EPA-NERL: 200.13:  Trace Elements by GFAA (w/ Preconcentration)

  • Summary
  • Analytes
  • Revision
  • Data and Sites
Official Method Name
 Determination of Trace Elements in Marine Waters by Offline Chelation Preconcentration with Graphite Furnace Atomic Absorption
Current Revision
Revision 1.0, September 1997
Media
 WATER
Instrumentation
 Graphite Furnace-Atomic Absorption Spectrometer
Method Subcategory
 Inorganic
Method Source
  EPA-NERL
Citation
  Methods for Determination of Chemical Substances in Marine and Estuarine Matrices - 2nd Edition (EPA/600/R-97/072)
Brief Method Summary
 A sample is refluxed with nitric acid to solubilize elements. The solubilized sample is buffered using an on-line system, and is then preconcentrated using a chelating column with an iminodiacetate functionalized chelating resin. Anions and Group I and II metals are eluted from the column with ammonium acetate. The elements of interest are then eluted into a dilute nitric acid matrix. The concentrations of elements in the matrix are measured using a graphite furnace atomic absorption (GFAA) system.
Scope and Application
 This method determines total recoverable elements in marine waters, including estuarine water, sea water, and brines.
Applicable Concentration Range
 Not Provided
Interferences

(A) Blackbody radiation: Emission of blackbody radiation from the oven can interfere with absorbance measurements.

(B) Elemental interferences: Spectral overlap of elemental absorptions can occur, but are relatively uncommon. Appropriate furnace temperature programs and high purity lamps can reduce interferences.

(C) Matrix interferences: Some matrix components can inhibit the formation of free atoms.

(D) Memory interferences: Analyte can carry over in the furnace and in the chelating columns between runs. Use low concentration samples to ensure that analytes do not carry over.

(E) Loss of analyte: Low recoveries may be encountered if the sample contains chelating agents (humic/fulvic) or colloids that compete with the chelation column. Acid solubilization of the sample minimizes this interference.
Quality Control Requirements
 Initial demonstration of laboratory capability and the periodic analysis of laboratory reagent blanks, fortified blanks, and other laboratory solutions as a continuing check on performance.
Sample Handling
 For the determination of total recoverable elements in aqueous samples, acidify with (1+1) nitric acid at the time of collection to pH <2 (normally 3 mL of acid per liter of samples is sufficient). The sample should not be filtered prior to analysis.
Maximum Holding Time
 6 months.
Relative Cost
 $201 to $400
Sample Preparation Methods
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