Rapid Analysis of Wet Soils Contaminated with Oil Hydrocarbons Using Sodium Sulfate as a Chemical Drying Agent

Sample preparation is a pressing issue in the quantitative analysis of natural wet soil samples for volatile petroleum hydrocarbons. The drying of soil to an air-dry state resulted in the loss of the most volatile hydrocarbons, while analysis of wet natural soil without sample preparation did not allow for complete extraction of petroleum products, and this led to underestimated results of the analysis. Currently available methods that make it possible to completely extract petroleum hydrocarbons are time consuming. The results of analysis are also affected by the sample weight of wet soil used for a single analysis and the number of repeated sample examinations. In this work, we investigated the possibility of using anhydrous sodium sulfate as a drying agent for the analysis of wet natural soil contaminated with diesel fuel. To determine the completeness of petroleum product extraction from wet soils, we compared sample preparation procedures with soil dying to an air-dry state and drying with sodium sulfate and also the analysis without sample preparation. The possibility of increasing the accuracy and precision of the analysis was assessed by extracting diesel fuel from 2-, 10-, and 15-g portions of model contaminated sand and wet natural soil. Each measurement was performed in two, five, and seven repetitions. It was found that chemical drying of wet soil with anhydrous sodium sulfate led to the most complete extraction of oil products from wet soil, and the use of 15-g samples and seven repeated measurements resulted in an increase in the accuracy of the analysis.