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Analytica Chimica Acta (v.761, #)

Editorial Board (pp. iii).

Combined data mining strategy for the systematic identification of sport drug metabolites in urine by liquid chromatography time-of-flight mass spectrometry by Juan C. Domínguez-Romero; Juan F. García-Reyes; Rubén Martínez-Romero; Paula Berton; Esther Martínez-Lara; María L. Del Moral-Leal; Antonio Molina-Díaz (pp. 1-10).

Display Omitted► A strategy based on the use of two complementary data mining tools is proposed. ► Accurate m/ z extraction of diagnostic ions and mass shifts from biotransformations. ► Nine sport drugs from different classes were studied after single doses to rats. ► Several non-previously reported metabolites were identified with the approach. ► 24 propranolol metabolites detected (15 non previously described in literature).The development of comprehensive methods able to tackle with the systematic identification of drug metabolites in an automated fashion is of great interest. In this article, a strategy based on the combined use of two complementary data mining tools is proposed for the screening and systematic detection and identification of urinary drug metabolites by liquid chromatography full-scan high resolution mass spectrometry. The proposed methodology is based on the use of accurate mass extraction of diagnostic ions (compound-dependent information) from in-source CID fragmentation without precursor ion isolation along with the use of automated mass extraction of accurate-mass shifts corresponding to typical biotransformations (non compound-dependent information) that xenobiotics usually undergo when metabolized. The combined strategy was evaluated using LC–TOFMS with a suite of nine sport drugs representative from different classes (propranolol, bumetanide, clenbuterol, ephedrine, finasteride, methoxyphenamine, methylephedrine, salbutamol and terbutaline), after single doses administered to rats. The metabolite identification coverage rate obtained with the systematic method (compared to existing literature) was satisfactory, and provided the identification of several non-previously reported metabolites. In addition, the combined information obtained helps to minimize the number of false positives. As an example, the systematic identification of urinary metabolites of propranolol enabled the identification of up to 24 metabolites, 15 of them non previously described in literature, which is a valuable indicator of the usefulness of the proposed systematic procedure.

Keywords: Liquid chromatography; High resolution mass spectrometry; Drug metabolites; Sport drug testing; Propranolol

A simple method for methylmercury, inorganic mercury and ethylmercury determination in plasma samples by high performance liquid chromatography–cold-vapor-inductively coupled plasma mass spectrometry by Samuel S. de Souza; Andres Dobal Campiglia; Fernando Barbosa Jr. (pp. 11-17).

Display Omitted► A simple, fast and ultra-sensible procedure for mercury speciation in plasma/serum is proposed. ► The method combines a fast separation by HPLC, Hg cold-vapor formation followed by ICP-MS detection. ► LODs of 12ngL⁻¹, 5ngL⁻¹ and 4ngL⁻¹ for inorganic mercury, ethylmercury and methylmercury were achieved.A simple and sensitive method with a fast sample preparation procedure is proposed for the determination of mercury species in plasma/serum. The method combines online high-performance liquid chromatography separation, Hg cold-vapor formation and inductively coupled plasma mass spectrometry detection. Prior to analysis, plasma (250μL) was accurately pipetted into 15mL conical tubes. Then, an extractant solution containing mercaptoethanol, L-cysteine and HCl was added to the samples following sonication for 10min. Quantitative mercury extraction was achieved with the proposed procedure. Separation of mercury species was accomplished in less than 8min on a C8 reverse phase column with a mobile phase containing 3% v/v methanol+97% v/v (0.5% v/v 2-mercaptoethanol+0.05% v/v formic acid). The method detection limits were found to be 12ngL⁻¹, 5ngL⁻¹ and 4ngL⁻¹ for inorganic mercury, ethylmercury and methylmercury, respectively. Method accuracy is traceable to Standard Reference Material (SRM) 966 Toxic Metals in Bovine Blood from NIST. Additional validation was provided by the analysis of a secondary reference serum sample from the INSQ-Canada. Finally, the method was successfully applied for the speciation of mercury in plasma samples collected from volunteers exposed to methylmercury through fish consumption. For the first time to our knowledge, levels of different species of Hg in plasma samples from riverside populations exposed to MeHg were determined.

Keywords: ICP-MS; Speciation; Plasma; Mercury; Sample preparation; Liquid chromatography

Determination of lead by hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS): On-line generation of plumbane using potassium hexacyanomanganate(III) by Vedat Yilmaz; Zikri Arslan; LaKeysha Rose (pp. 18-26).

Display Omitted► Potassium hexacyanomanganate(III), (K₃Mn(CN)₆, was utilized first time for hydride generation (HG). ► Hexacyanomanganate(III) promoted generation of lead hydride (PbH₄) remarkably. ► The HG method using K₃Mn(CN)₆ enhanced sensitivity by at least 40-fold. ► The method detection limits for Pb were as low as 8ngL⁻¹ by ICP-MS. ► The method is highly suitable for quantitative determination of Pb in various samples and salt matrices by ICP-MS.A hydride generation (HG) procedure has been described for determination of Pb by ICP-MS using potassium hexacyanomanganate(III), K₃Mn(CN)₆, as an additive to facilitate the generation of plumbane (PbH₄). Potassium hexacyanomanganate(III) was prepared in acidic medium as it was unstable in water. The stability of hexacyanomanganate(III) was examined in dilute solutions of HCl, HNO₃ and H₂SO₄. The solutions prepared in 1% v/v H₂SO₄ were found to be stable for over a period of 24h. The least suitable medium was 1% v/v HNO₃. For generation of plumbane, acidic hexacyanomanganate(III) and sample solutions were mixed on-line along a 5-cm long tygon tubing (1.14mm i.d.) and then reacted with 2% m/v sodium borohydride (NaBH₄). A concentration of 0.5% m/v K₃Mn(CN)₆ facilitated the generation of PbH₄ remarkably. In comparison to H₂SO₄, HCl provided broader working range for which optimum concentration was 1% v/v. No significant interferences were noted from transition metals and hydride forming elements, up to 0.5μgmL⁻¹ levels, except Cu which depressed the signals severely. The depressive effects in the presence of 0.1μgmL⁻¹ Cu were alleviated by increasing the concentration of K₃Mn(CN)₆ to 2% m/v. Under these conditions, the sensitivity was enhanced by a factor of at least 42 to 48. The detection limit (3s) was 0.008μgL⁻¹ for²⁰⁸Pb isotope. Average signal-to-noise ratio (S/N) ranged between 18 and 20 for 1.0μgmL⁻¹ Pb solution. The accuracy of the method was verified by analysis of several certified reference materials, including Nearshore seawater (CASS-4), Bone ash (SRM 1400), and Mussel tissue (SRM 2976). The procedure was also successfully applied to the determination of Pb in coastal seawater samples by ICP-MS.

