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Analytica Chimica Acta (v.740, #)

Editorial Board (pp. iii).

Miniaturization through lab-on-a-chip: Utopia or reality for routine laboratories? A review by Ángel Ríos; Mohammed Zougagh; Mónica Avila (pp. 1-11).

Display Omitted► LOC possibilities on routine laboratories are reviewed. ► LOC selected contributions have demonstrated the practical usefulness. ► LOC features – routine laboratory requirements are discussed. ► Main LOC ‘niche’ for practical developments is pointed out.Micro total analysis (μTAS), also called “lab-on-a-chip (LOC)” technology, promises solutions for high throughput and highly specific analysis for chemistry, biology and medicine, while consuming only tiny amounts of samples, reactants and space. This article reports selected contributions of LOC, which represent clear practical approaches for routine work, or presenting potentiality to be transferred to routine analytical laboratories. Taking into account the present LOC state-of-the-art, we identify various reasons for its scarce implementation in routine analytical laboratories despite its high analytical potential, as well as the probably main “niche” for successfully practical developments is suggested.

Keywords: Miniaturization; Lab-on-a-chip; Routine laboratories; Review

Instrument and process independent binning and baseline correction methods for liquid chromatography–high resolution-mass spectrometry deconvolution by Shaji Krishnan; Jack T.W.E. Vogels; Leon Coulier; Richard C. Bas; Margriet W.B. Hendriks; Thomas Hankemeier; Uwe Thissen (pp. 12-19).

Display Omitted► Appropriately collating the m/ z values over time is an effective machine independent scheme for aggregating a metabolite profile from a mass chromatogram. ► Entropy is an effective metric for baseline correction. ► The efficacy of each was proven on two LC–HR-MS datasets.Setting appropriate bin sizes to aggregate hyphenated high-resolution mass spectrometry data, belonging to similar mass over charge ( m/ z) channels, is vital to metabolite quantification and further identification. In a high-resolution mass spectrometer when mass accuracy (ppm) varies as a function of molecular mass, which usually is the case while reading m/ z from low to high values, it becomes a challenge to determine suitable bin sizes satisfying all m/ z ranges. Similarly, the chromatographic process within a hyphenated system, like any other controlled processes, introduces some process driven systematic behavior that ultimately distorts the mass chromatogram signal. This is especially seen in liquid chromatogram–mass spectrometry (LC–MS) measurements where the gradient of the solvent and the washing step cycle—part of the chromatographic process, produce a mass chromatogram with a non-uniform baseline along the retention time axis. Hence prior to any automatic signal decomposition techniques like deconvolution, it is a equally vital to perform the baseline correction step for absolute metabolite quantification. This paper will discuss an instrument and process independent solution to the binning and the baseline correction problem discussed above, seen together, as an effective pre-processing step toward liquid chromatography–high resolution-mass spectrometry (LC–HR-MS) data deconvolution.

Keywords: Accurate mass binning; Baseline correction; Liquid chromatography–mass spectrometry; Pre-processing; Deconvolution

Random frog: An efficient reversible jump Markov Chain Monte Carlo-like approach for variable selection with applications to gene selection and disease classification by Hong-Dong Li; Qing-Song Xu; Yi-Zeng Liang (pp. 20-26).

Display Omitted► The proposed method possesses advantages of RJMCMC algorithms. ► The proposed method is easier to implement than RJMCMC. ► Competitive results over published work were obtained. ► Random frog is computationally very efficient.The identification of disease-relevant genes represents a challenge in microarray-based disease diagnosis where the sample size is often limited. Among established methods, reversible jump Markov Chain Monte Carlo (RJMCMC) methods have proven to be quite promising for variable selection. However, the design and application of an RJMCMC algorithm requires, for example, special criteria for prior distributions. Also, the simulation from joint posterior distributions of models is computationally extensive, and may even be mathematically intractable. These disadvantages may limit the applications of RJMCMC algorithms. Therefore, the development of algorithms that possess the advantages of RJMCMC methods and are also efficient and easy to follow for selecting disease-associated genes is required. Here we report a RJMCMC-like method, called random frog that possesses the advantages of RJMCMC methods and is much easier to implement. Using the colon and the estrogen gene expression datasets, we show that random frog is effective in identifying discriminating genes. The top 2 ranked genes for colon and estrogen are Z50753, U00968, and Y10871_at, Z22536_at, respectively. (The source codes with GNU General Public License Version 2.0 are freely available to non-commercial users at:http://code.google.com/p/randomfrog/.)

