Analysis of PAH

Figure 9. Reversed-phase HPLC analysis of PAH s extracted from SRM 1649, urban dust/organics, with UV detection, not preceded by normal-phase HPLC clean-up, (Reprinted from reference 72.

Cyclodextrin-modified solvent extraction has been used to extract several PAHs from ether to an aqueous phase. Data evaluation shows that the degree of extraction is related to the size of the potential guest molecule and that the method successfully separates simple binary mixtures in which one component does not complex strongly with CDx. The most useful application of cyclodextrin-modified solvent extraction is for the simplification of complex mixtures. The combined use of CDx modifier and data-analysis techniques may simplify the qualitative analysis of PAH mixtures. 

Henry, R., "Principal Component Analysis of PAH Data for Sundsvall", Norsk Instltutt for Luftforsknlng, 1982. 

Lao RC, Thomas RS, Chiu C, et al. 1985. Analysis of PAH and organic compounds in environmental samples. In Cooke M, Dennis AJ, ed. Polynuclear aromatic hydrocarbons. Columbus, OH Battelle, 813-826. 

Ultimately major efforts to develop coupled chromatographic techniques have been performed to alleviate the problem of manual sample pretreatment and to enhance sensitivity and selectivity in the analysis of PAHs in foodstuffs (192) and environmental samples (193-195). Liquid chromatography/MS (196,197), GC/MS (175), HPLC with UV absorbance, fluorescence (177) (see Fig. 4), or electrochemical (ED) detection (179), and ELISA immunoassay (198) have been successfully used for the determination of HAAs. 

Analysis of PAH in air may be done by NIOSH Methods 5506 and 5515 (NIOSH, 1985). Air is passed over a sorbent filter consisting of PIFF and washed XAD-2. The sample volume and flow rate should be 200 to 1000 F and 2 F/min, respectively. The PAH compounds are extracted with a solvent and analyzed by HPFC using a UV or Fluorescence detector. UV absorbance is set at 254 nm. A fluorescence detector is set at excitation 340 nm or emission 425 nm. The solvent extract may be alternatively analyzed by GC-FID using a capillary column. 

Second detector confirmation is another compound confirmation technique. Two detectors with selectivity to different functional groups are connected in series to one column or in parallel to two columns. For example, two detectors, a UV/VIS detector and a fluorometer, connected in series to the HPLC column are used in the EPA Method 8310 for analysis of PAH compounds. If the second detector is connected to a second column of a dissimilar polarity, then the confirmation becomes even more reliable. An example of such a configuration is organophosphorus pesticides analysis the samples may be initially analyzed with an NPD, and then confirmed on a different column with an ECD or a FPD. 

For low detection limit analysis of PAHs, give preference to EPA Method 8270/SIM over EPA Method 8310. The detection limits may be comparable, but analysis with EPA Method 8270/SIM is less affected by interferences from oily matrices. 

MEPS has so far been applied mainly to the analysis of drugs in biological samples only one application for the extraction of PAHs in water has been published.26 One of the major advantages of the MEPS design is that the packed syringe can be used many times over, for example, more than 400 times for water samples. Moreover, the technique permits a fast handling time in the analysis of PAHs in water, the speed enhancement being 15 and 100 times compared to the literature procedures of solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE), respectively see Sections 4.2.3 and 4.2.4. 

On-Line Systems Flowing MMLLE systems have been established in different layouts with automation and on-line hyphenation to GC and HPLC analysis. An automated on-line FS-MMLLE-GC system with a loop-type interface compatible with LVI was used for the extraction of pesticides and PAHs in surface waters.86 In another study, pressurized hot water extraction (PH WE) was coupled on-line to a FS-MMLLE-GC-FID system and applied to the analysis of PAHs in soil, where MMLLE was used as a cleanup and concentration step of the PH WE extract prior to final GC analysis.87 In addition, an HF-MMLLE setup was incorporated in PHWE and GC, resulting in an online PHWE-HF-MMLLE-GC system, where the HF membrane module contained 10-100 HFs. The system served for the extraction and analysis of PAHs in soil and sediments ... 

Kuosmanen, K., T. Flyotylainen, K. Flartonen, J.A. Jonsson, and M.-L. Riekkola. 2003. Analysis of PAH compounds in soil with on-line coupled pressurised hot water extraction-microporous membrane liquid-liquid extraction-gas chromatography. Anal. Bioanal. Chem. 375 389-399. 