Keywords: Lead; Hydride generation; Hexacyanomanganate(III); ICP-MS

Species selective preconcentration and quantification of gold nanoparticles using cloud point extraction and electrothermal atomic absorption spectrometry by Georg Hartmann; Michael Schuster (pp. 27-33).

Display Omitted► We optimized cloud point extraction and ET-AAS parameters for Au-NPs measurement. ► A selective ligand (sodium thiosulphate) is introduced for species separation. ► A limit of detection of 5ng Au-NP per L is achieved for aqueous samples. ► Measurement of samples with high natural organic mater content is possible. ► Real water samples including wastewater treatment plant effluent were analyzed.The determination of metallic nanoparticles in environmental samples requires sample pretreatment that ideally combines pre-concentration and species selectivity. With cloud point extraction (CPE) using the surfactant Triton X-114 we present a simple and cost effective separation technique that meets both criteria. Effective separation of ionic gold species and Au nanoparticles (Au-NPs) is achieved by using sodium thiosulphate as a complexing agent. The extraction efficiency for Au-NP ranged from 1.01±0.06 (particle size 2nm) to 0.52±0.16 (particle size 150nm). An enrichment factor of 80 and a low limit of detection of 5ngL⁻¹ is achieved using electrothermal atomic absorption spectrometry (ET-AAS) for quantification. TEM measurements showed that the particle size is not affected by the CPE process. Natural organic matter (NOM) is tolerated up to a concentration of 10mgL⁻¹. The precision of the method expressed as the standard deviation of 12 replicates at an Au-NP concentration of 100ngL⁻¹ is 9.5%. A relation between particle concentration and the extraction efficiency was not observed. Spiking experiments showed a recovery higher than 91% for environmental water samples.

Keywords: Gold nanoparticles; Cloud point extraction; Pre-concentration; Species analysis; Waste water; Natural waters

Determination of phenolic compounds and authentication of PDO Lambrusco wines by HPLC-DAD and chemometric techniques by Elisa Salvatore; Marina Cocchi; Andrea Marchetti; Federico Marini; Anna de Juan (pp. 34-45).

Display Omitted► HPLC-DAD and multivariate curve resolution allows quantification of phenols in wines. ► This fast/cheap methodology does not require traditional complete chromatographic separation. ► MCR scores also provide a wine fingerprint to authenticate the different wine varieties. ► Multiset and constraints permit to solve scenarios of strong coelution and spectral overlap.This work proposes a fast and simple method for detection and quantification of phenolic compounds in PDO Lambrusco wines using HPLC-DAD and chemometric techniques. Samples belonging to three different varieties of Lambrusco (Grasparossa, Salamino and Sorbara) were analyzed to provide a methodology appropriate for routine analysis. Given the high complexity of the sample and the coelution among chromatographic peaks, the use of chemometric techniques to extract the information of the individual eluting compounds was needed. Multivariate curve resolution-alternating least squares (MCR-ALS) allowed the resolution of the chromatographic peaks obtained and the use of this information for the quantification of the phenolic analytes in the presence of interferences. Use of multiset analysis and local rank/selectivity information was proven to be crucial for the correct resolution and quantification of compounds. The quantitative data provided by MCR-ALS about the phenolic targets and additional compounds present in the samples analyzed provided wine composition profiles, which were afterwards used to distinguish among wine varieties. Principal component analysis applied to the wine profiles allowed characterizing the wines according to their varieties.

Keywords: Phenolic compounds; Lambrusco wine; Multivariate curve resolution-alternating least squares (MCR-ALS); Principal component analysis (PCA)

A spectral transfer procedure for application of a single class-model to spectra recorded by different near-infrared spectrometers for authentication of olives in brine by Paolo Oliveri; Maria Chiara Casolino; Monica Casale; Luca Medini; Francesca Mare; Silvia Lanteri (pp. 46-52).

Display Omitted► NIR spectroscopy was applied to assess authenticity of Taggiasca olives in brine. ► Two different FT-NIR spectrometers, with systematic response differences, were used. ► A spectral transfer procedure was developed to minimise instrumental differences. ► This made possible to apply UNEQ class models independently of the instrument used. ► The authentication model was validated on an external validation set of samples.Analytical methods for confirmation of food authenticity claims should be rapid, economic, non-destructive and should not require highly skilled personnel for their deployment. All such conditions are satisfied by spectroscopic techniques. In order to be extensively implemented in routine controls, an ideal method should also give a response independent of the particular equipment used. In the present study, near-infrared (NIR) spectroscopy was used for verifying authenticity of commercial olives in brine of cultivar Taggiasca. Samples were analysed in two laboratories with different NIR spectrometers and a mathematical spectral transfer correction – the boxcar signal transfer (BST) – was developed, allowing to minimise the systematic differences existing between signals recorded with the two instruments. Class models for the verification of olive authenticity were built by the unequal dispersed classes (UNEQ) method, after data compression by disjoint principal component analysis (PCA). Models were validated on an external test set.

Keywords: Food authenticity; Olive in brine; Near-infrared (NIR) spectroscopy; Boxcar signal transfer (BST); Chemometrics; Multivariate class-modelling

Modelling phenolic and technological maturities of grapes by means of the multivariate relation between organoleptic and physicochemical properties by E. Meléndez; M.C. Ortiz; L.A. Sarabia; M. Íñiguez; P. Puras (pp. 53-61).

Display Omitted► The ripeness of grapes at the harvest is interesting for obtaining high quality red wines. ► PLS models and a varimax rotation allows identifying technological and phenolic maturities in grapes. ► Organoleptic and physicochemical variables to study the degree of grapes maturity in D.O.C Rioja. ► Technological and phenolic maturities in grapes are not simultaneously reached.The ripeness of grapes at the harvest time is one of the most important parameters for obtaining high quality red wines. Traditionally the decision of harvesting is to be taken only after analysing sugar concentration, titratable acidity and pH of the grape juice (technological maturity). However, these parameters only provide information about the pulp ripeness and overlook the real degree of skins and seeds maturities (phenolic maturity). Both maturities, technological and phenolic, are not simultaneously reached, on the contrary they tend to separate depending on several factors: grape variety, cultivar, adverse weather conditions, soil, water availability and cultural practices. Besides, this divergence is increasing as a consequence of the climate change (larger quantities of CO₂, less rain, and higher temperatures).247 samples collected in vineyards representative of the qualified designation of origin Rioja from 2007 to 2011 have been analysed. Samples contain the four grape varieties usual in the elaboration of Rioja wines (‘tempranillo’, ‘garnacha’, ‘mazuelo’ and ‘graciano’).The present study is the first systematic investigation on the maturity of grapes that includes the organoleptic evaluation of the degree of grapes maturity (sugars/acidity maturity, aromatic maturity of the pulp, aromatic maturity of the skins and tannins maturity) together with the values of the physicochemical parameters (probable alcohol degree, total acidity, pH, malic acid, K, total index polyphenolics, anthocyans, absorbances at 420, 520 and 620nm, colour index and tartaric acid) determined over the same samples. A varimax rotation of the latent variables of a PLS model between the physicochemical variables and the mean of four sensory variables allows identifying both maturities. Besides, the position of the samples in the first plane defines the effect that the different factors exert on both phenolic and technological maturities.

