The number of applications that include our sample preparation solutions never ceases to amaze me, in particular the ones that use accelerated solvent extraction (link to ASE product page). This technique has demonstrated a high level of performance for the extraction of persistent organic pollutants (POPs) (link to POPs page) and contaminants of emerging concern (CECs) from solid and semi-solid matrices such as soil, sediments and tissues over the last 20 years, and remains a staple for automated sample preparation in laboratories throughout the world. Recently, scientists have made several advances in the utility of the accelerated solvent extraction technique through the use of in-cell adsorbents to achieve sample cleanup. This new technique has been coined Selective Pressurized Liquid Extraction (SPLE), and it greatly improves the throughput of sample processing prior to analysis with GC and GC-MS (link to product page).3 Peer Reviewed Articles on Selective Pressurized Liquid Extraction
I recently reviewed the scientific literature for advances in SPLE and found three exceptional articles published by Dr. Sascha Usenko of Baylor University. The first article summarizes the use of SPLE for a multitude of POPS and CECs across a diverse array of matrices, while the other two discuss SPLE use for dioxins, furans, and PCBs from animal tissue and sediments.
Study 1: SPLE Evaluated as a Sample Preparation Technique
Preparing samples for chromatographic analysis is a significant logistical bottleneck for the laboratory, and often incurs up to two-thirds of the time and cost required to process samples when using techniques such as Soxhlet (link to Royal Society of Chemistry definition and graphic) and ultrasonic extraction. Complex samples, including soil and tissue, will often produce co-extracting compounds that will compromise the quality of the analysis and must undergo a cleanup procedure to remove these interferences. Sample cleanup often involves offline techniques such as gel permeation chromatography (GPC) (link to Radboud University definition) and requires manual sample transfer and more time to process samples. Fortunately, recent advances in SPLE have enabled in-cell cleanup for a single combined sample preparation technique that eliminates the need for GPC and significantly reduces the amount of time required for sample preparation.
A recent study published in Trends in Analytical Chemistry titled Selective pressurized liquid extraction as a sample preparation technique for persistent organic pol... summarizes multiple approaches to adding adsorbents to accelerated solvent extractor cells to retain interfering compounds. Techniques for several compound classes are covered, including dioxins/furans, PCBs, brominated flame retardants, organochlorine and organophosphorous pesticides, PAHs, parabens, triclosan, and endocrine disruptors. To date, this is the most comprehensive summary of the different SPLE approaches, and can serve as an excellent reference for laboratories looking to improve the efficiency of their sample preparation while reducing the time required in performing these techniques.
Study 2: Extraction of Dioxins, Furans, and PCBs from Animal Tissue
Dr. Usenko’ s team developed an SPLE method for the analysis of polychlorodibenzo-p-dioxins, polychlorodibenzofurans (PCDD/Fs) and dioxin-like polychlobiphenyls (PCBs) in clam and crab tissue. The method was published in the Bulletin of Environmental Contamination and Toxicology and is the first example of combining all cleanup procedures required for these analyte classes in tissue with a single automated sample preparation technique. This groundbreaking work incorporated multiple cleanup adsorbents (alumina, florisil, silica gel, celite, and carbopac) in an extraction cell followed by analysis using high resolution gas chromatography/electron capture negative ionization mass spectrometry. This method overcomes the prior analytical challenges of separating PCBs from PCDD/Fs in tissue during the extraction, reduces analysis time by 92%, and reduces solvent consumption by 65% when compared to Soxhlet. This method will greatly benefit laboratories looking to improve the efficiency of their sample preparation for these two analyte classes.
Study 3: Extraction of Dioxins, Furans, and PCBs from Sediments
In this work, Dr. Usenko and his team developed another combined extraction and cleanup method for PCDD/Fs and PCBs using florisil, alumina, silica, and activated copper in the extraction cell. Sediment samples were obtained from the San Jacinto River Waste Pits (link to EPA page) Superfund site prior to remedial action and analyzed for dioxins and PCBs using high-resolution gas chromatography/electron-capture negative ionization mass spectrometry. This method was recently published in the journal Environmental Toxicology and Chemistry and is the first single-step automated extraction and cleanup of dioxins and PCBs from surficial sediments.
Learn more about solutions for persistent organic pollutants and contaminants of emerging concern by visiting our sample preparation page, where you will find application notes, webinars, and more. The pages are constantly updated, so please check back often.
Additional Resources
Watch this lively 9-minute video if you’re interested in learning more about the ASE system. It shows Aaron Kettle’s presentation at the 8th International Symposium on Recent Advances in POPs Analysis. Aaron shows how the ASE system can be used in POPs analysis, and focuses on simultaneous extraction of PAHs and PCBs in muscle tissue.
[embed]https://www.youtube.com/watch?v=5h6A04_3Dzg[/embed]
Do you have experience with SPLE as a sample preparation technique for POPs? If so, we’d love to hear about it. Share your comments below.
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