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Analytica Chimica Acta (v.773, #)

Editorial Board (pp. iii).

Tutorial: Simulating chromatography with Microsoft Excel Macros by Akinde Kadjo; Purnendu K. Dasgupta (pp. 1-8).

Display OmittedFor a video abstract of a developing isocratic separation, see ScienceDirect Link to Video athttp://dx.doi.org/10.1016/j.aca.2012.11.055.Display Omitted► This work describes modeling of chromatography using simple repeated equilibration. ► This is implemented in MS Excel, using macro subroutines. ► It is intended primarily for beginning students for pedagogic purposes. ► But it can model complex elution profiles, nonlinear isotherms etc.Chromatography is one of the cornerstones of modern analytical chemistry; developing an instinctive feeling for how chromatography works will be invaluable to future generation of chromatographers. Specialized software programs exist that handle and manipulate chromatographic data; there are also some that simulate chromatograms. However, the algorithm details of such software are not transparent to a beginner. In contrast, how spreadsheet tools like Microsoft Excel™ work is well understood and the software is nearly universally available. We show that the simple repetition of an equilibration process at each plate (a spreadsheet row) followed by discrete movement of the mobile phase down by a row, easily automated by a subroutine (a “Macro” in Excel), readily simulates chromatography. The process is readily understood by a novice. Not only does this permit simulation of isocratic and simple single step gradient elution, linear or multistep gradients are also easily simulated. The versatility of a transparent and easily understandable computational platform further enables the simulation of complex but commonly encountered chromatographic scenarios such as the effects of nonlinear isotherms, active sites, column overloading, on-column analyte degradation, etc. These are not as easily simulated by available software. Views of the separation as it develops on the column and as it is seen by an end-column detector are both available in real time. Excel 2010™ also permits a 16-level (4-bit) color gradation of numerical values in a column/row; this permits visualization of a band migrating down the column, much as Tswett may have originally observed, but in a numerical domain. All parameters of relevance (partition constants, elution conditions, etc.) are readily changed so their effects can be examined. Illustrative Excel spreadsheets are given in the Supporting Information; these are easily modified by the user or the user can write his/her own routine.

Keywords: Chromatography education; Chromatography simulation; MS Excel; ^®; Excel; ^®; Macro

Surface plasmon resonance sensing of nucleic acids: A review by Hana Šípová; Jiří Homola (pp. 9-23).

Display Omitted► Advances of nucleic acid (NA) surface plasmon resonance (SPR) sensors are presented. ► Bioanalytical applications of NA SPR biosensors are reviewed. ► Applications for study of molecular interactions involving NAs are also discussed.Biosensors based on surface plasmon resonance (SPR) have become a central tool for the investigation and quantification of biomolecules and their interactions. Nucleic acids (NAs) play a vital role in numerous biological processes and therefore have been one of the major groups of biomolecules targeted by the SPR biosensors. This paper discusses the advances of NA SPR biosensor technology and reviews its applications both in the research of molecular interactions involving NAs (NA–NA, NA–protein, NA–small molecule), as well as for the field of bioanalytics in the areas of food safety, medical diagnosis and environmental monitoring.

Keywords: Surface plasmon resonance; Nucleic acid; Biosensor; Hybridization

High quality drug screening by capillary electrophoresis: A review by Meera Shanmuganathan; Philip Britz-McKibbin (pp. 24-36).