Keywords: Grapes; Phenolic maturity; Technological maturity; Sensory analysis; Varimax rotation; PLS; D.O.C. Rioja

Robust calibrations on reduced sample sets for API content prediction in tablets: Definition of a cost-effective NIR model development strategy by Sigrid Pieters; Wouter Saeys; Tom Van den Kerkhof; Mohammad Goodarzi; Mario Hellings; Thomas De Beer; Yvan Vander Heyden (pp. 62-70).

Display Omitted► A cost-effective NIR model development strategy is proposed for API content prediction in tablets. ► Judicious use of prior spectral information improves PLS model performance. ► The clutter captures representative intra- and inter-batch spectral variability to be removed. ► Model requires completeness of the clutter rather than comprehensive calibration sets.Owing to spectral variations from other sources than the component of interest, large investments in the NIR model development may be required to obtain satisfactory and robust prediction performance. To make the NIR model development for routine active pharmaceutical ingredient (API) prediction in tablets more cost-effective, alternative modelling strategies were proposed. They used a massive amount of prior spectral information on intra- and inter-batch variation and the pure component spectra to define a clutter, i.e., the detrimental spectral information. This was subsequently used for artificial data augmentation and/or orthogonal projections. The model performance improved statistically significantly, with a 34–40% reduction in RMSEP while needing fewer model latent variables, by applying the following procedure before PLS regression: (1) augmentation of the calibration spectra with the spectral shapes from the clutter, and (2) net analyte pre-processing (NAP). The improved prediction performance was not compromised when reducing the variability in the calibration set, making exhaustive calibration unnecessary. Strong water content variations in the tablets caused frequency shifts of the API absorption signals that could not be included in the clutter. Updating the model for this kind of variation demonstrated that the completeness of the clutter is critical for the performance of these models and that the model will only be more robust for spectral variation that is not co-linear with the one from the property of interest.

Keywords: Near infrared spectroscopy; Prior spectral information; Tablets; Orthogonal projection methods; Augmentation methods

Rapid and sensitive electrochemiluminescence detection of rotavirus by magnetic primer based reverse transcription-polymerase chain reaction by Fangfang Zhan; Xiaoming Zhou; Da Xing (pp. 71-77).

In this work, we have developed and demonstrated a magnetic primer based RT-PCR assay for ECL detection of rotavirus. In the presence of two functional primers (magnetic primer and TBR-primer) and PCR reagents, cDNA from RT was amplified directly onto MPs during PCR cycles of denaturation, annealing and extension. The resulting MPs–TBR complexes were easily loaded on the electrode surface and produced a concentrated ECL signal. The figure shows the schematic illustration of magnetic primer RT-PCR based ECL assay for rotavirus detection.Display Omitted► A novel method for detection of rotavirus has been developed. ► In the presence of magnetic primer, TBR-primer and PCR reagents, cDNA form RT was amplified directly onto MPs. ► To obtain the best sensing and efficient performance, important parameters associated with the efficiency were investigated carefully. ► The proposed method will find numerous applications in food safety field and clinical diagnosis.A novel method for detection of rotavirus has been developed by integrating magnetic primer based reverse transcription-polymerase chain reaction (RT-PCR) with electrochemiluminescence (ECL) detection. This is realized by accomplishing RT of rotavirus RNA in traditional way and performing PCR of the resulting cDNA fragment on the surface of magnetic particles (MPs). In order to implement PCR on MPs and achieve rapid ECL detection, forward and reverse primers are bounded to MPs and tris-(2,2′-bipyridyl) ruthenium (TBR), respectively. After RT-PCR amplification, the TBR labels are directly enriched onto the surface of MPs. Then the MPs–TBR complexes can be loaded on the electrode surface and analyzed by magnetic ECL platform without any post-modification or post-incubation process. So some laborious manual operations can be avoided to achieve rapid yet sensitive detection. In this study, rotavirus in fecal specimens was successfully detected within 1.5h. Experimental results showed that the detection limit of the assay was 0.2pgμL⁻¹ of rotavirus. The ECL intensity was linearly with the concentration from 0.2pgμL⁻¹ to 400pgμL⁻¹. What's more, the specificity of this method was confirmed by detecting other fecal specimens of patients with nonrotavirus-associated gastroenteritis. We anticipate that the proposed magnetic primer based RT-PCR with ECL detection strategy will find numerous applications in food safety field and clinical diagnosis.

Keywords: Electrochemiluminescence; Rotavirus; Magnetic primer; RT-PCR

A novel protocol for ultra-trace detection of pesticides: Combined electrochemical reduction of Ellman's reagent with acetylcholinesterase inhibition by Jing Dong; Xianzhong Fan; Fengmin Qiao; Shiyun Ai; Hao Xin (pp. 78-83).

Display Omitted► A novel method was proposed for ultra-trace detection of pesticides. ► This method combined electrochemical reduction of DTNB with AChE inhibition. ► The fabricated biosensor determined methyl parathion with high sensitivity. ► The developed biosensor was used in real samples with satisfactory results.This paper proposed a novel method for ultra-trace detection of pesticides combining electrochemical reduction of Ellman's reagent with acetylcholinesterase (AChE) inhibition. The amperometric biosensor, fabricated by immobilizing AChE on multi-walled carbon nanotubes-chitosan (MWCNTs-Chi) nanocomposites modified glassy carbon electrode, enjoyed high sensitivity owing to the excellent conductivity and favourable biocompatibility of MWCNTs-Chi nanocomposites. Meanwhile, the sensitivity of the biosensor was further enhanced using the electrochemical reduction signal of DTNB for determination. Under optimum conditions, methyl parathion was detected based on its inhibition effect on AChE activity and the subsequent change in electrochemical reduction response of DTNB. Good relationship was obtained between the reduction current and pesticide concentration in the ranges of 5.0×10⁻⁷ to 1.0×10⁻¹²M with a detection limit of 7.5×10⁻¹³M (S/N=3). Moreover, the proposed protocol was successfully employed for the determination of methyl parathion in water and soil samples.

Keywords: Acetylcholinesterase; Ellman's reagent; Amperometric biosensor; Multi-walled carbon nanotubes-chitosan nanocomposites; Methyl parathion

Redox-active thionine–graphene oxide hybrid nanosheet: One-pot, rapid synthesis, and application as a sensing platform for uric acid by Zhoumin Sun; Haiying Fu; Liu Deng; Jianxiu Wang (pp. 84-91).

