PubMed · 4459893
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1974. Grand panel discussion: digoxin availability.. https://pubmed.ncbi.nlm.nih.gov/4459893/
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The solubility and bioavailability of cadmium (Cd) in infant foods, three cereal- and milk-based diets and two ready-to-use baby dishes, were studied after in vitro digestion and by using human intestinal Caco-2 cells. The solubility of Cd after in vitro digestion varied between diets; liver casserole had the highest solubility and was lower after infant as compared to adult digestion conditions. Generally, more Cd was soluble in infant intestinal than gastric juice in contrast to the results from the adult digestion. Caco-2 cells were incubated with supernatants of infant digests that had been equilibrated with (109)Cd during the in vitro digestion procedure, and cellular uptake and transport of (109)Cd were measured after 180 min. Statistically significant differences in both uptake and transport of Cd were detected between some of the diets and a control solution containing only digestive enzymes and (109)CdCl(2). Uptake of soluble Cd in the cells varied between diets from 4 to 6%, and the transport over the monolayers was 1-2% of the dose. We conclude that age specific digestion conditions as well as composition of diets affect both solubility and bioavailability of Cd.
Selenastrum capricornutum was grown in two lake waters of differing dissolved organic carbon content (1.8 vs. 9.1 mg DOCl(-1)) to determine the responses of population dynamics and photosynthesis to Cu, and to assess the modifying effects of varying ultraviolet radiation (UVR) exposure. In the absence of UVR, the mean EC(50) for Cu effect on population growth rate was 2.3-2.6 microg l(-1) in the low DOC water and 17.4-26.2 microg l(-1) in the high DOC water. The variable chlorophyll a fluorescence ratio, F(v)/F(m), decreased approximately in parallel with the diminished growth rates. Exposure of the higher DOC lake water to full spectrum artificial radiation caused an increase of Cu(2+) concentration, compared to samples held in darkness or in photosynthetically active radiation (PAR) only. Full spectrum exposures also resulted in a lower (although not significantly so) EC(50) for Cu effect on growth rate, consistent with response to the moderately elevated Cu(2+) concentration. Cu(2+) concentration was unaffected by radiation exposure in the low DOC water, and EC(50)s for growth were also unaffected except in the most severe UVR treatment, which was >40% inhibited even in the absence of added Cu. Using F(v)/F(m) as an end-point, there was no evidence of interactions between UVR and Cu under the relatively low PAR exposures used here. Algal growth and photosynthesis was extremely sensitive to Cu in these soft lake waters, with EC(50)s close to current water quality standards in the low DOC water.
A novel reversed phase ion-pair micro HPLC system with on-line fluorescence detection has been developed systematically and studied for the determination of cadmium in its bio-available fractions of soil samples. In this system, a micro ODS column of 1.0 mm i.d.x150 mm length and a mobile phase containing 6 mmol L(-1) 8-hydroxyquinoline 5-sulphonic acid (HQS), 3 mmol L(-1) cetyltrimethylammonium bromide (CTMABr), 10 mmol L(-1) acetic acid-acetate buffer (pH 5.1) as well as 50% acetonitrile at 50 microL min(-1) flow rate were employed to determine cadmium with a 2 microL flow cell through its fluorescence at 518 nm under 338 nm excitation. Furthermore, the composition of Cd-HQS chelate formed on the column was confirmed to be [Cd(HQS)(2)](2-) through a log-log plot method, and then combined with the ion-pair reagent by the electrostatic force under the chromatographic condition proposed. With such a method, the detection limit of cadmium was 8.48 ng mL(-1) (3sigma) with 1 microL sample injection, and the linear range for the determination of cadmium was 30-800 ng mL(-1) (R(2)=0.992). This method has been successfully applied to determination of cadmium in its bio-available fractions of BCR-483 and soil samples without interference from other coexistent metal ions. The RSD (n=6) was less than 7.3%. The results were in agreement with the indicative value for BCR-483 and those for the soil samples obtained by ICP-MS with a pretreatment of bis(1,1,3,3-tetramethylbutyl) phosphinic acid extraction.