EPA-NERL: 206.5:  Sample Digestion for Arsenic

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  • Revision
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Official Method Name
 Arsenic (Sample Digestion Prior to Total Arsenic Analysis by Silver Diethylthiocarbamate or Hydride Procedures)
Current Revision
Issued 1978
Media
 WATER
Instrumentation
 Preparatory Procedure
Method Subcategory
 Inorganic
Method Source
  EPA-NERL
Citation
  Methods for the Chemical Analysis of Water and Wastes (MCAWW) (EPA/600/4-79/020)
Brief Method Summary
 A sample containing 2 to 30 ug of arsenic is acidified with sulfuric and nitric acids. Evaporate the sample to sulfite fumes. Cool the sample, add distilled water and evaporate to sulfite fumes to expel oxides of nitrogen. Analyze the sample using EPA Method 206.3 or 206.4.
Scope and Application
 This method converts organically bound arsenic to inorganic arsenic, which may be measured by EPA Methods 206.3 or 206.4.
Applicable Concentration Range
 2 to 30 ug of arsenic.
Interferences
 Nitric acid: Nitric acid must be removed before analysis. Following the procedures should remove all nitric acid.
Quality Control Requirements
 None.
Sample Handling
 Carry out the digestion using a flask on a hot-plate or a Kjeldahl apparatus.
Maximum Holding Time
 6 months (MCAWW, Table 1).
Relative Cost
 Less than $50
Sample Preparation Methods
 None.
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