Display Omitted► Major configurations for conducting enzyme assays in capillary electrophoresis. ► New advances in drug screening for disease-related enzymes that reduce attrition. ► High quality screening of small molecules that function as inhibitors, stabilizers and/or catalytic uncouplers.High quality assays are needed in drug discovery to reduce the high attrition rate of lead compounds during primary screening. Capillary electrophoresis (CE) represents a versatile micro-separation technique for resolution of enzyme-catalyzed reactions, including substrate(s), product(s), cofactor(s) and their stereoisomers, which is needed for reliable characterization of biomolecular interactions in free solution. This review article provides a critical overview of new advances in CE for drug screening over the past five years involving biologically relevant enzymes of therapeutic interest, including transferases, hydrolases, oxidoreductases, and isomerases. The basic principles and major configurations in CE, as well as data processing methods needed for rigorous characterization of enzyme inhibition are described. New developments in functional screening of small molecules that modulate the activity of disease-related enzymes are also discussed. Although inhibition is a widely measured response in most enzyme assays, other important outcomes of ligand interactions on protein structure/function that impact the therapeutic potential of a drug will also be highlighted, such as enzyme stabilization, activation and/or catalytic uncoupling. CE offers a selective platform for drug screening that reduces false-positives while also enabling the analysis of low amounts of complex sample mixtures with minimal sample handling.

Keywords: Abbreviations; ACE; angiotensin I-converting enzyme; AChE; acetylcholinesterase; AD; Alzheimer's disease; ADP; adenosine diphosphate; AK; adenosine kinase; AMP; adenosine monophosphate; APES; aminopropyltriethoxysilane; APPI; atmospheric pressure photoionization; ATP; adenosine triphospate; BGE; background electrolyte; 3-BrPA; 3-bromo-2-oxopropionic acid; BVDU; (E)-5-(2-bromovinyl)-2′-deoxyuridine; CE; capillary electrophoresis; CK2; casein kinase II; ΔC; _M; mid-point for inactivation; Com; competitive inhibitor; CYP; cytochrome P450; EHNA; erythro-9-(2-hydroxy-3-nonyl) adenine; EOF; electroosmotic flow; ESI; electrospray ionization; ESI-MS; electrospray ionization- mass spectrometry; GCase; β-glucocerebrosidase; GCV; ganciclovir; HDB; hexadimethrine bromide; Hip-His-Leu; hippurylhisidylleucine tripeptide; HSV-1; herpes simplex virus type 1; HTS; high-throughput screening; HyPRE; Hydroxyproline epimerase; IC; ₅₀; half-maximal inhibition constant; IMER; immobilized enzyme microreactor; 5-IT; 5-iodotubercidin; K; _I; inhibition constant; K; _m; Michaelis–Menten constant; IFG; isofagomine; LC–MS; liquid chromatography–mass spectrometry; LIF; laser-induced ﬂuorescence; MAO-B; Monoamine oxidase B; MEKC; micellar electrokinetic chromatography; Mix; mixed-type inhibitor; MS/MS; tandem mass spectrometry; MU; 4-methylumbelliferone; MUG; 4-methylumbelliferyl-β-; d; -gluopyranoside; NADPH; nicotinamide adenine dinucleotide phosphate; nd; not determined; Non; non-competitive inhibitor; NPP; ecto-nucleotide pyrophosphatase-phosphodiesterase; ONPTG; 2-nitrophenyl-1-thio-β-; d; -thiogalactopyranoside; PA; polyacrylamide; PCs; pharmacological chaperones; PDDA; Poly(diallyldimethyl ammonium chloride; PEA; polyethylenamine; PEI; polyethylenimine; PNPG; p-nitrophenyl-β/α-; d; -glucopyranoside; PRAC; Proline epimerase; PYC; pyrrole 2-carboxylic acid; READ; restoration of enzyme activity upon denaturation; SDS; sodium dodecyl sulfate; SPR; surface plasmon resonance; TDLFP; transverse diffusion of laminar flow profiles; TK; thymidine kinase; TyrK; tyrosine kinase; WNK1; with-no-K[Lys] kinase; XOD; xanthine oxidaseCapillary electrophoresis; Enzyme kinetics; Drug screening; Inhibition; Biomolecular interactions

Toward chromium speciation in solids using wavelength dispersive X-ray fluorescence spectrometry Cr Kβ lines by J. Malherbe; F. Claverie (pp. 37-44).

