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Exposure to heavy metals, including arsenic (As), lead (Pb), cadmium (Cd), and mercury (Hg), is a major health hazard. The toxic effects of these heavy metals can exist in a latent state. These metals may accumulate through persistent exposure, causing adverse effects after several years to decades. Heavy metals are found in rice, the main staple food in East Asia. We studied the ecological effects of heavy metals on rice plant roots, straws, and seeds, and the soil and water used for rice cultivation. Food-grade rice grains were also analyzed. The toxicity level of As changed with the chemical form; therefore, species separation analysis of As was conducted. The concentrations of Pb, Cd, and As were analyzed by inductively coupled plasma – mass spectrometry (ICP-MS). The Pb concentration was the highest in soil (59.32 × 102 μg/kg), whereas Cd and As concentrations were the highest in rice roots at 52.36 and 20.65 × 102 μg/kg, respectively. In all samples, Hg was below the detection limit of the employed instrumentation. None of the heavy metal concentrations in the samples exceeded the Korean safety guideline levels. The heavy metal concentrations in the rice samples were the highest near the soil and decreased with distance, particularly As. The concentration of inorganic As was analyzed by high-performance liquid chromatography coupled with ICP-MS. The separation of As species in rice, consumed as food, showed the concentration of inorganic As was 69.51 μg/kg, which is below the Korean safety guideline levels. [ABSTRACT FROM AUTHOR]

Ionic liquid-modified silica particles with a large pore size were synthesized and used as the stationary phase for size exclusion chromatography coupled with a refractive index detector for the determination of polysaccharides, such as fucoidan, alginic acid, and laminarin from Undaria pinnatifida (seaweed). The molecular weight of polysaccharide was determined by a dextran standard curve (5-1100 kDa). The ionic liquid-modified silica column exhibited excellent size exclusion properties in separating laminarin from other components. The 1-butyl-3-methyl-imidazolium bis-(trifluoromethylsulfonyl)-amino silica column has superior resolution in laminarin separation than the other columns because the amino-group in ionic liquid provide π-π interactions due to aromaticity of the ring structure, which enhances the effect of the hydroxyl group in the target compound separation. The concentrations of polysaccharides were calculated using a standard linear equation to be 0.332-0.484 mg/g of fucoidan, 0.207-0.301 mg/g of alginic acid, and 0.154-0.297 mg/g of laminarin. [ABSTRACT FROM AUTHOR]

Size-exclusion chromatography has been developed for the separation of large biological molecules including proteins, polymers, peptides, nucleic acids, and polysaccharide according to their molecular size. This study determined the retention factors for dextran (5, 25, 50, 270, 670, and 1100 kDa) and polysaccharides, such as fucoidan, alginic acid, and laminarin, in the size-exclusion chromatography stationary phase. In addition, the molecular weights and retention factor of three polysaccharides were calculated from the dextran standard curve. The largest retention factor was 4.26 using the size-exclusion chromatography columns (5 kDa dextran). The molecular weights of fucoidan, alginic acid, and laminarin were determined to be 250, 200, and 5 to 64 kDa, respectively. [ABSTRACT FROM AUTHOR]