Display Omitted► A simple wet-chemical strategy for synthesis of thionine–graphene oxide hybrid nanosheets (T–GOs). ► T–GOs serve as a biocompatible matrix for enzyme assembly and a mediator. ► A simple and effective sensor for assay of uric acid at physiological levels. ►Demonstrate further application of GOs for biosensors and other fields.In this paper, we fabricate a sensitive and stable amperometric UA amperometric biosensor using nanobiocomposite derived from thionine modified graphene oxide in this study. A simple wet-chemical strategy for synthesis of thionine–graphene oxide hybrid nanosheets (T–GOs) through π–π stacking has been demonstrated. Various techniques, such as UV–vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and electrochemistry have been utilized to characterize the formation of the T–GOs. Due to the synergistic effect between thionine and graphene oxide, the nanosheets exhibited excellent performance toward H₂O₂ reduction. The incorporation of thionine onto graphene oxide surface resulted in more than a twice increase in the amperometric response to H₂O₂ of the thionine modified electrode. The as-formed T–GOs also served as a biocompatible matrix for enzyme assembly and a mediator to facilitate the electron transfer between the enzyme and the electrode. Using UOx as a model system, we have developed a simple and effective sensing platform for assay of uric acid at physiological levels. UA has been successfully detected at −0.1V without any interference due to other electroactive compounds at physiological levels of glucose (5mM), ascorbic acid (0.1mM), noradrenalin (0.1mM), and dopamine (0.1mM). The response displays a good linear range from 0.02 to 4.5mM with detection limit 7μM. The application of this modified electrode in blood and urine UA exhibited a good performance. The robust and advanced hybrid materials might hold great promise in biosensing, energy conversion, and biomedical and electronic systems.

Keywords: Graphene oxide; Thionine; Hybrid nanosheets; Uric acid; Biosensor

C₆₀-fullerene bound silica for the preconcentration and the fractionation of multiphosphorylated peptides by Martin Fischnaller; Rania Bakry; Rainer M. Vallant; Lukas A. Huber; Günther K. Bonn (pp. 92-101).

Display Omitted► Phosphopeptides can be selectively fractionated using C₆₀-aminopropylsilica. ► Selective isolation of mono- and multiphosphorylated peptides was performed according to their pI values. ► Elution was carried out using pH gradient in presence of different concentration of acetonitrile. ► The binding and fractionation can be attributed to amino groups together with the hydrophobic fullerene moieties.Phosphorylation of proteins is an important cellular regulatory process. The analysis of protein phosphorylation is challenging due to the high dynamic range and low abundance natures of phosphorylated species. Mass spectrometry (MS) of phosphopeptides obtained from tryptic protein digests is the method-of-choice for characterization of phosphorylated proteins. However, determination of phosphopeptides by MS represents a major challenge, especially in the presence of unmodified peptides. Due to lower ionization efficiency of phosphopeptides, as well as the fact that the stoichiometry of phosphorylation is often present at low relative abundance, efficient enrichment of the phosphorylated peptides prior to MS analysis is therefore of high demand. In addition, successful identification of peptides with different phosphorylation grades still remains challenging.This work presents a new strategy for enrichment and subsequent selective elution of multi-, mono- and nonphosphorylated peptides based on their difference in pI by using pH gradient elution in presence of different concentration of acetonitrile prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis (MALDI-MS). The developed protocol was successfully applied for α-casein tryptic digest and bovine serum albumin digest spiked with 9 synthetic phosphopeptides. Further selectivity for phosphopeptides was demonstrated by fractionation of peptides from a milk digest.

Keywords: C; ₆₀; -fullerene; Phosphopeptides; Grade of phosphorylation; MALDI-MS; Enrichment; Sample preparation

Stereoselective quantitation of mecoprop and dichlorprop in natural waters by supramolecular solvent-based microextraction, chiral liquid chromatography and tandem mass spectrometry by C. Caballo; M.D. Sicilia; S. Rubio (pp. 102-108).

Display Omitted► R- and S-mecoprop and dichlorprop are firstly determined by LC–MS/MS. ► Sample treatment consists of a simple, single-step microextraction and clean-up. ► Sensitivity is similar to GC–MS (LOQs 1–4ngL⁻¹) but the procedure is faster and simpler. ► The approach is a convenient method for the stereoselective quantitation of polar pesticides.Liquid chromatography (LC)/tandem mass spectrometry (MS/MS) after supramolecular solvent-based microextraction (SUSME) was firstly used in this work for the enantioselective determination of chiral pesticides in natural waters. The method developed for the quantitation of the R- and S-enantiomers of mecoprop (MCPP) and dichlorprop (DCPP) involved the extraction of the herbicides in a supramolecular solvent (SUPRAS) made up of reverse aggregates of dodecanoic acid (DoA), analyte re-extraction in acetate buffer (pH=5.0), separation of the target enantiomers on a chiral column of permethylated α-cyclodextrin under isocratic conditions, and detection of the daughter ions ( m/ z=140.9 and 160.6 for MCPP and DCPP, respectively) using a hybrid triple quadrupole mass spectrometer equipped with an electrospray source operating in the negative ion mode. Similar recoveries (ca. 75%) and actual concentration factors (ca. 94) were obtained for both phenoxypropanoic acids (PPAs). The quantitation limits were 1ngL⁻¹ for R- and S-MCPP, and 4ngL⁻¹ for R- and S-DCPP, and the precision, expressed as relative standard deviation ( n=6) was in the ranges 2.4–2.7% ([R-MCPP]=[S-MCPP]=5ngL⁻¹ and [R-DCPP]=[S-DCPP]=15ngL⁻¹) and 1.6–1.8% (100ngL⁻¹ of each enantiomer). The SUSME-LC–MS/MS method was successfully applied to the determination of the enantiomers of MCPP and DCPP in river and underground waters, fortified at concentrations between 15 and 180ngL⁻¹ at variable enantiomeric ratios (ER=1–9).

Keywords: Chiral analysis; Supramolecular solvent; Microextraction; Liquid chromatography/tandem mass spectrometry; Phenoxypropanoic acid herbicides; Natural waters

On-line solid phase extraction-liquid chromatography–mass spectrometry for trace determination of nerve agent degradation products in water samples by Bent T. Røen; Stig R. Sellevåg; Elsa Lundanes (pp. 109-116).

