Fast Sample Preparation and Shoot-and-Dilute GC for Flame Retardants in Fish

The shoot-and-dilute GC technique (split injection) is perfectly matched for the fast sample preparation approach of QuEChERS.  The QuEChERS concept provides a fast, multi-residue extraction and “just enough” cleanup.  The technique is quick and minimizes solvent usage, but the resulting extract can contain a large amount of coextracted nonvolatile material.  A split injection is an advantageous injection technique for dirty samples because less nonvolatile material ends up on the column and the flow through the liner is MUCH faster compared to a splitless injection.  Don’t just take my word for it; see these blogs for more information.

Shoot-and-Dilute GC – Used Motor Oil and PAHs – Rxi-5ms GC Column Performance

PAH Separations – Rxi-5ms GC Column – Shoot-and-Dilute GC

Using the Restek EZGC Method Translator and Flow Calculator to Support Shoot-and-Dilute GC Method Development – Going from GC-ECD to GC-MS

Screening fish and other fatty foods for the presence of halogenated flame retardants is important from a human health perspective.  While the historical PBDEs have been phased out in the US, some of the newer high-production flame retardants such as those found in Firemaster® 550, do not have any available food occurrence data.  In order to develop a screening method for halogenated flame retardants, we paired the fast, multiresidue, sample preparation concept of a modified QuEChERS extraction and a quick extract pass-through of a PSA (primary secondary amine) cleanup cartridge.  The PSA pass through removed large fatty acid interferences and the samples were then analyzed using GC-ECD and GC-MS/MS with a 15m x 0.25mm x 0.10µm Rtx-1614 and a 10:1 split injection.  Even though we employed a split injection, the sensitive detectors allowed us to detect in the low ng/g range.

QuEChERS_HFRs_FishPSA Pass Through_FishFish_Recovery

3 Responses to “Fast Sample Preparation and Shoot-and-Dilute GC for Flame Retardants in Fish”

  1. It is always advantageous in GC to inject less sample. Note that this only works if the sample components make it through the GC pathway and the detector used has enough sensitivity to allow a splitted sampling. Detecting lower levels will put a bigger challenge on all parts: liners, columns, transfer tubing, connections, ionization sources etc.

  2. Michelle Misselwitz says:

    Hi Jaap,

    Thanks for the comment, and I agree that it is always advantageous to inject less sample and that this is only made possible with sensitive detectors. In terms of putting a bigger challenge on all of the other parts of the system, I’m not sure this is accurate for a split injection. For example, we have found that using a split injection the liner and column perform longer when compared to a splitless injection. Less sample = less matrix contamination = longer system up-time. If we were injecting less sample, but still using a splitless injection, then I agree that it places a bigger burden on the sample pathway to get from injection to detection.

    -Michelle

  3. Hi Michelle, I know that you chose to use 1:1 hexane:acetone for extraction because that is the traditional extraction, but I wish your customers using old EPA Methods would want to do better! The hexane:acetone gives dirtier extracts, including nasty lipids to damage GC columns, and the PSA does not work as well with hexane:acetone for cleanup as in MeCN extract. Normal d-SPE in QuEChERS w/MgSO4+PSA+C18 is fine to avoid cartridges and manifolds and more solvent and more glassware, and more dilute extracts. Use of MeCN in d-SPE helps better removes the few remaining co-extracted lipids. Check out the papers of Yelena Sapozhnikova and other colleagues for faster QuEChERS-based extraction, (filter-vial) d-SPE cleanup, and low-pressure GC-MS/MS analysis for 200+ pesticides, PCBs, PAHs, PBDEs, and new flame retardants at <1 ng/g in 11 min The analysis is very rugged. Our paper in J. Agric. Food Chem. (currently online) shows it gives 100% extraction efficiency for incurred (real-world) fish samples of different fat content. Give it a try and tell your customers all about it!

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