Display Omitted► We investigate the potential of XRF to perform quantitative speciation analyses. ► As an example, we analyzed different soils and references containing chromium. ► We used three different chemometric methods to retrieve Cr(VI) mass fractions. ► We report accuracies in the range of ±15%.The determination of chromium speciation in solid samples is critical for environmental and industrial purposes. Several analytical methods exist to perform such a determination either directly in solid state or liquid state after an extraction step, each of them having some limitations. In this study, the use of a high-resolution wavelength-dispersive X-ray fluorescence spectrometer to determine and quantify chromium species is investigated by looking at the differences in the Kβ transition profiles between Cr(0), Cr(III) and Cr(VI) compounds. Three different approaches were tested and compared to determine the Cr(VI) fraction of known mixtures: relative height and peak fitting using calibration mixtures, partial least square regression (PLS) of pure compounds, and principal component regression (PCR) of pure compounds. The accuracy of these methods was found to be about the same with an average relative error in the range of 15%. However, PLS and PCR can be easily implemented in an automated way contrary to peak fitting which can be sometimes perceived as analyst-dependant. Another advantage of using PLS and PCR is that information concerning the other oxidation states present in the sample can be retrieved. Finally, PLS and the peak height approach can be used up to 0.5% total chromium which make the XRF an alternative technique to X-ray induced photoelectron spectroscopy (XPS) for chromium speciation in solid state.

Keywords: Hexavalent chromium; WD-XRF; Speciation; Kβ transition

Highly sensitive detection of urinary cadmium to assess personal exposure by Avni A. Argun; Ashley M. Banks; Gwendolynne Merlen; Linda A. Tempelman; Michael F. Becker; Thomas Schuelke; Badawi M. Dweik (pp. 45-51).

Display Omitted► An electrochemical sensor capable of detecting cadmium at parts-per-billion levels in urine. ► A novel fabrication method for Boron-Doped Diamond (BDD) ultramicroelectrode (UME) arrays. ► Unique combination of BDD UME arrays and a differential pulse voltammetry algorithm. ► High sensitivity, high reproducibility, and very low noise levels. ► Opportunity for portable operation to assess on-site personal exposure.A series of Boron-Doped Diamond (BDD) ultramicroelectrode arrays were fabricated and investigated for their performance as electrochemical sensors to detect trace level metals such as cadmium. The steady-state diffusion behavior of these sensors was validated using cyclic voltammetry followed by electrochemical detection of cadmium in water and in human urine to demonstrate high sensitivity (>200μAppb⁻¹cm⁻²) and low background current (<4nA). When an array of ultramicroelectrodes was positioned with optimal spacing, these BDD sensors showed a sigmoidal diffusion behavior. They also demonstrated high accuracy with linear dose dependence for quantification of cadmium in a certified reference river water sample from the U.S. National Institute of Standards and Technology (NIST) as well as in a human urine sample spiked with 0.25–1ppb cadmium.

Keywords: Boron-Doped Diamond (BDD); Ultramicroelectrode array; Electrochemical sensors; Urinary trace metal detection; Cadmium; Differential pulse stripping voltammetry (DPSV)

One-way and two-way pulsed electromembrane extraction for trace analysis of amino acids in foods and biological samples by Maryam Rezazadeh; Yadollah Yamini; Shahram Seidi; Ali Esrafili (pp. 52-59).

