Evaluating the impact of extraction and cleanup parameters on the yield of total petroleum hydrocarbons in soil

Abstract

Interlaboratory comparisons for the analysis of mineral oil in polluted soil using the GC-FID method indicate that extraction and cleanup conditions have significant effects on the analytical results. In this investigation a ruggedness test was performed on the extraction and cleanup method for the determination of total petroleum hydrocarbons in soil. A two-level Plackett-Burman design was utilized to study the effect of 11 different method parameters on the extraction recovery of total petroleum hydrocarbons (TPH) in soil. Both qualitative and quantitative factors were investigated. The results indicate that total petroleum hydrocarbons can be relatively reliably monitored through strict implementation of the ISO and CEN draft standards. However, variation in certain method parameters readily affects the validity of the results. The most critical factors affecting TPH recovery were the solvent and co-solvent used for extraction, the extraction time, adsorbent and its weight and sample TPH concentration. Because adaptation of the draft standards especially with respect to these factors easily leads to TPH recoveries higher than 200% or lower than 70%, the validity of the adapted method should always be verified. A proper estimate of the expanded uncertainty should also be appended to TPH results, because only then can the reliability of the results be guaranteed and further justification is gained to support the end-use of the data. This also supports the credibility of the analytical services and prevents the data end-users from drawing misleading conclusions concerning the environmental risks and potential remediation requirements.

A simple and rapid method for determination of petroleum oils in sewage sludge samples with ultrasonic solvent extraction by infrared spectrophotometry under optimized analytical conditions

“…The comparability and reliability of analytical methods for the determination of petroleum hydrocarbon are deficient. The use of different analytical methods [10][11][12][13][14][15] partially leads to slow method standardization, a long lack of certified reference materials, and differing environmental regulations on which hydrocarbons are to be included in the analysis. 16 Few research focuses on the determination of petroleum oils in sewage sludge samples in past literature.…”

“…Traditional Soxhlet extraction which is recommended by ISO (ISO/DIS 16703:2011) and US EPA (EPA Method 9071A), accelerated solvent extraction, solid phase micro extraction, microwave-assisted extraction, ultrasonic solvent extraction, and supercritical fluid extraction are the most frequently used extraction methods. [11][12][13][14][15][17][18][19] Soxhlet extraction provides stable test results, however, it takes lengthy extraction times (4 h per sample) and large volumes of organic solvents. [19][20][21][22] Accelerated solvent extraction, solid phase micro extraction, and supercritical fluid extraction need special and expensive instruments, and they are not well suited for routine analysis.…”