Plavšić, Marta; Lu, Xiankun; van den Berg, Constant M.G.
(1997)
A Voltammetric Study of the Reactivity of Folic Acid in Algal Cultures and in Natural Waters.
Croatica chemica acta, 70
(1).
pp. 179-191.
ISSN 0011-1643
Abstract
Folic acid (FA) can be determined in natural waters by adsorptive cathodic stripping voltammetry. The measurement suffers from interference due to the presence of humic acid (HA) in natural waters. At 2 mg/l of HA the peak of FA is fully suppressed. From non-equilibrium adsorption isotherms it was concluded that the adsorption of HA and FA is competitive, and that the folic acid is more strongly adsorbed than the HA. Measurements of the reactive folic acid concentration at low levels of HA found no evidence of complexation of folic acid by humic substances analogous with metal ions. The interfering effect of HA was eliminated by passing the sample through a C-18 cartridge. Water samples from marine and freshwater origin revealed the presence of folic acid. Algal culture experiments using marine algae illustrated that the folic acid is taken up by Phaeodactylum but not by Emiliania and Dunaliella ; this finding is tentative due to the possibility that bacteria contributed to the uptake as the cultures were not axenic. The results of these experiments suggest that folic acid could be important to certain species of marine microorganisms.
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