Clean-up methods for polycyclic aromatic hydrocarbons analyses by capillary gas chromatography

Summary Comparative results of pre-treatment methods for the extracts of polycyclic aromatic hydrocarbons (PAHs) from airborne particulate matter for quantitative determination by gas chromatography (GC) are presented. The first method included liquid-liquid extraction and column liquid adsorption chromatography. In the second procedure the extract was fractionated by liquid-liquid chromatography and liquid adsorption chromatography. In the last procedure two different solid phase extraction (SPE) cartridges examined makes it possible to separate PAHs and remove paraffinic compounds which is very important for the quantitative GC analysis of the PAHs. Recoveries of PAH standards and some their derivatives were determined and the contents of 15 of the most important PAHs, were compared. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996     

Rapid determination of trace polycyclic aromatic hydrocarbons in particulate matter using accelerated solvent extraction followed by ultra high performance liquid chromatography with fluorescence detection

A method has been developed for the trace analysis of polycyclic aromatic hydrocarbons, which are known as persistent organic pollutants and ubiquitous constituents of fine particulate matter that causes growing airborne pollution. The method, which was especially for samples of airborne particulate matter less than 2.5 μm in diameter, utilized accelerated solvent extraction and ultra high performance liquid chromatography with fluorescence detector. Four principal parameters of accelerated solvent extraction were optimized to obtain maximum extraction efficiency. Using the established synergetic programs of gradient elution and fluorescence wavelength switching, a rapid separation was achieved in 6.56 min with good linearity for 15 polycyclic aromatic hydrocarbons (coefficient of determination above 0.999). The limits of detection ranged from 0.833 to 10.0 pg/m³. The precision of the method expressed as inter‐day relative standard deviation ranged from 0.2 to 1%, which was calculated from nine repetitive measurements of 8.00 μg/L analytes. Average spiked recoveries ranged from 71.6 to 97.7%, with the exception of naphthalene. The rapid, sensitive, and accurate method can meet the pressing needs of health risk assessment and increasingly heavy daily tasks of air quality monitoring.     

Identification of oxygenated polycyclic aromatic hydrocarbons in diesel particulate matter by capillary gas chromatography and capillary gas chromatography/mass spectrometry

Summary Using a two-step liquid chromatographic separation on normalphase cartridges, crude extracts of diesel particulate matter can be separated without time-consuming sample handling into special fractions which mainly contain slightly-polar oxygenated polycyclic aromatic hydrocarbons (oxy-PAH) and nitrated polycyclic aromatic hydrocarbons (nitro-PAH). Subsequent analysis was by fused-silica capillary gas chromatography on a SE54 column along with flame-ionisation (GC/FID) and positive-ion electron-impact mass spectrometric detection (GC/MS) respectively. A number of individual oxy-PAH belonging to four different chemical classes (ketones, quinones, anhydrides and aldehydes) and several individual nitro-PAH were characterized by their retention times and mass spectra. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

Determination of chlorinated polycyclic aromatic hydrocarbons in water by solid‐phase extraction coupled with gas chromatography and mass spectrometry

Given the potential risks of chlorinated polycyclic aromatic hydrocarbons, the analysis of their presence in water is very urgent. We have developed a novel procedure for determining chlorinated polycyclic aromatic hydrocarbons in water based on solid‐phase extraction coupled with gas chromatography and mass spectrometry. The extraction parameters of solid‐phase extraction were optimized in detail. Under the optimal conditions, the proposed method showed wide linear ranges (1.0–1000 ng/L) with correlation coefficients ranging from 0.9952 to 0.9998. The limits of detection and the limits of quantification were in the range of 0.015–0.591 and 0.045–1.502 ng/L, respectively. Recoveries ranged from 82.5 to 102.6% with relative standard deviations below 9.2%. The obtained method was applied successfully to the determination of chlorinated polycyclic aromatic hydrocarbons in real water samples. Most of the chlorinated polycyclic aromatic hydrocarbons were detected and 1‐monochloropyrene was predominant in the studied water samples. This is the first report of chlorinated polycyclic aromatic hydrocarbons in water samples in China. The toxic equivalency quotients of chlorinated polycyclic aromatic hydrocarbons in the studied tap water were 9.95 ng the toxic equivalency quotient m^?3. 9,10‐Dichloroanthracene and 1‐monochloropyrene accounted for the majority of the total toxic equivalency quotients of chlorinated polycyclic aromatic hydrocarbons in tap water.     

