EPA-NERL: 300.0:  Inorganic Anions by Ion Chromatography

  • Summary
  • Analytes
  • Revision
  • Data and Sites
Official Method Name
Determination of Inorganic Anions by Ion Chromatography
Current Revision
Revision 2.1, August 1993
Ion Chromatography
Method Subcategory
Method Source
  Methods for the Determination of Inorganic Substances in Environmental Samples (EPA/600/R-93/100)
Brief Method Summary
A small volume of sample, typically 50-100 uL, is introduced into an ion chromatograph. The anions of interest are separated and measured, using a system comprised of a guard column, separator column, suppressor device, and conductivity detector.
Scope and Application
Part A of the test method covers the determination of common inorganic anions in drinking water, surface water, mixed domestic and industrial wastewaters, groundwater, reagent waters, solids (after extraction), leachates (when no acetic acid is used). Part B of the test method covers the determination of bromate, chlorate, and chlorite in drinking and reagent waters.
Applicable Concentration Range
DL - * (* Upper detection limit is defined as the highest calibration point, as determined by analyst.)
(1) Coeluting species (e.g., low-molecular-weight organic acids). (2) High concentration of anions can effect resolution of peaks and elution times. (3) Fluoride is especially sensitive to coeluting species, and "water dip" (corresponding to the elution of water) at low concentrations.
Quality Control Requirements
Calibration Blank (CB), Quality Control Sample (QCS), Performance Evaluation Sample (PE), Instrument Performance Check Solution (IPC), Laboratory Duplicate (LD), Field Duplicate (FD), Laboratory Fortified Matrix (LFM), Laboratory Fortified Blank (LFB), Laboratory Reagent Blank (LRB), Linear Calibration Range (LCR)
Sample Handling
Collect enough volume to ensure a representative sample and to allow for replicates. Either glass or plastic bottles may be used.

For Part A Analytes: No preservation is required for bromide, chloride, or fluoride. Refrigerate samples at 4 degrees C for nitrate-N, nitrite-N, orthophosphate-P, and sulfate. Samples being tested for nitrate/nitrite should be adjusted to pH < 2 with concentrated H2SO4 and refrigerated at 4 degrees C until analysis. Analyze samples being tested for bromide, chloride, fluoride, nitrate/nitrite, and sulfate within 28 days. Analyze samples being tested for nitrate-N, nitrite-N, and orthophosphate-P within 48 hours.

For Part B Analytes: Samples analyzed for bromate and chlorate may be held for 28 days without preservation. Chlorite should be analyzed for immediately (within 10 minutes). However, if the sample cannot be analyzed immediately, it may be preserved for up to 14 days if treated with ethylenediamine (ClO2 should be removed prior to this step) and chilled to 4oC.
Maximum Holding Time
Part A: 48 Hours (NO2-N, NO3-N, orthophosphate-P) 28 days (others)
Part B: Bromate and Chlorate (28 days) and chlorite (14 days with preservation -- otherwise analyze immediately).
Relative Cost
$51 to $200
Sample Preparation Methods