Mass Spectrometry & Spectroscopy
Ultra-low Level Analysis of Dioxins in Food using a triple quadrupole mass spectrometer (MS/MS) with Boosted
Effi ciency Ion Source Masato Takakura1
and Eberhardt Kuhn2 1
Masato-t@shimadzu.co.jp 2
Shimadzu Corporation, Analytical & Measuring Instruments Division, Kyoto, 604-8511, Japan, +81-75-823-1334; Shimadzu Scientifi c Instruments, Marketing Department, Columbia, MD 21046, USA, +1-410-910-0910;
erkuhn@shimadzu.com
Dioxins are a class of very toxic compounds found throughout the world in the environment. Equipment sensitivity is of great importance for the analysis of low concentrations of these highly-toxic compounds. Historically, analysis and detection of dioxins was done with magnetic sector-type high-resolution mass spectrometers (HRMS). However, in recent years, the performance of triple quadrupole mass spectrometers (MS/MS) has improved signifi cantly. In addition, the development of the Boosted Effi ciency Ion Source (BEIS) offers compound-specifi c sensitivity up to 4 times greater than previous ion sources and provides accurate quantitation of dioxins at levels comparable to HRMS. Detection limits as low as 20 fg for Tetrachlorodibenzo-p-dioxin (TCDD) were achieved. In this study, we analysed dioxins in about 250 samples of approximately 40 types of food and animal feed products using a GC-MS/MS with BEIS. Quantitation performance was evaluated by comparing the analysis results obtained by GC-HRMS and GC-MS/MS. We also evaluated the number of analyses possible while maintaining sensitivity at low concentrations in order to verify the durability of the GC-MS/MS instrument.
Introduction
Dioxin and Furan are the frequently used short names for polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) [1]. They belong to a group of toxic compounds known as Persistent Organic Pollutants (POPs) because they take a long time to break down in the environment. As such, dioxins are highly toxic to humans [2]. They are unwanted by-products of a wide range of manufacturing processes, including smelting, chlorine bleaching of paper pulp, and waste incineration. In nature, dioxins can be created by forest fi res and volcanic eruptions.
PCDD/Fs have long been an environmental concern. Due to their tendency to accumulate in biological tissues and their toxicity to biota, PCDD/Fs have received more widespread concern and have recently fallen under the scrutiny of the global food community.
At the same time, because of their extremely low level, they have been used as one of the benchmarks for evaluation the performance of the analytical instruments. In this study, seventeen congeners of dioxin were analysed by GC-MS/MS (Model GCMS-TQ8050 NX, (Shimadzu Corporation) in combination with Boosted Effi ciency Ion Source (BEIS). The developed instrument method was applied to real sample analysis, and the results (on a TEQ level basis) from the GC-MS/MS were consistent with results from GC-HRMS. The latter is the traditional method for analysis of dioxins [3, 4]. Durability of the instrument and ruggedness of the method was also evaluated with no decrease in sensitivity observed after more than 500 samples at low concentrations.
By optimising the focal point of the electron beams, the rate at which electron collide with the molecule is increased. Although the same number of electrons are produced by the fi lament, the ionisation rate is increased. This enables up to four-times higher sensitivity compared to previous ion sources. However, depending on the actual usage, the lifetime of the fi lament may be slightly shortened.
Materials and Methods Samples and Analysis Conditions All food and feed samples were prepared using automatic
BEIS was developed (Shimadzu Corporation) to maximise ionisation effi ciency through optimising the focal point of the electron beam in EI ionisation. This image illustrates the principle of BEIS:
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