Keywords: Variable selection; Gene expression-based disease classification; Markov Chain Monte Carlo; Random frog

High-performance liquid chromatography with fast-scanning fluorescence detection and multivariate curve resolution for the efficient determination of galantamine and its main metabolites in serum by María J. Culzoni; Ricardo Q. Aucelio; Graciela M. Escandar (pp. 27-35).

Display Omitted► A simple and direct analytical method for galantamine and its serum metabolites is developed. ► Low detection limits are rapidly achieved, with minimal organic reagents and sample amounts. ► Quantification is accomplished using green-chemistry principles.Based on green analytical chemistry principles, an efficient approach was applied for the simultaneous determination of galantamine, a widely used cholinesterase inhibitor for the treatment of Alzheimer's disease, and its major metabolites in serum samples. After a simple serum deproteinization step, second-order data were rapidly obtained (less than 6min) with a chromatographic system operating in the isocratic regime using ammonium acetate/acetonitrile (94:6) as mobile phase. Detection was made with a fast-scanning spectrofluorimeter, which allowed the efficient collection of data to obtain matrices of fluorescence intensity as a function of retention time and emission wavelength. Successful resolution was achieved in the presence of matrix interferences in serum samples using multivariate curve resolution-alternating least-squares (MCR-ALS). The developed approach allows the quantification of the analytes at levels found in treated patients, without the need of applying either preconcentration or extraction steps. Limits of detection in the range between 8 and 11ngmL⁻¹, relative prediction errors from 7 to 12% and coefficients of variation from 4 to 7% were achieved.

Keywords: Chromatography; Spectrofluorimetry; Multivariate calibration; Galantamine; Metabolites

A high-throughput approach for the determination of pesticide residues in cucumber samples using solid-phase microextraction on 96-well plate by Habib Bagheri; Ali Es’haghi; Ali Es-haghi; Noushin Mesbahi (pp. 36-42).

Display Omitted► A high-throughput method for the determination of pesticide residues in cucumber was developed. ► The simultaneous analysis was performed using a 96-fiber SPME array on 96-well plates. ► The SPME fibers consisted of 1.0cm length of polydimethylsiloxane tubing, coated on stainless steel rods.A high-throughput solid-phase microextraction (SPME) on 96-well plate together with gas chromatography–mass spectrometry (GC–MS) was developed for the determination of some selected pesticides in cucumber samples. Pieces with the length of 1.0cm of silicon tubing were precisely prepared and then coated on the end part of stainless steel wires. The prepared fibers were positioned in a home-made polytetrafluoroethylene (PTFE)-based constructed ninety-six holes block to have the possibility of simultaneous immersion of the SPME fibers into the center of individual wells. Pesticides such as diazinon, penconazol, tebuconazol, bitertanol, malathion, phosalone and chlorpyrifos-methyl were selected for their highly application in cucumber field. The performances of the SPME fibers, such as intra and inter-fibers reproducibility, were evaluated and the results showed a good similarity in extraction yields. A volume of 1mL of the aquatic supernatant of the cucumber samples was transferred into the 96-well plate and the array of SPME fibers was applied for the extraction of the selected pesticides. The important parameters influencing the whole extraction process including, organic solvent percent, salt addition, dilution factor, stirring rate and extraction time were optimized. The inter- and intra-day RSD% were found to be less than 15.4%. Limits of detection (LOD) and limits of quantification (LOQ) were below 60 and 180μgkg⁻¹, respectively. The coefficient of determination was satisfactory ( r²>0.99) for all the studied analytes. The developed method was successfully applied to the monitoring of several samples gathered from local markets.

Keywords: High-throughput; 96-Well plate; Pesticide residues; Cucumber analysis; Solid-phase microextraction

Multiresidue determination of pesticides from aquatic media using polyaniline nanowires network as highly efficient sorbent for microextraction in packed syringe by Habib Bagheri; Noshin Alipour; Zahra Ayazi (pp. 43-49).

