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Analytical and Bioanalytical Chemistry (v.375, #4)

Analysis of aqueous 2,4,6-trinitrotoluene (TNT) using a fluorescent displacement immunoassay by Ellen R. Goldman; George P. Anderson; Nikolai Lebedev; Brian M. Lingerfelt; Phan T. Winter; Charles H. Patterson; J. Matthew Mauro (pp. 471-475).

We report a rapid, simple, and sensitive assay that is potentially amenable to high throughput screening for analysis of 2,4,6-trinitrotoluene (TNT) present in aqueous solutions. The assay is based on the change in fluorescence emission intensity of a fluorescently labeled TNT analogue pre-bound to an anti-TNT antibody that occurs upon its competitive displacement by TNT. The assay can be performed in both cuvette- and 96-well plate-based formats. TNT at a level of 0.5 μg L^–1 (0.5 ppb) was detected in phosphate buffered saline; detection improved to 0.05 μg L^–1 (0.05 ppb) for TNT dissolved in artificial seawater.

Keywords: Environmental monitoring Seawater Explosives Fluorescent displacement immunoassay 2,4,6-Trinitrotoluene (TNT)

The homogeneity of heavy metal deposition on glass fibre filters collected using a high-volume sampler in the vicinity of an opencast chrome mine complex at Kemi, Northern Finland by R. Pöykiö; P. Perämäki; H. Rönkkömäki (pp. 476-481).

The homogeneity of heavy metal (Cr, Ni, Cu, Fe and Cd) distribution on glass fibre filters (Munktell MG 160, 203×254 mm, 75 g m^–2) collected using a high-volume sampler (Wedding & Associates) at an opencast chrome mine complex at Kemi, Northern Finland was studied. The heavy metals in the total suspended particulate (TSP) material were analysed by inductively coupled plasma atomic emission spectrometry (ICP–AES) or graphite furnace atomic absorption spectrometry (GFAAS). The glass fibre filters were digested in a microwave oven using a mixture of aqua regia+HF acids. There was significant non-uniform distribution of heavy metals on glass fibre filters. The TSP material containing chromite was very difficult to dissolve by acid digestion. The results from X-ray fluorescence spectrometry (XRF), and from energy filtering transmission electron microscope (EFTEM) equipped with energy dispersive X-ray spectrometer (EDS), showed that insoluble residue left after microwave oven digestion with aqua regia+HF acids was probably partly due to chemical reactions occurring during microwave heating.

Keywords: TSP High-volume sampler Glass fibre filter Airborne particulate matter XRF XRD EDS EFTEM

Combined micro-droplet and thin-film-assisted pre-concentration of lead traces for on-line monitoring using anodic stripping voltammetry by Inessa Belostotsky; Vladimir V. Gridin; Israel Schechter; Chaim N. Yarnitzky (pp. 482-488).

An improved analytical method for airborne lead traces is reported. It is based on using a Venturi scrubber sampling device for simultaneous thin-film stripping and droplet entrapment of aerosol influxes. At least threefold enhancement of the lead-trace pre-concentration is achieved. The sampled traces are analyzed by square-wave anodic stripping voltammetry. The method was tested by a series of pilot experiments. These were performed using contaminant-controlled air intakes. Reproducible calibration plots were obtained. The data were validated by traditional analysis using filter sampling. LODs are comparable with the conventional techniques. The method was successfully applied to on-line and in situ environmental monitoring of lead.

Keywords: Venturi Lead Environment Monitoring Film Pre-concentration

Size analysis of industrial carbon blacks by sedimentation and flow field-flow fractionation by Young Hun Park; Won Suk Kim; Dai Woon Lee (pp. 489-495).