Pulsed electromembrane extraction was performed for the first time, as a new concept of electrically enhanced microextraction method, for extraction and quantification of histidine, phenylalanine and tryptophan in different matrices.Display Omitted► Pulsed electromembrane extraction (PEME) was used for extraction of some amino acids. ► A mixture of NPOE and DEHP was used as the organic liquid membrane. ► The method offers good linearity with correlation coefficient higher than 0.9979. ► The method was applied to determine amino acids in foods and biological samples. ► Two-way PEME was employed for highly selective extraction of tryptophan.In the present work, pulsed electromembrane extraction (PEME) was performed for the first time, as a new concept of electrically enhanced microextraction method, for extraction and quantification of histidine, phenylalanine and tryptophan in different matrices. PEME offers an alternative to conventional electromembrane extraction (EME), which faces problems such as serious instabilities in the analysis of real samples with high concentration levels of ions. In these samples, increasing of the ion transportation across the liquid membrane results in Joule heating during the extraction process which may follow by punctuation of the organic membrane, increasing of the current level and bubble formation due to electrolysis reactions. A mixture of 2-nitrophenyl octyl ether (NPOE), di-(2-ethylhexyl) phosphate (DEHP) and tris-(2-ethylhexyl) phosphate (TEHP) was immobilized in the pores of hollow fiber as the organic liquid membrane. Other effective parameters such as extraction time, ion balance and pulse frequency were optimized using the experimental design. Extraction recoveries in the range of 7.1–21.6% and satisfactory repeatability (2.1−1 for tryptophan, phenylalanine and histidine, respectively. The method offers acceptable linearity with correlation coefficients higher than 0.9979. Furthermore, the figures of merit of PEME are compared with the results from conventional electromembrane extraction (EME), which proves the advantages of the proposed technique. The method was applied to the determination and quantification of amino acids in foods and biological samples. Also, two-way PEME was employed as a novel approach for highly selective extraction of tryptophan as a model analyte to introduce an interesting ability of the proposed technique.

Keywords: Pulsed electromembrane extraction; Amino acids; Biological fluid; Food sample

Determination of priority pollutants in aqueous samples by dispersive liquid–liquid microextraction by Julia Martín; Dolores Camacho-Muñoz; Juan Luis Santos; Irene Aparicio; Esteban Alonso (pp. 60-67).

Display Omitted► Dispersive liquid–liquid microextraction for routine monitoring of pollutants ► Determination of nonylphenols, sulfonates and phthalate in environmental samples ► Influence of seven parameters in dispersive liquid–liquid microextraction ► Limits of detection in the range 0.009–0.224μgL⁻¹ with just 8mL of sample ► Suitable for nonylphenol and phthalate according to limits in Directive 2008/105/ECA dispersive liquid–liquid microextraction (DLLME) method followed by high-performance liquid chromatography–triple quadrupole mass spectrometry has been developed for the simultaneous determination of linear alkylbenzene sulfonates (LAS C₁₀, C₁₁, C₁₂, and C₁₃), nonylphenol (NP), nonylphenol mono- and diethoxylates (NP₁EO and NP₂EO), and di-(2-ethylhexyl)phthalate (DEHP). The applicability of the method has been tested by the determination of the above mentioned organic pollutants in tap water and wastewater. Several parameters affecting DLLME, such as, the type and volume of the extraction and disperser solvents, sample pH, ionic strength and number of extractions, have been evaluated. Methanol (1.5mL) was selected among the six disperser solvent tested. Dichlorobenzene (50μL) was selected among the four extraction solvent tested. Enrichment factor achieved was 80. Linear ranges in samples were 0.01–3.42μg L⁻¹ for LAS C₁₀–₁₃ and NP₂EO, 0.09–5.17μgL⁻¹ for NP₁EO, 0.17–9.19μgL⁻¹ for NP and 0.40–17.9μgL⁻¹ for DEHP. Coefficients of correlation were higher than 0.997. Limits of quantitation in tap water and wastewater were in the ranges 0.009–0.019μgL⁻¹ for LAS, 0.009–0.091μgL⁻¹ for NP, NP₁EO and NP₂EO and 0.201–0.224μgL⁻¹ for DEHP. Extraction recoveries were in the range from 57 to 80%, except for LAS C₁₀ (30–36%). The method was successfully applied to the determination of these pollutants in tap water and effluent wastewater from Seville (South of Spain). The DLLME method developed is fast, easy to perform, requires low solvent volumes and allows the determination of the priority hazardous substances NP and DEHP (Directive 2008/105/EC).