An international round-robin study for the analysis of particulate semi-volatile organics by thermal desorption gas chromatography mass spectrometry

Thermal desorption gas chromatography mass spectrometry (TD-GC/MS) is becoming more commonly used for the quantification and identification of organic compounds in particulate matter (PM), including ambient and source PM such as diesel particulate matter (DPM). It has been proven as an alternative to the traditional solvent extraction (SE) method and liquid injection gas chromatograph mass spectrometry (LI-GC/MS). However, little information is available on how different types of TD-GC/MS systems compare to each other for analysis of real-world PM samples or to direct LI-GC/MS for analysis of PM components in a test solution. To address this, CanmetENERGY Characterization Laboratory initiated a round robin with the participation of 10 laboratories worldwide. Three sample types were analysed: (i) a test solution with a suite of pure compounds commonly found in PM, analysed by TD-GC/MS and LI-GC/MS; (ii) a DPM sample, analysed by TD-GC/MS and SE; and (iii) an ambient PM sample, analysed by TD-GC/MS. The first part of the study showed good overall performance and comparability between the different TD-GC/MS systems and LI-GC/MS method for the analysis of PM components in a test solution, with some variability of results due to system types and parameters used, concentration of calibration standards, and whether or not an internal standards was used. The analysis of the DPM sample showed greater variability between laboratories and methods as many PM components were present near the detection limit and matrix effects particularly affected the TD-GC/MS analysis of heavier n-alkanes. In the last part of the study, for the analysis of an ambient PM sample by TD-GC/MS, the analysis of variance showed good comparison between labs for polycyclic aromatic hydrocarbons (94% non-significant), but slightly lower for n-alkanes (68%) and biomarkers (57%).     

Determination of polycyclic aromatic hydrocarbons in soy isoflavone nutraceutical products by gas chromatography coupled to triple quadrupole tandem mass spectrometry

Thirteen polycyclic aromatic hydrocarbons have been determined in soy‐based nutraceutical products. First, an optimization of extraction procedure was performed, and a solid–liquid extraction assisted by sonication and a dilute and shoot procedure were compared, selecting the dilute and shoot approach for the extraction of target compounds, utilizing a mixture of acetone/n‐hexane (1:1 v/v) as extractant solvent. After this, a clean‐up step was needed bearing in mind the complexity of these matrices. Dispersive solid‐phase extraction, using a mixture of C₁₈ and Zr‐Sep+ (25 mg/mL each) was used. The separation was achieved by gas chromatography and detection with triple quadrupole tandem mass spectrometry. For quantification purposes, matrix‐matched calibration was used. The validation was applied at three concentration levels (20, 100 and 250 μg/kg), obtaining recoveries between 70 and 120% and precision values equal to or lower than 23%. Limits of detection and quantification were below 8 and 20 μg/kg, respectively. The method was applied in 11 samples, detecting five polycyclic aromatic hydrocarbons at concentrations ranging from 4.1 to 18.5 μg/kg.     

Capillary Column Gas Chromatography of Environmental Polycyclic Aromatic Compounds

Abstract

The methodologies are described for isolating clean fractions of polycyclic aromatic compounds from diverse environmental samples such as air particulate matter, sediments, and fish tissue. The common step in all procedures is the separation of the polycyclic aromatic compound fraction into well-defined chemical classes by adsorption chromatography on an alumina column. These procedures greatly facilitate the detailed characterization of the polycyclic aromatic hydrocarbons, sulfur heterocycles, and nitrogen heterocycles by capillary column gas chromatography.     

Determination of 1,3-, 1,6-, 1,8-dinitropyrene and 1-nitropyrene in airborne particulate by column liquid chromatography with electrochemical detection

Nitrated polycyclic aromatic hydrocarbons (NPAHs) in airborne particulate were determined by column liquid chromatography with electrochemical detection. NPAHs were extracted ultrasonically prior to being injected into the separation system. A reversed-phase C18 column was used to separate the NPAHs with an aqueous eluent containing acetonitrile and sodium monochloroacetate as buffer. Calibration graphs were linear with very good correlation coefficients (r>0.999) and the detection limits were ca. 20 pg for all analytes. The proposed method provides a relatively simple and convenient procedure for determining the NPAHs in airborne particulate.     