Carbon black is one of the most useful particulate materials in the industrial field. Among the various physical properties of carbon black, size and size distribution are the most important properties to affect the quality of a final product. However, it is difficult to measure the exact particle size of carbon black since it suffers unavoidable interference from flocculation. In this study, the effects of various factors on the dispersion of industrial carbon blacks were investigated for the determination of size and size distribution of carbon black particles. Sedimentation and flow field-flow fractionations (FIFFF) were used to determine the size of carbon black, and their optimum analytical conditions were tested by changing surfactant, pH, ionic strength, and method of dispersion. The results showed that surfactant structure and its concentration played significant roles in dispersion stability. Carbon black was dispersed well with a nonionic surfactant with a pH of around 8 and an ionic strength of 0.003 M. The mean diameters measured from two types of FFF and photon correlation spectroscopy are in good agreement. This study demonstrates the potential of sedimentation and flow FFF for analyzing highly adsorptive industrial particles and guides for sample preparation.

Keywords: Carbon black Particle size Dispersion Surfactant Field-flow fractionation Ionic strength pH

Homogeneity check of agricultural and food industries samples using near infrared spectroscopy by Marie E. Lafargue; Max H. Feinberg; Jean-Jacques Daudin; Douglas N. Rutledge (pp. 496-504).

Samples distributed in proficiency testing schemes (PTS) need to be homogeneous in order to be sure that if a laboratory has a result different from the other laboratories, its error can be attributed to its analysis method and not to its sample. This control must be done according to the ISO 13528 draft standard before sending the samples to the laboratories. It can be done by determining homogeneity targets by sub-contracting to accredited laboratories using reference methods, but this engenders logistic and financial problems. That is why a homogeneity check using Near Infrared Spectroscopy (NIR) has been developed for agricultural and food industries samples prepared for PTS at Bipea (Bureau Interprofessionnel d'Etudes Analytiques). To evaluate the homogeneity among samples, this procedure involves a comparison of NIR spectra, the determination of global homogeneity criteria and the use of control charts. The method of control developed and carried out at Bipea allows the rapid and easy monitoring of the performance of the sample preparation.

Keywords: Homogeneity Near infrared spectroscopy Spectra comparison Distances Control charts Samples for PTS

Effect of humic acid on the bioavailability of radionuclides to rice plants by Takuo Ozaki; Shizuko Ambe; Tomoko Abe; Arokiasamy J. Francis (pp. 505-510).

We investigated the effect of humic acid and solution pH on the uptake of the radionuclides, ⁸³Rb, ¹³⁷Cs, ⁵⁴Mn, ⁶⁵Zn, ⁸⁸Y, ¹⁰²Rh, and ⁷⁵Se in rice plants by the multitracer technique. The addition of humic acid to a culture medium containing SiO₂ increased the uptake of Mn and Zn at pH 4.3, whereas their uptake was decreased at pH 5.3. Humic acid depressed the uptake of Y at both pHs. The uptake of Se, which does not interact with humic acid, was not affected by its presence. These results suggest that uptake of the radionuclides by the rice plant is regulated by the affinity of radioactive nuclides for humic acid, as well as by the soil solution's pH.

Keywords: Adsorption Humic acid Rice plant Radionuclides SiO2

Ion-selective electrodes based on metalloporphyrins for gibberellic acid determination in agricultural products by Emília M. G. Santos; Cristina M. C. M. Couto; M. Conceição B. S. M. Montenegro; M. Graça P. M. S. Neves; Susana L. H. Rebelo; J. A. S. Cavaleiro; Boaventura F. Reis (pp. 511-516).

This work describes the construction, evaluation and analytical application of electrodes selective to the gibberellate anion for the determination of gibberellic acid in agricultural products. Several types of PVC membrane electrodes without internal reference solution were prepared using the manganese(III) complex of meso -tetraphenylporphyrin (TPP) as ionophore and dibutyl phthalate (DBP), as plasticizer. The incorporation of lipophilic chemical species as additives, was also carried out aiming the evaluation of the response characteristics of the electrodes. To accomplish the analysis of commercial agricultural products a selective membrane composed of 28.0% (w/w) of PVC, 66.0% (w/w) of plasticizer and 6% (w/w) of ionophore was used, with no additive. This potentiometric unit presented a linear response between 10^–4 and 10^–1 mol L^–1 in gibberellate, a slope of about −69 mV dec^–1 and a reproducibility of about ±1 mV day^–1. The potentiometric analysis of gibberellic acid in commercial products was carried out by direct potentiometry and the results obtained were compared with those provided by HPLC.

