Search

Abstract: The liquid chromatography/electrospray tandem mass spectrometry method was developed for analyses and characterization of oleanane-type saponins in the roots of Stephanotis mucronata. Collision-induced dissociation have been performed in order to elucidate the degradation pathways for the [M+Na]+ ions and their predominant product ions. The following characteristic fragmentation was observed from the title saponins: when the substituent (except hydroxyl group) located at C21 position, direct loss of terminal sugar residue from the [M+Na]+ ion was observed; when the substituent (except hydroxyl group) linked to C22 position, the loss of the terminal sugar cannot occur. To further confirm the structures, offline Fourier transform ion cyclotron resonance tandem mass spectrometry (FTICR-MS n ) was performed. The structures of four proposed saponins have been identified by 1D and 2D NMR experiments. In this study, 12 saponins were identified. Among them, to our knowledge, four saponins were reported in this plant for the first time and four saponins were presumed to be new compounds. Hence, the described method has wide applicability to rapidly screen and provide structural information of oleanane-type saponins in crude materials. [Copyright &y& Elsevier]

Abstract: In pH 4.2–4.8 HAc–NaAc buffer solution, folic acid (FA) could react with uranium (VI) to form a 2:1 anionic chelate which further reacted with some basic triphenylmethane dyes (BTPMD) such as Ethyl Violet (EV), Methyl Violet (MV) and Crystal Violet (CV) to form 1:2 ion-association complexes. As a result, not only the absorption spectra were changed, but also the intensities of resonance Rayleigh scattering (RRS) were enhanced greatly and the new RRS spectra were observed. The maximum RRS wavelengths were located at 328nm for EV system, 325nm for MV system and 328nm for CV system. The fading degree (ΔA) and RRS intensities (ΔI) of three systems were different. Under given conditions, the ΔA and ΔI were all directly proportional to the concentration of FA. The linear ranges and the detection limits of RRS methods were 0.0039–5.0μgmL−1 and 1.2ngmL−1 for EV system, 0.0073–4.0μgmL−1 and 2.2ngmL−1 for MV system, 0.014–3.5μgmL−1 and 4.7ngmL−1 for CV system. The RRS methods exhibited higher sensitivity, so they are more suitable for the determination of trace FA. The optimum conditions, the influencing factors and the effects of coexisting substances on the reaction were investigated. The method can be applied to the determination of FA in serum and urine samples with satisfactory results. The structure of the ternary ion-association complex and the reaction mechanism were discussed in this work. [Copyright &y& Elsevier]

Abstract: Lavandin, a sterile hybrid of Lavandula angustifolia P. Mill.× Lavandula latifolia (L.f.) Medikus (Lamiaceae) is a plant widely cultivated for essential oil production in the South of France. Chemometric treatment by mid-infrared (MID-IR) spectroscopy data was assessed for the differentiation of Grosso Lavandin Essential Oils of Controlled Area (GLEOCA) and results were compared to those obtained by gas chromatography for MID-IR short time technique validation. The quantification of the main 13 hydrocarbons and oxygenated compounds generally controlled by industrial perfumers in GLEOCA samples (n =83) of three geographic origins: “Simiane”, “Puimoisson” (with two producers) and “Richerenches” and their classification were successfully obtained by partial least square discriminant analysis (PLS-DA) by comparison with gas chromatography. The best prediction results were obtained using first derivate spectral data in the 1800–700cm−1 range. The spectroscopic interpretation of regression vectors showed that each geographic origin was correlated to components of GLEOCA. Chemometric MID-IR spectra treatments allowed us to obtain similar results than those obtained by time consuming analytical techniques such as GC and therefore constitute a robust and help fast method for authentication of GLEOCA and should be extended to other essential oils for authentication of geographic origin. [Copyright &y& Elsevier]

Abstract: A useful tool for the determination of eight UV filters in sediments which combines extraction and clean-up in a single-step has been developed. To this end, the protocol incorporates silica gel and copper powder placed directly in the pressurised-liquid extraction (PLE) cell. After extract evaporation, salicylate- and benzophenone-type UV filters are derivatised with N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA). Trimethylsilylation increases the sensitivity of these UV filters about 4–10-fold when they are finally analysed by gas chromatography–mass spectrometry (GC–MS). Derivatisation conditions (temperature, time and volume of BSTFA) and PLE parameters (temperature, time, number of cycles and solvent composition) were optimised using multivariate experimental designs. Under optimal conditions, the developed procedure provides an excellent linearity, detection limits (1–5ngg−1) and recoveries above 73% for all the compounds. Compared to the few existing methods, this analytical approach affords optimal throughput and method automation. Finally, the proposed method was applied to the analysis of three sediment samples. [Copyright &y& Elsevier]

Abstract: We analyzed polycyclic aromatic hydrocarbons (PAHs) present in lake sediment at low levels (<1μgg−1) by using Soxhlet extraction (Soxhlet), microwave-assisted extraction (MAE), and pressurized liquid extraction (PLE) in combination with gas chromatography and isotope-dilution mass spectrometry. Although all extraction techniques showed good repeatability for five target PAHs (relative standard deviation <5.2%, n =3), the results decreased in the order PLE>MAE>Soxhlet. Differences in the results originated mainly from differences in the extraction efficiencies of the techniques for native PAHs, because all techniques gave comparable recovery yields of corresponding 13C-labeled PAHs (13C-PAHs) (51–84%). Since non-negligible amounts of both native PAHs and 13C-PAHs were re-adsorbed on matrix in MAE, not only recovery yields of 13C-PAHs but also efficiencies of extraction of native PAHs should be examined to evaluate the appropriateness of any analytical procedures. [Copyright &y& Elsevier]

Abstract: A method for the accurate determination of Cd and Pb isotope compositions in sediment samples is presented. Separation of Cd and Pb was designed by using an anionic exchange chromatographic procedure. Measurements of Cd isotopic compositions were carried out by multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS), by using standard-sample bracketing technology for mass bias correction and Pb isotopic ratios were determined by thermal ionization mass spectrometry (TIMS). The factors that affect the accurate and precise Cd isotope compositions analysis, such as instrumental mass fractionation and isobaric interferences, were carefully evaluated and corrected. The Cd isotopic results were reported relative to an internal Cd solution and expressed as the δ 114/110Cd. Five Cd reference solutions and one Pb standard were repeatedly measured in order to assess the accuracy of the measurements. Uncertainties obtained were estimated to be lesser than 0.11‰ (2s) for the δ 114/110Cd value. Analytical uncertainties in 2s for Pb isotopic ratios were better than 0.5‰. The method has been successfully applied to the investigation of Cd and Pb isotope compositions in sediment samples collected from North River in south China. [Copyright &y& Elsevier]