Keywords: Priority pollutants; Dispersive liquid–liquid microextraction; Liquid chromatography; Triple quadrupole mass spectrometry; Tap water; Wastewater

Determination of polycyclic and nitro musks in environmental water samples by means of microextraction by packed sorbents coupled to large volume injection-gas chromatography–mass spectrometry analysis by J. Cavalheiro; A. Prieto; M. Monperrus; N. Etxebarria; O. Zuloaga (pp. 68-75).

Display Omitted► We developed a fully automated at-line MEPS-LVI-GC–MS method for musks analysis. ► The analytes were detected in the ngL⁻¹ range. ► The time for a MEPS extraction is reduced to ∼10min due to the high automation. ► Less matrix co-extraction was of special value for analysis of wastewater samples. ► SBSE vs. MEPS were compared and good agreement obtained except for DPMI analysis.In this work the development and validation of a new procedure for the simultaneous determination of 9 nitro and polycyclic musk compounds: musk ambrette (MA), musk ketone (MK), musk mosken (MM), celestolide (ADBI), phantolide (AHMI), tonalide (AHTN), traseolide (ATII), cashmeran (DPMI) and galaxolide (HHCB) in environmental water samples (estuarine and wastewater) using microextraction by packed sorbent (MEPS) followed by large volume injection-gas chromatography–mass spectrometry (LVI-GC–MS) was carried out. Apart from the optimization of the different variables affecting MEPS (i.e., nature of the sorbent, nature of the solvent elution, sample load, and elution/injection volume) extraction recovery was also evaluated, not only for water samples but also for environmental water matrices such as estuarine and waste water. The use of two deuterated analogs ([²H₃]-AHTN and [²H₁₅]-MX) was successfully evaluated in order to correct matrix effect in complex environmental matrices such as influent samples from wastewater treatment plants. Method detection limits (MDLs) ranged from 5 to 25ngL⁻¹, 7 to 39ngL⁻¹ and 8 to 84ngL⁻¹ for influent, effluent and estuarine samples, respectively. Apparent recoveries were higher than 75% for all target compounds in all the matrices studied (estuarine water and wastewater) and the precision of the method, calculated as relative standard deviation (RSD), was below 13.2% at 200ngL⁻¹ concentration level and below 14.9% at low level (20ngL⁻¹ for all the target analytes, except for AHTN which was set at 40ngL⁻¹ and HHCB at 90ngL⁻¹, due to the higher MDL values presented by those target compounds). Finally, this MEPS procedure was applied to the determination of the target analytes in water samples, including estuarine and wastewater, from two estuaries, Urdaibai (Spain) and Adour (France) and an established stir-bar sorptive extraction-liquid desorption/large volume injection-gas chromatography–mass spectrometry (SBSE-LD/LVI-GC–MS) method was performed in parallel for comparison. Results were in good agreement for all the analytes determined, except for DPMI.

Keywords: Microextraction by packed sorbents; Large volume injection; Musks; Water samples

Relative quantification of enantiomers of chiral amines by high-throughput LC–ESI-MS/MS using isotopic variants of light and heavyl-pyroglutamic acids as the derivatization reagents by Toshiki Mochizuki; Sayuri Taniguchi; Haruhito Tsutsui; Jun Zhe Min; Koichi Inoue; Kenichiro Todoroki; Toshimasa Toyo’oka (pp. 76-82).

