Polycyclic aromatic hydrocarbon analysis limitations

Limited data is available on the concentration of volatile organic compounds, semi-volatile organic compounds (SVOCs), and polycyclic aromatic hydrocarbons (PAHs) from gasification processes. The data that is available indicate that VOCs, SVOCs, and PAHs are either non-detectable in flue gas streams from IGCC process or, in some cases where they were detected, they are at extremely low levels (on the order of parts per billion and lower). The analysis of syngas also indicates greater than 99.99 percent chlorobenzene and hexachlo-robenzene destruction and removal efficiencies and part per billion or less concentration of selected PAHs and VOCs.9-14... 

The use of semi-permeable silicone rabber membranes for on-line analyte-enrichment in LC-MS was described in 1974 by Westover et al. [53]. Polycyclic aromatic hydrocarbons were analysed by MS after evaporation of the reversed-phase LC column effluent and passage of the vapom through a membrane-based solvent-separator. This system, designed by Jones et al. [54], is limited to the analysis of non-polar analytes which are sufficiently volatile at 250°C, the maximum operating temperature of the membrane. 

Electrochemical immunosensors have been widely used for environmental analysis in amperometric, potentiometric, and conductimetric configurations. Amperometric immunosensors measure the current generated by oxidation or reduction of redox substances at the electrode surface, which is held at an appropriate electrical potential. Wilmer et al. measured concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) in water by using an amperometric immunosensor with a limit of detection of 0.1 Jtg L-1 (Wilmer et al., 1997). Some examples of new developments are the disposable screen-printed electrodes for the detection of polycyclic aromatic hydrocarbons (PAHs)... 

Huckel s rule should not be applied to polycyclic aromatic hydrocarbons (Section 11.8). Huckel s analysis Is limited to monocyclic systems. 

Because of the large scale dilution of contaminants in the aquatic matrices, concentrations of many organic pollutants are below the detection limits of standard analytical and sampling methods. Thus, gas chromatography with specific detection methods such as electron capture detector and HPLC has been frequently used for analysis of pesticides and polycyclic aromatic hydrocarbons in water and biological samples. 

Formation, factors affecting concentrations, legal limits and occurrence of polycyclic aromatic hydrocarbons in smoked meat products and smoke flavor additives are briefly reviewed by Simko. The most widely employed techniques such as thin-layer chromatography (TLC), gas chromatography (GC), and high-performance liquid chromatography (HPLC) are evaluated. Moreover, sample preparation, pre-separation procedures, separation and detection systems being used for the determination have been evaluated with emphasis on the latest developments in applied food analysis and... 

The results of PAH analysis with different types of interfaces (e.g. ESI, APCI, PBI and TSP - were reported by Clench et al. reviewing the state of the art of various mass spectral techniques [28]. For more polar PAHs pneumatically assisted ESI-LC-MS was used to determine mixtures of hydroxy polycyclic aromatic hydrocarbons. The abundance of ions dependent on flow rates was shown. ESI inonization was found to be less sensitive compared to APCI ionisation [304]. PAH analysis with ESI-LC-MS combined with RP-LC with post-column addition of silver nitrate was applied for the determination of 10 PAHs in river water. PAHs resulted in [Mj and [M-i-Ag]. The detection limits of different PAHs in spiked samples ranged from 0.001 to 0.03 pg L [442]. 

The extractible fraction itself contains hundreds of compounds, and only a limited number can be routinely analysed. Among these molecules, the family of polycyclic aromatic hydrocarbons has been by far the most extensively studied, in terms of mechanism and properties. PAH are indeed quite easily produced in laboratory flames and can be routinely analysed, at least for molecdles with masses lower than 300 a.m.u. During the workshop, several papers have discussed in detail the analysis of polycyclic organic matter. However, as a brief introduction, it is useful to define the different compounds considered. 

Anthropologic sources for polycyclic aromatic hydrocarbons (PAH) and their emission factors are discussed. The major sources are divided into two categories, stationary sources (such as industrial sources, residential heating, power and heat generation, incineration and open fires) and mobile sources (such as cars, trucks and airplanes). The emission factor for each source of each category is established. Uncertainties in the emission factors are introduced by limited data from each source, different sampling methods, and different methods for PAH analysis. 

Fluorescence spectroscopy plays an important function in modern food analysis as can be seen from its wide use in the determination of numerous food components, contaminants, additives, and adulterants. This technique has made available very sensitive and selective methods that satisfy the requirements of food analysis, which are usually very complex, taking into account the large number of species to be determined, frequently at very low concentrations, and the wide variety of foodstuffs available. Initially, the use of fluorescence spectroscopy in food analysis was limited to the determination of species with intrinsic fluorescence (e.g., vitamins, aflatoxins, and some polycyclic aromatic hydrocarbons (PAHs)), but now it is widely applied to nonfluorescent species, using several physicochemical means such as chemical or photochemical derivatization reactions. Numerous techniques involve fluorescence detection in liquid chromatography (LC), frequently using pre- or postcolumn derivatization. In addition to conventional fluorime-try, which is commonly chosen for this purpose, other fluorimetric techniques such as laser-induced... 

Polycyclic aromatic hydrocarbons (PAHs) have routinely been analyzed by GC and LC. However, both techniques have limitations in terms of analyte molecular weight and analysis time. The greater molecular weight range of SFC... 

Fluorometry is used to determine elements such as boron, silicon, aluminum, beryllium, and zirconium [7], [129], [130], as well as organic compounds [131] (e.g., vitamins [132]). An important application in the field of trace analysis is the determination of aromatic hydrocarbons in wastewater [133], Here, the limits of detection can be improved considerably [64] if fluorescence is excited by a laser (LIF). This is very important for the measurement of polycyclic aromatic hydrocarbons [134],... 

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