Need a solution for on-site soil contaminants screening?

With the construction industry booming globally, especially in countries like China, Philippines and the UK, organisations need to look at how they are going to manage on-site contaminants screening for building sites.

Heavy elements have been used for years in many industrial, agricultural, and domestic applications. This has sometimes resulted in their accumulation in specific geographical areas, such as old industrial or mining sites.

Because of their detrimental impact on human health, many departments for public health and environment around the world have put in place soil screening and remediation programs to minimise and prevent exposure. In the United States for example, its Environmental Protection Agency (EPA) has put in place Soil Screening Guidance (SCG) to provide a framework for site evaluation and screening level development.

Using a handheld XRF analyser for soil screening helps site managers to considerably reduce analyses costs, by reducing the number of samples sent to an off-site laboratory: you can quickly identify the areas that require clean-up. By being able to determine the elemental composition of soil samples, both qualitative and semi-quantitative data can assist with decisions on further sampling strategy for the full assessment of soil quality. It also helps with monitoring remediation efforts.

Christelle Petiot, Product Manager, shares the benefits, limitations and her tips on how to get good results with a handheld XRF analyser for soil analysis:

Why invest in the latest handheld XRF analysers?

1. They’re  fast.  Latest advances in detector electronics have significantly reduced testing time. You’ll be able to increase test density for better-informed decision making and save time, as you’ll complete site screening surveys faster. No need to wait for lab results which can take weeks.
2. They’re fully portable and usable in harsh environments and weather conditions. Compact and lightweight, some HHXRFs like the X-MET8000 are IP64 rated (dust and splash water proof). and tested to MIL-STD-810G military standard for robustness.
3. ‘Point and shoot’ simplicity. No chemicals or reagents required and it works whilst wearing your gloves. With no or simple sample preparation required, it really is easy.

What you will need to consider

1. How detailed results do you need? The limits of detection are not as low as techniques like ICP-OES, ICP-MS or flame-AAS), so HHXRF cannot totally replace laboratory analysis.
2. What range of elements are you looking to measure? A handheld analyser is not sensitive enough for very light elements such as Li and Be. Typical elements range from Mg to U, depending on your application.

My tips on getting good results

The more effort you put into the pre-treatment of soil samples, the better the results:

Remove debris, rocks, and flatten the area to test with a non-metallic object to smooth out the surface.

Dry out the samples as much as you can. You can use absorbent paper, and/or leave the sample to air-dry in a well ventilated area if needed as moisture above 10% will have a detrimental effect on the results accuracy. Results are typically 70% – 80% of the laboratory reported values when they contain 15 to 25% water.

Sieve and/or grind to obtain a fine particle size, and then place the powder in a thin sample bag or cup.

Measure a blank (e.g. SiO₂ in a cup) at regular interval to check for contamination; change analysis window when needed.

Measure a known soil check sample at regular intervals to verify accuracy and stability.

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