Abstract: A novel disk electrochemical hydride generator has been developed for the determination of As and Sb. Compared with the traditional thin-layer cell, the disk cell combined the advantages of quick assembly and easy operation. This electrochemical system for hydride generation in neutral buffer solutions has been studied for analytical usefulness in coupling with atomic fluorescence spectrometry. It was found that the use of neutral phosphate buffer solution could markedly increase the fluorescence intensity of As(III) and Sb(III) and reduce the impact of cathode erosion on the stability of signal intensity. At the same time, the fluorescence intensity of As(V) and Sb(V) were almost suppressed totally. The detection limits (3σ) of 0.031μgL−1 As(III) and 0.026μgL−1 Sb(III) in aqueous solutions were obtained, respectively. The precisions (n =11) for 20μgL−1 As(III) and Sb(III) were 2.0% and 2.7%, respectively. The method was successfully applied for determination of different oxidation states of As and Sb in environmental samples. [Copyright &y& Elsevier]

Abstract: A new spectrofluorimetric method is developed for determination of adenosine disodium triphosphate (ATP). The interactions between prulifloxacin (PUFX)–Tb3+ complex and adenosine disodium triphosphate has been studied by using UV–vis absorption and fluorescence spectra. Using prulifloxacin–Tb3+ as a fluorescence probe, under the optimum conditions, ATP can remarkably enhance the fluorescence intensity of the prulifloxacin–Tb3+ complex at λ =545nm and the enhanced fluorescence intensity is in proportion to the concentration of ATP. Optimum conditions for the determination of ATP were also investigated. The dynamic range for the determination of ATP is 4.0×10−7 to 2.0×10−5 molL−1, and the detection limit (3 σ/k) is 1.7×10−8 molL−1. This method is simple, practical and relatively free interference from coexisting substances and can be successfully applied to determination of ATP in real pharmaceutical samples. The mechanism of fluorescence enhancement of prulifloxacin–Tb3+ complex by ATP was also discussed. [Copyright &y& Elsevier]

Abstract: In this study, short-wave near-infrared (NIR) spectroscopy at 800–1050nm region was investigated for the analysis of main compounds in milk powder. Through quantitative analysis, the feasibility is further demonstrated for the simultaneous measurement of fat, proteins and carbohydrate in milk powder. Two models, partial least-squares and least-squares support vector machine, were compared and utilized for regression coefficients and loading weights. The affect of standard normal variate spectral pretreatment to model performance was evaluated. Based on the resulted coefficients and loading weights, interesting wavelength regions of nutrition in milk powder are screened and the assignment of all specific wavelengths is firstly proposed in the details associated with chemical base. Instead of the whole short-wave NIR spectral data, these assigned wavelengths which can be reliably exploited were used for the content determination. Compared with other spectroscopy technique, assigned short-wave NIR spectral wavelengths did a good work. Determination coefficients for prediction are 0.981, 0.984, and 0.982, respectively for three components. The proposed wavelength assignment in the short-wave NIR region could be used for the component contents determination of milk powder, and could be as a guidance to interpret the spectra of milk powder. [Copyright &y& Elsevier]

Abstract: Two dimensional (2D) homonuclear 1H J-resolved (JRES) nuclear magnetic resonance spectroscopy is increasingly used in metabolomics. This approach visualises metabolite chemical shifts and scalar couplings along different spectral dimensions, thereby increasing peak dispersion and facilitating spectral assignments and accurate quantification. Here, we optimise the processing of 2D JRES spectra by evaluating different window functions, a traditional sine-bell (SINE) and a combined sine-bell–exponential (SEM) function. Furthermore, we evaluate different projection methods for generating 1D projected spectra (pJRES). Spectra were recorded from three disparate types of biological samples and evaluated in terms of sensitivity, reproducibility and resolution. Overall, the SEM window function yielded considerably higher sensitivity and comparable spectral reproducibility and resolution compared to SINE, for both 1D pJRES and 2D JRES datasets. Furthermore, for pJRES spectra, the highest spectral quality was obtained using SEM combined with skyline projection. These improvements lend further support to utilising 2D J-resolved spectroscopy in metabolomics. [Copyright &y& Elsevier]

Abstract: Ractopamine (RCT) is a member of the β-2-agonist (β-agonist) family. It is licensed for use as an animal growth promoter in more than 20 countries worldwide, including the United States and Canada, but is either not licensed or prohibited by over 150 others, including those within the European Union. The issue of the use of RCT in livestock bound for human consumption has risen to prominence recently following the decision by The People''s Republic of China to ban the import of pork from a number of processing plants after finding traces of RCT in shipments from the U.S.A. In order to monitor for the illegal use of such compounds within Europe, there is a requirement to have a robust and reliable testing scheme capable of the detection of low concentrations of RCT. In the present study an optical biosensor screening assay was developed. The developed assay was compared with a liquid chromatography/mass spectrometry/mass spectrometry (LC–MS/MS) confirmatory procedure. These methods were used to study the ability to detect RCT in pigs following treatment. Both testing procedures were capable of detecting low μgkg−1 concentrations of the drug in urine and liver. Liver was found to be a less suitable sample matrix, with RCT residue levels being undetectable after 5 days withdrawal of the drug. Urine samples however still contained detectable RCT residues several weeks after withdrawal. The correlation (as measured by r 2) between the biosensor and LC–MS/MS methods was 0.99 and 0.97 for urine and liver samples, respectively. It is concluded that testing regimes based on RCT analysis in liver are less likely to detect illegal administration of the drug than those based on urine analysis. Urine samples provide an excellent matrix for the detection of RCT residues for an extended period post withdrawal. [Copyright &y& Elsevier]

Abstract: We tried to develop a library search system using a portable, attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectrometer for on-site identification of 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA) tablets. The library consisted of the spectra from mixtures of controlled drugs (e.g. MDMA and ketamine), adulterants (e.g. caffeine), and diluents (e.g. lactose). In the seven library search algorithms, the derivative correlation coefficient showed the best discriminant capability. This was enhanced by segmentation of the search area. The optimized search algorithm was validated by the positive (n =154, e.g. the standard mixtures containing the controlled drug, and the MDMA/MDA tablets confiscated) and negative samples (n =56, e.g. medicinal tablets). All validation samples except for four were judged truly. Final criteria for positive identification were decided on the basis of the results of the validation. In conclusion, a portable ATR-FT-IR spectrometer with our library search system would be a useful tool for on-site identification of amphetamine-type stimulant tablets. [Copyright &y& Elsevier]

Abstract: The deconvolution of multi-component mixtures in NMR spectroscopy is a challenging problem due to the spectral non-linearities. In the present contribution, two data sets were studied (A) 10 samples of a four-component non-reactive mixture measured with 1H, 13C, 19F, 31P NMR and (B) a three-solute cyclo-addition reaction measured with 13C NMR. Both data sets were treated with a re-alignment procedure to correct for the non-stationary chemical shifts, followed by band-target entropy minimization (BTEM) analysis. For data set A, quite good spectral estimates of the two hydrogen-containing species, four carbon-containing species, two fluorine-containing species and two phosphorus-containing species were obtained from the multi-component data. For data set B quite good spectral estimates of all three carbon-containing reactants were obtained as well as their relative concentration profiles. The present contribution using model systems indicates the usefulness of re-alignment procedures for correcting non-stationary characteristics, prior to self-modeling curve resolution (SMCR), and the potential for investigating more complex problems. [Copyright &y& Elsevier]

