Polyaromatic hydrocarbons extraction efficiency

Significant differences at the 99% confidence level were observed for the extraction technique and for the polyaromatic hydrocarbons concentration in the soil. The average recovery by the Soxhlet technique was 74.5% whereas 62.8% was the average Polytron recovery. A much higher proportion was extracted with polyaromatic hydrocarbons at the 50pg/g level (72.6%) than at the 5pg/g level (64.6%) suggesting that the extraction efficiency is not constant with concentration. 

Lagenfeld et al. [48] studied the effect of temperature and pressure on the supercritical fluid extraction efficiencies of polyaromatic hydrocarbons and polychlorobiphenyls in soils. At 50°C raising the pressure from 350 to 650atm had no effect on recoveries. 

Polyaromatic hydrocarbons Study of effect of suspended solids on extraction efficiency of PALI from water and sampling techniques <0.1 Pg L- [35]... 

These compounds are another example of nonionic, nonpolar compounds. They are found in trace levels in water and result from combustion processes and hydrocarbon spills. They are trace enriched from water by sorption onto CN, C-8, or C-18 and elution with ethyl acetate/toluene. Toluene is added to the ethyl acetate eluent to increase solubility of the polyaromatic hydrocarbons (PAHs) and to enhance elution from the solid phase. The more hydrophobic PAHs, such as pyrene (Fig. 7.11), will recover more efficiently from a more polar reversed phase, such as CN or C-8 due to less strong van der Waals interactions between the analyte and the sorbent. The PAHs may be analyzed by either GC/MS or by HPLC. Soil samples may be processed as in Section 7.10.2 with 90% methanol extraction, followed by dilution with... 

It has been coupled with enzyme immunoassay for efficient and fast polyaromatic hydrocarbon (PAH) screening in soil [21]. In a number of studies both static and dynamic superheated water extraction has been coupled to solid-phase microextraction [15, 25, 28, 30, 35, 38], sometimes with other analytical methods also coupled. It has been coupled with gas chromatography-mass spectrometry [31], capillary electrophoresis [31], liquid chromatography-mass spectrometry [32] and liquid chromatography-gas chromatography [41]. Sometimes other chemicals are added to the water used, such as acid [42] or phosphate buffer [43]. Different trapping methods for analytical extraction have been examined [44]. 

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