GC×GC-ECD: a promising method for the determination of dioxins and dioxin-like PCBs in food and feed

Abstract

There is a need for cost-efficient alternatives to gas chromatography (GC)-high-resolution mass spectrometry (HRMS) for the analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) in food and feed. Comprehensive two-dimensional GC-micro electron capture detection (GC× GC-μECD) was tested and all relevant (according to the World Health Organisation, WHO) PCDD/Fs and PCBs could be separated when using a DB-XLB/LC-50 column combination. Validation tests by two laboratories showed that detectability, repeatability, reproducibility and accuracy of GC×GC-μECD are all statistically consistent with GC-HRMS results. A limit of detection of 0.5 pg WHO PCDD/ F tetrachlorodibenzo-p-dioxin equivalency concentration per gram of fish oil was established. The reproducibility was less than 10%, which is below the recommended EU value for reference methods (less than 15%). Injections of vegetable oil extracts spiked with PCBs, polychlorinated naphthalenes and diphenyl ethers at concentrations of 200 ng/g showed no significant impact on the dioxin results, confirming in that way the robustness of the method. The use of GC×GC-μECD as a routine method for food and feed analysis is therefore recommended. However, the data evaluation of low dioxin concentrations is still laborious owing to the need for manual integration. This makes the overall analysis costs higher than those of GC-HRMS. Further developments of software are needed (and expected) to reduce the data evaluation time. Combination of the current method with pressurised liquid extraction with in-cell cleanup will result in further reduction of analysis costs.

Die umfassende zweidimensionale Gaschromatographie – eine neue Dimension für analytische Trennwissenschaften

“…Auch wenn unpolare polare Phasenkombinationen in der GC GC in der Regel bevorzugt werden, gewinnen nichtklassische Kombinationen, wie polare mäßig polare Phasen, [28] flüssigkristalline Phasen, [29] Phasen aus ionischen Flüssigkeiten [30] und enantioselektive stationäre Phasen, [31][32][33][34] an Interesse, da sie zu hohen Auflçsungen der Analyten und auch zu Trennungen chromatographischer Regionen führen kçnnen. Omais und Mitarbeiter [35]…”

Comprehensive two dimensional gas chromatography review

“…Haglund et al [84] demonstrated very good results when comparing an alternative to the standard GC-HRMS (highresolution mass spectrometry) method for polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and PCBs in food and feed. Using an electron capture detector (ECD) they first tried 20 different column combinations to determine how many of a given set of target analytes could be separated.…”

A New Dimension in Separation Science: Comprehensive Two‐Dimensional Gas Chromatography

“…For instance, micro electroncapture detectors (mECD), typically with a 50 Hz sampling rate, have been reported as a useful alternative, specifically for the quantitative analysis and low-cost screening of polyhalogenated target compounds, such as polychlorinated paraffins, polychlorinated dibenzodioxins and dibenzofurans (PCDD/FS), and organochlorine pesticides. [18,29,56] Studies employing comprehensive GC GC systems coupled to nitrogen phosphorus detection (GC GC-NPD) demonstrated the potential and high sensitivity of NPD for the detection of nitrogen-containing substances in complex food matrices.…”

“…The maximization of orthogonality of different stationary-phase combinations has been described using constants of a solvation parameter model, such as the Abraham model. [26] A separation-space evaluation method based on Denaulays triangulation algorithms was proposed by Semard et al, [27] and then further used to optimize the selection of column sets, geometric parameters of the secondary column, Even though non-polar polar column combinations are often stated as the preferred approach for GC GC, nonclassical conditions, that is, polar moderately non-polar column combinations [28] as well as liquid crystalline, [29] ionic liquid, [30] and enantioselective stationary phases, [31][32][33][34] are gaining attention and can lead to high-resolution and grouptype separations. Moreover, Omais and co-workers [35] recently suggested that the non-polar polar column combination is not a necessary condition to achieve large peak distribution in the 2D plane, and non-classical conditions can occasionally provide a large occupation of 2D space.…”