Abstract: Imaging in Raman spectroscopy is a valuable tool for analytical chemistry. Although molecular characterization at micron level is achieved for many applications, it usually fails producing chemical images of micron size samples as expected in chemical, environmental and biological analysis. The aim of the work is to introduce the potential of super-resolution in vibrational spectroscopic imaging. This original chemometrics approach uses several low resolution images of the same sample in order to retrieve a higher resolution chemical image. It is thus possible to overcome in a certain way some physical and instrumentals limitations. To illustrate the methodology, sub-micronic details of a Si/Au sample are retrieved from low resolution images with different super-resolution algorithms. The better results are obtained with Iterative L2/Bilateral Total Variation regularization method. The use of a regularization procedure gives also better results since its first property is to preserve edges during the reconstruction of the super-resolved image. This concept of chemical image data processing should open new analytical opportunities. [Copyright &y& Elsevier]

Abstract: It was discovered that a second order spectra data matrix of Sudan I produced from the solvent components gradual change–visible absorption spectra can be expressed as the combination of two bilinear data matrices. Based on this discovery, a new method for the determination of Sudan I in gray systems using second order calibration algorithms has been developed. The second order calibration algorithms were based on the popular parallel factor analysis (PARAFAC) and rank annihilation factor analysis (RAFA), respectively. In the method described here, the components of the solvent were changed gradually by adding ethanol into cyclohexane, the absorption spectra of Sudan I and chilli samples in a series of cyclohexane–ethanol mixed solvents with various ethanol volume fractions were recorded, and then the second order data were obtained from the solvent components gradual change–visible absorption spectra. Thus, the concentration of Sudan I in a gray system could be determined from the spectra matrices using second order calibration algorithms. This method is simple, convenient and dependable. The method has been used to determine Sudan I in chilli powder with satisfactory results. [Copyright &y& Elsevier]

Abstract: Biodiesel is the main alternative to fossil diesel. The key advantages of its use are the fact that it is a non-toxic renewable resource, which leads to lower emissions of polluting gases. European governments are targeting the incorporation of 20% of biofuels in the general fuels until 2020. Chemically, biodiesel is a mixture of fatty acid methyl esters, derived from vegetable oils or animal fats, which is usually produced by a transesterification reaction, where the oils/fats react with an alcohol, in the presence of a catalyst. The European Standard (EN 14214) establishes 25 parameters that have to be analysed to certify biodiesel quality and the analytical methods that should be used to determine those properties. This work reports the use of near infrared (NIR) spectroscopy to determine the esters content in biodiesel as well as the content in linolenic acid methyl esters (C18:3) in industrial and laboratory-scale biodiesel samples. Furthermore, calibration models for myristic (C14:0), palmitic (C16:0), stearic (C18:0), oleic (C18:1), linoleic (C18:2) acid methyl esters were also obtained. Principal component analysis was used for the qualitative analysis of the spectra, while partial least squares regression was used to develop the calibration models between analytical and spectral data. The results confirm that NIR spectroscopy, in combination with multivariate calibration, is a promising technique to assess the biodiesel quality control in both laboratory-scale and industrial scale samples. [Copyright &y& Elsevier]

Abstract: Annihilation of the contribution of one chemical component from the original data matrix is a general method in rank annihilation factor analysis (RAFA). However, RAFA is not applicable for studying the protonation equilibria of multiprotic acids. In this work, a two-rank annihilation factor analysis (TRAFA) method was proposed for determination of the acidity constants of diprotic acids. After recording the electronic absorbance spectra of the acids at different pH, the contributions of both H2A and A2− were annihilated from the absorbance data, which made feasible the determination of two successive acidity constants. The method was validated by analysis of simulated data and its application to the determination of the acidity constants of calmagite, as a reference compound. A close agreement was obtained between the resulted values by TRAFA and the declared values. Indeed, the method was used for determination of the acidity constants of two new chromenone derivatives in binary solvents mixtures of methanol and water. The effects of changing solvent composition on acidity constant data were explained by linear solvation free energy relationships (LSFER) utilizing solvatochromic parameters. [Copyright &y& Elsevier]

Abstract: Isotope dilution mass spectrometry currently stands out as the method providing results with unchallenged precision and accuracy in elemental speciation. However, recent history of isotope dilution mass spectrometry has shown that the extent to which this primary ratio measurement method can deliver accurate results is still subject of active research. In this review, we will summarize the fundamental prerequisites behind isotope dilution mass spectrometry and discuss their practical limits of validity and effects on the accuracy of the obtained results. This review is not to be viewed as a critique of isotope dilution; rather its purpose is to highlight the lesser studied aspects that will ensure and elevate current supremacy of the results obtained from this method. [Copyright &y& Elsevier]

Abstract: We demonstrate the potential of Raman spectroscopy to detect cocaine concealed inside transparent glass bottles containing alcoholic beverages. A clear Raman signature of cocaine with good signal-to-noise was obtained from a ∼300g solution of adulterated cocaine (purity 75%) in a 0.7L authentic brown bottle of rum with 1s acquisition time. The detection limit was estimated to be of the order of 9g of pure cocaine per 0.7L (∼0.04molesL−1) with 1s acquisition time. The technique holds great promise for the fast, non-invasive, detection of concealed illicit compounds inside beverages using portable Raman instruments, thus permitting drug trafficking to be combated more effectively. [Copyright &y& Elsevier]

Abstract: A comprehensive review is presented addressing recent trends in the speciation and determination of vanadium in environmental and biological sample matrices, including important analytical aspects such as sample clean up, pre-concentration and method development. Methodology based on both separation and spectroscopic techniques for the determination of vanadium speciation is discussed. A brief outline of analytical principles, together with an overview of the recent developments and applications of vanadium speciation determination is included. The newer methods for detecting metal ions including hyphenated spectroscopic techniques and sample preparation schemes are also discussed. [Copyright &y& Elsevier]

Abstract: A radiochemical method for the isolation of plutonium-isotopes from environmental samples, based on the use of specific extraction chromatography resins for actinides (TEVA®, Eichrom Industries, Inc.), has been set up in our laboratory and optimised for their posterior determination by alpha spectrometry (AS) or accelerator mass spectrometry (AMS). The proposed radiochemical method has replaced in our lab a well-established one based on the use of a relatively un-specific anion-exchange resin (AG® 1X8, Bio-rad Laboratories, Inc.), because it is clearly less time consuming, reduces the amounts and molarities of acid wastes produced, and reproducibly gives high radiochemical yields. In order to check the reliability of the proposed radiochemical method for the determination of plutonium-isotopes in different environmental matrixes, twin aliquots of a set of samples were prepared with TEVA® and with AG® 1X8 resins and measured by AS. Some samples prepared with TEVA® resins were measured as well by AMS. As it is shown in the text, there is a comfortable agreement between AS and AMS, which adequately validates the method. [Copyright &y& Elsevier]