Display Omitted► Porous graphitic carbon and HILIC was combined in on-line SPE-LC–MS. ► Porous graphitic carbon strongly retains organophosphorous acids. ► Inorganic anions were removed by precipitation columns.Three primary nerve agent degradation products (ethyl-, isopropyl- and pinacolyl methylphosphonic acid) have been determined in water samples using on-line solid phase extraction-liquid chromatography and mass spectrometry (SPE-LC–MS) with electrospray ionisation. Porous graphitic carbon was employed for analyte enrichment followed by hydrophilic interaction chromatography. Diethylphosphate was applied as internal standard for quantitative determination of the alkyl methylphosphonic acids (AMPAs). By treating the samples with strong cation-exhange columns on Ba, Ag and H form, the major inorganic anions in water were removed by precipitation prior to the SPE-LC–MS determination. The AMPAs could be determined in tap water with limits of detection of 0.01–0.07μgL⁻¹ with the [M−H]⁻ ions extracted at an accuracy of ±5mDa. The within and between assay precisions at analyte concentrations of 5μgL⁻¹ were 2–3%, and 5–9% relative standard deviation, respectively. The developed method was employed for determination of the AMPAs in three natural waters and a simulated waste water sample, spiked at 5μgL⁻¹. Recoveries of ethyl-, isopropyl- and pinacolyl methylphosphonic acid were 80–91%, 92–103% and 99–106%, respectively, proving the applicability of the technique for natural waters of various origins.

Keywords: Abbreviations; OPCW; Organisation for Prohibition of Chemical Weapons; AMPAs; alkyl methylphosphonic acids; EMPA; ethyl methylphosphonic acid; IMPA; isopropyl methylphosphonic acid; PMPA; pinacolyl methylphosphonic acid; DEP; diethyl phosphate; AF; ammonium formate; PGC; porous graphitic carbonOn-line SPE-LC–MS; Porous graphitic carbon; Hydrophilic interaction liquid chromatography; Alkyl methylphosphonic acid; Diethyl phosphate

Combined use of liquid chromatography triple quadrupole mass spectrometry and liquid chromatography quadrupole time-of-flight mass spectrometry in systematic screening of pesticides and other contaminants in water samples by A. Masiá; M. Ibáñez; C. Blasco; J.V. Sancho; Y. Picó; F. Hernández (pp. 117-127).

Display Omitted► HPLC–QqQ-MS/MS combined with UPLC–QTOF MS to screen pesticides. ► LC–QqQ-MS/MS was validated to determine 43 pesticide residues. ► UPLC–QTOF MS identify several family compounds by searching in a home-made database containing more than 1100 organic pollutants. ► Waste and surface samples were successfully analyzed using the developed method.As a suitable way for routine screening of pesticides and control of other organic contaminants in water, the combination of liquid chromatography triple quadrupole tandem mass spectrometry (LC–QqQ-MS/MS) and liquid chromatography–hybrid quadrupole time-of-flight mass spectrometry (LC–QTOF-MS) has been applied to the analysis of 63 surface and waste water samples after conventional solid-phase extraction (SPE). The extracts were screened for 43 pesticides or degradation products by LC–QqQ-MS/MS achieving limits of detection (LOD) ranged from 0.04 to 2ngL⁻¹. Of the 43 selected pesticides, 33 were detected in water samples. The ESI–QTOF MS instrument was run using two simultaneous acquisition functions with low and high collision energy (MS^E approach) and acquiring the full mass spectra. A home-made database containing more than 1100 organic pollutants was used for substance identification. Around 250 of these compounds were available at the laboratory as reference standards. Five pesticides and 3 of their degradation products, different to those selected in the QqQ method, were detected by QqTOF-MS. Thirteen pharmaceuticals and two drugs of abuse were also identified in the samples. In practice, the sample preparation proved to be suitable for both techniques and for a wide variety of substances with different polarity. Mutual confirmation and evidence of co-occurrence of several other organic contaminants were the main advantages of the combination of both techniques.

Keywords: Surface water; Waste water; Pesticides; Organic pollutants; LC–MS/MS; LC–QTOF MS

Ultra high performance liquid chromatography-quadrupole-time of flight analysis for the identification and the determination of resveratrol and its metabolites in mouse plasma by M.C. Menet; C.H. Cottart; M. Taghi; V. Nivet-Antoine; D. Dargère; F. Vibert; O. Laprévote; J.-L. Beaudeux (pp. 128-136).

Simultaneous identification and determination of new resveratrol metabolites in mice by UHPLC-Q-TOF in full scan mode.Display Omitted► Fast method to quantify resveratrol and its main metabolites in the mouse plasma. ► Isotope-labeled standards to build a linear calibration curve. ► Linear calibration curve on a wide range of concentrations. ► Simultaneous identification and quantification of metabolites by using full scan mode. ► Detection of uncommon metabolites not yet described in mice.Resveratrol is a polyphenol that has numerous interesting biological properties, but, per os, it is quickly metabolized. Some of its metabolites are more concentrated than resveratrol, may have greater biological activities, and may act as a kind of store for resveratrol. Thus, to understand the biological impact of resveratrol on a physiological system, it is crucial to simultaneously analyze resveratrol and its metabolites in plasma. This study presents an analytical method based on UHPLC-Q-TOF mass spectrometry for the quantification of resveratrol and of its most common hydrophilic metabolites. The use of¹³C- and D-labeled standards specific to each molecule led to a linear calibration curve on a larger concentration range than described previously. The use of high resolution mass spectrometry in the full scan mode enabled simultaneous identification and quantification of some hydrophilic metabolites not previously described in mice. In addition, UHPLC separation, allowing run times lower than 10min, can be used in studies that requiring analysis of many samples.

Keywords: Abbreviations; ACN; acetonitrile; CV; coefficient of variation; DEV; deviation; ESI; electrospray ionization; FA; formic acid; HPLC; high performance liquid chromatography; IS; internal standard; IV; intravenous; LLOQ; lower limit of quantification; MeOH; methanol; MRM; multiple reaction monitoring; MS; mass spectrometry; QC; quality control; SD; standard deviation; SIDA; stable isotope dilution analysis; UHPLC-Q-TOF; ultra high performance liquid chromatography-quadrupole-time of flight; UV; ultravioletHigh resolution mass spectrometry; Resveratrol; Metabolites; Labeled standard; Ultra high performance liquid chromatography

Sensitive chemiluminescence aptasensor based on exonuclease-assisted recycling amplification by Sheng Cai; Yanhua Sun; Choiwan Lau; Jianzhong Lu (pp. 137-142).

