Solid phase micro extraction combined with gas chromatography-mass spectrometry for the trace analysis of polycyclic aromatic hydrocarbons in chocolate

Abstract

A brisk, lucrative, sensitive and reliable Solid Phase Micro Extraction (SPME) method combined with Gas Chromatography-Mass Spectrometry (GC-MS) is developed for the simultaneous trace level determination of 16 Polycyclic Aromatic Hydrocarbons (PAHs) in chocolate samples. Various parameters such as extraction temperature, extraction time, stirring speed, ionic strength or salting out effect, pH effect, desorption temperature and time that can affect the extraction efficiency were thoroughly studied. The sensitivity of the proposed method was evaluated and compared with that of Gas Chromatography-Flame Ionisation Detection (GC-FID) and GC-MS in both the full scan acquisition and selected ion monitoring (SIM) mode. The detection (S/N = 3) and quantification limits (S/N = 10) for GC with FID, MS in full scan acquisition and in SIM mode were found to be in the range of 0.1–3.3 ng g⁻¹, 0.04–1.11 ng g⁻¹, 0.004–0.44 ng g⁻¹ and 0.3–11 ng g⁻¹, 0.13–3.69 ng g⁻¹, 0.01–1.46 ng g⁻¹ respectively. The method showed good linearity behavior with coefficients of correlation (R²) ranging between 0.991–0.998, 0.989–0.998 and 0.991–0.999 for GC with FID, MS in full scan acquisition and SIM mode, respectively. The method was validated by its application to the determination of 16 PAHs in spiked chocolate samples. Average recoveries were found to vary between 84.7 and 105% for individual PAH at three spiked concentration levels, which illustrates that the optimized method was not greatly affected by the sample matrix for the determination of 16 PAHs. Moreover, the presented method that combines the advantage of SPME with GC has high sensitivity and can easily be applied in the determination of PAHs in real chocolate samples as well as their related products.