The Malaysian Journal of Analytical Sciences Vol. 12 No. 1 (2008) 46 APPLICATION OF SOLID PHASE MICROEXTRACTION (SPME) IN PROFILING HYDROCARBONS IN OIL SPILL CASES Zuraidah Abdullah Munir*, Nor’ashikin Saim, Nurul Huda Mamat Ghani Department of Chemistry, Faculty of Applied Sciences, Universiti Teknologi MARA 40450 UiTM Shah Alam, Selangor, Malaysia. Keywords: Profile of hydrocarbon, solid phase microextraction (SPME), oil spill Abstract. In environmental forensic, it is extremely important to have a fast and reliable method in identifying sources of spilled oil and petroleum products. In this study, solid phase microextraction (SPME) method coupled to gas chromatography-mass spectrometry was developed for the analysis of hydrocarbons in diesel and petroleum contaminated soil samples. Optimization of SPME parameters such as extraction time, extraction temperature and desorption time, was performed using 100-µm polydimethylsiloxane (PDMS) fiber. These parameters were studied at three levels by means of a central composite experimental design and the optimum experimental conditions were determined using response surface method. The developed SPME method was applied to determine the profiles of hydrocarbons in several oil contaminated soil sample. The SPME method was also used to study the effects of weathering on the profiles of hydrocarbons in unleaded gasoline, diesel and kerosene contaminated soil samples. After several days, significant losses of the lighter hydrocarbons were observed compared to the heavier ones. From these data, SPME method can be used to differentiate possible candidate sources in oil spill cases. Introduction Gasoline, diesel and kerosene are all created from crude oil by a variety of refining and distillation processes. Each product is produced by the combination of multiple individual hydrocarbon compounds all of which have slightly different vaporization and boiling temperatures. Gasoline is the combination of many lower boiling range compounds while the middle boiling range compounds are used in differing proportions to create kerosene and diesel. The profile of hydrocarbons in oil may hence be used to characterize the oil. This enables the identification of the candidate source of oil spill cases. In forensic chemistry, ability to identify the sources of an oil spill is very important and hydrocarbon fingerprinting method is now realized as one of the fastest and reliable method for identifying the origin of oil spill cases. In this study, a solid phase microextraction (SPME) method coupled to gas chromatography with mass spectrometry detector (GC-MSD) was developed for analyzing the profile of several types of oils. The simplicity of operation, sensitivity, selectivity, portability, and the solvent-free nature of the SPME method makes it a powerful tool for sample introduction method for gas chromatographic analyses of organic chemicals [1]. It is based on the enrichment of analytes on a polymer or adsorbent-coated fused-silica fiber either directly to the sample or its headspace. The extraction efficiency of SPME technique is dependent on several experimental parameters such as the extraction time, extraction temperature and desorption time [2,3]. These operating parameters were optimized using an experimental design approach that consisted of three stages; identifying the factors which may affect the result of an experiment, designing the experiment so that the effects of uncontrolled factors are minimized, and using statistical analysis to separate and evaluate the effects of the various factors involved. The optimized SPME method was used to analyze the effect of weathering on three types of oils: unleaded gasoline, diesel and kerosene. EXPERIMENTAL Preparation of spiked sample Three types of oil (unleaded gasoline, diesel and kerosene) were used in this study. About 1 L of each type of oil was poured into three separate plots of soil. After 2 weeks, the contaminated soil for each plot was mixed thoroughly, sieved and stored in an amber bottle at -4 ˚C until analysed for optimizing the experimental conditions.