Display Omitted► Development of chiral labeling reagent for a pair of amine enantiomers. ► High-throughput analysis of diastereomers by UPLC–ESI-MS/MS. ► Highly efficient separation and detection of the enantiomers. ► Differential analysis of enantiomer ratio in different sample groups using light and heavy labeling reagents.l-Pyroglutamic acid (l-PGA) was evaluated as a chiral labeling reagent for the enantioseparation of chiral amines in terms of separation efficiency by reversed-phase chromatography and detection sensitivity by ESI-MS/MS. Several amines and amino acid methyl esters were used as typical representatives of the chiral amines. Both enantiomers of the chiral amines were easily labeled withl-PGAs at room temperature for 60min in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 1-hydroxy-1 H-benzotriazole as the activation reagents. The resulting diastereomers were completely separated by reversed-phase chromatography using the small particle (1.7μm) ODS column (Rs=1.6–6.8). A highly sensitive detection at a low-fmol level (1–4fmol) was also obtained from the multiple reaction monitoring (MRM) chromatograms. Therefore, a high-throughput determination was achieved by the present UPLC–ESI-MS/MS method.An isotope labeling strategy using light and heavyl-PGAs for the differential analysis of chiral amines in different sample groups was also proposed in this paper. As a model study, the differential analysis of the R and S ratio of 1-phenylethylamine (PEA) was performed according to the proposed procedure using light and heavy reagents, i.e.,l-PGA andl-PGA- d₅. The R/S ratio of PEA, spiked at the different concentrations in rat plasma, was almost similar to the theoretical values. Consequently, the proposed strategy using light and heavy chiral labeling reagents seems to be applicable for the differential analysis of chiral amine enantiomers in different sample groups, such as healthy persons and disease patients.

Keywords: l; -Pyroglutamic acid; Enantioseparation; Chiral amines; Isotope-coded derivatization; Reversed-phase chromatography; Mass spectrometry

Indium-tin-oxide thin film transistor biosensors for label-free detection of avian influenza virus H5N1 by Di Guo; Ming Zhuo; Xiaoai Zhang; Cheng Xu; Jie Jiang; Fu Gao; Qing Wan; Qiuhong Li; Taihong Wang (pp. 83-88).

Display Omitted► A highly selective label-free biosensor is established based on indium-tin-oxide thin-film transistors (ITO TFTs). ► AI H5N1 virus was successfully detected through shift in threshold voltage and field-effect mobility of ITO TFT. ► The ITO TFT is applied in biosensor for the first time and shows good reusability and stability. ► Fabrication of the platform is simple with low cost, which is suitable for mass commercial production.As continuous outbreak of avian influenza (AI) has become a threat to human health, economic development and social stability, it is urgently necessary to detect the highly pathogenic avian influenza H5N1 virus quickly. In this study, we fabricated indium-tin-oxide thin-film transistors (ITO TFTs) on a glass substrate for the detecting of AI H5N1. The ITO TFT is fabricated by a one-shadow-mask process in which a channel layer can be simultaneously self-assembled between ITO source/drain electrodes during magnetron sputtering deposition. Monoclonal anti-H5N1 antibodies specific for AI H5N1 virus were covalently immobilized on the ITO channel by (3-glycidoxypropyl)trimethoxysilane. The introduction of target AI H5N1 virus affected the electronic properties of the ITO TFT, which caused a change in the resultant threshold voltage ( V_T) and field-effect mobility. The changes of I_D– V_G curves were consistent with an n-type field effect transistor behavior affected by nearby negatively charged AI H5N1 viruses. The transistor based sensor demonstrated high selectivity and stability for AI H5N1 virus sensing. The sensor showed linear response to AI H5N1 in the concentrations range from 5×10⁻⁹gmL⁻¹ to 5×10⁻⁶gmL⁻¹ with a detection limit of 0.8×10⁻¹⁰gmL⁻¹. Moreover, the ITO TFT biosensors can be repeatedly used through the washing processes. With its excellent electric properties and the potential for mass commercial production, ITO TFTs can be promising candidates for the development of label-free biosensors.

