A critical evaluation of an asymmetrical flow field-flow fractionation system for colloidal size characterization of natural organic matter

Zhou, Zhengzhen; Guo, Laodong

doi:10.1016/j.chroma.2015.04.035

Cited by 46 publications

(35 citation statements)

References 51 publications

(69 reference statements)

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“…Molecular size spectra of bulk soil‐DOM samples were characterized using a flow field‐flow fractionation (FlFFF) system (AF2000, Postnova) coupled online with a UV absorbance detector (Postnova SPD20A, set at 254 and 355 nm) and two fluorescence detectors (Shimadzu RF20A), with Ex/Em at 275/340 nm and 350/450 nm (Zhou & Guo, ). The coupling of FlFFF with online detectors allowed a continuous size separation and characterization of chromophoric, protein‐like, and humic‐like DOM components at the same time (Stolpe et al, ).…”

Section: Methodsmentioning

confidence: 99%

“…A polythersulfone ultrafiltration membrane with a NMWCO (nominal molecular weight cutoff) of 0.3 kDa (manufacturer‐rated) was used along with the FlFFF system. However, the apparent pore size or NMWCO of this 0.3 kDa membrane (manufacturer‐rated) was ~1.9 kDa (Zhou & Guo, ), based on a 90% recovery rate for a series of polystyrene sulfonate standards by the FlFFF system under the specific operational conditions (Table S1). Therefore, the molecular size spectra reported here were those of DOM >1.9 kDa.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the molecular size spectra reported here were those of DOM >1.9 kDa. Detailed instrument setting, calibration, analytical procedures (including sample dilution to avoid steric effects, see Benincasa et al, ) have been described elsewhere (Stolpe et al, ; Zhou & Guo, ). Specific flow setting was given in Table S1 (see the supporting information).…”

Section: Methodsmentioning

confidence: 99%

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Yields and Characterization of Dissolved Organic Matter From Different Aged Soils in Northern Alaska

2018

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Soil organic matter (SOM) in northern high-latitude regions is a major component of the global carbon cycle. However, the yield of soil-dissolved organic matter (DOM) during soil-water interactions and its chemical characteristics and reactivities remain poorly understood. We report here elemental composition and isotopic signatures of bulk-SOM from northern Alaska, and yields of water-leachable soil-DOM, including dissolved organic carbon, dissolved organic nitrogen, and dissolved organic phosphorus, and nutrients (dissolved inorganic nitrogen and phosphate). The bulk-SOM contained 5,400-373,900 μg-C/g-soil, 500-12,610 μg-N/g-soil, and 38.6-384 μg-P/g-soil, with a C/N ratio of 13-37 and a C/P ratio of 80-3,911. The water-extractable dissolved organic carbon, dissolved organic nitrogen, and dissolved organic phosphorus only accounted for 0.58-2.5%, 0.91-3.4%, and 1.2-3.0% of their corresponding total soil-OC, N, and OP, respectively. While SOM-δ 13 C was less variable (À27.08‰ to À26.49‰) showing the same overall C source, 14 C-ages varied widely from 1,170 ± 20 to 16,200 ± 55 years before present, indicating different deposition-conditions and subsequent-processes among the soil samples. The specific-UV-absorbance at 254 nm (or aromaticity) of soil-DOM differed considerably and was negatively correlated to spectral slope values. A humic-like (C1), a low-molecular-weight fulvic-like (C2), and a protein-like component (C3) were identified as the major fluorescent-DOM components. The C3/C2 and C3/C1 ratios generally increased with SOM-14 C-age, suggesting a preferential degradation/transformation of humic-like and fulvic-like components or a transformation/production of protein-like components within permafrost. Both biological and humification indices increased with 14 C-age, excluding the oldest soil, which pointed to a preferential preservation or transformation/production of protein-like DOM within permafrost, implying that soil-DOM derived from old permafrost can be highly vulnerable and readily decomposed upon permafrost thaw.Plain Language Summary The yields of soil dissolved organic matter (DOM) and nutrients (N and P) from different aged soils in northern Alaska were quantified in the laboratory mimicking soil-water interactions upon permafrost thaw. The overall fluxes of soil-DOM and nutrients can significantly influence carbon and nutrient cycle and the ecosystem as a whole in Arctic waterways and coastal environment although the yields were generally within 4% of their corresponding total mass in the bulk soil. Humic-like substances with high optical reactivity were the major organic components preserved in permafrost, but the relative percentage of protein-like components having high biological activity increased with increasing soil C-14 age. This implies that soil-DOM released from old-permafrost thaw can be highly vulnerable and readily decomposed, causing a positive feedback to climate change.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Yields and Characterization of Dissolved Organic Matter From Different Aged Soils in Northern Alaska

