Method Of Analysis

Method of Analysis Analyzing polycyclic hydrocarbon mostly done by comparing the reserve phase and normal phase chromatographic condition. The most widely used technique for analyzing polycyclic hydrocarbon are gas chromatography (GC) with either flame ionization detection (FID) or mass spectrometry detection (MSD), and high performance liquid chromatography (HPLC) with ultraviolet detection (UVD) or fluorometric detection (FMD). Other techniques that have also been used are thin-layer chromatography (TLC) with UVD or FLD, supercritical fluid chromatography (SFC) with UVD or MSD and liquid chromatography (LC) with MSD. In using liquid chromatography (LC), the UVD and FMD are widely used for measurement of the compounds. UVD does provide nearly universal detection of polycyclic hydrocarbon. While FMD on the other hand, offers far more higher sensitivity and selectivity than UVD since there a fewer compounds are fluorescent than UV absorbant. Mass spectrometry has gained wide acceptance for the analysis of polycyclic hydrocarbon. Although the technique is generally less sensitive than UV absorption and fluorescence methods, it does provide much meaningful information about a complex mixture of polycyclic hydrocarbon, because of the characteristically simple mass spectra obtained from these compounds. MSD can be used in combination with GC or LC. However, LC-MSD instruments are somewhat costly and, moreover, the union of LC with MS is not so easy, as compared with GC. As a consequence, GC-MSD instruments are more popular than LC-MSD. A comparison between LC-FLD and GC-MSD for the determination of polycyclic hydrocarbon in environmental samples has shown that accurate results can be achieved by both techniques. However, anthracene and perylene were measured more accurately and precisely using LC-FLD due to the high sensitivity and selectivity of fluorescence detection for these compounds. Currently, polycyclic hydrocarbon most commonly analysed by using HPLC or GC-MSD – techniques which requires long, high resolution separation and complicated MSD method. Another new technique that have been developed is atmospheric pressure photoionization. This technique uses the energy of photons to generate ions from the vaporized eluent of an LC. Reference: Manoli, E & Samara, C. 1999. Polycyclic aromatic hydrocarbons in natural waters: sources, occurrence and analysis. Trends in Analytical Chemistry 18(6). 417-428.