Polyaniline nanowires network was prepared using soft template technique and used as sorbent of microextraction in packed syringe for the multiresidue determination of selected analytes from triazine, organochlrorine and organophosphorous pesticides in aqueous samples.Display Omitted► Polyaniline nanowires network was synthesized using soft template method. ► The presence of micelles was an important parameter in shaping the growing polymer. ► The synthesized nanowires showed higher extraction capability in comparison with the bulk polymer.A simple, rapid and sensitive method based on microextraction in packed syringe (MEPS), in combination with gas chromatography–mass spectrometry (GC–MS) was developed. Polyaniline (PANI) nanowires network was synthesized and used as sorbent of MEPS for the multiresidue determination of selected analytes from triazine, organochlrorine and organophosphorous pesticides in aqueous samples. The PANI nanowires network was prepared using soft template technique and its characterization was studied by scanning electron microscopy (SEM). The presence of micelles in this methodology showed to be an important parameter in shaping the growing polymer. Hexadecyltrimethylammonium bromide (HTAB) was used as structure directing agent in PANI preparation procedure and this was led to the formation of nanowires with diameters ranging from 35nm to 45nm. The synthesized PANI nanowires network showed higher extraction capability in comparison with the bulk PANI. Important parameters influencing the extraction and desorption processes including desorption solvent, elution volume, draw–eject cycles of sample, draw–eject mode, pH effect and amount of sorbent were optimized. Limits of detection were in the range of 0.07–0.3ngmL⁻¹ using time scheduled selected ion monitoring (SIM) mode. The linearity of method was in the range from 0.5–200ngmL⁻¹ to 0.2–1000ngmL⁻¹. The method precision (RSD %) with three replicates were in the range of 5.3–18.4% at the concentration level of 5ngmL⁻¹. The developed method was successfully applied to the Zayandeh-rood river water samples and the matrix factor obtained for the spiked real water samples were in the range of 0.79–0.94.

Keywords: Polyaniline nanowires network; Soft template technique; Microextraction in packed syringe; Multiresidue determination; Gas chromatography–mass spectrometry

Ion-pair sorptive extraction of perfluorinated compounds from water with low-cost polymeric materials: Polyethersulfone vs polydimethylsiloxane by Eugenia Villaverde-de-Sáa; Inés Racamonde; José Benito Quintana; Rosario Rodil; Rafael Cela (pp. 50-57).

Display Omitted► Ion-pair disposable sorptive extraction of PFCs in water. ► Polydimethylsiloxane (PDMS) vs Polyethersulfone (PES). ► Different extraction variables optimized. ► PES provided better extraction efficiency of polar analytes. ► LODs in the 0.2–20ngL⁻¹ range with PES.A method for the determination of seven perfluorinated carboxylic acids and perfluorooctane sulphonate (PFOS) in aqueous samples using low-cost polymeric sorptive extraction as sample preparation technique, followed by liquid chromatography–tandem mass spectrometry (LC–MS/MS) determination has been developed and validated. Simplicity of the analytical procedure, low volume of solvent and sample required, low global price and a good selectivity providing cleaner extracts are the main advantages of this extraction technique. Polydimethylsiloxane (PDMS) and polyethersulfone (PES) materials were evaluated and compared to achieve the best extraction efficiencies. Hence, different variables have been optimized, viz.: sample pH, concentration of an ion-pairing agent (tetrabutylammonium), ionic strength, sample volume, extraction time, desorption solvent volume, desorption time and the need for auxiliary desorption techniques (sonication). Overall, PES leaded to a better sensitivity than PDMS, particularly for the most polar compounds, reaching detection limits (LODs) in the 0.2–20ngL⁻¹ range. The precision of the method, expressed as relative standard deviation (RSD), was lower than 16%. Finally, the PES material was employed for the analysis of sea, sewage and fresh water samples. Perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) were detected in all the analyzed influent samples reaching levels of up to 401ngL⁻¹. In surface water, perfluorohexanoic acid (PFHxA) exhibited the highest concentrations, up to 137ngL⁻¹.

Keywords: Perfluorinated compounds (PFCs); Perfluorooctane sulfonate (PFOS); Perfluorooctanoic acid (PFOA); Sorptive extraction; Polydimethylsiloxane (PDMS); Polyethersulfone (PES); Liquid chromatography–mass spectrometry (LC–MS); Water

Comparison of three different enrichment strategies for serum low molecular weight protein identification using shotgun proteomics approach by Anna Laura Capriotti; Giuseppe Caruso; Chiara Cavaliere; Susy Piovesana; Roberto Samperi; Aldo Laganà (pp. 58-65).