2018

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“…Despite it being widely recognized that NOM is a sink for a range of pollutants, including metals and organics, and thus influences their bioavailability, interactions with NOM are not considered as part of standard toxicity testing, nor indeed in modeling of pollutant fate and behavior. This becomes especially problematic for NMs, where their enormous surface area, and sizes similar to those of NOM complexes in aquatic systems (size partitioning of dissolved NOM samples using asymmetrical flow field flow fractionation has shown a predominant size in the <5 nm size range), means that it is no longer a question of NOM removing the pollutants from solution, but rather that the NOM binds to the surface of the NMs forming NM‐NOM complexes, or a NOM‐corona, thereby altering the NM surface properties and subsequent interactions. Other constituents of the aquatic environment, including exopolysaccharides secreted by bacteria and biofilms, and proteins and other biomolecules secreted and excreted by aquatic organisms, will also compete with NOM, depending on their affinities for the NM surface.…”

Section: Introductionmentioning

confidence: 99%

Nanomaterials in the Environment Acquire an “Eco‐Corona” Impacting their Toxicity to Daphnia Magna—a Call for Updating Toxicity Testing Policies

2019

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Nanomaterials (NMs) are particles with at least one dimension between 1 and 100 nm and a large surface area to volume ratio, providing them with exceptional qualities that are exploited in a variety of industrial fields. Deposition of NMs into environmental waters during or after use leads to the adsorption of an ecological (eco-) corona, whereby a layer of natural biomolecules coats the NM changing its stability, identity and ultimately toxicity. The eco-corona is not currently incorporated into ecotoxicity tests, although it has been shown to alter the interactions of NMs with organisms such as Daphnia magna (D. magna). Here, the literature on environmental biomolecule interactions with NMs is synthesized and a framework for understanding the eco-corona composition and its role in modulating NMs ecotoxicity is presented, utilizing D. magna as a model. The importance of including biomolecules as part of the current international efforts to update the standard testing protocols for NMs, is highlighted. Facilitating the formation of an eco-corona prior to NMs ecotoxicity testing will ensure that signaling pathways perturbed by the NMs are real rather than being associated with the damage arising from reactive NM surfaces "acquiring" a corona by pulling biomolecules from the organism's surface.novel and unique qualities that are not traditionally exhibited by bulk material of the same composition. NMs have been at the core of novel research for two decades and are incorporated into products spanning a range of industrial fields. For example, NMs properties are exploited in cancer research, such as the utilization of surface plasmon resonance properties of gold (Au) NMs; here the NMs are conjugated to antibodies complementary to antigens on cancer cells and are thereby internalized, following which oscillation of the Au electron cloud at a specific wavelength of light converts the absorbed light into localized heat to specifically destroy cancer cells. [1] Another example is exploitation of the antimicrobial properties of silver (Ag) NMs which undergo high dissolution to release Ag + ions [2] and where the dissolution site, rate (and thus toxicity) can be adjusted depending on the surface coating. [3] Considering that NMs are becoming so widely used, their release into the environment is inevitable. Despite this, considerably less research has focused on the implications of NMs on environmental organisms, especially under realistic conditions, than on development of their applications. NMs may enter freshwater systems from industrial effluent, where, for example, the concentrations of zinc oxide (ZnO) NMs, widely used in sunscreens and paints, in river waters has been found to be as high as 150 ng L −1 , [4] while gold (Au) NMs excreted following use in medical applications into surface waters have been predicted to be 470 pg L −1 [5] With deposition of NMs into environmental waters increasing, concerns regarding the potential for toxicity posed by NMs have demanded action, although the standard testing approaches h...