Abstract: In an extended introduction, key aspects of resonance Raman spectroscopy (RRS) such as enhanced sensitivity and selectivity are briefly discussed in comparison with normal RS. The analytical potential is outlined. Then achievements in different fields of research are highlighted in four sections, with emphasis on recent breakthroughs: (1) The use of visible RRS for analyzing carotenoids in biological matrices, for pigments and dyes as dealt with in art and forensics, and for characterizing carbon nanotubes. (2) The use of RRS in the deep UV (excitation below 260nm) in the bioanalytical and life sciences fields, including nucleic acids, proteins and protein–drug interactions. Metalloproteins can be studied by visible RRS in resonance with their chromophoric absorption. (3) Progress in theoretical calculations of RRS excitation profiles and enhancement factors, which ultimately might facilitate analytical RRS. (4) Instrumental and methodological achievements including fiber-optic UV–RRS, coupling of RRS to liquid chromatography and capillary electrophoresis. Sensitivities can approach the single-molecule level with surface-enhanced RRS or tip-enhanced RRS. Last but not least, promising fluorescence background rejection techniques based on time-gated detection will be presented. This review ends with a concluding section on future expectations for RRS, in particular its potential as an analytical technique. [Copyright &y& Elsevier]

Abstract: The determination of 90Sr through the Cerenkov radiation emitted by its descendant 90Y is a well-known method and firmly established in literature. Nevertheless, in order to obtain an accurate result based on a Cerenkov measurement, the experimental work must be extremely rigorous because the efficiency of Cerenkov counting is especially sensitive to the presence of colour. Any traces of colour in the sample produce a decrease in the number of photons detected in the photomultipliers and, therefore, this might cause a diminution in Cerenkov counting efficiency. It is essential not only to detect the effect of colour quenching in the sample but also to correct the decrease in counting efficiency. For this reason, colour quenching correction curves versus counting efficiency are usually done when measuring through Cerenkov counting. One of the most widely used techniques to evaluate colour quenching in these measurements is the channel ratio method, which consists of the measurement of the shift of the spectrum measuring the ratio of counts in two different windows. The selection of the windows for the application of the corrections might have an influence on the quality of the fitting parameters of the correction curves efficiency versus colour quenching degree and hence on the final 90Sr result. This work is focused on the calculation of the counting efficiency decrease using the channel ratio method and on obtaining the best fitting correction curve. For this purpose, empirical curves obtained through artificial quenchers have been studied and the results have been tested in real samples. Additionally, given that the Packard Tri-Carb 3170 TR/SL liquid scintillation counter is a novel detector for use in Cerenkov counting, the previous calibration of the Tri-Carb 3170 TR/SL detector, necessary for the measurement of 90Sr, is included. [Copyright &y& Elsevier]

Abstract: In this paper we explore the possibilities of Raman spectroscopy in order to deduce information on the fatty acid composition of bacterial cells. Therefore, representative strains of two bacterial taxa were each cultured in different conditions and in parallel analyzed by Raman spectroscopy and gaschromatographic FAME analysis. Raman spectra of pure fatty acids were recorded and used as reference spectra. The culturing conditions for each strain could be easily distinguished by the fatty acid information retrieved from bacterial Raman spectra. Chemometric techniques such as EMSC and PCA allowed to extract information about groups of fatty acids, that was consistent with the results from FAME analysis. Although the information retrieved from Raman spectroscopy is not as refined as that from FAME analysis, the presented methods could be useful to obtain basic information on the fatty acid present in bacteria when performing Raman spectroscopic analysis for fast whole cell profiling, which provides information for different types of cell components (fatty acids, amino acids, primary metabolites, etc.). [Copyright &y& Elsevier]

Abstract: Near infrared spectroscopy (NIRS) is an analytical technique that can be very useful for stability studies in particular because of its non destructive analytical capability. However, the spectral interpretation and treatment of this kind of multivariate data remains difficult without the use of chemometrics. In this article, a recent chemometrics method, analysis of variance – principal component analysis (ANOVA-PCA), was used for NIRS stability studies of sunflower and bread wheat external reference materials (ERM). It provided a practical tool for the study of the significance of various storage conditions according to an experimental design. Thus, the effect of the temperature, the nature of the atmosphere in the packaging and the storage duration were tested. ANOVA-PCA highlighted the influence of temperature and storage duration on the stability of the sunflower materials. For the bread wheat materials, the storage conditions did not have a significant effect on stability. Consequently, by applying ANOVA-PCA to near infrared spectral data, the sunflower materials were found to be considered stable for the time length of the study, i.e. 18 months stored in a cold room, while the bread wheat materials were found to be considered stable for the time length of the study, i.e. 12 months under the same conditions. [Copyright &y& Elsevier]

Abstract: Mean centering of ratio spectra is applied to resolve two-way kinetic-spectral data and acquire the rate constants and the spectrum of intermediate component. The proposed method can be applied for two-step consecutive reactions. The method is based on the mean centering of ratio spectra in order to obtain kinetic profile of intermediate component. Rate constants can be obtained using computational fitting. Given the kinetic parameters, the absorption spectrum of intermediate can be obtained through least squares regression. The proposed method can be applied to the reaction systems that reactant, intermediate or final product does not absorb in the investigation wavelength region. Also for very slow one-step reactions that pure spectrum for product is not available or overlaps completely with reactant spectrum, the proposed method can be used to resolve kinetic profile and consequently the pure spectrum of product. The applicability of the method has been evaluated by using model data. Alkaline hydrolysis of dimethyl phthalate as a real system was also studied by the proposed method. [Copyright &y& Elsevier]

Abstract: A selective and sensitive liquid chromatography coupled with triple stage quadruple tandem mass spectrometry (HPLC/TSQ-MS/MS) was developed and validated for simultaneous quantification of calycosin-7-O-β-d-glycoside (CCSG), formononetin-7-O-β-d-glycoside (Ononin) and (6R,10R)-9,10-dimethoxypterocarpan-3-O-β-d-glycoside (DPG) in rabbit plasma. Plasma samples were extracted with solid-phase extraction (SPE), separated on an Inertsil ODS-3 column and detected by tandem mass spectrometry with electrospray ionization (ESI) interface in positive selective reaction monitoring (SRM) mode. 3,7,8-Trimethoxy-xanthone-1-O-primaverose was used as internal standard (IS) for quantitative measurement. For each analyte, one major product ion was chosen and used for screening of it. Calibration curves were generated over the range of 2–1000ngmL−1 with the correlation coefficients greater than 0.99 by using a weighted (1/χ) least squares linear regression. The method had the lower limit quantification of 0.15, 0.21 and 0.19 for CCSG, Ononin and DPG, respectively, with precision less than 20%. The intra- and inter-day precisions ranged from 2.48 to 6.38% and 4.81 to 11.78% (R.S.D.%), respectively. This assay is suitable for determining the above three trace glycosides in rabbit plasma simultaneously and thus investigating the pharmacokinetics of glycosides from Astragalus mongholicus extract in rabbits. [Copyright &y& Elsevier]

