Determination of polycyclic aromatic hydrocarbons (PAHs) in a complex mixture by second-derivative constant-energy synchronous spectrofluorimetry

In this work, the combination of the excellent band narrowing features of derivative spectrometry with constant-energy synchronous fluorescence spectrometry for the simultaneous determination of different polycyclic aromatic hydrocarbons (PAHs) in a mixture of 18 is assessed. This mode of scanning allowed for the identification and quantification of 10 PAHs and the grouping of some of these.     

Method for determination of polycyclic aromatic hydrocarbons by fluorodensitometry

A TLC fluorodensitometric method for the determination of total PAHs in aqueous and hydroalcoholic solutions at the parts per billion level has been developed. The PAHs are extracted into cyclohexane and separated as a class on a chemically bonded reversed-phase TLC plate using stepwise development. In the fluorescence scanning of the plate the PAHs are located by reference to a mixture of 16 PAHs designated by EPA as primary pollutants and measured as benzo(a)pyrene.     

Simplified determination of polycyclic aromatic hydrocarbons

Accurate quantitative analysis for selected polycyclic aromatic hydrocarbons present on urban dust can be obtained by using a simple procedure consisting of sonic-probe extraction with cyclohexane; clean-up with Florisil((R))-XAD-4((R)), and measurement by high-resolution gas chromatography with flame-ionization detection (HRGC/FID). The analysis can be further simplified by eliminating the clean-up step if HRGC/electron-impact mass-spectrometry (MS) is available. Both the FID and MS methods give results consistent with those obtained by standard procedures. The direct HRGC/MS procedure, combined with chemical ionization, can also be applied to the determination of polycyclic organic materials present in solvent-refined coal, shale oil and crude oil.     

Standard reference materials for the determination of polycyclic aromatic hydrocarbons

Summary Since 1980 a number of Standard Reference Materials (SRM's) have been issued by the National Bureau of Standards (NBS) to assist in validating measurements for the determination of polycyclic aromatic hydrocarbons (PAH) and other polycyclic aromatic compounds (PAC). These SRM's are certified for selected PAC and range in analytical difficulty from calibration solutions to complex natural matrix materials, such as air and diesel particulate matter, shale oil, and crude oil. In the past year three new SRM's have been introduced: (1) SRM 1647a Priority Pollutant PAH in Acetonitrile, (2) SRM 1491 Aromatic Hydrocarbons in Hexane/Toluene, and SRM 1597 Complex Mixture of PAH from Coal Tar. The SRM's available from NBS for use in the determination of PAC are described and the concentrations of PAC determined in the natural matrix SRM's are summarized and compared. The primary analytical techniques used for the measurement of PAC in these SRM's were gas chromatography, liquid chromatography, and gas chromatography/mass spectrometry.

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Standardreferenzmaterialien für die Bestimmung von polycyclischen aromatischen Kohlenwasserstoffen

     

The spectrophotometric determination of polycyclic aromatic hydrocarbons

The determination of polycyclic aromatic hydrocarbons by elution chromatography from alumina columns followed by ultra-violet spectrophotometry has been elaborated for a more extended range of substances than has been published previously. The methods have been standardised and tables of absorption peaks are provided for easy identification of a number of compounds commonly found as traces in combustion products. Recommendations are given for the preparation of samples for determinations by this method, which has been successfully employed for the analysis of carbon blacks, soots, urban air solids, condensible smokes such as tobacco smoke, wood smoke and coal tar. thermal decomposition or pyrolysis products and other substances, such as urban vegetation, soil, tobacco, snuff, smoked food, and surface drainage water, which have been subjected to the action of smokes or other combustion products.     

