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Abstract: Stir bar sorptive extraction and liquid desorption followed by large volume injection coupled to gas chromatography–quadrupole mass spectrometry (SBSE–LD/LVI-GC–qMS) had been applied for the determination of volatiles in wines. The methodology was optimised in terms of extraction time and influence of ethanol in the matrix; LD conditions, and instrumental settings. The optimisation was carried out by using 10 standards representative of the main chemical families of wine, i.e. guaiazulene, E,E-farnesol, β-ionone, geranylacetone, ethyl decanoate, β-citronellol, 2-phenylethanol, linalool, hexyl acetate and hexanol. The methodology shows good linearity over the concentration range tested, with correlation coefficients higher than 0.9821, a good reproducibility was attained (8.9–17.8%), and low detection limits were achieved for nine volatile compounds (0.05–9.09μgL−1), with the exception of 2-phenylethanol due to low recovery by SBSE. The analytical ability of the SBSE–LD/LVI-GC–qMS methodology was tested in real matrices, such as sparkling and table wines using analytical curves prepared by using the 10 standards where each one was applied to quantify the structurally related compounds. This methodology allowed, in a single run, the quantification of 67 wine volatiles at levels lower than their respective olfactory thresholds. The proposed methodology demonstrated to be easy to work-up, reliable, sensitive and with low sample requirement to monitor the volatile fraction of wine. [Copyright &y& Elsevier]

Abstract: This review is intended to give readers a snapshot of current mass spectrometry for proteomics research. It covers a brief history of mass spectrometry proteomic research, peptidomics and proteomics for biomarker search, quantitative proteomics, proteomics with post-translational modification and future perspective of proteomics. [Copyright &y& Elsevier]

Abstract: This paper provides analytical chemical information on selected new molecular entities (NMEs) which are drugs that have recently been approved by the FDA. These are the antiretroviral drugs, atazanavir, indinavir and emtricitabine, the antibacterial gemifloxacin, rosuvastatine which is a cholesterol-lowing drug, the anti-cancer drug gefitinib and aprepitant for neurological disorders. Electrospray ionisation-quadrupole ion trap mass spectrometry (ESI-MS n ) was employed to generate tandem mass spectrometric (MS2) data of the drugs studied and structural assignments of product ions were supported by quadrupole time-of-flight mass spectrometry (QToF-MS/MS). These fragmentation studies were then utilised in the development and validation of a specific and sensitive liquid chromatographic method (LC–ESI-MS2) to identify and determine these drugs at therapeutic concentration levels in serum after a single protein precipitation procedure with acetonitrile. In addition, this method was compared to the application of gas liquid chromatography-flame ionisation detection (GLC-FID) and differential pulse polarography (DPP) for the analysis of these NMEs in serum. [Copyright &y& Elsevier]

Abstract: In the present paper we describe a robust and simple method to measure dissolved iron (DFe) concentrations in seawater down to <0.1nmolL−1 level, by isotope dilution multiple collector inductively coupled plasma mass spectrometry (ID-MC-ICP-MS) using a 54Fe spike and measuring the 57Fe/54Fe ratio. The method provides for a pre-concentration step (100:1) by micro-columns filled with the resin NTA Superflow of 50mL seawater samples acidified to pH 1.9. NTA Superflow is demonstrated to quantitatively extract Fe from acidified seawater samples at this pH. Blanks are kept low (grand mean 0.045±0.020nmolL−1, n =21, 3×S.D. limit of detection per session 0.020–0.069nmolL−1 range), as no buffer is required to adjust the sample pH for optimal extraction, and no other reagents are needed than ultrapure nitric acid, 12mM H2O2, and acidified (pH 1.9) ultra-high purity (UHP) water. We measured SAFe (sampling and analysis of Fe) reference seawater samples Surface-1 (0.097±0.043nmolL−1) and Deep-2 (0.91±0.17nmolL−1) and obtained results that were in excellent agreement with their DFe consensus values: 0.118±0.028nmolL−1 (n =7) for Surface-1 and 0.932±0.059nmolL−1 (n =9) for Deep-2. We also present a vertical DFe profile from the western Weddell Sea collected during the Ice Station Polarstern (ISPOL) ice drift experiment (ANT XXII-2, RV Polarstern) in November 2004–January 2005. The profile shows near-surface DFe concentrations of ∼0.6nmolL−1 and bottom water enrichment up to 23nmolL−1 DFe. [Copyright &y& Elsevier]