Development of a magnetic solid‐phase extraction coupled with gas chromatography and mass spectrometry method for the analysis of semivolatile organic compounds

Semivolatile organic compounds are a category of organic micropollutants including phthalate esters, polycyclic aromatic hydrocarbons and so on, which are commonly analyzed by solid‐phase extraction followed by gas chromatography with mass spectrometry. In this work, a highly sensitive and feasible method of magnetic solid‐phase extraction combined with gas chromatography with mass spectrometry was established for the determination of semivolatile organic compounds in water. The novel method was based on a permanent magnetic resin with uniform particle size and high surface area (1154.3 m²/g). The results demonstrated that the extraction efficiency of the resin was superior to that of a C₁₈ cartridge. The method was proved to be of satisfactory recoveries (75–115.7%) and limits of detection and quantification (0.063–6.524 and 0.212–21.745 μg/L, respectively). The method was applied to the analysis of semivolatile organic compounds in the midstream Huai River. It was observed that polychlorinated biphenyls exceeded current water standards. To further illustrate the potential effects on human health, health risk assessment was conducted based on the obtained data. The existence of health risk was proved, with hexachlorobenzene and 2,2’,4,4’‐tetrachlorobiphenyl as the major causes. The method possesses the characteristics of high efficiency and rapid analysis, offering a good prospect of applications in large quantities of practical water.     

Determination of polycyclic aromatic hydrocarbons in water samples by gas chromatography coupled to triple quadrupole tandem mass spectrometry using macroporous resin solid‐phase extraction

A method for the determination of 16 polycyclic aromatic hydrocarbons in water has been developed. First, we made a solid‐phase extraction column. After this, the parameters affecting the efficacy of the experimental method were optimized, including appropriate selection of a solid‐phase extraction column and cleanup conditions on columns. The separation was achieved by gas chromatography and detection with triple quadrupole tandem mass spectrometry. The method showed satisfactory linearity (R² > 0.999) over the range assayed (0.01–1 μg/mL), and limits of quantification ranging from 0.0011 to 0.0199 μg/L. The recoveries ranged from 83 to 113%. The relative standard deviation is in the range 0.86–3.1%. The results indicated that this method had high selectivity and precision that was suitable for the simultaneous determination of 16 polycyclic aromatic hydrocarbons in water.     

Simultaneous extraction of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in agricultural soils by pressurized liquid extraction and determination by gas chromatography coupled to tandem mass spectrometry

A simple and rapid method based on pressurized liquid extraction has been validated for the simultaneous extraction of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) from agricultural soil samples. Effective extraction was carried out in less than 17 min for all the studied compounds, and good recoveries were obtained for PAHs and PCBs, ranging from 70% to 112%, when blank samples were spiked at 2.5 μg kg⁻¹, except for naphthalene with recoveries close to 40%. The separation and determination were performed by gas chromatography coupled to tandem mass spectrometry using a triple quadrupole mass analyzer. The target compounds were detected by electron impact with selected reaction monitoring, and mass spectrometric conditions were optimized in order to increase selectivity and sensitivity. The developed method was validated, and matrix-matched calibration was used for quantification purposes. Repeatability and interday precision ranged from 0.9% to 16.8% and from 1.6% to 22.3%, respectively. Limits of quantification ranged from 0.07 to 2.50 μg kg⁻¹. The proposed method was applied to the analysis of agricultural soil samples collected from Almeria (Spain), and PAHs and PCBs were detected in some samples at concentrations ranging from 0.1 to 210 μg kg⁻¹.     