Magnetic ionic liquids as non-conventional extraction solvents for the determination of polycyclic aromatic hydrocarbons

This work describes the applicability of magnetic ionic liquids (MILs) in the analytical determination of a group of heavy polycyclic aromatic hydrocarbons. Three different MILs, namely, benzyltrioctylammonium bromotrichloroferrate (III) (MIL A), methoxybenzyltrioctylammonium bromotrichloroferrate (III) (MIL B), and 1,12-di(3-benzylbenzimidazolium) dodecane bis[(trifluoromethyl)sulfonyl)]imide bromotrichloroferrate (III) (MIL C), were designed to exhibit hydrophobic properties, and their performance examined in a microextraction method for hydrophobic analytes. The magnet-assisted approach with these MILs was performed in combination with high performance liquid chromatography and fluorescence detection. The study of the extraction performance showed that MIL A was the most suitable solvent for the extraction of polycyclic aromatic hydrocarbons and under optimum conditions the fast extraction step required ∼20 μL of MIL A for 10 mL of aqueous sample, 24 mmol L⁻¹ NaOH, high ionic strength content of NaCl (25% (w/v)), 500 μL of acetone as dispersive solvent, and 5 min of vortex. The desorption step required the aid of an external magnetic field with a strong NdFeB magnet (the separation requires few seconds), two back-extraction steps for polycyclic aromatic hydrocarbons retained in the MIL droplet with n-hexane, evaporation and reconstitution with acetonitrile. The overall method presented limits of detection down to 5 ng L⁻¹, relative recoveries ranging from 91.5 to 119%, and inter-day reproducibility values (expressed as relative standard derivation) lower than 16.4% for a spiked level of 0.4 μg L⁻¹ (n = 9). The method was also applied for the analysis of real samples, including tap water, wastewater, and tea infusion.     

Critical point measurement of some polycyclic aromatic hydrocarbons

The critical temperatures and the critical pressures of five polycyclic aromatic compounds, namely, acenaphthene, fluorene, anthracene, phenanthrene, and pyrene have been measured. All the compounds studied decompose at near-critical temperatures. A pulse-heating technique applicable to measuring the critical properties of thermally unstable compounds has been used. The times from the beginning of a heating pulse to the moment of reaching the critical temperature were from (0.06 to 0.85) ms. The short residence times provide little degradation of the substances in the course of the experiments. The experimental critical parameters of the polycyclic aromatic compounds have been compared with those estimated by five predictive methods. The acentric factors of polycyclic aromatic compounds studied have been calculated.     

Adsorption preconcentration in the luminescence determination of polycyclic aromatic hydrocarbons

The adsorption of polycyclic aromatic hydrocarbons (PAHs)—pyrene, anthracene, phenanthrene, and fluorene—by a cellulose matrix of micellar media containing sodium dodecyl sulfate and a nonionogenic polymer, namely, polyethylene glycol is studied. Procedures are proposed for the luminescence determination of PAHs in the adsorbent phase.     

Chromatographic determination of polycyclic aromatic hydrocarbons in oil sludge

It has been demonstrated that the Oasis HLB polymer adsorbent can be used for the purification of hexane extracts of oil sludge for the determination of polycyclic aromatic hydrocarbons by high-performance liquid chromatography with a fluorometric detector in these samples. The determination of polycyclic aromatic hydrocarbons has been carried out in samples of different wastes.     

Accelerated extraction for determination of polycyclic aromatic hydrocarbons in marine biota

A rapid and simple method is proposed for determination of polycyclic aromatic hydrocarbons (PAH) in complex matrices such as marine biota. The method uses sonication, by means of an ultrasonic probe, as a new tool for assisted extraction, coupled with reversed-phase liquid chromatography (RP-LC) with fluorescence detection (FL) for determination of 16 US EPA priority PAH. Separation and detection of the 16 PAH were complete in 45 min by RP-LC with a C₁₈ column and acetonitrile–water gradient elution. Multivariate optimisation of the variables affecting extraction (ultrasound radiation amplitude, sonication time, and temperature of the water-bath in which the extraction cell was placed) was conducted. The accuracy of the method was determined by analysis of a certified reference material and comparison of the results obtained with those from another method (microwave-assisted extraction and GC–MS). The new technique avoids the main problems encountered in the determination of PAH in complex matrices such as marine biota, and no clean-up step is necessary. The method was applied to determination of PAH in estuarine biota samples from the Urdaibai estuary (Biscay, Spain).     

