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R9 Laboratory SOP 405
PREPARATION OF SOLID SAMPLES FOR GFAA & ICP-AES ANALYSIS
Summary
This method provides two separate sample preparation procedures, one for the preparation of sediment, sludge and soil samples for analysis by Graphite Furnace Atomic Absorption (GFAA) and one for the preparation of sediment, sludge and soil samples for analysis by Inductively Coupled Plasma - Atomic Emission Spectrometry (ICP-AES). The analyses of samples prepared in this method is detailed in Region 9 SOPs 503 and 513. This SOP is based on EPA Method 3050B.
This method is not a total digestion technique for most samples. It is a very strong acid digestion that will dissolve almost all elements that could become "environmentally available." By design, elements bound in silicate structures are not normally dissolved by this procedure as they are not usually mobile in the environment. If absolute total digestion is required use Method 3052.
For the digestion of solid samples, a representative 1 gram (wet weight) sample is digested with repeated additions of nitric acid (HNO3) and hydrogen peroxide (H2O2).
For GFAA analysis, the resultant digestate is reduced in volume while heating and then diluted to a final volume of 200 mL. The digestate is analyzed using the Perkin-Elmer 5100 graphite furnace atomic absorption spectrophotometer and is detailed in Region 9 SOP 513.
For ICP-AES analysis, hydrochloric acid (HCl) is added to the initial digestate and the sample is refluxed and then diluted to a final volume of 200 mL. The digestate is analyzed using the Thermo Jarrell Ash ICP-61E atomic emission spectrophotometer and is detailed in Region 9 SOP 503.
A separate sample aliquot shall be dried for a total percent solids determination.