Abstract: In order to solve the calibration transformation problem in near-infrared (NIR) spectroscopy, a method based on canonical correlation analysis (CCA) for calibration model transfer is developed in this work. Two real NIR data sets were tested. A comparative study between the proposed method and piecewise direct standardization (PDS) was conducted. It is shown that the transfer results obtained with the proposed method based on CCA were better than those obtained by PDS when the subset had sufficient samples. [Copyright &y& Elsevier]

Abstract: Aspiration ion mobility spectrometry (IMS) has been used for the first time to screen 3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexaoxacyclononane explosive, the most commonly known as triacetone triperoxide (TATP). Gaseous TATP was generated from synthesized solid compound, sublimed and directed to a portable chemical detection system comprised of an aspiration-type IMS detector and six semiconductor sensors. Different unknown TATP gas phase concentrations were produced and corresponding IMS and semiconductor responses were measured. The experimental concentrations were determined by gas chromatography–mass spectrometry (GC–MS). The results evidenced that the monitored compound in the gas phase was TATP. In addition, the determined TATP concentrations and corresponding IMS intensities showed that the IMS response values were proportional to the measured TATP concentrations. [Copyright &y& Elsevier]

Abstract: Gas chromatography–mass spectrometry (GC–MS) combined with Chemometric resolution techniques were proposed as a method for the analysis of volatile components of Iranian damask rose oil. The essential oil of damask rose was extracted using hydrodistillation method and analyzed with GC–MS in optimized conditions. A total of 70 components were identified using similarity searches between mass spectra and MS database. This number was extended to 95 components with concentrations higher than 0.01% accounting for 94.75% of the total relative content using Chemometric techniques. For the first time in this work, an approach based upon subspace comparison is used for determination of the chemical rank of GC–MS data. The peak clusters were resolved using heuristic evolving latent projection (HELP) and multivariate curve resolution-alternating least square (MCR-ALS) by applying proper constraints, and the combination of both methods for some cases. It is concluded that a thorough analysis of the complex mixtures such as Iranian damask rose requires sophisticated GC–MS coupled with the Chemometric techniques. [Copyright &y& Elsevier]

Abstract: The quantification of mixtures of (R)- and (S)-propranolol (PRO) in the pure form and in the pharmaceutical preparations is described. The methodology is based on chiral recognition of propranolol by formation of an inclusion complex with β-cyclodextrin (CD), a chiral auxiliary, in the presence of 1-butanol. The excitation–emission fluorescence surface and second-order multivariate calibration such as bilinear least squares (BLLS) and parallel factor analysis (PARAFAC) were used in the model development. BLLS performed better than PARAFAC, presenting relative mean error in the order of 3.5%, analytical sensitivity of 0.07% and 0.08%, detection limit of 0.23% and 0.28% and quantification limit of 0.71% and 0.84% for the pure form and pharmaceutical preparations, respectively. These results indicate that the proposed methodology can be an alternative for the determination of propranolol enantiomeric composition. [Copyright &y& Elsevier]

Abstract: After a soft ionizing method was established, MS (mass spectrometry) has become a more common tool in biochemistry because soft ionization made it possible to detect large molecules such as proteins. Many kinds of applications were established to further utilize MS for the identification or quantitation of biomolecules. In this review, we introduce recent applications with special focus on chemical modification techniques and chemical probes developed for the MS determination of biomolecules. [Copyright &y& Elsevier]