Hydrogenation of polycyclic aromatic hydrocarbons as a factor affecting the cosmic 6.2 micron emission band

While many of the characteristics of the cosmic unidentified infrared (UIR) emission bands observed for interstellar and circumstellar sources within the Milky Way and other galaxies, can be best attributed to vibrational modes of the variants of the molecular family known as polycyclic aromatic hydrocarbons (PAH), there are open questions that need to be resolved. Among them is the observed strength of the 6.2 micron (1600 cm(-1)) band relative to other strong bands, and the generally low strength for measurements in the laboratory of the 1600 cm(-1) skeletal vibration band of many specific neutral PAH molecules. Also, experiments involving laser excitation of some gas phase neutral PAH species while producing long lifetime state emission in the 3.3 micron (3000 cm(-1)) spectral region, do not result in significant 6.2 micron (1600 cm(-1)) emission. A potentially important variant of the neutral PAH species, namely hydrogenated-PAH (H(N)-PAH) which exhibit intriguing spectral correlation with interstellar and circumstellar infrared emission and the 2175 A extinction feature, may be a factor affecting the strength of 6.2 micron emission. These species are hybrids of aromatic and cycloalkane structures. Laboratory infrared absorption spectroscopy augmented by density function theory (DFT) computations of selected partially hydrogenated-PAH molecules, demonstrates enhanced 6.2 micron (1600 cm(-1)) region skeletal vibration mode strength for these molecules relative to the normal PAH form. This along with other factors such as ionization or the incorporation of nitrogen or oxygen atoms could be a reason for the strength of the cosmic 6.2 micron (1600 cm(-1)) feature.     

Acridine dyes in the triplet state as reagents for the selective luminescence determination of polycyclic aromatic hydrocarbons

The possibility of the selective determination of several polycyclic aromatic hydrocarbons (PAH) by sensitized room-temperature phosphorescence (SRTP) in sodium dodecylsulfate (SDS) micelles was studied. Acridine dyes (trypaflavine, acridine yellow, and acridine orange) were used as triplet-energy donors. It was found that the presence of external heavy atoms of thallium(I) is a prerequisite to SRTP in the system of an acridine dye (donor) and a PAH (acceptor). The linear concentration ranges, detection limits, and selectivity factors for the determination of pyrene, anthracene, and 1,2-benzanthracene by fluorimetry, room-temperature phosphorescence (RTP), and proposed SRTP were compared.     

A review of techniques for the determination of polycyclic aromatic hydrocarbons in air

We provide an extensive review of the common methodologies employed in the analysis of airborne polycyclic aromatic hydrocarbons (PAHs). The review focuses on gas-chromatography-based approaches, in the light of their universal application with excellent separation, resolution, and sensitivity.We first describe collection methods for airborne PAHs in the gas and particle phases. We then evaluate the efficiency of extraction techniques employed for separating target PAHs from sampling media, using conventional solvent-based and emerging thermal-desorption approaches.We also describe commonly employed analytical methods with respect to their applicability to PAHs in gas and particle phases, collected from diverse environmental settings. As an essential part of basic quality assurance, we examine each method with special emphasis on key parameters (e.g., limit of detection and reproducibility).Finally, we address the likely directions of methodological developments, their limitations, and the future prospects for PAH analysis.     

The spectrophotometric determination of polycyclic aromatic hydrocarbons. II

In repetitive determinations of polycyclic aromatic hydrocarbons in combustion products the use of incompletely separated Chromatographic fractions is often an advantage favouring rapid work. Such fractions may be submitted to an approximate quantitative analysis by using tables of absorption peak heights measured from a base-line drawn between theminima on each side of the peak. Convenient tables for this method are provided in this paper.     

Application of counter-current chromatography as a new pretreatment method for the determination of polycyclic aromatic hydrocarbons in environmental water

Counter‐current chromatography (CCC) was investigated as a new sample pretreatment method for the determination of trace polycyclic aromatic hydrocarbons (PAHs) in water environmental samples. The experiment was performed with a non‐aqueous binary two‐phase solvent system composed of n‐heptane and acetonitrile. The CCC column was first filled with the upper stationary phase, and then a large volume of water sample was pumped into the column while the CCC column was rotated at 1600 rpm. Finally, the trace amounts of PAHs extracted and enriched in the stationary phase were eluted out by the lower mobile phase and determined by gas chromatography–flame ionization detector (GC‐FID) or gas chromatography–mass spectrometry (GC‐MS). The enrichment and cleanup of PAHs can be fulfilled online by this method with high recoveries (84.1–103.2%) and good reproducibility (RSDs: 4.9–12.2%) for 16 EPA PAHs under the optimized CCC pretreatment conditions. This method has been successfully applied to determine PAHs in lake water where 8 PAHs were detected in the concentration of 40.9–89.9 ng/L. The present method is extremely suitable for the preparation of large volume of environmental water sample for the determination of trace amounts of organic pollutants including PAHs as studied in this paper.     

