The 7th International Symposium on Brominated Flame Retardants (BFR 2015) will be held April 21–24, 2015 in Beijing. Michelle Misselwitz, a leader in BFR work at Restek, will attend and present her most recent work on improving the analysis of brominated flame retardants. With decades of combined experience in brominated flame retardant work, Restek is pleased to support this well-respected meeting as a corporate sponsor. Michelle’s presentations are described in the abstracts below.
Half the Column, Same Chromatogram: Trimming the GC Column for Maintenance While Maintaining Critical Resolution between BDE 49 and BDE 71
Monitoring of polybrominated diphenyl ethers (PBDEs) in biota and environmental matrices can be difficult due to sample complexity, structural isomers that must be separated chromatographically, and thermally-labile compounds that can break down during gas chromatography (GC). GC column and inlet maintenance is especially important for BDE analysis because nonvolatile matrix material persists in sample extracts and deposits onto the front of the column and liner. This can cause poor transfer of BDEs onto the GC column, which compromises quantification and sensitivity. That same material at the head of the GC column also leads to poor peak shapes and reduced resolution between critical congeners, such as BDEs 49 and 71.
Trimming a coil (0.5 m to 0.7 m) off of the front of the column and changing the inlet liner restores performance and significantly increases the column lifetime. While trimming a column instead of immediately replacing it saves time and money, care must be taken to properly translate the analytical method for the shorter column length in order to maintain the original separation. If the GC method is not translated after column trimming, the column flow rate will be very fast, which will decrease resolution and detectability. The flow rate may also exceed the pumping capacity of many mass spectrometers.
EZGC® method translation software can help analysts accurately adjust the GC oven program for shorter column lengths so that the elution profile of the original chromatogram is maintained. Using a 15 m x 0.25 mm x 0.10 µm Rtx®-1614 GC column—a column that was specifically designed to meet EPA Method 1614 resolution requirements for BDE congeners 49 and 71—we investigated how much of the GC column could be trimmed off for maintenance before the Method 1614 resolution requirement for BDE 49 and BDE 71 could no longer be met.
Modified QuEChERS Extraction and Shoot-and Dilute GC: Fast Sample Preparation and Analysis of Newer Brominated Flame Retardants in Fish
Sample preparation often is a bottleneck in a busy analytical laboratory. Soxhlet or pressurized liquid extractions (PLE) are commonly used, but they can take several hours and hundreds of milliliters of solvents. In addition, complex sample extracts may require extensive cleanup to remove fat or other nonvolatile compounds prior to injection on to the GC. Screening fish and other fatty foods for the presence of halogenated flame retardants is important from a human health perspective. In addition to commonly analyzed older BFRs of known concern, some of the newer high-production flame retardants, such as those found in Firemaster® 550, are increasingly being included as target analytes as they lack established data on food occurrence.
In order to develop a fast, effective screening method for both older and newer brominated flame retardants in fish, we paired a modified QuEChERS extraction with a quick extract cleanup on a primary secondary amine (PSA) cartridge. We then used “shoot-and-dilute” GC (split injection) instead of a traditional splitless injection to introduce samples onto the column. This allowed us to reduce the impact of matrix effects on compound response and it also increased instrument ruggedness. Using both GC micro-ECD and GC-MS/MS, we evaluated fish for both newer flame retardants (e.g., 2-ethylhexyl-2,3,4,5-tetrabromobenzoate and bis(2-ethylhexyl)tetrabromophthalate) and historically significant polybrominated diphenyl ethers (PBDEs).
The sample preparation method developed here allowed a set of six samples to be processed in less than 4 hours, using only 20 mL of solvent per sample. The combination of this sample preparation procedure and a rugged shoot-and-dilute GC-MS/MS analysis yielded good recoveries of target BFRs in tuna and sardine samples. Significant time and solvent savings were achieved with this sample preparation method and the shoot-and-dilute (split injection) approach allowed more samples to be analyzed before system maintenance needed to be performed.