Schonmann and Kern [33] have used on-line enrichment for microgram per litre analysis of PAHs in water by high performance liquid chromatography. The trace enrichment method is based on the affinity of non polar pollutants for reversed phase chromatography supports. 

An early reference to the use of high performance liquid chromatography in the analysis of PAHs is the work of Jentoft and Gouw [183] and Vaughan et al. [184], These workers used ultraviolet, visible fluorescence detection and were able to detect 0.4ng of anthracene and 15ng of acenaphthalene. 

Harrison et al. [33] studied the factors governing the extraction and gas chromatographic analysis of PAHs in water. Factors such as initial concentration, presence of suspended solids and prolonged storage of the samples affected considerably extraction efficiencies. It is recommended that water samples should be collected directly into the extraction vessel and that analysis should be carried out as soon as possible after extraction. 

As noted in the preceding table, elution of PAHs is detected by UV absorbance at two different wavelengths 280 nm and 365 nm. Fluorescence detectors are also applicable to the HPLC analysis of PAHs (9, 19). The UV detector monitors the sample simultaneously at two wavelengths, aiding in compound identification. For a specific compound, the ratio of absorbances at two different wavelengths is an intrinsic physical characteristic. Therefore, it is possible, in principle, to identify a sample analyte by this characteristic ratio. The chromatographic retention time of each of the specific peaks observed in the sample eluate is compared with those of known standard compounds for tentative analyte identification. For quantitation, peak areas of each standard, at each of six... 

The analysis of PAHs by fluorescence detection HPLC is often the water analysts first introduction to HPLC. The analysis of the WHO six PAHs (section 11.8.1.1) namely fluoranthene, benzo[6]fluoranthene, henzo[k]fluoranthene, benzo[a]pyrene, benzo[g/j/ perylene and indeno[l,2,3-cd]pyrene was carried out using fixed excitation and emission E wavelengths. With the advent of relatively cheap variable wavelength programmable fluorescence detectors, the detectors can be optimised for each separate PAH with a resultant lowering of detection limit. Ultratrace determination of PAHs down to 180fg of benzo[a]pyrene was reported as early as 1983. 

Figure 4.3.1 Schematic diagram of the procedure used for direct front-face fluorimetric analysis of PAHs in fortified Maas river water after adsorption on a tab-shaped element cut from a Cig extraction disk...

The spiking solution for analysis of PAHs in RM07 was prepared also in acetonitrile. The robustness of the reconstitution protocol for this spring water was verified by the Organic Analysis Laboratory of the RM Unit at IRMM. Several samples were analysed following the protocol for liquid-liquid extraction given to the PT participants. The standard deviation for reconstitution was found to be lower than 10% for all 9 PAHs included in the study. 

Wood, L.W., O Keefe, P. and Bush, B. (1997) Similarity analysis of PAH and PCB bioaccumulation patterns in sediment-exposed Chironomus tentans larvae. Environ. Toxicol. Chem., 16, 283-292. 

Lamotte M, Rima J, Garrigues P, et al. 1985. Quantitative analysis of PAH (polynuclear aromatic hydrocarbons) in environmental samples by fluorometry in Shpol skii matrices at low temperature. Polynuclear Aromatic Hydrocarbons 785-798. 

Saber A, Morel G, Paturel L, et al. 1991. Application of the high-resolution low temperature spectrofluorometry to analysis of PAHs in lake sediments marine intertidal sediments and organisms. Fresenius J Anal Chem 339(10) 716-721. 

Case Study Quick Turnaround Analysis of PAHs... 

Case Study Quick Turnaround Analysis of PAHs by HPLC in Multimedia Samples This case study describes quick turnaround HPLC methodologies for the analysis of 16 priority pollutant PAHs in multimedia samples such as contaminated soil, air particulate matter, used engine oil, and... 

High-molecular-mass PAHs — There has been increased interest in the analysis of PAHs with molecular mass >328. This has resulted in the development of GC columns that withstand temperatures up to 370°C, and these have been used for resolution of PAHs in carbon black and in coal-tar extracts with seven rings (benzo[c]picene, Mr 328), eight rings (benzo[a]coronene, Mr 350), and nine rings (d ibenzo[a,/ ]coronene, Mr 400) (Berngard et al. 1993). 

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