Parallel factor analysis of 4.2K excitation-emission matrices for the direct determination of dibenzopyrene isomers in coal-tar samples with a cryogenic fiber optic probe coupled to a commercial spectrofluorimeter

Several studies have shown high concentrations of polycyclic aromatic hydrocarbons (PAHs) in living spaces and soil adjacent to parking lots sealed with coal-tar-based products. Recent attention has been paid to the presence of seven PAHs in coal-tar samples ? namely, benz[a]anthracene, benzo[k]-fluoranthene, benzo[b]fluoranthene, benzo[a]pyrene, chrysene, dibenz[a,h]anthracene, and indeno[1,2,3-cd]pyrene ? and their association to significant increases in estimated excess lifetime cancer risk for nearby residents. Herein, we present an analytical approach to screen the presence of five highly toxic, high-molecular weight PAHs (HMW-PAHs) in coal-tar samples. These include dibenzo[a,l]pyrene, dibenzo[a,i]pyrene, dibenzo[a,e]pyrene, dibnezo[a,h]pyrene and naphtho[2,3-a]pyrene. Their direct analysis ? no without chromatographic separation ? - in a reference coal-tar sample is made possible with the combination of excitation-emission matrices (EEMs) and parallel-factor analysis (PARAFAC). EEMs are recorded at 4.2 K with the aid of a cryogenic fiber optic probe and a commercial spectrofluorimeter. The simplicity of the experimental procedure and the excellent analytical figures of merit demonstrate the screening potential of this environmentally friendly approach for the routine analysis of numerous coal-tar samples.Fil: Moore, Anthony F. T.. University of Central Florida; Estados UnidosFil: Goicoechea, Hector Casimiro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; ArgentinaFil: Barbosa, Fernando Jr.. Universidade de Sao Paulo; BrasilFil: Campiglia, Andres D.. University of Central Florida; Estados Unido

Determination Of Polycyclic Aromatic Hydrocarbons In Drinking Water Samples By Solid-Phase Nanoextraction And High-Performance Liquid Chromatography

A novel alternative is presented for the extraction and preconcentration of polycyclic aromatic hydrocarbons (PAH) from water samples. The new approach - which we have named solid-phase nanoextraction (SPNE) - takes advantage of the strong affinity that exists between PAH and gold nanoparticles. Carefully optimization of experimental parameters has led to a high-performance liquid chromatography method with excellent analytical figures of merit. Its most striking feature correlates to the small volume of water sample (500 μL) for complete PAH analyses. The limits of detection ranged from 0.9 (anthracene) to 58 ng·L-1 (fluorene). The relative standard deviations at medium calibration concentrations vary from 3.2 (acenaphthene) to 9.1% (naphthalene). The analytical recoveries from tap water samples of the six regulated PAH varied from 83.3 ± 2.4 (benzo[k]fluoranthene) to 95.7 ± 4.1% (benzo[g,h,i]perylene). The entire extraction procedure consumes less than 100 μL of organic solvents per sample, which makes it environmentally friendly. The small volume of extracting solution makes SPNE a relatively inexpensive extraction approach. © 2008 American Chemical Society

Determination Of Polycyclic Aromatic Hydrocarbon Metabolites In Milk By A Quick, Easy, Cheap, Effective, Rugged And Safe Extraction And Capillary Electrophoresis

We describe the first application of a quick, easy, cheap, effective, rugged and safe extraction technique to the CZE analysis of monohydroxylated metabolites of polycyclic aromatic hydrocarbons in milk. Complete resolution of 2-hydroxyfluorenene, 1-hydroxynaphthalene, 2-hydroxynaphthalene, 3-hydroxyphenanthrene, and 9-hydroxyphenanthrene was accomplished in 4 min of electrophoretic run. Limits of detection at the parts-per-billion were obtained with a single solvent (acetonitrile) for metabolite extraction and sample stacking. The small sample volume (1.2 mL) and the conservative usage of chemicals provided a simple and rapid procedure for the simultaneous extraction of numerous samples. Adding 4 min of electrophoretic run per sample, it should be possible to screen ten samples in approximately 1 h of analysis time. The nanoliter extract volume required for sample injection allows for further chromatographic usage and confirmation of positive samples. The unique electrophoretic pattern of the studied metabolites demonstrates the potential for the unambiguous determination of positional isomers with very similar chromatographic behaviors and undistinguishable mass fragmentation patterns. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