Negative ion laser desorption ionization time-of-flight mass spectrometry of nitrated polycyclic aromatic hydrocarbons

Nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) are widespread environmental pollutants that are generated by incomplete combustion and by atmospheric transformation of polycyclic aromatic hydrocarbons (PAHs). Many nitro-PAH compounds are potent genotoxins and some are direct acting mutagens. Detection of nitro-PAHs in aerosols is complicated by small sample sizes and nitro-PAH abundances that are 1–2 orders of magnitude less than analogous unsubstituted PAHs. Selective detection of several nitro-PAHs by using laser desorption ionization time-of-flight mass spectrometry in negative ion mode has been achieved. Desorption and ionization of nitro-PAHs were effected by using pulsed UV radiation at 266 and 213 ran. Intense molecular anions were observed in addition to fragments identified as CN^? and NO ₂ ^? , which were characteristic indicators of the presence of nitro-PAHs. Selective detection of nitro-PAHs in negative ion mode was demonstrated in the analysis of a diesel particulate sample.     

Determination of methylarsenic compounds in airborne particulate matter by gas chromatography with atomic absorption spectrometry

A sensitive method is described for the determination of mono-, di- and tri-methylarsenic compounds in airborne particulate matter by hydride-generation and gas-liquid chromatography with atomic absorption spectrometric detection. Interferences of various species are discussed. Absolute detection limits are 70, 80 and 100 pg As, respectively for the mono-, di- and tri-methylarsenic species. Recoveries of methylarsenic compounds added to airborne particulate matter are almost 100%. An iron/nitrate mixture interfered strongly but this was overcome by adding EDTA.     

Trace determination of nitrated polycyclic aromatic hydrocarbons using liquid chromatography with on-line electrochemical reduction and fluorescence detection

An efficient clean-up procedure coupled with a high performance liquid chromatography (HPLC) with on-line electrochemical (EC) reduction and fluorescence detection (FLD) was developed to quantify nitrated polycyclic aromatic hydrocarbons (NPAHs) in the airborne particulate. In this process, NPAHs were extracted ultrasonically followed by analysis by using a reversed phase column with an aqueous eluent containing 70% aqueous acetonitrile and sodium monocholoroacetate as a buffer solution. The extraction efficiencies were above 83% for 1-nitropyrene and 1,3-dinitropyrene (1,3-DNP) 1,6-DNP, and 1,8-DNP, and calibration graphs were linear with very good correlation coefficients (r>0.999) and the detection limits were in the range of 1.0-2.2 pg for dinitropyrenes and nitropyrene. The proposed method provides a relatively simple and convenient procedure for determining the NPAHs samples in airborne particulate.     

Determination of polycyclic aromatic hydrocarbons in fractions in asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization

An analytical method using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization for the determination of polycyclic aromatic hydrocarbons in asphalt fractions has been developed. The 14 compounds determined, characterized by having two or more condensed aromatic rings, are expected to be present in asphalt and are considered carcinogenic and mutagenic. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all of the compounds. The limits of detection ranged from 0.5 to 346.5 μg/L and the limits of quantification ranged from 1.7 to 1550 μg/L. The method was validated against a diesel particulate extract standard reference material (NIST SRM 1975), and the obtained concentrations agreed with the certified values. The method was applied to asphalt samples after its fractionation according to ASTM D4124 and the method of Green. The concentrations of the seven polycyclic aromatic hydrocarbons quantified in the sample ranged from 0.86 mg/kg for benzo[ghi]perylene to 98.32 mg/kg for fluorene.     

Determination of priority organic micro-pollutants in water by gas chromatography coupled to triple quadrupole mass spectrometry

A multiclass method has been developed for screening, quantification and confirmation of organic micro-pollutants in water by gas chromatography coupled to mass spectrometry with a triple quadrupole analyzer. The work has been focused on the determination of more than 50 compounds belonging to different chemical families: 19 organochlorine and organophosphorus insecticides, 6 herbicides, 7 polychlorinated biphenyls, 16 polycyclic aromatics hydrocarbons, 2 brominated diphenyl ethers, and 3 octyl/nonyl phenols and pentachlorobenzene. Most of these analytes are included in the list of priority substances in the framework on European Water Policy.Analyte extraction was performed by solid phase extraction using C₁₈ cartridges, and five isotopically labeled standards were added before extraction as surrogates. Analyses were performed by gas chromatography with tandem mass spectrometry (MS/MS) in electron impact mode. Accuracy and precision were evaluated by means of recovery experiments using water samples fortified at two concentration levels (25 and 250 ng L⁻¹), with satisfactory results for most of analytes. The excellent selectivity and sensitivity reached in selected reaction monitoring mode allowed us satisfactory quantification and confirmation at levels as low as 25 ng L⁻¹. Two MS/MS transitions were acquired for each analyte, using the Q/q intensity ratio as a confirmatory parameter. The method developed was applied to the analysis of surface, ground and wastewater samples collected from the Valencia Region (Spain).Analytical methodology using negative chemical ionization mode was also validated for the organochlorine compounds selected, showing a superior sensitivity and lower detection limits.     

