An alternative to trial and error methodology in solid phase extraction: an original automated solid phase extraction procedure for analysing PAHs and PAH-derivatives in soot†
This paper introduces the generalization of reverse-phase HPLC fundamentals to normal-phase liquid chromatography and Automated Solid Phase Extraction (A-SPE). This paper upholds that the same fundamentals and principles of reverse-phase HPLC are also applicable in normal phase HPLC and A-SPE. Based on these fundamentals, we could overlook the trial and error method and accomplish a rational and fast selection of the most suitable SPE procedure for analyzing aromatic hydrocarbons and polar-aromatic-hydrocarbons in soot from methyloctanoate–kerosene blends. These fundamentals and procedure could be applied to any sample. Application to soot samples was carried out for demonstrating the high efficiency of the procedure to very complex matrices. The analytical methodology introduced here consists of: (i) creating a solution of the soot sample in hexane, (ii) extraction of the target analytes by filtration twice through PTFE filters, (iii) A-SPE fractioning through a silica column by using an HPLC pump and hexane at a flow rate of 0.05 ml min−1 as the mobile phase, and (iv) analysis of the fractions collected by reverse-phase HPLC with a photodiode array detector (PDA). The methodology developed was successfully applied to the identification of 56 PAHs and 44 PAH-derivatives (belonging to 14 different chemical classes) in soot from methyloctanoate–kerosene blends in a reproducible, simple, and environmental friendly way. The aforementioned procedure can be implemented in any lab with an HPLC system.