Abstract: The potential of the near infrared spectroscopy (NIRS) technique for the analysis of red paprika for aflatoxin B1, ochratoxin A and total aflatoxins is explored. As a reference, the results from a chromatographic method with fluorescence detection (HPLC-FD) following an immunoaffinity cleanup (IAC) were employed. For the NIRS measurement, a remote reflectance fibre-optic probe was applied directly onto the samples of paprika. There was no need for pre-treatment or manipulation of the sample. The modified partial least squares (MPLS) algorithm was employed as a regression method. The multiple correlation coefficients (RSQ) and the prediction corrected standard errors (SEP(C)) were respectively 0.955 and 0.2μgkg−1, 0.853 and 2.3μgkg−1, 0.938 and 0.3μgkg−1 for aflatoxin B1, ochratoxin A and total aflatoxins, respectively. The capacity for prediction of the developed model measured as ratio performance deviation (RPD) for aflatoxin B1 (5.2), ochratoxin A (2.8) and total aflatoxins (4.4) indicate that NIRS technique using a fibre-optic probe offers an alternative for the determination of these three parameters in paprika, with an advantageously lower cost and higher speed as compared with the chemical method. Content of aflatoxin B1 and total aflatoxins are the parameters currently employed by the food regulations to limit the levels of the four aflatoxins in many foodstuffs. In addition, aflatoxin B1 itself is an excellent indicator for aflatoxins’ contamination since it is always the most abundant and toxic. [Copyright &y& Elsevier]

Abstract: A method based on the coupling of HPLC with ICP-MS with an on-line pre-concentration micro-column has been developed for the analysis of inorganic and methyl mercury in the dissolved phase of natural waters. This method allows the rapid pre-concentration and matrix removal of interferences in complex matrices such as seawater with minimal sampling handling. Detection limits of 0.07ngL−1 for inorganic mercury and 0.02ngL−1 for methyl mercury have been achieved allowing the determination of inorganic mercury and methyl mercury in filtered seawater from the Venice lagoon. Good accuracy and reproducibility was demonstrated by the repeat analysis of the certified reference material BCR-579 coastal seawater. The developed HPLC separation was shown to be also suitable for the determination of methyl mercury in extracts of the particulate phase. [Copyright &y& Elsevier]

Abstract: We synthesized a new long-wavelength latent fluorimetric probe BCC (6) to detect physiologically significant thiols. The fluorogenic chemical transformation of BCC triggered by thiols is through a tandem reaction, thiol-induced benzoquinone reduction, and quinone–methide-type rearrangement reaction, which are spontaneous and irreversible at physiological temperature in aqueous media. The fluorescence signal revealed by this process is specific and exhibited in the near-red spectrum region with emission maxima at 595nm, and it could be competitively inhibited by thiols scavenger, N-ethylmaleimide. The fluorescent response of BCC is insensitive to various non-thiol amino acids and biological reductants. This novel fluorimetric probe demonstrates a good relationship in detecting thiols in 1–100μM range, which presents to the applicability for the construction of fiber-optic biosensors in the future clinical diagnostic. [Copyright &y& Elsevier]

Abstract: A direct and fast method for determination of the adulterant diethylene glycol (DEG) in toothpaste and gel dentifrices combining attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy with partial least squares (PLS) regression has been proposed. Considering the high heterogeneity of dentifrices available in the market, the possibility of reducing the number of calibration samples for PLS was evaluated. Similar prediction performance was achieved by both employing a large calibration set of 20 dentifrices spiked with different amounts of DEG and a reduced calibration set of seven ones selected by means of hierarchical cluster analysis (HCA). The feasibility of using the simple calibration model to predict DEG adulteration in a wide variety of unknown dentifrice samples increases the applicability of the proposed method. With this approach, DEG was quantified with a root mean squared error of prediction value of 1.1% for a validation set of 40 different dentifrices containing DEG in the range 0–16% (w:w). [Copyright &y& Elsevier]

Abstract: Knowledge and control of the polymorphic phases of chemical compounds are important aspects of drug development in the pharmaceutical industry. Salmeterol xinafoate, a long acting β-adrenergic receptor agonist, exists in two polymorphic Forms, I and II. Raman and near infrared spectra were obtained of these polymorphs at selected wavelengths in the range of 488–1064nm; significant differences in the Raman and near-infrared spectra were apparent and key spectral marker bands have been identified for the vibrational spectroscopic characterisation of the individual polymorphs which were also characterised with X ray diffractometry. The solid-state transition of salmeterol xinafoate polymorphs was studied using simultaneous in situ portable Raman spectroscopy and differential scanning calorimetry isothermally between transitions. This method assisted in the unambiguous characterisation of the two polymorphic forms by providing a simultaneous probe of both the thermal and vibrational data. The study demonstrates the value of a rapid in situ analysis of a drug polymorph which can be of potential value for at-line in-process control. [Copyright &y& Elsevier]