Comprehensive analysis of polycyclic aromatic hydrocarbons in wastewater using stir bar sorptive extraction and gas chromatography coupled to tandem mass spectrometry

The objective of this study was the optimization and comparison of two extraction methods for the determination of polycyclic aromatic hydrocarbons (PAHs) in wastewater (WW). A distribution study of the target compounds between the aqueous phase and the suspended particulate matter (SPM) has been performed in order to establish whether the analysis of both phases is necessary. In this sense, the feasibility of stir bar sorptive extraction (SBSE) and solid-phase extraction (SPE) for the determination of 24 PAHs in WW samples has been evaluated. The results demonstrated the suitability of SBSE to perform a comprehensive analysis of liquid samples containing high amounts of SPM, such as in the determination of PAHs in WWs. A gas chromatography triple quadrupole mass spectrometry (GC-QqQ-MS/MS) method has been also optimized for the separation and detection of the target compounds, avoiding the co-elution of some groups of isomers, such as benzo[b], [j] and [k] fluoranthenes and indene[1,2,3-cd]pyrene/dibenz[a,h]anthracene. For that purpose, a specific capillary column developed for PAH determination was used. The SBSE procedure was validated and adequate parameters (such as recovery, linearity, precision, limits of detection and quantification) were obtained. Finally, the validated method was applied to the analysis of real samples collected from an experimental WW treatment plant, detecting some PAHs at concentrations in the range 0.007-0.022 μg L(-1).     

Determination of polynuclear aromatic hydrocarbons in environmental samples by Micellar liquid chromatography

A method for the separation of polycyclic aromatic hydrocarbons (PAHs) by high-performance liquid chromatography using a hybrid micellar mobile phase is described. The detection of PAHs was carried out using the fluorescence method with programmable excitation and emission wavelength. The method is applied to the analysis of several environmental samples (sea water, sediments, limpets, sea worms) and several of these compounds are quantitated at concentration below 70 ng L⁻¹(kg⁻¹) in the original samples.     

Capillary column gas chromatography of environmental polycyclic aromatic compounds

The methodologies are described for isolating clean fractions of polycyclic aromatic compounds from diverse environmental samples such as air particulate matter, sediments, and fish tissue. The common step in all procedures is the separation of the polycyclic aromatic compound fraction into well-defined chemical classes by adsorption chromatography on an alumina column. These procedures greatly facilitate the detailed characterization of the polycyclic aromatic hydrocarbons, sulfur heterocycles, and nitrogen heterocycles by capillary column gas chromatography.     

Solid‐phase microextraction with gas chromatography and mass spectrometry determination of benzo(a)pyrene in microcrystalline waxes used as food additives

Microcrystalline waxes are mixtures of solid, saturated hydrocarbons mainly branched and characterized by a carbon number over C₆₀. They are used as food additives for the surface treatment of confectionery and some fruit varieties, in chewing gum base, protective coatings, defoaming agents, and surface finishing agents. Commission Regulation No 231/2012 established physical and chemical specifications for microcrystalline waxes to use in food, and posed a limit of 50 μg/kg for benzo(a)pyrene. Due to the low solubility of microcrystalline waxes in organic solvents and matrix interferences, analytical determination of benzo(a)pyrene represents a difficult task. The official method for indirect determination of total polycyclic aromatic hydrocarbons uses unspecific spectrophotometric detection and a quite laborious, time‐ and solvent‐consuming extraction method. A liquid–liquid partition method followed by solid‐phase microextraction was developed to isolate benzo(a)pyrene from the bulk of saturated hydrocarbons in microcrystalline waxes, with the aim to have a simple and effective method to verify compliance with the legal limit. The final determination was carried out by gas chromatography coupled to mass spectrometry. Good linearity was obtained, along with a recovery of about 80% from the liquid–liquid partitions. The repeatability of the entire method was <6% and accuracy was <3%.