Keywords: Gibberellic acid Ion-selective electrodes Potentiometry Metalloporphyrins Agricultural products

Quantitative analysis of geraniol, nerol, linalool, and α-terpineol in wine by D. Sejer Pedersen; Dimitra L. Capone; George K. Skouroumounis; Alan P. Pollnitz; Mark A. Sefton (pp. 517-522).

A mixture of [²H₇]-geraniol, [²H₇]-nerol, [²H₇]-linalool and [²H₇]-α-terpineol was prepared for use as internal standards in a rapid and accurate analytical method, employing gas chromatography–mass spectrometry (GC/MS), to determine the concentration of geraniol, nerol, linalool and α-terpineol in wine. The method avoids the possible formation, degradation and interconversion of these compounds during their analysis.

Keywords: GC/MS Wine Geraniol Nerol Linalool α-Terpineol Artefacts

Study of the acid–base properties of fulvic acid-like substances extracted from senescent leaves of eucalyptus and oak by Juan Antelo; Rocio López; Sarah Fiol; Juan M. Antelo; Florencio Arce (pp. 523-526).

The acid–base properties of two fulvic acids (FA) extracted from senescent leaves of eucalyptus and oak were characterized by carrying out potentiometric titrations at two FA concentrations and four ionic strengths (0.005 M <[KNO₃] <1.0 M). Experimental data were analyzed by means of the master curve approach, which includes an electrostatic spherical double layer model, and the Langmuir–Freundlich isotherm was used to fit the data. The contribution of the electrostatic effect to the proton binding reaction was lower than that observed for soil fulvic acids. The chemical heterogeneity of both samples was described by two acid sites with pKs of about 4 and 7.5, the most abundant being the carboxylic site of pK = 4.

Keywords: Senescent leaf extracts Fulvic acid Proton binding

Column-switching high-performance liquid chromatography electrospray mass spectrometry coupled with on-line of extraction for the determination of mono- and di-(2-ethylhexyl) phthalate in blood samples by Koichi Inoue; Migaku Kawaguchi; Fumio Okada; Yoshihiro Yoshimura; Hiroyuki Nakazawa (pp. 527-533).

A novel method based on column-switching high-performance liquid chromatography–electrospray mass spectrometry (LC–MS) coupled with an on-line extraction column containing conjugated avidin has been developed for direct injection analysis of di(2-ethylhexyl) phthalate (DEHP) and its metabolite, mono(2-ethylhexyl) phthalate (MEHP), in blood samples. The sample preparation for on-line extraction involved the mixing of blood samples with internal standards, DEHP-d₄ and MEHP-d₄, in LC glass vials. A linear response was found for column-switching LC–MS when tests were conducted within the validated range of 25 to 1000 ng mL^–1 for DEHP and 5 to 1000 ng mL^–1 for MEHP, with correlation coefficients (r) greater than 0.999. In addition, the recoveries of DEHP and MEHP from human plasma were calculated by using this method with on-line extraction, yielding recoveries of up to 91.2% (RSD<5%). We measured the background levels of DEHP and MEHP in six human plasma samples from healthy volunteers and three fetal bovine serum samples for cell-line culture. DEHP and MEHP were not detected in all human plasma samples (N.D. is <25 ng mL^–1 for DEHP, and N.D. is <5.0 ng mL^–1 for MEHP). In contrast, high DEHP contamination of commercially available fetal bovine serum samples was found by this method.