A convenient signal amplification strategy for sensitive and selective chemiluminescence determination of adenosine is demonstrated which employs an endonuclease-based enzymatic recycling cleavage strategy in the aptasensing platform. This new strategy might create a novel technology for the detection of various targets and find wide applications in the environmental and biomedical fields.Display Omitted► An Exo III-assisted aptamer-based target recycling amplification assay is reported. ► Exo III catalyzes the removal of nucleotides from aptamers, liberating the target. ► A decreased hybridization with gold probes is used as a readout signal.We report herein an exonuclease-assisted aptamer-based target recycling amplification strategy for sensitive and selective chemiluminescence (CL) determination of adenosine. This aptasensor is based on target-induced release of aptamers from capture probes immobilized on the 96-well plate surface, and thus leading to a decreased hybridization with gold nanoparticle-functionalized reporter sequences followed by a CL signal. The introduction of exonuclease III catalyzes the stepwise removal of mononucleotides from 3′-hydroxyl termini of duplex DNAs of aptamers, liberating the adenosine. Therefore, a single copy of target adenosine can lead to the release and digestion of numerous aptamer strands from the 96-well plates and ultimately an enhanced sensitivity is achieved. Experimental results revealed that the exonuclease-assisted recycling strategy enabled the monitoring of adenosine with wide working ranges and low detection limits (LOD: 0.5nM). This new CL strategy might create a novel technology for the detection of various targets and could find wide applications in the environmental and biomedical fields.

Keywords: Chemiluminescence; Aptasensor; Exonuclease III; Recycling amplification

Streptavidin binding bifunctional aptamers and their interaction with low molecular weight ligands by Thao T. Le; Steven Scott; Anthony E.G. Cass (pp. 143-148).

Display Omitted► Aptamers can be made that bind two different ligands to a single RNA sequence. ► Ligand binding is characterized by fluorescence, SPR and dynamic light scattering. ► Affinities are comparable in solution and on gold surfaces for single and dual site aptamers. ► Binding isotherms show that binding of one ligand does not perturb the affinity for the second. ► RNA secondary structure predictions are consistent with experimental data.This paper describes the measurement of the binding affinities of two bifunctional RNA aptamers to their respective ligands. The aptamers comprise either a theophylline or malachite green binding sequence fused to a streptavidin binding sequence. These bifunctional aptamers are shown to bind simultaneously to both the small ligand and to streptavidin whether in free solution or on gold surfaces. Binding isotherms for both interactions were measured by different physiochemical techniques: surface plasmon resonance, fluorescence spectroscopy and dynamic light scattering. Both qualitatively and quantitatively there is little difference in binding affinities between the bifunctional aptamers and their monofunctional components. The respective K_d values for streptavidin binding in the monofunctional aptamer and in the theophylline bifunctional aptamer were 12nM and 65nM, respectively whilst the K_d values for theophylline binding in the monofunctional aptamer and the streptavidin bifunctional aptamer were 300nM and 120nM. These results are consistent with treating each aptamer sequence as a module that can be combined with others without significant loss of function. This allows for the use of streptavidin based immobilization strategies without either the cost of biotinylated dNTPs or the variable yields associated with the chemical biotinylation of RNA.

Keywords: Aptamers; RNA; Surface plasmon resonance; Theophylline; Nanoparticles

Development of a ratiometric time-resolved luminescence sensor for pH based on lanthanide complexes by Mingjing Liu; Zhiqiang Ye; Chenglong Xin; Jingli Yuan (pp. 149-156).

Display Omitted► A lanthanide complex-based ratiometric luminescent pH sensor was developed. ► The sensor can luminously respond to pH in weakly acidic to neutral media. ► The sensor can be used for monitoring pH with time-resolved luminescence mode. ► The sensor can be also used for monitoring pH with absorbance mode. ► The utility of the sensor for the luminescent cell imaging was demonstrated.Time-resolved luminescence bioassay technique using lanthanide complexes as luminescent probes/sensors has shown great utilities in clinical diagnostics and biotechnology discoveries. In this work, a novel terpyridine polyacid derivative that can form highly stable complexes with lanthanide ions in aqueous media, (4′-hydroxy-2,2′:6′,2′′-terpyridine-6,6′′-diyl) bis(methylenenitrilo) tetrakis(acetic acid) (HTTA), was designed and synthesized for developing time-resolved luminescence pH sensors based on its Eu³⁺ and Tb³⁺ complexes. The luminescence characterization results reveal that the luminescence intensity of HTTA–Eu³⁺ is strongly dependent on the pH values in weakly acidic to neutral media (p K_a=5.8, pH 4.8–7.5), while that of HTTA–Tb³⁺ is pH-independent. This unique luminescence response allows the mixture of HTTA–Eu³⁺ and HTTA–Tb³⁺ (the HTTA–Eu³⁺/Tb³⁺ mixture) to be used as a ratiometric luminescence sensor for the time-resolved luminescence detection of pH with the intensity ratio of its Tb³⁺ emission at 540nm to its Eu³⁺ emission at 610nm, I540_nm/ I610_nm, as a signal. Moreover, the UV absorption spectrum changes of the HTTA–Eu³⁺/Tb³⁺ mixture at different pHs (pH 4.0–7.0) also display a ratiometric response to the pH changes with the ratio of absorbance at 290nm to that at 325nm, A290_nm/ A325_nm, as a signal. This feature enables the HTTA–Eu³⁺/Tb³⁺ mixture to have an additional function for the pH detection with the absorption spectrometry technique. For loading the complexes into the living cells, the acetoxymethyl ester of HTTA was synthesized and used for loading HTTA–Eu³⁺ and HTTA–Tb³⁺ into the cultured HeLa cells. The luminescence imaging results demonstrated the practical utility of the new sensor for the time-resolved luminescence cell imaging application.

Keywords: Lanthanide complexes; Time-resolved luminescence bioassay; Ratiometric luminescent pH sensor; Luminescent cell imaging

An excellent copper selective chemosensor based on calix[4]arene framework by Mansoor Ahmed Qazi; Ümmühan Ocak; Miraç Ocak; Shahabuddin Memon (pp. 157-168).

p-(N,N-diphenylamino)methylcalix[4]arene (PAC4) was found to be a highly Cu(II) selective and sensitive colorimetric/fluorescent sensor material. High selectivity of PAC4 may be due to its compatibility with Cu(II) in respect of size of cavity, ionic radii, nature and number of binding sites, and geometry that help in selective complexation.Display Omitted► Using PAC4 sensor, Cu(II) selective binding ability has been explored among series of various cations. ► PAC4 shows remarkable discernable colorimetric variations on addition of Cu(II) ions. ► TGA and FT-IR spectroscopic method also verifies the fluorescence and UV–visible spectral results.The article depicts a detailed study regarding copper selective chemosensing and complexation nature of 5,11,17,23-tetrakis[(N,N-diphenylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (PAC4). Its photophysical characteristics in various solvents of different polarities along with the influence of acid and base on its spectral properties in these solvents are also discussed. The complexation affinity of PAC4 with regard to its latent applications as Cu(II) selective colorimetric and fluorescent sensor among the selected series of various cations such as Li(I), Na(I), K(I), Rb(I), Ba(II), Sr(II), Al(III), Fe(III), Cd(II), Co(II), Hg(II), Mn(II), Ni(II), Pb(II) and Zn(II) was examined by UV–visible and fluorescence emission spectroscopy in dichloromethane:acetonitrile (DCM:MeCN) solvent system. In addition, the process of complexation has been investigated through Job's plot and it has been observed that the complex between PAC4 and Cu(II) is formed in 1:1 stoichiometric ratio. The complex formation between PAC4 and Cu(II) has also been confirmed by FT-IR spectroscopy and thermal gravimetric analysis (TGA).