Keywords: Indium-tin-oxide; Thin film transistor; Avian influenza H5N1 virus; Biosensor; Label-free detection

On-line immunoaffinity capillary electrophoresis based on magnetic beads for the determination of alpha-1 acid glycoprotein isoforms profile to facilitate its use as biomarker by Gabriel Morales-Cid; Jose Carlos Diez-Masa; Mercedes de Frutos (pp. 89-96).

Display Omitted► On-line coupling of immunopurification and capillary electrophoresis is developed. ► Magnetic beads are captured by magnets placed in the cartridge of the instrument. ► Alpha-1 acid glycoprotein is immunocaptured by antibody bound to magnetic beads. ► The procedure allows analysis of 10 isoforms of alpha-1 acid glycoprotein in serum. ► On-line purification, concentration and isoforms separation takes about 1h.An immunoaffinity purification method coupled on-line to capillary electrophoresis (IACE) which allows the determination of several isoforms of intact alpha-1 acid glycoprotein (AGP) in serum samples using UV detection is developed. The immunoaffinity step is based on anti-AGP antibodies (Abs) covalently bound to magnetic beads (MBs) which are captured at the inlet end of the capillary using permanent magnets placed inside the cartridge of the CE instrument. The on-line method includes injection of the MBs with the Ab bound (MBs–Ab) and their trapping by the magnets at the entrance of the separation column, injection of serum sample and capture of AGP by the Abs, release of captured AGP, focus of desorbed protein, separation of AGP isoforms, and removal of MBs–Ab. The optimization of the different factors involved in each step allowed purification, separation and detection of AGP isoforms in a single electrophoretic analysis in about 1h. Automation, sample and reagents consumption as well as analysis time was improved compared to off-line alternatives which use purification of AGP in an immunochromatographic column and CE separation of AGP isoforms in two independent operations. The analytical methodology developed allows the separation of 10 AGP isoforms in serum samples from a healthy donor. For a serum sample, precision (expressed as relative standard deviation) in terms of corrected area percentage was better than 0.5% for each peak accounting for more than 10% of total AGP and it was better than 4.0% in terms of relative migration time of each AGP isoform considering the whole process.

Keywords: On-line sample preparation; Orosomucoid; AGP; Isoforms separation; Magnetic beads; Immunoassay

Detailed elucidation of hydrocarbon contamination in food products by using solid-phase extraction and comprehensive gas chromatography with dual detection by Giorgia Purcaro; Peter Q. Tranchida; Laura Barp; Sabrina Moret; Lanfranco S. Conte; Luigi Mondello (pp. 97-104).

•Analysis of mineral oil (both MOSH and MOAH fractions) in food products.•Use of a comprehensive gas chromatographic system (GC×GC), with dual detection (FID and MS).•Silver nitrate silica gel solid-phase extraction (SPE) cartridge was exploited for sample preparation.•Comparison of quantitative results obtained via GC×GC, off-line GC-FID, and on-line liquid–gas chromatography (LC–GC).The present work is focused on the development/optimization of a comprehensive two-dimensional gas chromatography method, with dual detection [flame ionization (FID) and mass spectrometric], for the simultaneous identification and quantification of mineral-oil contaminants in a variety of food products. The two main classes of contaminants, namely saturated and aromatic hydrocarbons, were previously fractionated on a manually-packed silver silica solid-phase extraction (SPE) cartridge. The quantitative results were compared with those obtained by performing a large volume injection, in a GC-FID system, after the same SPE process and by an on-line liquid–gas chromatography method, with very similar results observed. The presence of a series of unknown compounds, that appeared when using the off-line methods, was investigated using the mass spectrometric data, and were tentatively-identified as esterified fatty acids, most probably derived from vegetable oil based ink.

Keywords: Comprehensive gas chromatography; GC; ×; GC; Mineral oil; Mineral oil saturated hydrocarbons (MOSH); Mineral oil aromatic hydrocarbons (MOAH)

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Analytica Chimica Acta (v.773, #)

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Analytica Chimica Acta (v.773, #)