Heavy Metals Testing in Water and Soil

Element’s environmental laboratories provide analysis of water, leachate, waste, sediments, paint flakes, plant and animal tissue and soil to test for heavy metals that are harmful to the environment and human health.

A wide range of metallic elements are considered heavy metals. These elements can be harmful in high enough concentrations and they must be quantified by expert testing. Our laboratory experts test for heavy metals using inductively coupled plasma (ICP), coupled with either optical emission spectroscopy (OES) or mass spectrometry (MS).

Element tests for many heavy metals, including arsenic, lead, uranium, and mercury, in a variety of different environmental matrices. Reporting limits for the target metals are usually measured in ppb (parts per billion) but can be as low as ppt (parts per trillion). Our laboratory can provide sample containers, filters, syringes and preservatives to assist with your testing needs.

Heavy metals in soil testing

Depending on which method is required, soil samples are typically extracted using acids such as HNO3 or Aqua Regia and digested in an enclosed system in a hot block or microwave. Other extractions can be used for available metals such as DTPA or water. Once the metals are extracted the digested sample is filtered and ready for analysis by ICP.

When testing for heavy metals in soil samples there is no maximum holding time; however, practically, the lab typically holds the sample for 30-60 days. If following best practice, samples should be placed in an airtight container, kept cool, and out of direct sunlight.

Heavy metals in water testing

When taking water samples in the field, they are filtered (for dissolved metals analysis) and preserved with acid. Water should be preserved with nitric acid to bring the pH to below 2. This ensures the metals stay as soluble salts and prevents the conversion to insoluble salts which drop out of solution and can bias results artificially low.

For dissolved metals testing, samples should be filtered in the field through a 0.45µm filter and then preserved with nitric acid which is provided by the lab. Once preserved, the sample holding time can be extended up to 6 months (although the lab tends to only keep samples in-house for 1-2 months).

For total metals testing in water, simply add nitric acid directly into the sampled water. If sediments are present in the sample, metals will leach from the solids resulting in a higher concentration of metals in water than when testing for dissolved metals. This is a test typically completed on surface water and gives an overall view of the mobility of metals in the environment through the water.

Heavy metals testing with inductively coupled plasma (ICP)

Inductively coupled plasma testing is a technique that can determine concentrations of trace to major elements and can detect most elements in the periodic table.

A solution containing dissolved metals is aspirated through the nebulizer into the spray chamber of the ICP instrument, where it is mixed with argon gas to form a fine aerosol. This aerosol then passes into the plasma.

A series of solutions of known concentration are analyzed to give a calibration curve for each element. The instrument software compares the samples to the calibration curves and calculates the concentrations of each element.

The Element advantage

Element experts have the expertise, facilities and equipment to provide a wide range of testing services for soil, water, and other substances of interest. Our laboratories are accredited to ISO 17025 and we test to ASTM E1613 and MIL specifications for metals testing. We are your single-source provider for accurate and timely environmental testing pertaining to every major industry.

Contact Element for more information on our environmental testing capabilities.