The monitoring of the Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in stack gas emission has
evolved in the last decades due to both technical and legislation advances. With the deployment of continuous
sampling techniques filling the gap of spot measurements, the technique behind the analysis of the sample seems
to be the next step forward.
The reference method for the analysis of PCDD/Fs is the High Resolution Gas Chromatography coupled to High Resolution Mass Spectrometry (HRGC/HRMS) due to its high selectivity and sensitivity. Nevertheless, the constant search of an alternative to the HRGC/HRMS for the analysis of those compounds has resulted in the appearance of different techniques such as Ion trap working in MS-MS mode and Time of Flight analyzers which have provided promising results but at the same time they have not been robust enough for the routine analysis of these contaminants.
Today, new generation of triple quadrupoles with novel soft-ionization techniques has shown a significant increase in their sensitivity making this technique suitable for the analysis of dioxin like compounds. Atmospheric Pressure Chemical Ionization (APCI) is characterized by a reduced fragmentation making possible to use the molecular ion as precursor ion, thus improving both sensitivity and selectivity of developed methods. In this work, GC-MS/MS fitted with an APCI source is assessed for the analysis of emission from stationary sources. Achieved data are compared with the results obtained by HRGC-HRMS.
Materials and methods
The study was carried out using samples that had been previously analyzed by HRGC-HRMS following the requirements described in accordance to the European Standard EN1948. A new approach was assessed based on the APGC-MS/MS analysis as an alternative to the well accepted HRGC/HRMS. The APCI-GC-MS/MS analysis were performed on an Agilent 7890A (Agilent, Palo Alto, CA, USA) coupled to a triple quadrupole mass spectrometer (Xevo TQ-S, Waters, Manchester, UK) operated in multiple reaction monitoring mode and equipped with an APCI ionization source (APGC, Waters, Manchester, UK). The injector was operated in splitless mode, injecting 1 μL at 280 °C and the interface temperature was set to 310 °C. Nitrogen was used as auxiliary gas at 250 L/h with tube to waste and as cone gas at 170 L/hr. The APCI corona pin was operated at 1.8 mA and the cone voltage was set to 30 V. Quantitative analysis was carried out by monitoring two transitions for each of the native PCDD/F congeners and their corresponding 13C-labeled analogues. The molecular ion [M•+] was always selected as precursor ion for all compounds and fragmented by collision in the T-wave collision cell. The data were processed using TargetLynxTM software.
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