Highly sensitive determination of polycyclic aromatic hydrocarbons in ambient air dust by gas chromatography-mass spectrometry after molecularly imprinted polymer extraction.

A method based on solid--phase extraction with a molecularly imprinted polymer (MIP) has been developed to determine five probable human carcinogenic polycyclic aromatic hydrocarbons (PAHs) in ambient air dust by gas chromatography-mass spectrometry (GC-MS). Molecularly imprinted poly(vinylpyridine-co-ethylene glycol dimethacrylate) was chosen as solid-phase extraction (SPE) material for PAHs. The conditions affecting extraction efficiency, for example surface properties, concentration of PAHs, and equilibration times were evaluated and optimized. Under optimum conditions, pre-concentration factors for MIP-SPE ranged between 80 and 93 for 10 mL ambient air dust leachate. PAHs recoveries from MIP-SPE after extraction from air dust were between 85% and 97% and calibration graphs of the PAHs showed a good linearity between 10 and 1000 ng L(-1) (r = 0.99). The extraction efficiency of MIP for PAHs was compared with that of commercially available SPE materials--powdered activated carbon (PAC) and polystyrene-divinylbenzene resin (XAD)--and it was shown that the extraction capacity of the MIP was better than that of the other two SPE materials. Organic matter in air dust had no effect on MIP extraction, which produced a clean extract for GC-MS analysis. The detection limit of the method proposed in this article is 0.15 ng L(-1) for benzo[a]pyrene, which is a marker molecule of air pollution. The method has been applied to the determination of probable carcinogenic PAHs in air dust of industrial zones and satisfactory results were obtained.

Molecularly imprinted nanoporous polyacrylate surface for benzo(alpha)pyrene recognition.

Molecularly imprinted polymers (MIPs) were synthesized using co-polymerization of methacrylic acid with cross-linking agent ethylene glycol dimethacrylate in the presence of benzo(alpha)pyrene (BAP) followed by the extraction of BAP from cross-linked polymer matrix. The MIP formed by this way contains nanopores, which are geometrically specific to the BAP molecule. BAP belongs to one of the carcinogenic airborne atmospheric pollutants. Morphological characteristics of MIP showed presence of nanopores with an average pore diameter of 27.19 A and Brunauer-Emmett-Teller (BET) surface area of 827.87 +/- 1.63 m2g(-1). The adsorption capacity of BAP onto MIP was determined using equilibrium experiments. The cross-reactivity (CR) experiments were also conducted to found selectivity of BAP in the presence of 5 other polyaromatic hydrocarbon (PAH) compounds. The selectivity factors were calculated for MIP, based on experimental data derived from CR studies. It was found that the PAH molecules smaller being in molecular length (pyrene) than BAP, showed higher interference (up to 40%) compared with other PAH compounds. By increasing the concentration of other PAH compounds (100 microg mL(-1)), the selectivity (alpha) of MIP was reduced from 3.5 to 1.6. The value of equilibrium binding constant for BAP, K(E) = 0.236 microg mL(-1), was larger than other PAH compounds (K(E) values range from 0.011 to 0.028 microg mL(-1)). These properties demonstrate that MIP prepared shows greater binding capacity and selectivity due to creation of homogenous nanopores patterned uniformly in the polymer matrix. This method of preparation of ordered materials at micro and nano-scale are useful in the field of nanodevices and sensors for environmental, defense and biomedical applications.

Fluorescence spectrophotometer analysis of polycyclic aromatic hydrocarbons in environmental samples based on solid phase extraction using molecularly imprinted polymer.

A molecularly imprinted polymer (MIP) was synthesized using a polycyclic aromatic hydrocarbon (PAH) standard as a template, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and acetonitrile as a porogen. This polymer was used as a solid phase adsorbent for the quantitative enrichment of PAHs in coastal sediments, atmospheric particulates, and industrial effluents. The MIP selective adsorption capacity for PAHs started reducing when the chemical oxygen demand (COD) and total dissolved solids (TDS) was more than 800 mg L(-1) in the targeted environmental samples. The adsorption stability of the MIP was tested by the consecutive contact of environmental samples, and it was shown that the performance of the MIP did not vary after 10 enrichments and desorption cycles. Recoveries of eight PAH compounds, extracted from 10 g of coastal sediments and 1 L of industrial effluent spiked with 10 microL of standard PAHs, showed recoveries between 85 and 96%. The fluorescence spectrophotometer limit of detection of PAHs varied from 10 to 30 etag L(-1) in industrial effluent and from 0.1 to 2.9 etag kg(-1) in solid samples (coastal sediment and atmospheric particulates), and this indicates that the environmental analytical method is significantly sensitive, when compared with other commonly used methods such as gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry.