Comparison of chelating agents as extractants for metals in diverse soil materials
Five chelating agents - DTPA, EDTA, EGTA, HEDTA, and NTA - were compared at pH 5.3 as extractants for Al, Fe, Mn, Zn, Cu, Cd, and Ni in 25 diverse soils. All extractants yielded clear filtrates that aspirated and burned cleanly during analysis by flame atomic absorption spectrometry. At the 5:1 extractant/soil ratio used, all buffered extractants maintained their pH satisfactorily. DTPA and HEDTA were among the most effective ligands for extracting all seven metals. EDTA extracted somewhat lower concentrations but was also a good extractant for all metals. NTA was among the best extractants for Al and Ni but among the least effective extractants for Fe, Mn, and Cu. EGTA was the least effective chelator of Fe, Zn, Ni, and especially Al. Despite this alkaline pH of 7.3, the DTPA soil-testing solution was a moderately effective extractant for metals except Mn and ferrous Fe. Acid soils, reduced soils and sediments, and metal-contaminated soils may release enough strongly complexed metal to reduce the effectiveness and the capacity of chelating extractants. Recently dredged lake sediment released particularly large concentrations of metals, primarily MnS and FeS . Extracting metals effectively from metal-rich soils may require increased concentration of chelating agents, higher extractant/soil ratios, or more than one extraction per sample.
- Research Organization:
- Dept. of Agriculture, Ithaca, NY
- OSTI ID:
- 6115694
- Journal Information:
- Soil Sci. Soc. Am. J.; (United States), Journal Name: Soil Sci. Soc. Am. J.; (United States) Vol. 48:5; ISSN SSSJD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Terrestrial-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ABSORPTION SPECTROSCOPY
ALCOHOLS
ALUMINIUM
AMINO ACIDS
CADMIUM
CARBOXYLIC ACIDS
CHELATING AGENTS
CHEMICAL ANALYSIS
COMPARATIVE EVALUATIONS
COPPER
DRUGS
DTPA
EDTA
EGTA
ELEMENTS
EXTRACTION
GLYCOLS
HEDTA
HYDROXY ACIDS
HYDROXY COMPOUNDS
IRON
MANGANESE
METALS
NICKEL
NTA
ORGANIC ACIDS
ORGANIC COMPOUNDS
PERFORMANCE TESTING
PH VALUE
QUANTITATIVE CHEMICAL ANALYSIS
RADIOPROTECTIVE SUBSTANCES
SEPARATION PROCESSES
SOILS
SPECTROSCOPY
TESTING
TRANSITION ELEMENTS
ZINC