A Review On Analytical Techniques Used For Forensic Fiber Analysis

Textile fibers are a key form of trace evidence, and play a very important role in crime scene investigation. Different kinds of techniques are used for fiber analysis, identification and/or differentiation. The focus of this chapter is to provide readers with a detailed review of different analytical methods that use light sources for either illumination or detection of trace samples for forensic fiber examination purposes. UV-vis MSP is mainly used for the examination of colors on fibers. Additional determination of dyes and pigments on the fibers is provided by Raman spectroscopy. Sometimes, it also provides information regarding the polymeric nature of the fibers; however, FTIR spectroscopy is recommended to determine the nature, class and subclass of fibers. Being complementary to each other, both Raman and FTIR spectroscopy should be used together in order to perform a comprehensive analysis of the evidence at molecular levels. More informative spectroscopic techniques such as IR-chemical imaging and X-ray fluorescence spectroscopy are emerging in the field of fiber analysis. Recently, our group employed fluorescence microscopy for enhancing textile fiber identification using detergent fluorescence, and for the discrimination of visually and microscopically indistinguishable single fiber pairs. This chapter aims to provide readers with a comprehensive review regarding several analytical techniques that are used for forensic fiber analysis; along with their advantages and limitations. Microscopic, spectroscopic, and chromatographic techniques will be reviewed according to earlier reports published by several researchers and forensic experts

Direct Determination Of Benzo[A]Pyrene In Water Samples By A Gold Nanoparticle-Based Solid Phase Extraction Method And Laser-Excited Time-Resolved Shpol\u27Skii Spectrometry

The strong affinity between polycyclic aromatic hydrocarbons (PAH) and the surface of gold colloids is investigated to device an extraction method for water samples. Within the 20-100 nm particle diameter range, the 20 nm gold nanoparticles showed the best extraction efficiencies for all the studied analytes. The new approach is combined to laser-excited time-resolved Shpol\u27skii spectrometry for the direct analysis of benzo[a]pyrene in drinking water samples. For a 500 μL sample volume, the analytical figures of merit demonstrate precise and accurate analysis at the parts-per-trillion level. The extraction efficiencies are statistically equivalent to 100% with relative standard deviations lower than 2%. The average recoveries were varied from 87.5% to 96.5% for different concentration of analytes. The simplicity of the experimental procedure, the low analysis cost, and the excellent analytical figures of merit demonstrate the potential of this approach for routine analysis of drinking water samples. © 2010 Elsevier B.V

Direct Determination Of Dibenzo[A,L]Pyrene And Its Four Dibenzopyrene Isomers In Water Samples By Solid-Liquid Extraction And Laser-Excited Time-Resolved Shpol\u27Skii Spectrometry

Dibenzo[a,l]pyrene is considered the most potent carcinogen of all polycyclic aromatic hydrocarbons ever tested. Its four isomers, which include dibenzo[a,e]-pyrene, dibenzo[a,h]pyrene, dibenzo[a,i]pyrene, and dibenzo[e,l]pyrene, are also carcinogenic and, therefore, a potential threat to humans. The method presented here provides a direct way for their determination in water samples. The entire procedure - from water extraction to LETRSS analysis - takes less than 15 min/sample and it consumes only 100 μL of organic solvent. This fact makes our approach environmentally friendly and cost-effective. Unambiguous isomer determination is accomplished via multidimensional data formats, namely, wavelength time matrixes, excitation - emission matrixes, and time-resolved excitation - emission matrixes. The analytical figures of merit demonstrate precise and accurate analysis at the sub-parts-per-billion level. Limits of detection are at the parts-per-trillion level. The potential of this approach for real-world analysis is illustrated with a heavily contaminated water samples. © 2005 American Chemical Society

Laser-Excited Time-Resolved Shpol\u27Skii Spectroscopy For The Direct Analysis Of Dibenzopyrene Isomers In Liquid Chromatography Fractions

We present a unique method for the unambiguous determination of dibenzo[a,l]pyrene, dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,l]pyrene, and dibenzo[e,i]pyrene in high-performance liquid chromatography (HPLC) fractions. Chemical analysis is performed via laser-excited time-resolved Shpol\u27skii spectroscopy with the aid of a cryogenic fiber-optic probe, pulsed tunable dye laser, spectrograph, and intensified charge-coupled device. Unambiguous identification is accomplished via wavelength time matrix formats, which give simultaneous access to spectral and lifetime information. Prior to spectroscopic analysis, HPLC fractions are pre-treated with liquid-liquid extraction or solid-liquid extraction at the tip of the fiber-optic probe. Solid-liquid extraction gives the best limits of detection, which vary from 40 pg mL 1 (dibenzo[a,l]pyrene) to 0.2 1pg mL -1 (dibenzo[e,l]pyrene)

