Priority pollutants,fluorescence detection

Separation of a Series of Priority Pollutants with Programmed Fluorescence Detection... 

Another useful standard Is SRM 1647, priority pollutant polynuclear aromatic hydrocarbons (in acetonitrile). It can be used to calibrate liquid chromatographic Instruments (retention times. Instrument response), to determine percent recoveries, and to fortify aqueous samples with known PAH concentrations. Figure 8 Illustrates the HPLC separation and UV detection (fluorescence is also used extensively) for the 16 priority pollutants. 

Two analytical methods for priority pollutants specified by the USEPA (38) use HPLC separation and fluorescence or electrochemical detection. Method 605, 40 CFR Part 136, determines benzidine and 3,3-dichlorobenzidine by amperometric detection at +0.80 V, versus a silver/silver chloride reference electrode, at a glassy carbon electrode. Separation is achieved with a 1 1 (v/v) mixture of acetonitrile and a pH 4.7 acetate buffer (1 M) under isocratic conditions on an ethyl-bonded reversed-phase column. Lower limits of detection are reported to be 0.05 /xg/L for benzidine and 0.1 /xg/L for 3,3-dichlorobenzidine. Method 610, 40 CFR Part 136, determines 16 PAHs by either GC or HPLC. The HPLC method is required when all 16 PAHs need to be individually determined. The GC method, which uses a packed column, cannot adequately individually resolve all 16 PAHs. The method specifies gradient elution of the PAHs from a reversed-phase analytical column and fluorescence detection with an excitation wavelength of 280 nm and an emission wavelength of 389 nm for all but three PAHs naphthalene, acenaphthylene, and acenaphthene. As a result of weak fluorescence, these three PAHs are detected with greater sensitivity by UV-absorption detection at 254 nm. Thus, the method requires that fluores-... 

PAHs to demonstrate the excellent potential of CEC by resolving in under 10 min in isocratic mode 16 PAHs classified as priority pollutants by the U.S. Environmental Protection Agency. Yan et al. employed laser-induced fluorescence (LIF) for the detection of PAHs [80]. The limits of detection (LOD) for individual PAHs ranged between 1 nM and 10 pM, as the linear response spanned 4 orders of magnitude in concentration. A sample of 16 PAHs was also tested by Ngola et al. [26] on a new hydrophobic monolith (Figure 16, from Ref. 26). The synthetic procedure was readily transferable to the chip format and the first CEC separations on a chip were reported [26,81] (Figure 17). 

The purpose of this entry is to provide an overview of the main HPLC techniques to determine priority organic pollutants in water. The recent developments in detection techniques (including diode-array detection, fluorescence detection, electrochemical detec-... 

Fluorescence and GC/MS analyses show Chat carbonized coal hydrocarbons are widespread contaminants of sediments In the Elizabeth River, Norfolk, Va. The highest levels are found In the vicinity of suspected sources and generally decrease with Increased distance from these sources. Parent aromatic compounds are the predominant hydrocarbon component of carbonized coal and can be uniquely detected even In the presence of petroleum hydrocarbons. Carbonized coal products are a chronic source of priority pollutant polynuclear aromatic hydrocarbons in the Elizabeth River. 

Ferrer, R., Beltran, J. L., and Guiteras, J., Use of cloud point extraction methodology for the determination of PAHs priority pollutants in water samples by high-performance liquid chromatography with fluorescence detection and wavelength programming. Anal. Chim. Acta, 330, 199-206, 1996. 

Chudyk et al. [IS] reported results obtained in a test of remote fluorescence analysis of groundwater contaminants using UV laser light sources and fiber optics. Several priority pollutants such as phenols, toluene, and xylenes and also naturally occuring humic acid, all of which display UV fluorescence, were readily detected over a distance of 20-25 m. Typical detection limits over this distance are 10 ppb for phenol, 1 ppb for o-cresol, and 0.07 ppb for xylenes. A prototype instrument for monitoring phenolic groundwater contaminants has been described, and its suitability demonstrated by using phenol as a model contaminant [16]. 

Figure 4.56 Comparison of RP-HPLC chromatograms for the separation and detection of a 1-ppm reference standard containing the 16 priority pollutant PAHs between an UV absorbance and fluorescence HPLC detector.

Other separation techniques, such as capillary electrophoresis (CB) and supercritical fluid chromatography (SBC), have been shown to perform well for the separation of phenols. Several papers describing the use of CB for the separation of phenolic compoimds in water samples have been published lately [97-100]. The majority of these employ UV detection, but BSP-MS in the negative-ion mode [101] and indirect fluorescence detection [102] have also been used. In one study, a comparison between HPLC and CB was performed to assess their suitability for the determination of the 11 priority pollutants in water [16]. The authors claim that CB gave a shorter analysis time and smaller matrix effects. However, it was not possible to achieve the desired detection limits without a preconcentration on solid-phase material. 

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