Abstract: Near-infrared (NIR) spectrometry is now widely used in various fields and great attention is paid to the application of it to addressing complex problems, which brings about the need for the calibration of systems that fail to exhibit satisfactional linear relationship between input–output data. In this work we present a novel method to build a multivariate calibration model for NIR spectra, i.e. genetic algorithm–radial basis function network in wavelet domain (WT-GA–RBFN), which combines the advantages of wavelet transform and genetic algorithm. The variable selection is accomplished in two stages in wavelet domain: at the first stage, the variables are pre-selected (compressed) by variance and at the second stage the variables are further reduced by a special designed GA. The proposed method is illustrated through presenting its application to three NIR data sets in different fields and the comparison to PLS model. [Copyright &y& Elsevier]

Abstract: Microwave-assisted extraction (MAE) has been used for the simultaneous isolation of polar and nonpolar compounds from alperujo using methanol–water and n-hexane as extractant system. Multivariate methodology has been used to establish the optimum extraction conditions. The target fractions (phenol compounds and fatty acids) were quantitatively extracted within 14min. Following leaching and separation of the two phases by centrifugation, the polar and nonpolar fractions were analysed by HPLC–MS–MS and GC–MS, respectively. The proposed method was compared with the reference method for the isolation of each fraction (Folch method and stirring-based method for fatty acids and biophenols extraction, respectively) in terms of efficiency and extract composition. The paramount importance of both fractions, the simplicity of the MAE approach and the low costs of the raw material make advisable the implementation of the proposed method at an industrial scale. [Copyright &y& Elsevier]

Abstract: Preparation and application of gold 2-mercaptosuccinic acid self-assembled monolayer (Au-MSA SAM) electrode for determination of iron(III) in the presence of iron(II) is described by cyclic voltammetry, electrochemical impedance spectroscopy, and Osteryoung square wave voltammetry. The square wave voltammograms showed a sharp peak around positive potentials +0.250V that was used for construction of the calibration curve. Parameters influencing the method were optimized. A linear range calibration curve from 1.0×10−10 to 6.0×10−9 M iron(III) with a detection limit of 3.0×10−11 M and relative standard deviation (R.S.D.) of 6.5% for n =8 at 1.0×10−9 M iron(III) was observed in the best conditions. Possible interferences from the coexisting ions were also investigated. The results demonstrated that sensor could be used for determination of iron(III) in the presence of various ions. The validity of the method and applicability of the sensor were successfully tested by determining of iron(III) in natural waters (tap and mineral waters) and in a pharmaceutical sample (Venofer® ampoule) without interference from sample matrix. The experimental data are presented and discussed from which the new sensor is characterized. [Copyright &y& Elsevier]

Abstract: Samples of fluoxetine of different origin were submitted to natural abundance 2H NMR spectroscopy. The deuterium content at the various sites of the molecule was found to depend on its synthetic history. Hints on the synthetic procedure can be obtained by comparison with standard compounds, whose synthesis is known. These preliminary results give an idea of the potential of site-specific isotope ratio analysis in the fight against patent infringement and drug counterfeiting. [Copyright &y& Elsevier]

Abstract: We report the use of a calibration transfer strategy to correct for drift in the quantitative sensitivity of a portable quadrupole mass spectrometer (QMS) aimed at process monitoring applications. Gas mixtures of CH4/Ar/C2H6/CO2 were studied with calibration phase measurements made of the pure gases for a univariate analysis and of 40 multi-component mixtures for a multivariate approach. To evaluate calibrations, test set spectra of a CH4/Ar/C2H6/CO2 gas mixture were recorded bi-weekly over a period of 12 months. As part of the strategy a standard of pure argon was measured during both calibration and test phases so that correction factors could be calculated for each measurement day. It was shown that in the absence of a calibration transfer strategy quantifications of test set spectra could be inaccurate by more than an order of magnitude over 12 months. Furthermore, due to the effects of drift in the sensitivity over the 6 days required to record the training set in the calibration phase it was found that the multivariate analysis quantified test spectra less accurately than the univariate analysis. However, by applying the calibration transfer strategy across all measurements (both calibration and test phases) it was shown that the errors in prediction using the multivariate analysis previously seen after 2 weeks were not observed until approximately 12 months later. [Copyright &y& Elsevier]

Abstract: The combination of the near infrared (NIR) and Fourier-transform infrared (FTIR) absorbance spectra (1100–2500nm and 4000–600cm−1) of 100 cocoa powder samples was used to build calibration models for the determination of the content of fat, nitrogen, and moisture. The samples that comprised the dataset had an average composition of 13.51% of fat, 3.77% nitrogen, and 3.98% moisture. The fat content ranged from 2.42 to 22.00%, the nitrogen from 0.88 to 4.48%, and moisture from 1.60 to 7.80%. For NIR, the relative root mean square error of cross-validation (RMSECV) was 7.0% (R 2 =0.96) for fat, 1.7% (R 2 =0.98) for nitrogen, and 5.2% (R 2 =0.94) for moisture. For FTIR, the relative RMSECV was 10.4% (R 2 =0.94) for fat and 3.9% (R 2 =0.95) for nitrogen. However, for moisture, it was not possible to build a calibration model with suitable predictability. The combination of the NIR and FTIR domains (data fusion) by outer product analysis PLS1 allowed to predict these parameters and to characterise frequencies in one domain based on the information of the other domain. This work allows to conclude that the second derivative of NIR is the recommended procedure to quantify fat, nitrogen, and moisture content in cocoa powders by infrared spectroscopy. [Copyright &y& Elsevier]

Abstract: In this paper, a flow-through optosensor based on diffuse reflectance spectroscopy and multivariate regression modelling is proposed for simultaneous multiresidue determination of trace level concentrations of nitro-substituted phenols. The optrode integrates on-line anion-exchange sorptive preconcentration and matrix removal with direct detection of sorbed species onto the sensing layer and chemometric deconvolution of overlapped spectra. After recording of the reflectometric spectrum, fast chemosensor regeneration is accomplished with an acidic methanolic eluent followed by a metered volume of alkaline solution. The full automation of the analytical procedure is ensured by flow-programming as executed via a software-controlled multisyringe pump and a set of multiposition and solenoid valves. Under the optimized chemical and physical variables, the 3σ blank detection limits for 2-, and 4-nitrophenol and 2,4-dinitrophenol were 0.69, 0.42 and 0.37μgL−1, respectively, for a sample loading volume of 4.0mL with enrichment factors of 73, 74 and 81, respectively, and repeatability better than 3.0%. The analytical applicability of the optosensing system was asserted by the satisfactory results attained in its application to monitoring of nitrophenol derivatives in spiked environmental waters including highly saline matrices via the standard additions method. [Copyright &y& Elsevier]

