Removing Semi-Volatile Organic Compounds from Soil

Image Credit:Shutterstock/DanteBusquets

Semi-volatile organic compounds (SVOCs) are a subgroup of volatile organic compounds (VOCs) that have high molecular weight as well as high boiling points. Pesticides and herbicides primarily belong under this category. Prolonged exposure to such compounds, especially indoors, is a public health concern.

This is because many of these compounds have been listed by the US EPA as hazardous air pollutants (HAPs), pollutants that could cause serious physiological effects such as allergies, asthma, endocrine and thyroid disruption, reproductive toxicity, fetal and child development delays, and even cancer.

Soil is one of the most common matrices in which these compounds are present, the extraction of these compounds from soil can be a lengthy and tedious process. The CEM EDGE™ is a simple yet revolutionarily system that facilitates the rapid extraction of semi-volatile organic compounds (SVOCs) from soil that is more than six times faster than other automated techniques. Its patent pending Q-Cup Technology™, the EDGE™, makes the extraction process fast and simple, and meets the requirements of EPA 3545.

Introduction

Semi-volatile organic compounds consist of substances with a wide range of chemical properties and structural features. These differences make it challenging to extract all needed analytes using just a single method. Additionally, the soil matrix from which the SVOCs are to be extracted often includes multiple components that make extraction more difficult. The CEM EDGE with Q-Cup Technology can effectively extract a difficult set of analytes from complex matrices with one simple method.

Traditional methods of extraction, like Soxhlet, are time consuming and use a large amount of solvent. Automated methods often require tedious sample preparation with complex sample holders. EDGE is the fastest exaction system currently available in the market. It utilizes a minimal amount of solvent. The Q-Cup™ sample holder is comprised of two easy-to-assemble pieces that allow samples to be prepared in a matter of seconds.

SVOCs are persistently accumulating and concentrating within the environment. To ensure safety, such compounds need to be extracted, identified, and quantified. An efficient extraction determines the accuracy of SVOC analysis. EDGE produces an efficient extract that is filtered, cooled, and ready for analysis in less than five minutes.

EPA 3545 is a method of extracting water-insoluble or slightly water-soluble volatile and semi volatile compounds in soils, clays, sediments, sludges, and waste solids. EDGE meets the requirements of EPA 3545 and is pre-programmed with its methodology.

Instrumentation

The EDGE uses the Q-Cup Technology that combines pressurized fluid extraction and dispersive solid phase extraction in a single instrument that produces rapid and efficient extraction. The easy-to-assemble Q-Cup™ sample holder boasts of a unique open cell concept that creates a dispersive effect and facilitates rapid extraction and filtration. The result is fast, simple, and efficient extractions.

It is easy to setup a sample preparation using the EDGE. A Q-Disc™ must be placed in the Q-Cup base, and the two parts must be screwed together. A sorbent or drying agent may be added along with wet or dry food samples not exceeding five grams. The EDGE will utilize only 40 mL of solvent per extraction, which includes solvent for diffusive extraction and sample rinse.

The EDGE Process

Figure 1. The EDGE Process

During system cleaning, the device may use up to an additional 30 mL of solvent. The rapid heating of the extraction chamber combined with diffusive action enables a temperature of up to 180 °C to be achieved in less than two minutes.

Sample is Loaded

The Q-Cup is automatically loaded into the chamber by the auto sampler. The pressure cap then creates a pressurized seal on the top of the Q-Cup.

Solvent is Extracted

Solvent is first added through the bottom to fill the gap between the chamber and Q-Cup, aiding in heat transfer. The solvent is then added through the top of the Q-Cup to wet the sample.

As the chamber walls are heated, the pressure in the gap increases. This process overcomes the pressure inside the Q-Cup, forcing the solvent to disperse into the sample.

Extract is Collected

Once the sample reaches the target temperature, the solvent is dispensed through the Q-Disc, the cooling coil, and into a collection vial.

Procedure and Method

Ten grams of sand, loam, or clay spiked with 250 µl of spike solution was weighed into an assembled Q-Cup containing a Q-Disc. Ten grams of CRM 110-100 from Sigma Aldrich was also prepared. The Q-Cups were placed in the EDGE removable rack each with a collection vial. The rack was slid into place on the EDGE.

The One Touch Method™ for EPA 3545 was used. The extracts were injected into the Agilent 7890A with a 5975C MSD for analysis adhering to EPA 8270. A Phenomenex ZB-5MSplus 30 m, 0.25 mm column was used.

Samples

Sand, loam, and clay purchased from Sigma Aldrich were spiked with SPEX CertiPrep TCLP Base/Neutral/Acid Extractable Spike Solution in Methylene Chloride, (Part#: TCLP-BNA). CRM 110-110 was purchased from Sigma Aldrich. CRM and spiked samples were extracted using both the EDGE and Soxhlet. A 50/50 mixture of acetone/hexane was used as the extraction and rinse solvent. The system was washed with hexane and acetone.

Results and Discussion

The EDGE extracted sand, loam, and clay samples in less than minutes, including filtration, cooling, and system washing. No post clean-up, solvent exchange, or concentration was necessary. The extracts were directly injected into the GCMS for analysis.

The results for all three types of spiked soil were comparable to Soxhlet. Table 1 shows the percentage of recoveries in comparison to Soxhlet from the spiked soil of some difficult-to-extract semi-volatile organic compounds. As seen in Table 2, the extraction of CRM 110-100 via EDGE was also comparable to Soxhlet.

Table 1. % recovery data as compared to Soxhlet for spiked sand, loam, and clay

Analyte Sand (% Soxhlet) Clay (% Soxhlet) Soil (% Soxhlet)
1,4 dichlorobenzene 94 98 93
hexachloroethane 91 94 88
4-methylphenol 82 91 85
nitrobenzene 86 101 95
hexachlorobutadiene 94 97 89
2,4,5-trichlorophenol 87 76 81
2,4,6-trichlorophenol 92 73 86
2,4-dinitrotoluene 85 85 86
hexachlorobenzene 86 84 82

Table 2. % recovery data as compared to Soxhlet for CRM 110-100

Compound % Soxhlet
2-nitroanaline 94
2,4-dinitrotoluene 114
dibenzofuran 92
fluorene 105

This information has been sourced, reviewed and adapted from materials provided by CEM Corporation - Analytical.

For more information on this source, please visit CEM Corporation - Analytical.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    CEM Corporation - Analytical. (2018, August 14). Removing Semi-Volatile Organic Compounds from Soil. AZoM. Retrieved on July 22, 2019 from https://www.azom.com/article.aspx?ArticleID=16483.

  • MLA

    CEM Corporation - Analytical. "Removing Semi-Volatile Organic Compounds from Soil". AZoM. 22 July 2019. <https://www.azom.com/article.aspx?ArticleID=16483>.

  • Chicago

    CEM Corporation - Analytical. "Removing Semi-Volatile Organic Compounds from Soil". AZoM. https://www.azom.com/article.aspx?ArticleID=16483. (accessed July 22, 2019).

  • Harvard

    CEM Corporation - Analytical. 2018. Removing Semi-Volatile Organic Compounds from Soil. AZoM, viewed 22 July 2019, https://www.azom.com/article.aspx?ArticleID=16483.

Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Submit