural organic matter.

Fluorescence Analysis of Natural Organic Matter Fractionated by Ultrafiltration: Contrasting Between Urban-Impacted Water, and Radio-Contaminated Water from a Near-Pristine Site

Aqueous natural organic matter (NOM) impacted by two contrasting human impacts was analyzed using by multiresponse fluorescence, decoupled with the resolution routine PARAFAC. The first site is Chalk River, Ontario, Canada, near a pit formerly used to dispose low-level wastes. The second site is the Grand River in Cambridge, south-central Ontario, which is impacted by urban activities and agriculture. Our analysis included raw water, plus fractions from ultrafiltration and solid-phase extraction (SPE). The fluorescence spectra of the NOM, resolved with PARAFAC, showed three common features: humic-like components, at excitation/emission wavelengths 325–350/450–475 nm, fulvic-like components at 325/380–420 nm and protein-like components, at 275/300 nm. Ultrafiltration revealed that most of the NOM comprised fine material below 5,000 Da cut-off (<4% of the total) in the urban-impacted sites and the clean site at Chalk River, but the colloidal fraction (larger than 5,000 Da) was substantially higher in the contaminated water, with ∼18–26% of the total. The protein-like components in the contaminated Chalk River water were affected by ultrafiltration, but less so in the clean Chalk River sample and the urban-impacted waters. SPE preferentially removed the protein-like component in the contaminated Chalk River water (typically 89–95% signal decrease), but had a limited effect on humic- and fulvic-like components elsewhere. In conclusion, multiresponse fluorescence provided new information on the NOM quality from two contrasting sites, aided by ultrafiltration and SPE. These results are consistent with the in situ production of NOM in the Chalk River contaminated site, and natural production at the other sites.

Determination of mass transport characteristics for natural organic matter (NOM) in ultrafiltration (UF) and nanofiltration (NF) membranes

This study is mainly concerned with establishing a reliable method of the quantitative analysis of natural organic matter (NOM) transport characteristics through ultrafiltration (UF) and nanofiltration (NF) membranes with molecular weight cutoffs of 8000 (GM) and 250 (ESNA), respectively. Filtrations were conducted with a cross-flow filtration unit and hydrodynamic operating conditions were controlled by a J0/k ratio (the ratio of initial permeate flux [J0] to a back diffusional mass transfer coefficient [k]). A four-parameter (the apparent mass transfer coefficient [ka], the solute concentration near the membrane surface [Cm], the solute permeability [Pm], and the reflection coefficient (σ) model based on concentration polarization and irreversible thermodynamics was used to manipulate experimental results quantitatively. With the values of the determined parameters, the transport characteristics of NOM due to different solution chemistries such as pH and ionic strength through UF/NF membrane pores were investigated. This model was also used to demonstrate the effects of NOM structure (hydrophobic/transphilic/hydrophilic) on transport through the membranes, with XAD-8/4 resins fractionation and isolation procedures. Four parameters estimated through the model were revealed to be relevant to elucidate the behaviors of NOM in membranes and corresponding transport-related results were in good agreement with the theoretical descriptions related to the interactions between NOM molecules and membrane surface/pores.