Ultra-fast gas chromatographic with flame ionization detector (UFGC-FID) and sonication methods for determination of total petroleum hydrocarbons fractions and BTEX in soil

Abstract

In the environmental monitoring at gas stations, total petroleum hydrocarbons (TPH) and aromatic hydrocarbons, such as benzene, toluene, ethylbenzene, and xylenes (BTEX), are determined to verify soil contamination. However, the determination by conventional GC requires a long time of analysis and expensive autosamplers for volatile compounds extraction. Therefore, the present work aimed at the development, validation, and application of ultra-fast chromatographic methods with flame ionization detector (UFGC-FID) capable of determining the TPH fractions (GRO, DRO, and ORO) and BTEX in a faster and less costly way than conventional methods. In addition, sonication extraction methods were developed and validated for two groups of compounds (volatile and semivolatile). The optimum conditions of the extraction methods were obtained through regression models generated from designs of experiment (DOE). The UFGC-FID methods provided determinations in 5 min and presented good linearity (R2 > 0.997), selectivity (Rs > 1.00), sensitivity (γ > 0.02 mg kg− 1), precision (repeatability <7%), and accuracy (recoveries between 70% and 130%). Moreover, the BTEX solutions prepared in ethanol showed great intermediate precision (RSD < 1%) when stored at −19 °C over a period of 15 days. The optimized sonication method provided extractions in 13.5 min per sample and presented relative standard deviations (RSD) <7% and recoveries between 70% and 130%. Therefore, the environmental monitoring can be a faster, lower costly, and more environmentally friendly process through UFGC-FID associated with sonication extraction methods.