GC Application Notes

Restek's TriMax deactivation can greatly ease the GC-MS/MS analysis of semivolatiles by EPA Method 8270E. This note compares the performance of four commonly used analytical columns using peak asymmetry, calibration linearity, recovery, and repeatability tests across a wide range of compound chemistries. Results show that RMX-5Sil MS columns, built with a new TriMax deactivation technology, have a significantly more inert surface that meets performance criteria across acidic, basic, and neutral semivolatiles whereas other columns met criteria only for certain classes of compounds. Competitive performance across a wide range of semivolatiles at low levels allows labs to streamline operations through microextraction sample preparation (e.g., EPA Method 3511) or method consolidation.

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Get fast separations without sacrificing resolution by using Restek’s proprietary Rtx®-CLPesticides and Rtx®-CLPesticides2 columns for multiple environmental methods. Instead of changing columns between GC-ECD methods, you can save time by analyzing chlorinated pesticides, PCBs, herbicides, and other halogenated compounds on a single column set using an Agilent® micro-ECD. As shown in the applications in this brochure, Rtx®-CLPesticides and Rtx®-CLPesticides2 columns have a unique selectivity and are ideal for multiple GC-ECD methods. Compare them to your current column set (Table I) and you’ll see the Restek advantage!

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While using matrix-matched calibration standards can mitigate matrix effects and increase reporting accuracy, this approach is time-consuming, labor intensive, and sometimes limited by the availability of suitable blank matrix. The use of analyte protectants (AP) in gas chromatography is an intriguing alternative because it is much simpler in practice and can allow good results to be achieved with solvent-based calibration standards [1]. Analyte protectants, such as the sugar derivative shikimic acid, work by binding strongly to active sites in the inlet, which effectively blocks these sites from interacting with target compounds. This prevents analyte loss, improves transfer to the column, minimizes degradation in peak shape and response, and can potentially improve accuracy and reliability for low-level analysis.Since using matrix-matched calibration standards is not feasible in all...

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What Is the “Ortho Effect?”The term “ortho effect” can refer to two different phenomena related to PCB congener identification. The one that this article focuses onis how ortho chlorine substitution patterns affect PCB fragmentation during ionization in the mass spectrometer. This is the spectral orthoeffect. The chlorine substitution can also affect the chromatographic separation of PCB congeners, but we will not focus on this chromatographicortho effect because its manifestation can be very column dependent.The 10 possible substitution sites on the biphenyl molecule where chlorine can bond to make PCBs are each identified by both a number anda name that describes the position relative to the bond that joins the phenyl rings together (Figure 1). Chlorines that occupy the 2,2´,6, and 6´ points are in the “ortho” position but just having a chlorine in the ortho position does not mean a ...

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