Abstract: Multi-walled carbon nanotubes (MWNTs) were modified by oxyfluorination treatment at several different temperatures of 20, 100, 200, and 300°C. The changes of surface properties of oxyfluorinated MWNTs were investigated using X-ray photoelectron spectroscopy (XPS) method. As a result, it was found that surface fluorine contents were varied with changing an oxyfluorination temperature and showed a maximum value at 100°C. By changing the treatment temperature in the process of oxyfluorination for carbon supports, the surface characteristics of MWNTs had been modified, resulting that the size and loading content of deposited Pt on the modified carbon supports could be changed. Consequently, Pt deposited MWNTs that were treated at 100°C (Pt/100-MWNTs) showed the best electroactivity among samples. The enhanced electroactivity was dependent on the higher surface area of electrochemical reaction for metal catalyst, which was related to the particle size and the morphology of the deposited particle catalysts. [Copyright &y& Elsevier]

Abstract: We report preparation of a novel platform for effective DNA hybridization and its application to the detection of single mismatched DNA. Cone-shaped dendrimer molecules have been immobilized on the gold surface at equidistance, 3.1nm, from each other with a probe DNA molecule attached to the top of each dendrimer so that enough space would be secured for effective hybridization. This arrangement allows each probe DNA molecule to form a natural DNA double helix upon hybridization with a target DNA molecule. The single nucleotide polymorphism at either the central or end position of the 25-mer target DNA has been shown to be effectively discriminated against on this platform from each other as well as from a complementary DNA by electrochemical impedance measurements. We also report adverse effects exerted by probe ions, Fe(CN)6 3−/4−, on DNA hybridization reactions. The significance of the results for the use in DNA analysis is discussed. [Copyright &y& Elsevier]

Abstract: A ball lens hollow-fiber Raman probe (BHRP) is a powerful tool for in vivo nondestructive subsurface analysis of biomedical tissues in a living body. It has confocal-like optical properties, but its collection volume is rather large in comparison with that of a conventional confocal Raman system. Therefore, the obtained Raman spectra have contributions from the upper and lower layers at different rates depending on the thickness of the upper layer when the measurement point is close to the boundary surface of the two layers. In the present study, we describe a methodology to extract quantitative information about the thickness of the subsurface layer structure by using a BHRP combined with the partial least-square regression (PLSR) analysis. The simulation study indicates that distribution of the collection efficiency in the collection volume of the BHRP is similar to a Gaussian distribution. The empirical study suggests that the PLSR model built with only a principal component (PC) 1 based on the linearized depth data gives good prediction. [Copyright &y& Elsevier]

Abstract: An efficient method for detecting malicious and accidental contamination of foods has been developed using a combined 1H nuclear magnetic resonance (NMR) and chemometrics approach. The method has been demonstrated using a commercially available carbonated soft drink, as being capable of identifying atypical products and to identify contaminant resonances. Soft-independent modelling of class analogy (SIMCA) was used to compare 1H NMR profiles of genuine products (obtained from the manufacturer) against retail products spiked in the laboratory with impurities. The benefits of using feature selection for extracting contaminant NMR frequencies were also assessed. Using example impurities (paraquat, p-cresol and glyphosate) NMR spectra were analysed using multivariate methods resulting in detection limits of approximately 0.075, 0.2, and 0.06mM for p-cresol, paraquat and glyphosate, respectively. These detection limits are shown to be approximately 100-fold lower than the minimum lethal dose for paraquat. The methodology presented here is used to assess the composition of complex matrices for the presence of contaminating molecules without a priori knowledge of the nature of potential contaminants. The ability to detect if a sample does not fit into the expected profile without recourse to multiple targeted analyses is a valuable tool for incident detection and forensic applications. [Copyright &y& Elsevier]