Display Omitted► Serum low molecular weight protein fractionation suitable for biomarker discovery. ► Comparison of three recent high-throughput methods for serum protein enrichment. ► Shotgun proteomics study of low molecular weight proteins isolated in serum.Serum low-molecular weight (LMW) proteins potentially contain useful biological information and their identification can be used to discover novel potential biomarkers. Given the high complexity of serum samples, in the last years several different prefractionation and enrichment strategies have been developed. In this study three different methods, i.e. hydrogel nanoparticles, Proteominer^® peptide ligand affinity beads and Sartorius Vivaspin^® centrifugal ultrafiltration device, were compared and evaluated in order to select the best strategy for the enrichment and prefractionation of LMW proteins. A shotgun proteomics approach was adopted, with in-solution proteolytic digestion of the whole protein mixture and determination of the resulting peptides by nanoHPLC coupled with a high-resolution Orbitrap LTQ-XL mass spectrometer. Data analysis, focusing on the LMW proteome (MW≤40kDa), has shown that the hydrogel nanoparticles performed better in enriching the LMW protein profiles, with 115 proteins identified against 93 and 95 for Proteominer^® beads and Sartorius Vivaspin^® device, respectively.

Keywords: Abbreviations; LMW; low molecular weight; HMW; high molecular weight; MW; molecular weight; Poly(NIPAm/CB) core (VSA); poly(N-isopropylacrilamide/Cibacron Blue) core (vinylsulfonic acid)Affinity beads; Biomarker discovery; Hydrogel nanoparticles; Low-molecular weight proteins; Serum; Ultrafiltration

Evaluating the complexation behavior and regeneration of boron selective glucaminium-based ionic liquids when used as extraction solvents by Manishkumar D. Joshi; Daniel J. Steyer; Jared L. Anderson (pp. 66-73).

Display Omitted► Glucaminium-based ILs exhibit high selectivity for boron species using DLLME. ► The concentration of glucaminium-based IL affects type of boron complex formed. ► Use of 0.1M HCl allows for regeneration of the IL solvent following extraction. ► Selectivity of the glucaminium-based ILs for boron species in seawater is similar to Milli-Q water.Glucaminium-based ionic liquids are a new class of solvents capable of extracting boron-species from water with high efficiency. The complexation behavior of these ILs with borate was thoroughly studied using¹¹B NMR. Two different complexes, namely, monochelate complex and bischelate complex, were observed.¹¹B NMR was used extensively to determine the formation constants for monochelate and bischelate complexes. The IL concentration was observed to have a significant effect on the IL–borate complexes. Using an in situ dispersive liquid–liquid microextraction (in situ DLLME) method, the extraction efficiency for boron species was increased dramatically when lithium bis[(trifluoromethyl)sulfonyl]imide (LiNTf₂) was used as the metathesis salt in an aqueous solution containing 0.1M sodium chloride. IL regeneration after extraction was achieved using 0.1M hydrochloric acid. The extraction efficiency of boron species was consistent when the IL was employed after three regeneration cycles. The selectivity of the IL for boron species in synthetic seawater samples was similar to performing the same extraction from Milli-Q water samples.

Keywords: Ionic liquids; Borate ion; Boric acid; Extraction; Seawater

A naked-eye based strategy for semiquantitative immunochromatographic assay by Daohong Zhang; Peiwu Li; Qi Zhang; Ran Li; Wen Zhang; Xiaoxia Ding; Chang Ming Li (pp. 74-79).

