Gas chromatography and mass spectrometry of polybrominated diphenyl ethers
Sammanfattning: The aim of this thesis has been to develop accurate and sensitive analytical methods for the determination of polybrominated diphenyl ethers (PBDEs). It focuses on the development and optimization of gas chromatographic and mass spectrometric analysis of PBDE.PBDEs are widely used as additative flame retardants and an increasing environmental occurrence and persistence rise concern about these compounds as environmental contaminants. However, the chemical and physical properties of the PBDEs yield a number of problems associated with the analysis of these compounds. This thesis provides an overview of the gas chromatographic separation system used for determination of PBDE and suggestions of improvements of the analytical methods. It is shown that by careful selection and optimization of the injection technique, the column system and the detection technique, the precision of the analytical method for PBDEs is significantly improved.To increase sensitivity and overcome some of the problems associated with sample preparation, large volume injection technique is recommended. Both large volume programmable temperature vaporizing (PTV) injection and the loop type injector has been optimized and evaluated with respect to the PBDEs. It is also demonstrated that the GC injection technique most commonly used for PBDE analysis, discriminate the high molecular weight congeners such as the decabrominated diphenyl ether congener (BDE-209).The dimensions and the type of GC column system strongly affect the yield of the PBDE. Degradation in the GC system of high molecular weight polybrominated diphenyl ether (BDE) congeners, especially BDE-209, is also dependent on the residence time in the column system. There is a large difference in performance between columns with supposedly similar stationary phase and by selecting a short narrow bore columns it is possible to dramatically decrease the degradation of high molecular weight PBDEs.Mass spectrometric properties of BDE-209 is presented, and carbon 13 labeled BDE-209 is evaluated and proposed as internal surrogate standard for the determination of BDE-209 in mass spectrometric detection in electron capture negative ionization (ECNI) mode.
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