Keywords: Di(2-ethylhexyl) phthalate, DEHP Mono(2-ethylhexyl) phthalate, MEHP LC–MS Column switching On-line extraction Blood

High-performance liquid chromatographic determination of cocaine and benzoylecgonine by direct injection of human blood plasma sample into an alkyl-diol-silica (ADS) precolumn by Rosario Brunetto; Lubin Gutiérrez; Yelitza Delgado; Máximo Gallignani; José Luis Burguera; Marcela Burguera (pp. 534-538).

A column-switching high-performance liquid chromatographic method with UV detection for the determination of cocaine (COC) and benzoylecgonine (BZE) in human blood plasma samples is described. The method uses an alkyl-diol-silica ADS-C18 extraction precolumn. A 50-µL plasma sample was introduced to the ADS precolumn in order to separate the analytes from proteins and endogenous compounds. The fraction containing COC and BZE was back-flushed and transferred to an Alltech mixed-mode C₁₈/cation-exchange analytical column for final separation. The validation of the method revealed quantitative recoveries from 95.0 to 99.0% for COC at three different concentrations (0.5, 1.0 and 2.0 µg mL^–1), and from 96.0 to 99.0% for BZE at the same concentration levels with coefficients of variation <4.00% (n=5). The detection limit (signal to noise ratio (S/N)>3) was 0.03 µg mL^–1 for all the compounds with an injection volume of 50 µL. However, it was possible to enhance the sensitivity further by injecting larger plasma volumes, up to 200 µL, at the same optimal conditions. The overlap of sample preparation, analysis and reconditioning of the extraction column, increase the overall sample throughput to 5 samples h^–1. The developed method has been applied to human blood plasma samples from subjects suspected of cocaine abuse.

Keywords: Cocaine Benzoylecgonine Column switching Alkyl-diol-silica column Restricted-access materials Human blood plasma samples

Application of a gold electrode, modified by a self-assembled monolayer of 2-mercaptodecylhydroquinone, to the electroanalysis of hemoglobin by Jingdong Zhang; Kyoungja Seo; Il Cheol Jeon (pp. 539-543).

A gold electrode modified by a self-assembled monolayer of 2-mercaptodecylhydroquinone (H₂Q(CH₂)₁₀SH) was applied to investigate the electrochemical response of hemoglobin in aerated buffer solutions. Compared with a bare gold electrode, the monolayer of H₂Q(CH₂)₁₀SH could suppress the reduction wave of dissolved oxygen in the buffer while effectively promoting the rate of electron transfer between hemoglobin and the electrode. Thus, a convenient way for electroanalysis of hemoglobin in air was achieved at the H₂Q(CH₂)₁₀SH/Au electrode. A linear relationship existed between peak current and concentration of hemoglobin in the range 1×10⁻⁷–1×10⁻⁶ mol L^–1.

Keywords: Hemoglobin 2-Mercaptodecylhydroquinone Self-assembled monolayer Cyclic voltammetry

Simultaneous electrochemical determination of xanthine and uric acid at a nanoparticle film electrode by Yanyi Sun; Junjie Fei; Kangbing Wu; Shengshui Hu (pp. 544-549).

A sensitive electrochemical method was developed for simultaneous determination of uric acid (UA) and xanthine (XA) at a glassy carbon electrode modified with multi-wall carbon nanotubes (MWNTs) film. The oxidation peak currents of UA and XA were increased at the MWNTs film electrode significantly. The experimental parameters, which influence the peak currents of UA and XA, such as the amount of MWNTs on the glassy carbon electrode, the pH of the solution, accumulation time, and scan rate, were optimized. Under optimum conditions, the peak currents were linear to the concentration of UA over the wide range from 1×10⁻⁷ mol L⁻¹ to 1×10⁻⁴ mol L⁻¹ and to that of XA over the wide range from 2×10⁻⁸ mol L⁻¹ to 2×10⁻⁵ mol L⁻¹. The interferences studies showed that the MWNTs-modified electrode exhibited excellent selectivity in the presence of ascorbic acid, dopamine, and hypoxanthine. The proposed procedure was successfully applied to detect UA and XA in human serum without any preliminary treatment.

