Whatman glass fiber filter

The extraction and analysis of soil samples from the MVs for PAH characterization followed the method in Nor et al. [42 ]. In this method, about 500 mg of the soil samples were dissolved using a mixture of 25 mL n-hexane and acetone (7:3, v/v). A microwave extraction arrangement was used with its pressure carefully controlled for 45 minutes. After cooling, the extract was filtered with a Whatman glass fiber filter in a glass bottle, followed by a concentration of the extract to 1.5 mL using a rotatory evaporator. PAH was determined by the GC quadrupole Mass Spectrometer (GC-MSD) (Agilent 5975 MSD). The sample was separated into its components by chromatographic separation using a capillary column of an internal diameter of 30 m×0.25 mm and film thickness of 0.25 μm, HP-5MS and a helium carrier gas of high purity (99.5%), having a flow rate of 1 mL/min from a steel cylindrical pipe. The chromatographic separation conditions include an injector temperature of 250°C and an initial 70°C temperature of the chromatographic column which was held for 1 minute. The temperature increase by 30°C/min to 200°C, by 35°C/min to 250°C, and by 10°C/min to 300°C and this was maintained for 25 minutes. The PAH content of the soil samples was quantified from the resulting chromatogram as earlier reported [43 ,44 ].

The TPH content of the soil samples was extracted according to the methods earlier described by some authors [36 –38 ]. 10 g of the soil sample was carefully mixed with 150 mL dichloromethane which was used as the extraction solvent and extracted for 4 hours 30 minutes. This was done in the presence of 2.5 g of dried sodium sulfate and 300 μg/mL of 1-chloro-octadecane as a surrogate standard. 0.3 g of silica was introduced into the extraction mixture after the extraction to facilitate the adsorption of polar materials like animal fats and oil from vegetable materials. The extracts were later passed through a Whatman glass fiber filter for filtration. The materials not removed by silica gel such as oil and grease were considered PHs [39 ]. The separation and determination of TPH contained in the soil samples were carried out with Gas Chromatography equipped with Flame Ionization Detector (GC-FID) (Agilent 6890N). A concentrated 3 μL of the sample was introduced into the GC column with a micro-syringe previously rinsed with dichloromethane (blank) and the sample. The TPH was determined at a specific chromatogram in mg/kg [40 ,41 ].