Abstract: A bootstrap method for point-based detection of candidate biomarker peaks has been developed from pattern classifiers. Point-based detection methods are advantageous in comparison to peak-based methods. Peak determination and selection are problematic when spectral peaks are not baseline resolved or on a varying baseline. The benefit of point-based detection is that peaks can be globally determined from the characteristic features of the entire data set (i.e., subsets of candidate points) as opposed to the traditional method of selecting peaks from individual spectra and then combining the peak list into a data set. The point-based method is demonstrated to be more effective and efficient using a synthetic data set when compared to using Mahalanobis distance for feature selection. In addition, probabilities that characterize the uniqueness of the peaks are determined. This method was applied for detecting peaks that characterize age-specific patterns of protein expression of developing and adult mouse cerebella from matrix assisted laser desorption/ionization (MALDI) mass spectrometry (MS) data. The mice comprised three age groups: 42 adults, 19 14-day-old pups, and 16 7-day-old pups. Three sequential spectra were obtained from each tissue section to yield 126, 57 and 48 spectra for adult, 14-day-old pup, and 7-day-old pup spectra, respectively. Each spectrum comprised 71,879 mass measurements in a range of 3.5–50kDa. A previous study revealed that 846 unique peaks were detected that were consistent for 50% of the mice in each age group (C. Laurent, D.F. Levinson, S.A. Schwartz, P.B. Harrington, S.P. Markey, R.M. Caprioli, P. Levitt, Direct profiling of the cerebellum by MALDI MS: a methodological study in postnatal and adult mouse, J. Neurosci. Res. 81 (2005) 613–621.). A fuzzy rule-building expert system (FuRES) was applied to investigate the correlation of age with features in the MS data. FuRES detected two outlier pup-14 spectra. Prediction was evaluated using 100 bootstrap samples of 2 Latin-partitions (i.e., 50:50 split between training and prediction set) of the mice. The spectra without the outliers yielded classification rates of 99.1±0.1%, 90.1±0.8%, and 97.0±0.6% for adults, 14-day-old pups, and 7-day-old pups, respectively. At a 95% level of significance, 100 bootstrap samples disclosed 35 adult and 21 pup distinguishing peaks for separating adults from pups; and 8 14-day-old and 15 7-day-old predictive peaks for separating 14-day-old pup from 7-day-old pup spectra. A compressed matrix comprising 40,393 points that were outside the 95% confidence intervals of one of the two FuRES discriminants was evaluated and the classification improved significantly for all classes. When peaks that satisfied a quality criterion were integrated, the 55 integrated peak areas furnished significantly improved classification for all classes: the selected peak areas furnished classification rates of 100%, 97.3±0.6%, and 97.4±0.3% for adult, 14-day-old pups, and 7-day-old pups using 100 bootstrap Latin partitions evaluations with the predictions averaged. When the bootstrap size was increased to 1000 samples, the results were not significantly affected. The FuRES predictions were consistent with those obtained by discriminant partial least squares (DPLS) classifications. [Copyright &y& Elsevier]

Abstract: The active pharmaceutical ingredient (ambroxol) in an intact capsule formulation has been non-destructively quantified using Raman spectroscopy. To improve the problem of insufficient representive sampling inherent in Raman measurements, we have employed a wide area illumination (WAI) scheme that enables much improved sample coverage through a circular excitation laser spot with a 6mm diameter. One of the anticipated sources of variation for this measurement was variation in the capsule shells. However, the WAI scheme significantly decreased the spectral variation among empty capsules compared to a measurement with a traditional small-spot excitation. Therefore, measurement variations emanating from the capsule shell did not significantly influence the accuracy of the determination of ambroxol concentrations. The resulting standard error of prediction (SEP) using the WAI scheme was comparable to that from previous Raman measurements which used a conventional small-spot excitation and employed a sampling scheme that involved rotation of an ambroxol pellet. It is further noteworthy that the SEP was also similar to that obtained from the use of transmission NIR spectroscopy, which was achieved by collection of spectra of the powdered capsule contents removed from the shell. The proposed Raman measurement using the WAI scheme in this case was sufficient to achieve the quantitative measurement of the active pharmaceutical ingredient (API) content of capsules non-destructively. [Copyright &y& Elsevier]

The Raman spectra of several pairs of alkenyl methyl ethers of general structure R1R2C = C(R3R4)OCH3 and R1R2C(OCH3)C(R5) = R4 (R1, R2, R3, R4, R5 = H or CnH2n+1, n =1–3) are reported and discussed, with a view to establishing whether Raman spectroscopy offers a viable means of distinguishing between these isomeric unsaturated species. Key bands associated with the ν(sp2C-H) and ν(C=C) stretching modes are found to be particularly useful in this connection: R1R2C = CHCH2OCH3 and R1R2C(OCH3)CH = CH2 ethers (R1, R2 =CH3, C2H5) are easily distinguished on this basis. Differentiation of their lower homologues, R1CH = CH2OCH3 and R1CH(OCH3)CH = CH2 (R1 = CH3, C2H5, C3H7), by similar means is also quite straightforward, even in cases where cis and trans isomers are possible. Pairs of isomeric ethers, such as CH3CH = C(CH3)CH2OCH3 and CH3CH(OCH3)C(CH3) = CH2, in which the structural differences are more subtle, may also be distinguished with care. Deductions based on bands ascribed to the stretching vibrations are usually confirmed by consideration of the signals associated with the corresponding δ(sp2C-H) deformation vibrations. Even C2H5CH = CHCH(C3H7)OCH3 and C3H7CH = CHCH(C2H5)OCH3 are found to have distinctive Raman spectra, but differentiation of these closely related isomers requires additional consideration of the low wavenumber region. [Copyright &y& Elsevier]

Abstract: The ν-support vector regression (ν-SVR) was used to construct the calibration model between soluble solids content (SSC) of apples and acousto-optic tunable filter near-infrared (AOTF-NIR) spectra. The performance of ν-SVR was compared with the partial least square regression (PLSR) and the back-propagation artificial neural networks (BP-ANN). The influence of SVR parameters on the predictive ability of model was investigated. The results indicated that the parameter ν had a rather wide optimal area (between 0.35 and 1 for the apple data). Therefore, we could determine the value of ν beforehand and focus on the selection of other SVR parameters. For analyzing SSC of apple, ν-SVR was superior to PLSR and BP-ANN, especially in the case of fewer samples and treating the noise polluted spectra. Proper spectra pretreatment methods, such as scaling, mean center, standard normal variate (SNV) and the wavelength selection methods (stepwise multiple linear regression and genetic algorithm with PLS as its objective function), could improve the quality of ν-SVR model greatly. [Copyright &y& Elsevier]

Abstract: A multi-method approach has been developed for the characterisation of the proteinaceous binding media, drying oils and pigments present in samples from the panel paintings of the Church of the Assumption in Cephalonia (Ionian Islands, Greece). The analytical protocol involved the use of scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX), Raman spectroscopy and gas chromatography. The identification of the pigments was achieved by SEM/EDX and Raman spectroscopy. The latter technique was also used for the detection of the binding media, while their characterisation was achieved by gas chromatographic analysis of ethyl chloroformate derivatives. The aim of this multi-method protocol was to obtain as much information as possible from the panel paintings of the Church of the Assumption, through non-destructive methods, before proceeding to gas chromatography. Little scientific information is available for the understanding of the construction technique and the materials used by the post-Byzantine artists and whatever is available comes mainly from artists’ manuals. One of the aims of this paper is to provide a scientific background to the technology of the Ionian post-Byzantine icons. [Copyright &y& Elsevier]