Keywords: Calixarene; Solvatochromic effect; Complexation; Metal ions; Supramolecular chemistry

An efficient and selective flourescent chemical sensor based on 5-(8-hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane as a new fluoroionophore for determination of iron(III) ions. A novel probe for iron speciation by Mojtaba Shamsipur; Marzieh Sadeghi; Alessandra Garau; Vito Lippolis (pp. 169-177).

Display Omitted► Preparation of a novel fluorescent sensor for sensitive and selective determination of Fe³⁺ ions. ► 5-(8-Hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane as fluoroionophore. ► Highly selective, sensitive and fast recognition of Fe³⁺ ions. ► Application to determination of iron(III) content of straw of rice, spinach and water samples. ► Use of the fluorescent sensor for Fe³⁺/Fe²⁺ speciation in aqueous solutions.A novel fluorescent chemical sensor for the highly sensitive and selective determination of Fe³⁺ ions in aqueous solutions is prepared. The iron sensing system was prepared by incorporating 5-(8-hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane (L) as a neutral Fe³⁺-selective fluoroionophore in the plasticized PVC membrane containing sodium tetraphenylborate as a liphophilic anionic additive. The response of the sensor is based on the strong fluorescence quenching ofL by Fe³⁺ ions. At pH 5.5, the proposed sensor displays a calibration curve over a wide concentration range from 6.0×10⁻⁴ to 1.0×10⁻⁷M, with a relatively fast response time of less than 2min. In addition to a high stability and reproducibility, the sensor shows a unique selectivity toward Fe³⁺ ion with respect to common coexisting cations. The proposed fluorescence optode was applied to the determination of iron(III) content of straw of rice, spinach and different water samples. The fluorescent sensor was also used as a novel probe for Fe³⁺/Fe²⁺ speciation in aqueous solution.

Keywords: Optode membrane; Fluoroionophore; Selective Fe; ³⁺; determination; Fluorescence quenching; Fe; ³⁺; /Fe; ²⁺; speciation

Upconversion nanoparticle-based fluorescence resonance energy transfer assay for Cr(III) ions in urine by Baoxia Liu; Hongliang Tan; Yang Chen (pp. 178-185).

Display Omitted► We report an upconversion fluorescence energy transfer assay for Cr³⁺ in urine. ► Lysine-capped NaYF₄:Yb/Er upconversion particles were used as the energy donor. ► Small molecules was used for the surface conjugation and specific recognition. ► Very high signal-to-noise ratio available in urine. ► Advantageous for the detection of biosamples with autofluorescence.A novel assay of chromium(III) ion based on upconversion fluorescence resonance energy transfer was designed and established. Lysine-capped NaYF₄:Yb/Er upconversion nanoparticles (UCNPs) and dimercaptosuccinic acid-capped gold nanoparticles (AuNPs) were used as the energy donor and acceptor, respectively. They were bound together via electrostatic interaction, resulting in the quenching of the fluorescence of UCNPs by AuNPs. Chromium(III) ions can specifically and strongly interact with dimercaptosuccinic acid that was modified on the surface of AuNPs, leading to the separation of AuNPs from UCNPs and the recovery of fluorescence of UCNPs. The fluorescence recovery of UCNPs showed a good linear response to Cr³⁺ concentration in the range of 2–500nM with a detection limit of 0.8nM. This method was further applied to determine the levels of Cr³⁺ in urine. Compared with other fluorescence methods, current method displayed very high sensitivity and signal-to-noise ratio because of the excitation of near-infrared that can eliminate autofluorescence, providing a promising examination of biological samples for the diagnostic purposes.

Keywords: Upconversion nanoparticles; Gold nanoparticles; Fluorescence resonance energy transfer; Fluorescence recovery; Chromium(III) ion; Urine

Production of polyclonal antibodies directed to recombinant methionyl bovine somatotropin by C. Suárez-Pantaleón; A.C. Huet; O. Kavanagh; H. Lei; G. Dervilly-Pinel; B. Le Bizec; C. Situ; Ph. Delahaut (pp. 186-193).

Display Omitted► Production of polyclonal antibodies directed to recombinant methionyl bovine somatotropin (rMbST). ► Multiple antigen peptide mimicking rMbST N-terminus used as immunogen. ► Immunodiscrimination between native and recombinant bovine somatotropins by ELISA.The administration of recombinant methionyl bovine somatotropin (rMbST) to dairy cows to increase milk yield remains a common practice in many countries including the USA, Brazil, Mexico, South Africa and Korea, whereas it has been forbidden within the European Union (EU) since 1999. A rapid screening immunoanalytical method capable of the unequivocal determination of rMbST in milk would be highly desirable in order to effectively monitor compliance with the EU-wide ban for home-made or imported dairy products. For decades, the production of specific antibodies for this recombinant isoform of bovine somatotropin (bST) has remained elusive, due to the high degree of sequence homology between both counterparts (e.g. methionine for rMbST in substitution of alanine in bST at the N-terminus). In this study, we compared several immunizing strategies for the production of specific polyclonal antibodies (pAbs), based on the use of the full-length recombinant protein, an rMbST N-terminus peptide fragment and a multiple antigen peptide (MAP) which consists of an oligomeric branching lysine core attached to the first two N-terminus amino acids of rMbST, methionine and phenylalanine (MF-MAP). The immunization with KLH-conjugated MF-MAP led to the production of the pAb with the highest rMbST/bST recognition ratio amongst the generated battery of antibodies. The pAb exhibited a specific binding ability to rMbST in a competitive antigen-coated ELISA format, which avidity was further improved after purification by rMbST N-terminus peptide-based affinity chromatography. These results suggest that immunodiscrimination between structurally related proteins can be achieved using immuno-enhanced immunogens such as MAPs.

Keywords: Abbreviations; bST; bovine somatotropin; rMbST; recombinant methionyl bovine somatotropin; MAP; multiple antigen peptide; pAb; polyclonal antibodyRecombinant methionyl bovine somatotropin; Polyclonal antibodies; Immunodiscrimination; Multiple antigen peptide

A fluorescent and chemiluminescent difunctional mesoporous silica nanoparticle as a label for the ultrasensitive detection of cancer cells by Liang Tao; Chaojun Song; Yuanjie Sun; Xiaohua Li; Yunyun Li; Boquan Jin; Zhujun Zhang; Kun Yang (pp. 194-200).