Keywords: Multi-wall carbon nanotubes Uric acid Xanthine Modified glassy carbon electrode Voltammetry

Unilamellar liposomes covalently coupled on silica gel for liquid chromatography by Xiqin Mao; Liang Kong; Xin Li; Baochuan Guo; Hanfa Zou (pp. 550-555).

Silica gel was used as a support for the covalent coupling of liposomes, which could overcome drawbacks of soft gel beads in column efficiency and separation speed. The influences of the concentration of added dimethylaminopyridine and reaction time on the chloroformate activation reaction of silica gel were investigated. Temperature and pH for covalent coupling of liposomes on the activated silica gel were also optimized. Experimental results indicated that the stability of the covalently coupled liposome columns was obviously superior to that of the noncovalently coated liposome columns but the selectivity of both columns was basically identical. Separation and analysis of a crude extract of a traditional Chinese medicine Ligusticum Wallichii and a mixture of small peptides on both columns further support this conclusion.

Keywords: Covalent coupling Liposome Silica gel Peptides Chinese medicine

Spectrophotometric methods for determination of enalapril and timolol in bulk and in drug formulations by Magda M. Ayad; Abdalla Shalaby; Hisham E. Abdellatef; Mervat M. Hosny (pp. 556-560).

Two simple and accurate spectrophotometric methods for determination of timolol and enalapril maleate are described. The first method is based on chelate formation with palladium(II) chloride in buffered medium. The second method is based on the formation of the colored complex between palladium(II), eosin, and the two cited drugs using methylcellulose as surfactant to increase the solubility and intensity of the formed complexes. Under optimum conditions the complexes showed maximum absorption at 369.4 nm and 362.8 nm for timolol and enalapril maleate, respectively, in the first method and 552.2 and 550.6 nm for the second method. Apparent molar absorptivities were 1.8×10³ and 1.3×10³ and Sandell's sensitivities were 5.9×10^–4 and 2.7×10^–4 for timolol and enalapril maleate in the first method; in the second method molar absorptivities were 2.8×10⁴ and 1.1×10⁴ while Sandell's constants were 9.1×10^–3 and 2.3×10^–3 for timolol and enalapril maleate. The solutions of the complexes obeyed Beer's law in the concentration ranges 20–200 μg mL^–1 and 50–300 μg mL^–1 for timolol and enalapril maleate, respectively. In the second method, because the reaction was more sensitive the ranges were reduced to 1.6–16 μg mL^–1 for timolol 8–56 μg mL^–1 for enalapril maleate. The proposed methods were applied to the determination of the two drugs in their pharmaceutical formulation.

Keywords: Enalapril maleate Timolol Pd(II) chloride Spectrophotometric determination Pharmaceutical application

Determination of phosphorus in small amounts of protein samples by ICP–MS by J. Sabine Becker; Sergei F. Boulyga; Carola Pickhardt; J. Becker; Stefan Buddrus; Michael Przybylski (pp. 561-566).