Abstract: The freshness of virgin olive oils (VOO) from typical cultivars of Garda regions was evaluated by attenuated total reflectance (ATR) and Fourier transform infrared (FTIR) spectroscopy, in combination with multivariate analysis. The olive oil freshness decreased during storage mainly because of oxidation processes. In this research, 91 virgin olive oils were packaged in glass bottles and stored either in the light or in the dark at room temperature for different periods. The oils were analysed, before and after storage, using both chemical methods and spectroscopic technique. Classification strategies investigated were partial least square discriminant analysis (PLS-DA), linear discriminant analysis (LDA), and soft independent modelling of class analogy (SIMCA). The results show that ATR-MIR spectroscopy is an interesting technique compared with traditional chemical index in classifying olive oil samples stored in different conditions. In fact, the FTIR PCA results allowed a better discrimination among fresh and oxidized oils, than samples separation obtained by PCA applied to chemical data. Moreover, the results obtained by the different classification techniques (PLS-DA, LDA, SIMCA) evidenced the ability of FTIR spectra to evaluate the olive oil freshness. FTIR spectroscopy results are in agreement with classical methods. The spectroscopic technique could be applied for the prediction of VOOs freshness giving information related to chemical modifications. The great advantages of this technique, compared to chemical analysis, are related to rapidity, non-destructive characteristics and low cost per sample. In conclusion, ATR-MIR represents a reliable, cheap and fast classification tool able to assess the freshness of virgin olive oils. [Copyright &y& Elsevier]

Abstract: The resinous materials from the interior surfaces of two Roman and one Iberian amphora were studied with Fourier transform infrared (FTIR) spectroscopy. The results were then compared with those obtained by synchrotron radiation-FTIR, scanning electron microscopy (SEM), and gas chromatography–mass spectrometry (GC–MS). The FTIR spectra obtained by the technique of KBr micropellets, prepared directly with the materials scraped from the amphora without any further sample preparation, provided enough information to establish their diterpenoic nature, and even to differentiate between the two main materials employed for waterproofing purposes, pitch and wood tar. Methyl dehydroabietic acid (DHAM) is the main chemical marker that allows a distinction to be made between these two materials. Pitch and wood tar were prepared in the laboratory heating pine resin and resinous pine wood, respectively. These resinous waterproofing materials were compared with the coatings extracted from the amphorae. The samples whose direct FTIR spectra showed a signal at ∼1740cm−1, attributed to a carbonyl group of methyl ester, presented as well a peak of DHAM in the GC–MS chromatogram of the neutral fraction of their extract. Samples without this signal in their spectra did not present DHAM in their chromatogram. This work studies, for the first time, waterproofing of an amphora attributed to the Iberian culture. [Copyright &y& Elsevier]

Abstract: Flavonoid O-diglycosides are important bioactive compounds from genus Citrus. They often occur as isomers, which makes the structural elucidation difficult. In the present study, the fragmentation behavior of six flavonoid O-diglycosides from genus Citrus was investigated using ion trap mass spectrometry in negative electrospray ionization (ESI) with loop injection. For the flavonoid O-rutinosides, [M −H−308]− ion was typically observed in the MS2 spectrum, suggesting the loss of a rutinose. The fragmentation patterns of flavonoid O-neohesperidosides were more complicated in comparison with their rutinoside analogues. A major difference was found in the [M −H−120]− ion in the MS2 spectrum, which was a common feature of all the flavonoid O-neohesperidosides. The previous literature for naringin located the loss of 120Da to the glycan part, whereas the present study for naringin had shown that the [M −H−120]− ion was produced by a retro-Diels-Alder reaction in ring C, and this fragmentation pattern was confirmed by the accurate mass measurement using an orthogonal time-of-flight mass spectrometer. Combined with high performance liquid chromatography (HPLC) and diode array detection (DAD), the established approach to the structural identification of flavonoid O-diglycosides by ion trap mass spectrometry was applied to the analysis of extracts of two Chinese medicines derived from genus Citrus, namely Fructus aurantii and F. aurantii immaturus. According to the HPLC retention behavior, the diagnostic UV spectra and the molecular structural information provided by multistage mass spectrometry (MS n ) spectra, 13 flavonoid O-glycosides in F. aurantii and 12 flavonoid O-glycosides in F. a. immaturus were identified rapidly. [Copyright &y& Elsevier]

Abstract: An improved analytical method for determination of human pharmaceuticals in natural and wastewaters with ngL−1 sensitivity is presented. The method is applicable to pharmaceuticals from a wide range of therapeutic classes including antibiotics, analgesics, anti-inflammatories and anti-cancer compounds. Pharmaceuticals were extracted from waters using solid-phase extraction, and after concentration, analysed by high performance liquid chromatography with tandem mass spectrometric detection (HPLC–MS/MS). Identification of each compound was secured using retention time and by the selected reaction monitoring of two transitions, one of which was additionally used for quantification. Limits of detection ranged from 0.03 to 0.96ngL−1 and were up to two orders of magnitude lower than those of previously published methods. The method was validated using spiked samples prepared from tap, river and sea water as well as wastewater effluents, collected from the North of Scotland. Analysis of wastewater effluents revealed the presence of mefenamic acid, ibuprofen, erythromycin, diclofenac and trimethoprim. None of the selected pharmaceuticals were detected in river, tap or sea water samples. [Copyright &y& Elsevier]

Abstract: A strategy, named as removing uncertain variables based on ensemble partial least squares (RUV-EPLS), was proposed. In this strategy, the uncertainty in PLS regression coefficients is evaluated by the criterion of stability, and the variables whose regression coefficients carry a relatively large uncertainty are eliminated. Then, a new EPLS model with the remaining variables is constructed. To reasonably control the quality of the PLS member models in the RUV-EPLS, an objective criterion based on the F-test is used, which makes the RUV-EPLS convenient to perform in practice. To validate the effectiveness and universality of the strategy, it was applied to two different sets of near-infrared (NIR) spectra. It is of great interest to be found that the RUV-EPLS is not so sensitive to the outliers as many other calibration methods, and the selected variables are indeed known to be informative for corresponding compounds, which results in a reliable and high-quality calibration model. The study reveals that the RUV-EPLS method is of value to improve stability and predictive ability of multivariate calibration involving complex matrices that may contain a small number of outliers. [Copyright &y& Elsevier]

