ASTM D7106 Arsenic and Selenium Determination Test in Soil
The ASTM D7106 standard test method is a critical tool for environmental testing laboratories, particularly those involved with soil quality assessment. This method provides a standardized approach to the determination of arsenic (As) and selenium (Se) concentrations in soil samples. The significance of this test cannot be overstated, as both elements are known carcinogens that can pose serious health risks when present at elevated levels.
ASTM D7106 is widely recognized for its precision and accuracy, making it a preferred choice among environmental scientists, regulatory agencies, and private sector laboratories. The test method covers the extraction of arsenic and selenium from soil samples using nitric acid digestion followed by analysis via inductively coupled plasma mass spectrometry (ICP-MS).
The first step involves thoroughly mixing the sample with a known amount of nitric acid to dissolve organic matter, allowing for the subsequent determination of total arsenic and selenium content. This process is crucial because it ensures that all forms of these elements are accounted for in the final analysis.
Once the samples have been digested, they undergo thorough filtration before being analyzed using ICP-MS equipment. The precision of this analytical technique allows for detection limits as low as 0.1 μg/g for both arsenic and selenium. This sensitivity is essential for ensuring compliance with environmental regulations and identifying potential contamination sources.
Environmental testing laboratories play a vital role in safeguarding public health by providing accurate data on soil quality parameters like those specified in ASTM D7106. These results help inform decisions regarding remediation efforts, land use planning, and policy development related to soil contamination issues.
Applied Standards
- American Society for Testing and Materials (ASTM) D7106
| Standard Name | Description | Relevant Elements |
|---|---|---|
| American Society for Testing and Materials (ASTM) D7106 | Determination of Arsenic (As) and Selenium (Se) in Soil by Digestion with Nitric Acid Followed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) | Ar2, Se16 |
Scope and Methodology
The scope of ASTM D7106 encompasses the determination of total arsenic (As) and selenium (Se) in soil samples using a combination of nitric acid digestion followed by inductively coupled plasma mass spectrometry (ICP-MS). This method is applicable to various types of soils including agricultural, industrial, and residential areas where contamination might be suspected.
The methodology begins with sample preparation which includes sieving the soil down to a particle size appropriate for digestion. After ensuring homogeneity through mixing, an accurate mass of the prepared soil is weighed into a suitable container. An adequate volume of nitric acid (~10 mL) is then added to begin the digestion process.
Following digestion, which typically takes several hours depending on the initial soil moisture content, the solution is filtered using appropriate filter paper or membrane filters. The filtrate containing arsenic and selenium is transferred into a clean container ready for ICP-MS analysis.
The analytical procedure involves introducing the sample solution into the plasma where it ionizes and excites atoms of arsenic and selenium producing characteristic spectra that are then measured by mass spectrometry. Calibration curves derived from standards prepared under similar conditions ensure accurate quantification.
Use Cases and Application Examples
- Evaluating soil contamination levels in residential areas adjacent to industrial plants
- Assessing the effectiveness of remediation efforts after site cleanup operations
- Determining baseline values for establishing long-term monitoring programs
- Supporting legal disputes involving alleged environmental damage
| Application Scenario | Description of Use Case |
|---|---|
| Evaluating soil contamination levels in residential areas adjacent to industrial plants | This involves sampling soils from various locations around the perimeter of an industrial facility to determine if any arsenic or selenium has migrated into nearby residential zones. |
| Assessing the effectiveness of remediation efforts after site cleanup operations | In this scenario, soil samples are taken both before and after remediation activities have been completed. The results help quantify any changes in arsenic or selenium concentrations. |