Inductively coupled plasma mass spectrometry (ICP–MS) is used for phosphorus determination in protein samples. A small amount of solid protein sample (down to 1 µg) or digest (1–10 µL) protein solution was denatured in nitric acid and hydrogen peroxide by closed-microvessel microwave digestion. Phosphorus determination was performed with an optimized analytical method using a double-focusing sector field inductively coupled plasma mass spectrometer (ICP–SFMS) and quadrupole-based ICP–MS (ICP–QMS). For quality control of phosphorus determination a certified reference material (CRM), single cell proteins (BCR 273) with a high phosphorus content of 26.8±0.4 mg g^–1, was analyzed. For studies on phosphorus determination in proteins while reducing the sample amount as low as possible the homogeneity of CRM BCR 273 was investigated. Relative standard deviation and measurement accuracy in ICP–QMS was within 2%, 3.5%, 11% and 12% when using CRM BCR 273 sample weights of 40 mg, 5 mg, 1 mg and 0.3 mg, respectively. The lowest possible sample weight for an accurate phosphorus analysis in protein samples by ICP–MS is discussed. The analytical method developed was applied for the analysis of homogeneous protein samples in very low amounts [1–100 µg of solid protein sample, e.g. β-casein or down to 1 µL of protein or digest in solution (e.g., tau protein)]. A further reduction of the diluted protein solution volume was achieved by the application of flow injection in ICP–SFMS, which is discussed with reference to real protein digests after protein separation using 2D gel electrophoresis.The detection limits for phosphorus in biological samples were determined by ICP–SFMS down to the ng g^–1 level. The present work discusses the figure of merit for the determination of phosphorus in a small amount of protein sample with ICP–SFMS in comparison to ICP–QMS.

Keywords: ICP–SFMS ICP–QMS Proteins Phosphorus

Figures of merit of pneumatic and ultrasonic sample introduction systems in inductively coupled plasma–multichannel-based emission spectrometry in an ultra-clean environment by K. V. Desboeufs; R. Losno; J. L. Colin (pp. 567-573).

Conventional figures of merit such as limits of detection, signal to background ratio or repeatability, are used to determine the performance of pneumatic and ultrasonic sample introduction systems in an ultra-clean environment with an axially viewed inductively coupled plasma–atomic emission spectrometry and multichannel detection. We observed that the ultrasonic nebuliser offered a large improvement of signal intensity (10–133 greater) compared to a cyclone chamber coupled with a pneumatic Meinhard nebuliser. This improvement is associated with an average increase of signal to background ratio by a factor 86 and an average decrease of detection limits by a factor 6. The improvement factors generally depend on the element and for the same element on spectral lines. Typically, the observed values of detection limits in this work are lower than those published and obtained in non-ultra-clean conditions. The results emphasize that the environmental conditions of cleaning and analysis are essential to avoid and control cross contamination of the samples and hence to obtain low detection limits.

Keywords: ICP–AES Trace elements Ultrasonic nebuliser Cyclonic nebuliser Clean environment

Determination of Cu, Ni, and Zn in fuel ethanol by FAAS after enrichment in column packed with 2-aminothiazole-modified silica gel by P. S. Roldan; I. L. Alcântara; G. R. Castro; J. C. Rocha; C. C. F. Padilha; P. M. Padilha (pp. 574-577).

This work describes the synthesis and characterization of 2-aminothiazole-modified silica gel (SiAT), as well as its application for preconcentration (in batch and column technique) of Cu(II), Ni(II) and Zn(II) in ethanol medium. The adsorption capacities of SiAT determined for each metal ion were (mmol g^–1): Cu(II)=1.20, Ni(II)=1.10 and Zn(II)=0.90. In addition, results obtained in flow experiments, showed a recovery of ca. 100% of the metal ions adsorbed in a column packed with 500 mg of SiAT. The eluent was 2.0 mol L^–1 HCl. The sorption–desorption of the studied metal ions made possible the development of a preconcentration method for metal ions at trace level in fuel ethanol using flame AAS for their quantification.

Keywords: Preconcentration 2-Aminothiazole-modified silica gel Fuel ethanol

Mercury determination in solid phases from application of the modified BCR-sequential extraction procedure: a valuable tool for assessing its mobility in sediments by A. Sahuquillo; G. Rauret; M. Bianchi; A. Rehnert; H. Muntau (pp. 578-583).

