Universal Route to Polycyclic Aromatic Hydrocarbon
Analysis in Foodstuff: Two-Dimensional Heart-Cut Liquid Chromatography–Gas Chromatography–Mass Spectrometry
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Abstract
Analysis of polycyclic aromatic hydrocarbons
(PAHs) in complex
foodstuff is associated with complicated and work-intensive sample
preparation. Chromatographic interference has to be faced in many
situations. The scope of the current work was the development of a
highly efficient two-dimensional heart-cut LC-LC-GC-MS method. Detection
was performed with a time-of-flight mass spectrometer (TOF-MS) to
allow for a comprehensive evaluation of the obtained data in terms
of cleanup efficiency. Additionally, routine detection was performed
with single quadrupole MS. An easy and quick generic sample preparation
protocol was realized as a first step. During method development,
focus was given to optimizing HPLC cleanup for complex foodstuff.
Silica-, polymeric-, and carbon-based HPLC phases were tested. Coupling
of silica gel to π-electron acceptor modified silica gel showed
the best cleanup properties. A four rotary valve configuration allowed
the usage of a single binary HPLC pump. Screening of several fatty
and nonfatty food matrices showed the absence of unwanted matrix compounds
in the cleaned-up PAH fraction down to the low picogram range using
TOF-MS. Limits of quantitation (LOQ) were below 0.1 μg/kg for
all EU priority PAHs. Recovery rates ranged from 82 to 111%. Validation
data fully complied with EU Regulation 836/2011. Sample preparation
was possible in 20 min. Interlacing of HPLC and GC allowed an average
method runtime of 40 min per sample