To offer semiquantitative analytical ability for a single analyte, the naked-eye based strategy used three test lines (TL-I–III) instead of the traditional application of a single test line per analyte or multi-test lines for multi-analyte in simultaneous detection strips. The three test lines, containing the same capture reagent, was the key point of the strategy and also the basis of semiquantitative analytical ability of the NSI-strip. In the assay, with the increase of concentration, the analyte caused the TLs to disappear in a graduated sequence due to competition between the analyte and the immobilized capture reagent to bind with the nanogold-Ab probe, in other words, the disappearance of each test line represented a threshold level of analyte concentration. Analyte concentration levels could thus be determined by observing the number of TLs developed in the test zone. In this way, the NSI-strip assay improved the qualitative presence/absence detection of traditional strip by measuring the content (range) of target analytes semiquantitatively.Display Omitted► A novel naked-eye based strategy for semiquantitative immunochromatographic assay was described by dispensing three test lines (TLs) on a nitrocellulose membrane to form the test zone and validated with aflatoxin B₁ as a model analyte. ► Compared to traditional strips, the naked-eye based semiquantitative immunochromatographic strip (NSI-strip) could offer more parameter information of analyte content, these parameters were: three threshold concentrations, five detection ranges and a visual detection limit. ► The NSI-strip improved the qualitative presence/absence detection of traditional strip by measuring the content (range) of target analytes semiquantitatively.It is critical to develop a cost-effective quantitative/semiquantitative assay for rapid diagnosis and on-site detection of toxic or harmful substances. Here, a naked-eye based semiquantitative immunochromatographic strip (NSI-strip) was developed, on which three test lines (TLs, TL-I, TL-II and TL-III) were dispensed on a nitrocellulose membrane to form the test zone. Similar as the traditional strip assay for small molecule, the NSI-strip assay was also based on the competitive theory, difference was that the analyte competed three times with the capture reagent for the limited number of antibody binding sites. After the assay, the number of TLs developed in the test zone was inversely proportional to the analyte concentration, thus analyte content levels could be determined by observing the appeared number of TLs. Taking aflatoxin B₁ as the model analyte, visual detection limit of the NSI-strip was 0.06ngmL⁻¹ and threshold concentrations for TL-I–III were 0.125, 0.5, and 2.0ngmL⁻¹, respectively. Therefore, according to the appeared number of TLs, the following concentration ranges would be detectable by visual examination: 0–0.06ngmL⁻¹ (negative samples), and 0.06–0.125ngmL⁻¹, 0.125–0.5ngmL⁻¹, 0.5–2.0ngmL⁻¹ and >2.0ngmL⁻¹ (positive samples). That was to say, compared to traditional strips the NSI-strip could offer more parameter information of the target analyte content. In this way, the NSI-strip improved the qualitative presence/absence detection of traditional strips by measuring the content (range) of target analytes semiquantitatively.

Keywords: Semiquantitative; Immunochromatographic assay; Naked-eye; On-site

Photoluminescent and electrochemiluminescent dual-signaling probe for bio-thiols based on a ruthenium(II) complex by Wenzhu Zhang; Run Zhang; Jingmei Zhang; Zhiqiang Ye; Dayong Jin; Jingli Yuan (pp. 80-87).

Display Omitted► A unique ruthenium(II) complex-based probe for bio-thiols was developed. ► The probe can respond to bio-thiols to give PL and ECL dual-signals. ► The probe was used for the PL and ECL detection of bio-thiols in aqueous media. ► The endogenous intracellular thiols were luminously imaged using the probe.Photoluminescence (PL) and electrochemiluminescence (ECL) detection techniques are highly sensitive and widely used methods for clinical diagnostics and analytical biotechnology. In this work, a unique ruthenium(II) complex, [Ru(bpy)₂(DNBSO-bpy)](PF₆)₂ (bpy: 2,2′-bipyridine; DNBSO-bpy: 2,4-dinitrobenzenesulfonate of 4-(4-hydroxyphenyl)-2,2′-bipyridine), has been designed and synthesized as a highly sensitive and selective PL and ECL dual-signaling probe for the recognition and detection of bio-thiols in aqueous media. As a thiol-responsive probe, the complex can specifically and rapidly react with bio-thiols in aqueous solutions to yield a bipyridine-Ru(II) complex derivative, [Ru(bpy)₂(HP-bpy)]²⁺ (HP-bpy: 4-(4-hydroxyphenyl)-2,2′-bipyridine), accompanied by the remarkable PL and ECL enhancements. The complex was used as a probe for the PL and ECL detections of cysteine (Cys) and glutathione (GSH) in aqueous solutions. The dose-dependent PL and ECL enhancements showed good linear relationships against the Cys/GSH concentrations with the detection limits at nano-molar concentration level. Moreover, the complex-loaded HeLa cells were prepared for PL imaging of the endogenous intracellular thiols. The results demonstrated the practical utility of the complex as a cell-membrane permeable probe for PL imaging detection of bio-thiols in living cells.

Keywords: Ruthenium(II) complex; Bio-thiols; Photoluminescence; Electrochemiluminescence; Bioimaging

A graphene-based real-time fluorescent assay of deoxyribonuclease I activity and inhibition by Zhixue Zhou; Chengzhou Zhu; Jiangtao Ren; Shaojun Dong (pp. 88-92).

