Ecotoxicology of Nanoparticles
Suresh C. Pillai, Yvonne Lang in Toxicity of Nanomaterials, 2019
The presence of ligands can influence the dissolution. Sigg and Lindauer (2015) found that the presence of cysteine resulted in an initial increase of dissolved Ag while chloride and fulvic acids had little effect on the dissolution of AgNPs. Gunsolus et al. (2015) demonstrated the effects of humic acids on AgNP stability and fate. This provides further evidence for temporal variation in AgNP fate as humic acids increase in autumn when leaf litter is at its highest and geographical variation as heavily forested areas are likely to have higher humic acid concentrations. Humic acid is sometimes used in the production of nanoparticles and hence may encourage their formation in solution (Dubas & Pimpan, 2008; Gunsolus et al., 2015).
Radionuclide Concentrations in Soils lution-Processed Organic Solar Cells
Michael Pöschl, Leo M. L. Nollet in Radionuclide Concentrations in Food and the Environment, 2006
Humic substances such as humic acid (HA) and fulvic acid (FA) are a fraction of the organic matter in a soil. These have a high affinity for actinide and lanthanide metal ions in a terrestrial system. Chung et al. [17] investigated the possibility of retaining fallout radionuclides in an organic matter-rich soil of Jeju Island, Korea. In order to simulate the behavior of actinide metals, Eu(III) was used as a tracer. Synchronous fluorescence spectroscopy (SyFS) was used to characterize the Eu(III) binding to humic substances. The element composition of HA and FA (carbon, hydrogen, nitrogen, and sulfur) was determined by a combustion method.
Organic Matter
Michael J. Kennish in Ecology of Estuaries Physical and Chemical Aspects, 2019
Carbon and oxygen comprise more than 80% of the elemental content of fulvic and humic acids (Table 3). The carbon content of fulvic acids ranges from 40 to 50%, and the oxygen content from 44 to 50%. Humic acids, however, have a higher carbon content and lower oxygen content than fulvic acids, with carbon concentrations ranging from 50 to 60% and oxygen concentrations from 30 to 35%. Minor elements in both fractions include hydrogen (4 to 6%), nitrogen (<1 to 3% in fulvic acids; 2 to 6% in humic acids), and sulfur (0 to 2%). Humins have a similar elemental composition as humic acids.2
The toxicology of air pollution predicts its epidemiology
Published in Inhalation Toxicology, 2018
Andrew J. Ghio, Joleen M. Soukup, Michael C. Madden
Humic substances (HS) are ubiquitous, heterogeneous, amorphous, organic materials occurring in all terrestrial and aqueous environments including composts, sediments, peat bogs, coals, rivers, lakes, and oceans (Stevenson, 1985). The molecular weights for HS can range from a few hundred to millions of daltons. Chemically, they are a complex mixture of many different acids with prominent numbers of carboxylate and phenolate groups (Figure 1). HS include three different fractions: humic acid, fulvic acid and humin. Humic acid is the major extractable component of soil HS; it is insoluble in water under acidic conditions (pH <2) but soluble at higher pH values and dark brown to black in color. Fulvic acid is that fraction of HS soluble in water under all pH conditions and remains in solution after removal of humic acid by acidification; it is light yellow to yellow-brown in color. Humin is the fraction of HS that is not soluble in water at any pH value and is black in color.
Carbohydrate-derived fulvic acid wellness drink: its tolerability, safety and effect on disease markers in pre-ART HIV-1 positive subjects
Published in South African Family Practice, 2018
ME Botes, IS Gilada, JR Snyman, JPL Labuschagne
Humic substances are present wherever organic matter is decomposing.8–10 Humic substances can be defined as: ‘a general category of naturally occurring, biogenic, heterogeneous organic substances that can generally be characterized as being yellow to black in colour and of high molecular weight’. Humic substances can be subdivided into humic acid (HA), fulvic acid (FA) and humin. The average molecular weight of humic substances may range from 500 to 5 000 Da for FA and 3 000 to 1 000 000 Da for HA.9 These substances are characterised on the basis of their solubility in water as a function of pH. FA is the fraction that is soluble in water under all pH conditions. In general, FA is also lower in molecular size and weight and lower in colour intensity than the HA. The novel medicinal properties and applications of HA and FA have been researched over many decades for various applications.8,9
Formulation design, optimization and in vivo evaluation of oral co-encapsulated resveratrol-humic acid colloidal polymeric nanocarriers
Published in Pharmaceutical Development and Technology, 2021
Rahul Hasija, Sundeep Chaurasia, Swati Gupta
Humic acid (HA) falls under the category of humic substances as an affluent resource of shilajit, and the most governing fraction of natural organic matters (Kong et al. 1987; Acharya et al. 1988). Humic substances are omnipresent: in the soil, in the river and in the sewage water, and macromolecular negatively charged polyelectrolytes. Intensive studies have highlighted humic substances as constituent components which are primarily comprised of humus approximately 60%–80% and other components such as benzoic acid, hippuric acid, fatty acid, ellagic acid, resin, triterpenes, sterols, aromatic carboxylic acid, amino acids, 3–4 benzocoumarins, and phenolic lipids (Agarwal et al. 2007; 2010). The average molecular weight of the HA is reported to be 6500 Da (Ghosal 2003). HA serves as a potent bioenhancer for poorly water-soluble active molecules. HA consists of dark brown to blackish colour and is insoluble under acidic conditions (pH < 2) but freely soluble at higher pH.
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