Abstract: Background: Urinary nucleosides are potential biomarkers for many kinds of cancers. But up to now, it has been little focused in bladder cancer recognition. The aim of present study is try to validate the potential of urinary nucleoside as biomarker for bladder cancer diagnosis by finding out some urinary nucleosides with good discriminative performance for bladder cancer recognition in urinary nucleoside profile. Methods: 20 urinary samples for cancer and the same number for control are collected and treated by capillary electrophoresis–mass spectrometry experiments to achieve urinary nucleoside profile, in which 44 peaks were integrated and the ratios of the relative peak area to the concentration of urinary creatinine were used as features to describe all samples. Support vector machine based recursive feature elimination (SVM-RFE) and a new feature selection method called support vector machine based partial exhaustive search algorithm (SVM-PESA) were used for biomarker identification and seeking optimal feature subsets for bladder cancer recognition. Results: Based on the urinary nucleoside profile, 22 optimal feature subsets consist of 3–4 features were found with 95% 5-fold cross validation accuracy, 100% sensitivity and 90% specificity by SVM-PESA, whose performance were much better than that of optimal feature subset selected by SVM-RFE. By analyzing the statistical histogram of features’ appearance frequency in several best feature subsets, urinary nucleosides with m/z 317, 290 and 304 were thought as potential biomarkers for bladder cancer recognition. Conclusions: These results indicated urinary nucleosides may be useful as tumor biomarkers for bladder cancer, and the new method for biomarker selection is effective. [Copyright &y& Elsevier]

Abstract: Near infrared (NIR) spectra of a sample can be treated as a signature, allowing samples to be grouped on basis of their spectral similarities. Near infrared spectroscopy (NIRS) combined with probabilistic neural networks (PNN) have been used to discriminate producing area and variety of loquats. Two varieties of loquats (‘Dahongpao’ and ‘Jiajiaozhong’) picked from two producing areas of ‘Tangxi’ and ‘Cunan’ in Zhejiang province were analyzed in this study. Principal component analysis (PCA) was applied before PNN modeling and the results indicated that the dimension of the vast spectral data can be effectively reduced. For each model, half samples were used to train the network and the remaining half were used to test the network. The results of the PCA–PNN models for discriminating the variety of samples from the same producing area or for discriminating the producing area of the same variety samples were much better than those of the PCA–PNN models for discriminating variety or producing area of all loquat samples. The results of this study show that NIRS combined with PCA–PNN is a feasible way for qualitative analysis of discriminating fruit producing areas and varieties. [Copyright &y& Elsevier]

Abstract: Tracking of Hg2+ in solutions as well as in living cells was conducted with a fluorescent chemodosimeter by measuring the spectral shift of its fluorescence under single- or two-photon excitation. The spectral hypsochromic shifts of this chemodosimeter when reacting with Hg2+ were found to be about 50nm in acetonitrile/water solutions and 32nm in Euglena gracilis 277 living cells. This chemodosimeter shows high sensitivity and selectivity, and is not influenced by the pH values. It can signal Hg2+ in solutions down to the ppb range under either single-photon excitation (SPE) at 405nm or two-photon excitation (TPE) at 800nm. However, with low cellular chemodosimeter concentrations, the SPE spectra were disturbed by the auto-fluorescence from the native fluorophore in the cell, while the TPE spectra were still of high quality since the two-photon absorption cross section of this chemodosimeter is much larger than that of the native fluorophores in the cell. [Copyright &y& Elsevier]

Abstract: Aiming at ion mobility spectrometry (IMS), computer-assisted ion mobility prediction (CAIMP) has been recently developed to simulate and predict diverse IMS behaviors in assistance of mathematics and computer science. Of that, quantitative structure–property relationship (QSPR) plays a vital role, dedicating to predict properties of unknown samples by creating statistical model based on known samples. In QSPR, the key lies in how to transform structural characteristics of target compounds into a group of numerical codes. In consideration that future IMS applications may mainly focus on intricate drug/biological systems, a novel molecular structural characterization method referring to molecular graphic fingerprint (MoGF) is proposed in this paper. In MoGF approach, radical distribution function is employed to map intrinsic interatomic correlations into a coordinate system according to a reasonable sampling interval, thus forming the characteristic graph curve which is rich in information on molecular structural characteristics, possessing of great merits in easy calculation, independent of experiments, large information contents, explicit structural meanings and intuitive expressions, etc. Consequently, MoGF is utilized to QSPR studies on 579 singly protonated peptide collision cross sections, and the constructed partial least square (PLS) regression model is confirmed to be robust and predictable by rigorous both internal and external validations, with statistics as r 2 =0.991, q 2 =0.990, RMSEE=5.526, RMSCV=5.572, , , , , k =1.003, k′=0.996 and RMSEP=5.561, respectively. [Copyright &y& Elsevier]

Abstract: Magnetic microspheres are optically encoded by doping with three luminescent dyes. The combination of a fluorophore with a nanosecond decay profile and two phosphorescent Ruthenium metal ligand complexes with a microsecond decay profile generates a characteristic signature described by three features: bead brightness, luminescent decay time and dual lifetime referencing (DLR). The beads are identified by time resolved imaging in the microsecond range. A series of fluorophores is tested and the interference of the resulting luminescent code in the red and green label detection channels is investigated. A detailed staining procedure is worked out to increase the staining efficiency of the dyes with hydrophilic character into the lipophilic polystyrene microspheres. A mathematical model is established to calculate the dye amounts that are needed for staining a bead family with a specific feature set. Nineteen bead families were prepared representing the grid points in the three planes of a cube referring to the three features. The coefficient of variation over all bead families is 7%, 1.4% and 1.6% for bead brightness, luminescence decay time and DLR, respectively. The combination of these features and the bead size as additional feature enables the creation of 840 distinguishable bead families. [Copyright &y& Elsevier]

Abstract: Herein is reported, for the first time, a simple and reliable chiral reversed-phase liquid chromatographic method coupled to ultraviolet (UV) detection for simultaneous determination of eslicarbazepine acetate (ESL) and its metabolites, S-licarbazepine (S-LC), R-licarbazepine (R-LC) and oxcarbazepine (OXC), in mouse plasma and brain, liver and kidney tissue homogenates. All analytes and the internal standard were extracted from plasma and tissue homogenates by a solid-phase extraction procedure using Waters Oasis® hydrophilic–lipophilic balance cartridges. The chromatographic separation was performed by isocratic elution with water/methanol (88:12, v/v), pumped at a flow rate of 0.7mLmin−1, on a LichroCART 250-4 ChiraDex (β-cyclodextrin, 5μm) column at 30°C. The UV detector was set at 225nm. Calibration curves were linear (r 2 ≥0.996) in the ranges 0.4–8μgmL−1, 0.1–1.5μgmL−1 and 0.1–2μgmL−1 for ESL and OXC and in the ranges 0.4–80μgmL−1, 0.1–15μgmL−1 and 0.1–20μgmL−1 for R-LC and S-LC in plasma, brain and liver/kidney homogenates, respectively. The overall precision not exceeded 11.6% (%CV) and the accuracy ranged from −3.79 to 3.84% (%bias), considering all analytes in all matrices. Hence, this method will be a useful tool to characterize the pharmacokinetic disposition of ESL in mice. [Copyright &y& Elsevier]