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“…The recovery of the optimised method was calculated by injecting 20 µl of the sample with the cross-flow set to zero and calculating the area under the curve of the UV-Vis (Geiss et al 2013; Zhou & Guo 2015). Next, another 20 µl of the same sample were injected under the optimised conditions, in which the sum of the area of the void peak and the main peak (together with the corresponding release peak, which elutes after minute 65 when the CF is stopped) were estimated in the UV-Vis and the recovery was calculated by dividing the areas of interest: …”

Section: Resultsmentioning

confidence: 99%

Optimisation of asymmetric flow field-flow fractionation for the characterisation of nanoparticles in coated polydisperse TiO₂ with applications in food and feed

Omar

Boix

Kerckhove

et al. 2016

Food Additives & Contaminants: Part A

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Titanium dioxide (TiO2) has various applications in consumer products and is also used as an additive in food and feeding stuffs. For the characterisation of this product, including the determination of nanoparticles, there is a strong need for the availability of corresponding methods of analysis. This paper presents an optimisation process for the characterisation of polydisperse-coated TiO2 nanoparticles. As a first step, probe ultrasonication was optimised using a central composite design in which the amplitude and time were the selected variables to disperse, i.e., to break up agglomerates and/or aggregates of the material. The results showed that high amplitudes (60%) favoured a better dispersion and time was fixed in mid-values (5 min). In a next step, key factors of asymmetric flow field-flow fraction (AF4), namely cross-flow (CF), detector flow (DF), exponential decay of the cross-flow (CFexp) and focus time (Ft), were studied through experimental design. Firstly, a full-factorial design was employed to establish the statistically significant factors (p < 0.05). Then, the information obtained from the full-factorial design was utilised by applying a central composite design to obtain the following optimum conditions of the system: CF, 1.6 ml min–1; DF, 0.4 ml min–1; Ft, 5 min; and CFexp, 0.6. Once the optimum conditions were obtained, the stability of the dispersed sample was measured for 24 h by analysing 10 replicates with AF4 in order to assess the performance of the optimised dispersion protocol. Finally, the recovery of the optimised method, particle shape and particle size distribution were estimated.

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A critical evaluation of an asymmetrical flow field-flow fractionation system for colloidal size characterization of natural organic matter

Cited by 46 publications

References 51 publications

Yields and Characterization of Dissolved Organic Matter From Different Aged Soils in Northern Alaska

Yields and Characterization of Dissolved Organic Matter From Different Aged Soils in Northern Alaska

Nanomaterials in the Environment Acquire an “Eco‐Corona” Impacting their Toxicity to Daphnia Magna—a Call for Updating Toxicity Testing Policies

Optimisation of asymmetric flow field-flow fractionation for the characterisation of nanoparticles in coated polydisperse TiO₂ with applications in food and feed

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A critical evaluation of an asymmetrical flow field-flow fractionation system for colloidal size characterization of natural organic matter

Cited by 46 publications

References 51 publications

Yields and Characterization of Dissolved Organic Matter From Different Aged Soils in Northern Alaska

Yields and Characterization of Dissolved Organic Matter From Different Aged Soils in Northern Alaska

Nanomaterials in the Environment Acquire an “Eco‐Corona” Impacting their Toxicity to Daphnia Magna—a Call for Updating Toxicity Testing Policies

Optimisation of asymmetric flow field-flow fractionation for the characterisation of nanoparticles in coated polydisperse TiO2 with applications in food and feed

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Optimisation of asymmetric flow field-flow fractionation for the characterisation of nanoparticles in coated polydisperse TiO₂ with applications in food and feed