Improved ultrasonic extraction procedure for the determination of polycyclic aromatic hydrocarbons in sediments

The aim of this work was to optimize an ultrasonic extraction procedure for the determination of polycyclic aromatic hydrocarbons (PAHs) in sediments and to compare it with the reflux procedure using methanolic potassium hydroxide. Sample extracts were purified with a miniaturized silica gel chromatographic column and analyzed by gas chromatography-mass spectrometry (GC-MS). Ultrasonication using n-hexane-acetone (1:1, v/v) solvent mixture on dried homogenized marine sediment gave better precision (smaller relative standard deviation (RSD) values) and comparable quantities of individual PAH's compared to the reflux procedure. Ultrasonication with the n-hexane-acetone (1:1, v/v) mixture, utilizing four 15 min extraction cycles, was found to be sufficient for extracting PAHs from wet sediments. The optimized ultrasonic extraction procedure extracted aliphatic and aromatic hydrocarbons from the National Institute of Standards and Technology SRM 1941a with recoveries greater than 90%. The major advantages of ultrasonication compared to the reflux method are the lower extraction times, simplicity of the apparatus and extraction procedure. The optimized ultrasonication procedure has been used in our laboratory to extract hydrocarbons from naturally wet sediments from rivers, and coastal and marine areas.     

超分子溶剂直提测定水中的多环芳烃

超分子溶剂是两亲化合物通过分子间有序的自组装过程形成的具有纳米结构的胶束聚集体,是一种高效提取溶剂。该文以高效液相色谱-荧光检测法为测试手段,系统地对超分子溶剂组成及用量进行了优化,发展了一种直接提取、快速测定水中多环芳烃的方法,并进行了方法学验证及实际样品检测。结果表明,采用四氢呋喃和1-辛醇制备的超分子溶剂对4种多环芳烃的回收率为89.08%~102.47%,相对标准偏差(RSD,n=5)为1.38%~3.92%。4种多环芳烃在一定范围内线性关系良好(相关系数R~20.999),检出限为1.26~9.23 ng/L。该方法前处理过程简单,有利于实现快速分析;溶剂使用量少,符合绿色化学的发展趋势,具有一定的推广价值。     

自来水中七种多环芳烃的快速测定

多环芳烃（PAH）在环境中分布广、浓度低，空气、土壤和水的样品中均能检出。PAH大都含有致癌和促进致癌的物质及变异性成分。世界卫生组织拟定了饮用水中六种有代表性多环芳烃总的最高可接受浓度为200ng／L。     

Relevance of polycyclic aromatic hydrocarbons as environmental carcinogens

Summary All emissions from incomplete combustion contain polycyclic aromatic hydrocarbons (PAH) which are a well-known class of carcinogens. The question whether additional carcinogenic compounds do exist in these emissions can be answered by separating the emission condensate into a PAH-containing and a PAH-free part. These parts have been tested in an animal experiment by means of a carcinogen-specific test system such as topical application onto the skin of mice or injection into the lung of rats. The investigation on the contribution of PAH-fractions and of benzo(a)pyrene to the carcinogenic potential of emission condensate from gasoline driven engines, Diesel engines, coal combustion in domestic furnaces and sidestream smoke of cigarettes shows that the carcinogenic effect of the particle phase of these pyrolytic condensates is predominantly caused by polycyclic aromatic compounds such as PAH. In all cases investigated the PAH-fraction containing 4 and more rings accounted for more than 75% of the total carcinogenic effect resulting from the implantation into the lung of rats or from the topical application onto mouse skin. The contribution of benzo(a)pyrene to the carcinogenic potency of various condensates, however, is minor in all cases investigated and accounts for only 0.17% to 4% of the total carcinogenicity as evaluated from implantation into the lung of rats (Table 1).