Abstract
High resolution gas chromatography coupled with high resolution mass spectrometry systems are often used for the analyses of
dioxins at low concentrations in environmental sample matrices such as soil, vegetation, sediment, air and food. Since the
construction and operation costs of these systems are so expensive, the most of the laboratories in the developing countries
haven’t the systems with high resolution mass spectrometry. Thus, cheaper systems with similar sensitivity such as high
resolution gas chromatography coupled with low resolution mass spectrometry systems in negative chemical ionization mode
may be beneficial to assess the dioxin pollution levels in environmental samples before the elaborate studies on dioxin
contamination and stochastic risk assessment. In this manuscript, 17 toxic congeners of dioxins were analyzed by a system with
low resolution mass spectrometry. The sensitivity, stability and resolution power of the system for the analysis of dioxins were
investigated. The calibration experiments in 3 different periods were studied and the minimum detection limits were determined
by using the labeled and unlabeled standard solutions. The differences according to operation conditions of the ion source were
examined and expounded by using relative response factor and relative standard deviation values obtained from sequential
injections. Finally, it was performed a sample analysis program for some local food samples with the aim of observing the
feasibility of the system on food samples that have very low level dioxin concentrations such as egg and cow's milk. It was found
that the systems with low resolution mass spectrometry in negative chemical ionization mode are capable to fulfill the
requirements for the environmental analyses of dioxins at ppt levels, with the exception of 2,3,7,8-TCDD showing lower
sensitivity in negative chemical ionization. Thus, using the systems with low resolution mass spectrometry in negative chemical
ionization mode may be recommended for the some environmental studies for dioxins in the absence of the systems with high
resolution. On the other hand, the proposed methodology cannot be used for the direct analysis of dioxins without improvement
of 2,3,7,8-TCDD detection and quantification.