Display Omitted► Difunctional amino mesoporous silica nanoparticles (FCMSN) were synthesized. ► The fluorescence and chemiluminescence properties of the FCMSN were studied. ► The NaIO₄ oxidation method was used for modification of the FCMSN. ► Liver cancer 7721 cell was detected. ► The specificity affected by FCMSN's amino groups was studied.A new kind of ultrabright fluorescent and chemiluminescent difunctional mesoporous silica nanoparticle (FCMSN) is reported. A luminescent dye, Rhodamine 6G or tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate (Rubpy), is doped inside nanochannels of a silica matrix. The hydrophobic groups in the silica matrix avoid the leakage of dye from open channels. The amines groups on the surface of the FCMSN improve the modification performance of the nanoparticle. Because the nanochannels are isolated by a network skeleton of silica, fluorescence quenching based on the inner filter effect of the fluorescent dyes immobilized in nanochannels is weakened effectively. The Quantum Yield of obtained 90nm silica particles was about 61%. Compared with the fluorescent core–shell nanoparticle, the chemiluminescence reagents can freely enter the nanoparticles to react with fluorescent dyes to create chemiluminescence. The results show that the FCMSN are both fluorescent labels and chemiluminescent labels. In biological applications, the NaIO₄ oxidation method was proven to be superior to the glutaraldehyde method. The amount of amino could affect the specificity of the FCMSN. The fluorescence microscopy imaging demonstrated that the FCMSN is viable for biological applications.

Keywords: Mesoporous silica nanoparticle; Ultrabright fluorescence; Fluorescent label; Chemoluminescent label; Fluorescence intensity; Photostablity

Aligned electrospun nanofibers for ultra-thin layer chromatography by Michael C. Beilke; Joseph W. Zewe; Jonathan E. Clark; Susan V. Olesik (pp. 201-208).

Display Omitted► Aligned electrospun nanofibers are applied as a stationary phase in UTLC (AE-UTLC). ► AE-UTLC phases showed 2 times greater reproducibility than non-aligned phases. ► Aligning the nanofibers increased efficiency up to 100 times. ► AE-UTLC showed 2–2.5 times faster time of analysis relative to non-aligned E-UTLC.The fabrication and implementation of aligned electrospun polyacrylonitrile (PAN) nanofibers as a stationary phase for ultra-thin layer chromatography (UTLC) is described. The aligned electrospun UTLC plates (AE-UTLC) were characterized to give an optimized electrospun mat consisting of high nanofiber alignment and a mat thickness of ∼25μm. The AE-UTLC devices were used to separate a mixture of β-blockers and steroidal compounds to illustrate the properties of AE-UTLC. The AE-UTLC plates provided shorter analysis time (∼2–2.5 times faster) with improved reproducibility (as high as 2 times) as well as an improvement in efficiency (up to100 times greater) relative to non-aligned electrospun-UTLC (E-UTLC) devices.

Keywords: Abbreviations; AE-UTLC; aligned electrospun ultra-thin layer chromatography; E-UTLC; electrospun ultra-thin layer chromatography; PAN; polyacrylonitrileElectrospinning; Nanofibers; Chromatography; Ultra-thin layer chromatography; Alignment; Drug analysis

Polyhedral oligomeric silsesquioxanes as functional monomer to prepare hybrid monolithic columns for capillary electrochromatography and capillary liquid chromatography by Junjie Ou; Zhenbin Zhang; Hui Lin; Jing Dong; Hanfa Zou (pp. 209-216).

.Display Omitted► A POSS reagent was selected as monomer to prepare hybrid monolithic column. ► Two resulting hybrid monoliths were successfully applied for CEC and cLC. ► The hybrid poly(POSS- co-BPADMA) monolith exhibits better selectivity for PAHs.A simple approach to fabricate hybrid monolithic column within the confines of fused-silica capillaries (75μm i.d.) was introduced. A polyhedral oligomeric silsesquioxanes (POSS) reagent containing a methacrylate group was selected as functional monomer, and copolymerized with bisphenol A dimethacrylate (BPADMA) or ethylene dimethacrylate (EDMA) in the presence of porogenic solvents via thermally initiated free radical polymerization. After optimization of the preparation conditions, two POSS-containing hybrid monoliths were successfully prepared and exhibited good permeability and stability. By comparison of the separation efficiencies of the resulting poly(POSS- co-BPADMA) and poly(POSS- co-EDMA) monoliths in capillary electrochromatography (CEC) and capillary liquid chromatography (cLC), it was indicated the former has better column efficiencies for alkylbenzenes, phenols, anilines and PAHs in CEC and cLC than the latter. Particularly, the hybrid poly(POSS- co-BPADMA) monolith is more suitable for separation of PAHs due to π–π interaction between the analytes and aromatic rings in the surface of monolithic stationary phase.

Keywords: Monolithic column; Polyhedral oligomeric silsesquioxanes; Organic–silica hybrid; Capillary electrochromatography; Capillary liquid chromatography

New way to quantify multiple steroidal compounds in wastewater by comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry by Matias Kopperi; José Ruiz-Jiménez; Janne I. Hukkinen; Marja-Liisa Riekkola (pp. 217-226).

Display Omitted► New quantitation approach based on PLSR was developed for steroidal compounds analyzed by GC×GC–TOFMS. ► Mass spectra were utilized to build up partial-least-squares regression model. ► Exhaustive sample preparation method was developed for the measurement of all steroidal species in the samples. ► Distribution of free and conjugated steroids in wastewater and suspended particles was measured. ► Method developed was applied to samples collected from wastewater treatment plant.The applicability of comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry to the screening of steroidal compounds in wastewater is demonstrated. Advanced software was utilized to identify unknown compounds in complex two-dimensional chromatograms exploiting retention indices and two different mass spectral databases. Response factors calculated as a function of the individual mass spectra of six commercial standards at different concentrations were used to develop a model allowing the quantitation of all steroidal compounds identified in the sample. The model, based on partial least squares regression equations, provided good accuracy (prediction error<16%) in the quantitation of steroidal compounds, so offering a valuable alternative to conventional quantitation methods where reference compounds are required for the verification of analytical measurements. Special attention was paid to the development of an exhaustive sample preparation method for the separate analysis of conjugated and free steroids in both water phase and suspended solid particles. The method, including the exploitation of chemometrics, was successfully applied to the determination of steroidal compounds in effluent and influent waters collected at a local wastewater treatment plant.

Keywords: GC; ×; GC–TOFMS; Emerging organic contaminants; Steroids; Wastewater; Chemometrics; PLSR

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Analytica Chimica Acta (v.761, #)

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Analytica Chimica Acta (v.761, #)