Determination of Four Priority Polycyclic Aromatic Hydrocarbons in Food Samples by Gas Chromatography - Mass Spectrometry (GC-MS) after Vortex Assisted Dispersive Liquid-Liquid Microextraction (DLLME)

Dispersive liquid-liquid microextraction (DLLME) is a useful preconcentration technique but its direct application is limited to aqueous samples. Two pretreatment methods for solid samples, QuEChERS (quick easy cheap efficient rugged and safe) and a standard method, were used to isolate four polycyclic aromatic hydrocarbons (PAHs) from the sample matrix. However, since these methods result in analyte dilution, DLLME was used to augment them by concentrating the analytes from 8.0 mL of sample into 150 mu L of 1,2-dichloroethane. Under the optimum conditions, the instrumental detection limit was enhanced by approximately 100-fold for chrysene, benzo[a]pyrene, benz[a]anthracene, and benzo[k]fluoranthene with corresponding detection limits of 29, 29, 30, and 28 ng/L, respectively. The precision of the method based on inter-analyst and inter-day analysis yielded relative standard deviations less than 9.0 and 4.0%, respectively. The optimized method was applied to snail samples spiked at 5.0, 10, 20, and 50 ng/g and the recoveries were nearly 100%. Matrix matched standards were also used to determine the recoveries; the results did not vary significantly from the direct calibration recoveries.

Automated summary

The study demonstrated the enhancement of DLLME in conjunction with QuEChERS and standard methods for the preconcentration and analysis of PAHs with improved instrumental detection limits and stable precision. Application to snail samples showed nearly 100% recoveries, indicating the effectiveness and reliability of the optimized method.