Analysis Of Co-Eluted Isomers Of High-Molecular Weight Polycyclic Aromatic Hydrocarbons In High Performance Liquid Chromatography Fractions Via Solid-Phase Nanoextraction And Time-Resolved Shpol\u27Skii Spectroscopy

We present an accurate method for the determination of isomers of high-molecular weight polycyclic aromatic hydrocarbons co-eluted in HPLC fractions. The feasibility of this approach is demonstrated with two isomers of molecular weight 302 with identical mass fragmentation patterns, namely dibenzo[a,i]pyrene and naphtho[2,3-a]pyrene. Qualitative and quantitative analysis is carried out via laser-excited time-resolved Shpol\u27skii spectroscopy at liquid helium temperature. Unambiguous identification of co-eluted isomers is based on their characteristic 4.2K line-narrowed spectra in n-octane as well as their fluorescence lifetimes. Pre-concentration of HPLC fractions prior to spectroscopic analysis is performed with the aid of gold nanoparticles via an environmentally friendly procedure. In addition to the two co-eluted isomers, the analytical figures of merit of the entire procedure were evaluated with dibenzo[a,l]pyrene, dibenzo[a,h]pyrene and dibenzo[a,e]pyrene. The analytical recoveries from drinking water samples varied between 98.2±5.5 (dibenzo[a,l]pyrene) and 102.7±3.2% (dibenzo[a,i]pyrene). The limits of detection ranged from 51.1ngL -1 (naphtho[2,3-a]pyrene) to 154ngL -1 (dibenzo[a,e]pyrene). The excellent analytical figures of merit associated to its HPLC compatibility makes this approach an attractive alternative for the analysis of co-eluted isomers with identical mass spectra. © 2011 Elsevier B.V

Determination Of Polycyclic Aromatic Hydrocarbons With Molecular Weight 302 In Water Samples By Solid-Phase Nano-Extraction And Laser Excited Time-Resolved Shpol\u27Skii Spectroscopy

Monitoring of high-molecular weight polycyclic aromatic hydrocarbons (HMW-PAH) via simple and cost effective methods still remains a challenge. In this article, we combine solid-phase nano-extraction (SPNE) and 4.2 K laser-excited time resolved Shpol\u27skii spectroscopy (LETRSS) into a valuable alternative for the water analysis of dibenzo[a,l]pyrene, dibenzo[a,h]pyrene, dibenzo[a,i]pyrene and naphtho[2,3-a]pyrene. In comparison to the original SPNE procedure, the present method improves PAH recoveries and reduces extraction time from 30 to 20 min per sample. Quantitative release of HMW-PAH into the Shpol\u27skii matrix (n-octane) is best accomplished with a mixture of 48 μL of methanol and 2 μL of 1-pentanethiol. Their migration into the 50 μL layer of n-octane provides highly resolved spectra with distinct fluorescence lifetimes for unambiguous isomer determination. Complete analysis takes less than 30 min per sample and consumes only 100 micro-liters of organic solvents. 500 μL of water are sufficient to obtain limits of detection ranging from 16 ng L-1 (dibenzo[a,l]pyrene) to 55 ng L-1 (dibenzo[a,i]pyrene), relative standard deviations better than 3% and analytical recoveries above 90%. Although a straightforward comparison to chromatographic methods is not possible because of the lack of analytical figures of merit on HMW-PAH, the excellent precision of measurements, limits of detection and overall recoveries makes SPNE-LETRSS an attractive approach to water analysis of HMW-PAH. © 2011 The Royal Society of Chemistry

Solid-Phase Nano-Extraction And Laser-Excited Time-Resolved Shpol\u27Skii Spectroscopy For The Analysis Of Polycyclic Aromatic Hydrocarbons In Drinking Water Samples

A unique method for screening polycyclic aromatic hydrocarbons in drinking water samples is reported. Water samples (500 μl) are mixed and centrifuged with 950 μl of a commercial solution of 20 nm gold nanoparticles for pollutants extraction. The precipitate is treated with 2 μl of 1-pentanethiol and 48 μl of n-octane, and the supernatant is then analyzed via laser-excited time-resolved Shpol\u27skii spectroscopy. Fifteen priority pollutants are directly determined at liquid helium temperature (4.2 K) with the aid of a cryogenic fiber-optic probe. Unambiguous pollutant determination is carried out via spectral and lifetime analysis. Limits of detection are at the parts-per-trillion level. Analytical recoveries are similar to those obtained via high-performance liquid chromatography. The simplicity of the experimental procedure, use of microliters of organic solvent, short analysis time, selectivity, and excellent analytical figures of merit demonstrate the advantages of this environmentally friendly approach for routine analysis of numerous samples