Display Omitted► A novel graphene-based real-time fluorescent assay of deoxyribonuclease I (DNase I) activity and inhibition is developed. ► DNase I activity can be quantitatively analyzed by the velocity of the enzymatic reaction, and 1.75UmL⁻¹ DNase I can be significantly detected. ► Crystal violet (CV) is found to inhibit DNase I with IC₅₀ values of 0.35μM.Using the remarkable difference in the affinity of graphene oxide (GO) with double strand DNA (dsDNA) and short DNA fragments, we report for the first time a GO-based nonrestriction nuclease responsive system. Our system was composed of GO and a fluorescent dye fluorescein amidite (FAM)-labeled dsDNA substrate (F-dsDNA). At first, the fluorescence of this F-dsDNA substrate was quenched upon addition of GO. When nuclease was added to the mixture of dsDNA and GO, hydrolysis of dsDNA was initiated and small DNA fragments were produced. As a result, the short FAM-linked DNA fragments were released from GO due to the weak affinity of GO with short DNA fragments, and the fluorescence got a restoration. At present, many sensing systems are based on the fact that GO prefers to bind long single strand DNA (ssDNA) over dsDNA or short ssDNA. As for our system, GO has a prior binding with dsDNA over short DNA fragments. Compared with previous methods, this assay platform has some advantages. First, since GO can be prepared in large quantities from graphite available at very low cost, this method shows advantages of simplicity and cost efficiency. Besides, the proposed GO-based nuclease assay provides high sensitivity due to the super quenching capacity of GO. Using deoxyribonuclease I (DNase I) as a model system, DNase I activity can be quantitatively analyzed by the velocity of the enzymatic reaction, and 1.75UmL⁻¹ DNase I can be significantly detected. Moreover, the fluorescent intensity with various concentrations of nuclease becomes highly discriminating after 3–8min. Thus, it is possible to detect nuclease activity within 3–8min, which demonstrates another advantage of quick response of the present system. Finally, use of dsDNA as substrate, our method can achieve real-time nuclease activity/inhibition assay, which is time-saving and effortless.

Keywords: Graphene oxide; Nonrestriction nuclease; Deoxyribonuclease I; DNA; Fluorescent assay

Determination of polycyclic aromatic hydrocarbons and their oxy-, nitro-, and hydroxy-oxidation products by R.E. Cochran; N. Dongari; H. Jeong; J. Beránek; S. Haddadi; J. Shipp; A. Kubátová (pp. 93-103).

Display Omitted► We describe a method for determining PAHs and their oxidation products. ► Solid-phase extraction was used to fractionate PAHs and their oxidation products. ► Gas chromatography–mass spectrometry methods were optimized. ► The developed method was applied to two particulate matter (PM) samples.A sensitive method has been developed for the trace analysis of PAHs and their oxidation products (i.e., nitro-, oxy-, and hydroxy-PAHs) in air particulate matter (PM). Following PM extraction, PAHs, nitro-, oxy-, and hydroxy-PAHs were fractionated using solid phase extraction (SPE) based on their polarities. Gas chromatography–mass spectrometry (GC–MS) conditions were optimized, addressing injection (i.e., splitless time), negative-ion chemical ionization (NICI) parameters, i.e., source temperature and methane flow rate, and MS scanning conditions. Each class of PAH oxidation products was then analyzed using the sample preparation and appropriate ionization conditions (e.g., nitro-PAHs exhibited the greatest sensitivity when analyzed with NICI–MS while hydroxy-PAHs required chemical derivatization prior to GC–MS analysis). The analyses were performed in selected-ion-total-ion (SITI) mode, combining the increased sensitivity of selected-ion monitoring (SIM) with the identification advantages of total-ion current (TIC). The instrumental LODs determined were 6–34pg for PAHs, 5–36pg for oxy-PAHs, and 1–21pg for derivatized hydroxy-PAHs using electron ionization (GC-EI-MS). NICI–MS was found to be a useful tool for confirming the tentative identification of oxy-PAHs. For nitro-PAHs, LODs were 1–10pg using negative-ion chemical ionization (GC-NICI-MS). The developed method was successfully applied to two types of real-world PM samples, diesel exhaust standard reference material (SRM 2975) and wood smoke PM.

Keywords: PAHs; Nitro-PAHs; Hydroxy-PAHs; SPE; Fractionation; Particulate matter

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Analytica Chimica Acta (v.740, #)