Abstract: Formaldehyde cross-linking of proteins is emerging as a novel approach to study protein–protein interactions in living cells. It has been shown to be compatible with standard techniques used in functional proteomics such as affinity-based protein enrichment, enzymatic digestion, and mass spectrometric protein identification. So far, the lack of knowledge on formaldehyde-induced protein modifications and suitable mass spectrometric methods for their targeted detection has impeded the identification of the different types of cross-linked peptides in these samples. In particular, it has remained unclear whether in vitro studies that identified a multitude of amino acid residues reacting with formaldehyde over the course of several days are suitable substitutes for the much shorter reaction times of 10–20min used in cross-linking experiments in living cells. The current study on model peptides identifies amino-termini as well as lysine, tryptophan, and cysteine side chains, i.e. a small subset of those modified after several days, as the major reactive sites under such conditions, and suggests relative position in the peptide sequence as well as sequence microenvironment to be important factors that govern reactivity. Using MALDI-MS, mass increases of 12Da on amino groups and 30Da on cysteines were detected as the major reaction products, while peptide fragment ion analysis by tandem mass spectrometry was used to localize the actual modification sites on a peptide. Non-specific cross-linking was absent, and could only be detected with low yield at elevated peptide concentrations. The detailed knowledge on the constraints and products of the formaldehyde reaction with peptides after short incubation times presented in this study is expected to facilitate the targeted mass spectrometric analysis of proteins after in vivo formaldehyde cross-linking. [Copyright &y& Elsevier]

Abstract: Very severe reaction conditions are required in the conventional synthesis of molecularly imprinted polymers (MIPs), which is unfavorable to their applications in chemical separation and analysis. A simple surface molecular imprinting approach was developed to synthesize MIP-coated SiO2 micro-particles in aqueous solutions. The 1H NMR and UV–vis spectroscopic analysis indicated that via hydrogen bonding, the functional monomer (o-phenylenediamine) can associate with the target (template) 2,4-dinitrophenol (2,4-DNP), as a model compound of organic pollutants, to form a precursor in aqueous solution. The copolymerization of this precursor and the free monomer was performed in the aqueous suspension of surface modified SiO2 particles, leading to the formation of MIP-coated SiO2 micro-particles. The MIP-coated silica particles were characterized with FT-IR, TGA, and UV–vis solid-state reflection spectroscopy, and were further demonstrated to have high adsorption capacity, excellent selectivity and site accessibility for 2,4-DNP. The new absorbent was successfully used in solid-phase extraction (SPE) to selectively enrich and determine 2,4-DNP in aqueous samples. The experimental results indicated that the MIP-SPE column yielded recoveries higher than 92% with R.S.D. <2.8%, much better than the commercial C18-SPE column, which produced a recovery less than 30% with R.S.D. <3.0%. [Copyright &y& Elsevier]

Abstract: A rapid and nondestructive near infrared (NIR) method combined with chemometrics was used to discriminate Ganoderma lucidum according to cultivation area. Raw, first, and second derivative NIR spectra were compared to develop a robust classification rule. The chemical properties of G. lucidum samples were also investigated to find out the difference between samples from six varied origins. It could be found that the amount of polysaccharides and triterpenoid saponins in G. lucidum samples was considerably different based on cultivation area. These differences make NIR spectroscopic method viable. Principal component analysis (PCA), discriminant partial least-squares (DPLS) and discriminant analysis (DA) were applied to classify the geographical origins of those samples. The results showed that excellent classification could be obtained after optimizing spectral pre-treatment. For the discriminating of samples from three different provinces, DPLS provided 100% correct classifications. Moreover, for samples from six different locations, the correct classifications of the calibration as well as the validation data set were 96.6% using the DA method after the SNV first derivative spectral pre-treatment. Overall, NIR diffuse reflectance spectroscopy using pattern recognition was shown to have significant potential as a rapid and accurate method for the identification of herbal medicines. [Copyright &y& Elsevier]

