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Evaluation of Three Aluminum Assay Techniques for Excluding Aluminum Complexed with Fluoride or Sulfate
Author(s) -
Alva A. K.,
Sumner M. E.,
Miller W. P.,
Li Y. C.
Publication year - 1989
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1989.03615995005300010008x
Subject(s) - reagent , chemistry , aluminium , sulfate , fluoride , genetic algorithm , nuclear chemistry , medicinal chemistry , inorganic chemistry , organic chemistry , biology , evolutionary biology
Aluminon, 8‐hydroxyquinoline and ferron reagents are often used to measure Al in solutions. Since Al complexed with F ‐ or SO 2‐ 4 is less phytotoxic, in solutions containing these ligands an estimate of Al excluding that complexed with F ‐ and/or SO 2‐ 4 represents predominantly phytotoxic Al. In the present study, the capacity of the above reagents to exclude Al complexed with F ‐ or SO 2‐ 4 was evaluated in solutions containing 40 µ M Al with 20 to 640 µ M F ‐ or 40 to 5120 µ M SO 2‐ 4 at pH 4.5. The effects of varying reaction time from 15 s to 30 min on the recovery of Al by the respective reagents was also investigated. The sum of predicted (by MINTEQ speciation model) concentrations of Al 3+ and hydroxy‐Al monomers decreased to 45% or to 0.6% of total Al in solutions with 5120 µ M SO 2‐ 4 or 80 µ M F ‐ . The concentration of Al measured by 8‐hydroxyquinoline (15‐ or 60‐s reaction) or aluminon (15‐s reaction) appeared to exclude entirely Al complexed with F ‐ . All three reagents, however, regardless of reaction time, failed to exclude Al complexed with SO 2‐ 4 . Therefore, 8‐hydroxyquinoline (15‐ or 60‐s reaction) aluminon (15‐s reaction) reactive Al would accurately represent phytotoxic Al in the presence of F ‐ , while ferron reagent is likely to overestimate the phytotoxic Al. In the presence of SO 2‐ 4 , however, all three reagents are likely to overestimate the phytotoxic Al.