ABSTRACT
The use of gas chromatography coupled to high-resolution magnetic sector mass spectrometers (GC-HRMS) is well established for dioxin and furan analysis. However, the use of gas chromatography coupled to triple quadrupole (MS/MS) and time of flight (TOF) mass spectrometers with atmospheric pressure ionization (API) and traditional electron ionization (EI) for dioxin and furan analysis is emerging as a viable alternative to GC-HRMS screening. These instruments offer greater versatility in the lab for a wider range of compound identification and quantification as well as improved ease of operation. The instruments utilized in this study included 2 API-MS/MS, 1 traditional EI-MS/MS, an API-quadrupole time of flight mass spectrometer (API-QTOF), and a EI-high-resolution TOF (EI-HRTOF). This study compared these 5 instruments to a GC-HRMS using method detection limit (MDLs) samples for dioxin and furan analysis. Each instrument demonstrated acceptable MDL values for the 17 chlorinated dioxin and furans studied. The API-MS/MS instruments provide the greatest overall improvement in MDL value over the GC-HRMS with a 1.5 to 2-fold improvement. The API-QTOF and EI-TOF demonstrate slight increases in MDL value as compared with the GC-HRMS with a 1.5-fold increase. The 5 instruments studied all demonstrate acceptable MDL values with no MDL for a single congener greater than 5 times that for the GC-HRMS. All 5 instruments offer a viable alternative to GC-HRMS for the analysis of dioxins and furans and should be considered when developing new validated methodologies.
ABSTRACT
A rapid extraction and cleanup method for the screening of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in sediments is described which combines a modified QuEChERS extraction with carbon reversed-phase solid phase extraction cleanup. This approach is compared to the classical Soxhlet extraction and multi-column cleanup method in terms of toxic equivalence quotients (TEQs), precision, instrumental chromatography, method detection limits (MDLs), recovery of (13)C-labelled quantitation standard, sample preparation time, workload capacity, and sustainability factors. TEQs of 32 sediment samples were found to be well correlated and differed by 16 ± 10 % between the two methods. Certified and standard reference sediments differed by 4.1 and 6.7 %, respectively. Precision and instrumental chromatography were comparable. While the modified QuEChERS method had higher MDLs and lower recoveries, in terms of preparation time and workload capacity, the modified QuEChERS approach can prepare approximately 30 samples per day as compared to 10-20 samples in 3 to 4 days for the classic method. The modified QuEChERS method was also found to be safer and greener. The appreciable improvement in capacity makes the modified QuEChERS approach a suitable alternative to the classical method for applications where turnaround time and the number of samples that can be analyzed are more important than minimal detection limits. Graphical Abstract Created using Microsoft Paint for Windows 7 Professional A bar graph with the structures of dioxins and furans on the x axis shows agreement between two sets of data. A legend labels the first set of data as Soxhlet. The Soxhlet set is illustrated as four days crossed off of a calendar page, a Soxhlet extractor, and several packed chromatography columns. The legend identifies the second set of data as QuEChERS. The QuEChERS set is represented by a clock face marked with twenty four hours, two centrifuge tubes containing the sediment and reagents before and after salting out, and a carbon column attached to a reservoir.
ABSTRACT
The goal of this study was to qualify gas chromatography coupled to atmospheric pressure ionization tandem mass spectrometry (APGC-MS/MS) as a reliable and valid technique for analysis of halogenated dioxins and furans that could be used in place of more traditional gas chromatography coupled to high-resolution mass spectrometry (GC-HRMS) analysis. A direct comparison of the two instrumental techniques was performed. APGC-MS/MS system sensitivity was demonstrated to be on the single femtogram level. The APGC-MS/MS analysis also demonstrated method detection limits (MDLs) in both sediment and fish that were 2-18 times lower than those determined for the GC-HRMS. Inlet conditions were established to prevent issues with sample carry-over, due largely to the enhanced sensitivity of this technique. Additionally, this work utilized direct injection for sample introduction through the split/splittless inlet. Finally, quantification of both sediment and fish certified reference materials were directly compared between the APGC-MS/MS and GC-HRMS. The APGC-MS/MS performed similarly to, if not better than, the GC-HRMS instrument in the analysis of these samples. This data is intended to substantiate APGC-MS/MS as a comparable technique to GC-HRMS for the analysis of dioxins and furans.