Abstract: The use of accurate mass measurement as a confirmation tool is examined on a TOF-MS and compared with confirmation using a triple quadrupole mass spectrometer (QqQ-MS). Confirmation of the identity of a substance using mass-spectrometric detection has been described. However, the use of accurate mass measurement for confirmatory analysis has not been taken into account. In this study, criteria for confirmation with accurate mass are proposed and feasibility is demonstrated. Mass accuracy better than 3ppm of the quasi-molecular ion and a fragment and their relative ratios determined with LC/TOF-MS are compared to the criteria of two transition ions and their ratio of LC/QqQ-MS. The results show that these criteria can be met for Trenbolone in samples of bovine urine and that single MS accurate mass measurement is comparable to nominal mass MS/MS for confirmation. The increase in popularity and availability of LC/TOF-MS instruments and the ease, of which exact masses can be measured, make it important to formulate criteria for this type of instrumentation. It is shown in this study that accurate mass measurement can be used for confirmatory analysis. However, more experiments need to be conducted to demonstrate the applicability of accurate mass measurement in general for residue analysis. [Copyright &y& Elsevier]

Abstract: This work presents an exploratory study of the photochemical degradation process of decabromodiphenyl ether (decaBDE) and gives an interpretation of the kinetic pathway, species and effects of the key factors involved in the degradation process. Use of lowly brominated diphenyl ethers (PBDE) has been banned by the EU and there seems to be evidence of the photolytic degradation of highly brominated PBDEs into lowly brominated congeners. Hence, the importance of knowing the photodegradation process of decaBDE. The photodegradation was investigated under UV light by UV-spectrophotometric monitoring. A novel hybrid data analysis approach, based on the combination of hard- and soft-spectrophotometric multivariate curve resolution, was applied to elucidate the mechanism of the degradation process, to resolve kinetic profiles and pure spectra of the photodegradation products and to evaluate the rate constants. The photodegradation process could be described with a kinetic model based on three consecutive first-order reactions and a decrease of the degradation process was observed as solvent polarity increased. Complementary identification of photodegradation products by gas chromatography coupled to mass spectrometry using negative chemical ionization (GC-NCI–MS) is attempted. This work presents a novel attempt of describing in a comprehensive way the photochemical degradation process of decaBDE, with all successive steps and related rate constants. This study proves also the potential of the proposed hybrid data analysis methodology as a general strategy to interpret the evolution of these photochemical reactions. [Copyright &y& Elsevier]

Abstract: In the paper, the effect of several fungicide residues (famoxadone, fenhexamid, fluquinconazole, kresoxim-methyl, quinoxyfen and trifloxystrobin) has been studied in relation to the aroma composition of Monastrell red wines in terms of each compound concentration and OAV (Odour Activity Value) values. Two fungicide treatments were carried out with authorized formulates following the manufacturer doses. The first one was carried out under good agricultural practices (GAP), obeying the preharvest interval, and the second one under critical agricultural practices (CAP), applying at the day of harvesting. The wines obtained in the thirteen trials (one control, six with treated grapes obeying the preharvest interval and six treated at the day of harvesting or at most unfavourable conditions) were analysed by stir bar sorptive extraction and gas chromatography–mass spectrometry (SBSE–GC–MS). The method proposed showed good linearity over the concentration range tested, with correlation coefficients higher than 0.9 for all the analytes. The reproducibility and repeatability of the method was estimated between 1.0 and 18.52%. The detection and quantification limits of all analytes were lower than the concentration found in these Monastrell wines. The identified wine volatile compounds have been grouped according to: ethyl esters, acetates, C6 compounds, terpenoids, acids and ethyl acetate, 3-methyl-1-butanol, 2-phenylethanol and benzaldehyde, as individual level. As results, it was observed that all fungicide treatments significantly affect the wine aroma composition. Each group of compounds has been associated to sensorial descriptor series (fatty, floral, fruity, herbaceous, solvent, rose and vinous), resulting that the best sensory valuated wines were the ones treated with fluquinconazole and fenhexamid under GAP. [Copyright &y& Elsevier]