The present paper presents a feasibility study for the evaluation of mercury mobility in sediments by application of the modified BCR three-step sequential extraction procedure (BCR-SEP). The aim of the study was to evaluate the effect of acidification, reduction and oxidation processes on mercury mobility from sediments, once the SEP was validated with other trace metals.As extractable mercury amounts were mostly found below detection limits of the advanced mercury analyser (AMA-254) used for measuring the extracts (L.D.<0.5 ng), the use of a solid sampling atomic absorption spectrometer with a specially designed furnace for Hg atomisation was found to be an optimal technique to quantify Hg in the solid residues coming from the SEP.With this approach, mercury was found to be hardly mobile and only for one of the moderately polluted sediments (BCR CRM 320), extractable mercury (exchangeable fraction, BCR procedure step 1) has been found. An oxidation step with H₂O₂ was required to obtain extractability up to 64% of the total content in a highly polluted lagoon sediment.

Keywords: Mercury Solid-sample atomic absorption spectroscopy Sequential extractions Sediment

Microwave-assisted steam distillation with simultaneous liquid/liquid extraction of pentachlorophenol from organic wastes and soils by Rolf-Alexander Düring; Xiaolei Zhang; Hans E. Hummel; Janusz Czynski; Stefan Gäth (pp. 584-588).

An efficient method for extracting pentachlorophenol (PCP) from organic solid matrices and soils using direct excitation of the fresh samples by microwave energy is presented. Steam-volatile PCP partitioned into the organic solvent n-hexane within the closed extraction vessel, resulting in recovery rates of 85–92% from aged samples. Condensed water provided a boundary layer between extract and sample thus preventing any contact of PCP with and re-partitioning into the sample. Duration of the microwave-assisted process was 35 min. Crude extracts were derivatized by heptafluorobutyric anhydride (HFBA) to improve selectivity and sensitivity resulting in detection limits of 1–2 µg kg⁻¹. GC–MS/MS analyses proved that suitable extracts with only minor impurities were obtained. Common sample treatment steps like drying, thorough grinding, frequent transferring, and tedious clean-up, and concentration procedures which all can cause certain losses of analyte were minimized. The efficiency of the method was verified by comparison with an established ultrasonic extraction procedure. This microwave-assisted pressurized steam distillation with simultaneous partition into an organic phase thus provides a streamlined and efficient strategy which requires no additional investment in standard equipment for microwave-assisted extractions (MAE). Degradation of analytes at longer extraction times must be taken into account.

Keywords: Sample preparation Substituted phenols Microwave-assisted steam distillation Closed vessel system Derivatization

Evaluation of the efficiency of extraction of PAHs from diesel particulate matter with pressurized solvents by Luigi Turrio-Baldassarri; Chiara Laura Battistelli; Anna Laura Iamiceli (pp. 589-595).

Pressurized Fluid Extraction (PFE) was evaluated for the extraction of polycyclic aromatic hydrocarbons (PAHs) and nitro-derivatives from diesel particulate matter. Extraction conditions were set up by performing several tests in which temperature, solvent strength, pressure, and static time were gradually increased. The results obtained on a laboratory test material made of a "lean" (low content of soluble fraction) Diesel particulate matter indicate that very severe conditions were needed in order to obtain better recoveries of the higher molecular weight molecules. Moreover, extraction efficiency seems to be influenced by the amount of soluble matter in the particulate, so that a "lean" particulate appears more difficult to extract. Recoveries of the deuterated standards of certain PAHs (i.e. indeno[1,2,3- cd]pyrene) were incomplete even with the toughest conditions tested. Experiments carried out on a certified material (SRM 1650 from NIST) also indicate that PFE can perform a better extraction of some of the PAHs than the method used for certification, but still incomplete. Comparison of results obtained on the SRM with different extraction techniques suggests that the composition of the extract varies considerably with the extraction technique and conditions. It is relevant to notice that recent Diesel engines produce leaner particulate: for future materials more drastic extraction conditions will be required.

Keywords: Pressurized fluid extraction (PFE) Diesel particulate matter PAHs

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Analytical and Bioanalytical Chemistry (v.375, #4)