EXPRESS ANALYSIS OF MOIST SOILS CONTAMINATED WITH PETROLEUM HYDROCARBONS USING SODIUM SULFATE AS A CHEMICAL DESICCANT

Sample preparation is a relevant problem in the quantitative analysis of natural moist soil samples for volatile petroleum hydrocarbon content. Drying the soil to an air-dry state leads to the loss of the most volatile hydrocarbons, while analyzing moist natural soil without preparation does not allow complete extraction of petroleum products, leading to underestimated results. Existing methods that enable complete extraction of petroleum hydrocarbons are time-consuming. The results of analysis are also influenced by the mass of the moist soil sample used for a single analysis and the number of repeated sample studies. This work investigates the possibility of using anhydrous sodium sulfate as a drying agent for analyzing moist natural soil contaminated with diesel fuel. To determine the completeness of petroleum product extraction from moist soils, sample preparation methods with drying to air-dry state, drying with sodium sulfate, and analysis without preparation were compared. The possibility of increasing the accuracy and precision of analysis was evaluated when extracting diesel fuel from aliquots of 2, 10, and 15 g of model contaminated sand and moist natural soil. Each measurement was performed in 2, 5, and 7 replicates. It was established that chemical drying of moist soil with anhydrous sodium sulfate leads to the most complete extraction of petroleum products from moist soil, and using 15 g aliquots and performing seven replicate measurements increases the accuracy of the analysis.