Abstract: High-performance liquid chromatography (HPLC)-UV and HPLC–Mass Spectrometry (MS) methods were developed for the quantitative analysis of the family of Hoodia gordonii steroid glycosides with appetite suppressing properties in dried plant material, in purified and enriched extracts and in various prototype food-products fortified with H. gordonii extracts. For solid materials, e.g. dried plants or for non-fatty foods, extraction of the steroid glycosides is performed using methanol. For products where the steroid glycosides are present in an oil matrix, direct injection of the oil after dilution in tetrahydrofuran is applied. The HPLC separation is performed on an octyl-modified reversed-phase column in the gradient mode with UV detection at λ =220nm. Quantification is performed against an external calibration line prepared using either one of the pure steroid glycosides or geranyl-tiglate. Short- and long-term repeatabilities of the methods are better than 3 and 6%, respectively. Recoveries are better than 85%, even in the analysis of the least abundant steroid glycosides in a complex yoghurt drink. Linearity is better than 3–4 orders of magnitude and the detection limits are below approximately 2μgg−1 for the individual steroid glycosides in dried plant material and food products. HPLC–MS is used to confirm that the steroid glycosides contain the characteristic steroid core, the carbohydrate chain and the tigloyl group. [Copyright &y& Elsevier]

Abstract: An improved method for the analysis of carbonyls is described utilizing a headspace solid-phase microextraction (HS-SPME) step and on-fiber derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) hydrochloride. Thermal desorption of the oxime derivatives formed on the fiber is followed by gas chromatographic separation coupled to an ion trap tandem mass spectrometer (GC–ITMS). Selecting specific fragment ions within the electron ionization (EI+) mass spectra of these oxime derivatives as precursor ions for MS–MS fragmentation provides a suitable method for the target analysis of individual carbonyl classes, such as alkanals, (E)-2-alkenals, (E,E)-2,4-alkadienals, and others. Retention indices on polar as well as on apolar stationary phases along with EI+ mass spectra patterns are presented for a large set of oxime derivatives, giving valuable information needed for unambiguous assignment of substances in complex sample matrices. The fast sample preparation and derivatization step via HS-SPME can be automated and is applicable to a variety of biological samples and foodstuffs, allowing rapid and sensitive screening analyses of important aldehydic biomarkers and aroma active compounds. [Copyright &y& Elsevier]

Abstract: Increasing consumer awareness of food safety issues requires the development of highly sophisticated techniques for the authentication of food commodities. The food products targeted for falsification are either products of high commercial value or those produced in large quantities. For this reason, the present investigation is directed towards the characterization of coffee samples according to the geographical origin. The conducted research involves the development of a rapid headspace solid-phase microextraction (HS-SPME)–gas chromatography–time-of-flight mass spectrometry (GC–TOFMS) method that is utilized for the verification of geographical origin traceability of coffee samples. As opposed to the utilization of traditional univariate optimization methods, the current study employs the application of multivariate experimental designs to the optimization of extraction-influencing parameters. Hence, the two-level full factorial first-order design aided in the identification of two influential variables: extraction time and sample temperature. The optimum set of conditions for the two variables was 12min and 55°C, respectively, as directed by utilization of Doehlert matrix and response surface methodology. The high-throughput automated SPME procedure was completed by implementing a single divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) 50/30μm metal fiber with excellent durability properties ensuring the completion of overall sequence of coffee samples. The utilization of high-speed TOFMS instrument ensured the completion of one GC–MS run of a complex coffee sample in 7.9min and the complete list of benefits provided by ChromaTOF software including fully automated background subtraction, baseline correction, peak find and mass spectral deconvolution algorithms was exploited during the data evaluation procedure. The combination of the retention index (RI) system using C8–C40 alkanes and the mass spectral library search was utilized for the confirmation of analyte identity in the reference authentic Brazilian coffee sample. The semi-quantitative results were then submitted to statistical evaluation, namely principal component analysis (PCA) for the establishment of geographical origin discriminations. [Copyright &y& Elsevier]

Abstract: Tear fluid is a complex aqueous solution containing proteins, metabolites, electrolytes and lipids. This study uses Raman spectroscopy to analyse the composition of human tear fluid from three healthy volunteers. Two different methods are used to obtain Raman spectra from the 3μL tear samples: (i) solution-phase Raman spectroscopy, and (ii) drop coating deposition Raman spectroscopy (DCDRS). Tear samples were either basal fluid, or yawn reflex secreted fluid. Calibration of the solution technique with standard protein solutions (5–15mgmL−1) showed that this method could predict the protein concentration (cross-validation) with an error of less than 1mgmL−1. The Raman signals from the tear fluid were very weak but signals due to protein and urea were clearly observable in all samples. The drop coating deposition technique was shown to produce very high signal-to-noise spectra for relatively short acquisition times, and small sample volumes. Raman point mapping combined with principal components analysis showed that the protein, urea, bicarbonate and lipid could all be detected in the tear samples and that the distribution of these components was inhomogeneous. Their position within the drying pattern was shown to depend on their relative solubilities. The results of this study suggest that solution Raman measurements may be calibrated to give the total tear protein concentration and DCDRS could be used to give a fingerprint of the tear protein (and lipid) composition. [Copyright &y& Elsevier]

Abstract: A procedure is proposed for the determination of the total amount of sterols in brown algae Bifurcaria bifurcata, Cladostephus hirsitus, Dictyota dichotoma and Cystoseira sedoides, globally determined as fucosterol, which is the major sterol contained in these algae. The method involves the use of cholesterol as reference standard and a correction factor of 1.259±0.003, which represents the ratio between the slopes of calibration lines obtained from fucosterol and cholesterol. The method provides precise and accurate results for the IR analysis of real samples. [Copyright &y& Elsevier]

Abstract: Based on the characteristics of synchronous fluorescence spectroscopy (SFS), a new method with high sensitivity and selectivity was developed for rapid determination of silver ion with functional cadmium sulphide (CdS) nanoparticles as a fluorescence probe. When Δλ (λ em − λ ex)=215nm, maximum synchronous fluorescence is produced at 304nm. Under optimal conditions, functional cadmium sulphide displayed a calibration response for silver ion over a wide concentration range from 0.8×10−10 to 1.5×10−8 molL−1. The limit of detection was 0.4×10−10 molL−1 and the relative standard deviation of seven replicate measurements for the lowest concentration (0.8×10−10 molL−1) was 2.8%. Compared with several fluorescence methods, the proposed method had a wider linear range and improved the sensitivity. Furthermore, the concentration dependence of the synchronous fluorescence intensity is effectively described by a Langmuir-type binding isotherm. [Copyright &y& Elsevier]

Abstract: Preprocessing of raw near-infrared (NIR) spectral data is indispensable in multivariate calibration when the measured spectra are subject to significant noises, baselines and other undesirable factors. However, due to the lack of sufficient prior information and an incomplete knowledge of the raw data, NIR spectra preprocessing in multivariate calibration is still trial and error. How to select a proper method depends largely on both the nature of the data and the expertise and experience of the practitioners. This might limit the applications of multivariate calibration in many fields, where researchers are not very familiar with the characteristics of many preprocessing methods unique in chemometrics and have difficulties to select the most suitable methods. Another problem is many preprocessing methods, when used alone, might degrade the data in certain aspects or lose some useful information while improving certain qualities of the data. In order to tackle these problems, this paper proposes a new concept of data preprocessing, ensemble preprocessing method, where partial least squares (PLSs) models built on differently preprocessed data are combined by Monte Carlo cross validation (MCCV) stacked regression. Little or no prior information of the data and expertise are required. Moreover, fusion of complementary information obtained by different preprocessing methods often leads to a more stable and accurate calibration model. The investigation of two real data sets has demonstrated the advantages of the proposed method. [Copyright &y& Elsevier]

Abstract: The fiber weight per unit area in prepreg is an important factor to ensure the quality of the composite products. Near-infrared spectroscopy (NIRS) technology together with a noncontact reflectance sources has been applied for quality analysis of the fiber weight per unit area. The range of the unit area fiber weight was 13.39–14.14mgcm−2. The regression method was employed by partial least squares (PLS) and principal components regression (PCR). The calibration model was developed by 55 samples to determine the fiber weight per unit area in prepreg. The determination coefficient (R 2), root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP) were 0.82, 0.092, 0.099, respectively. The predicted values of the fiber weight per unit area in prepreg measured by NIRS technology were comparable to the values obtained by the reference method. For this technology, the noncontact reflectance sources focused directly on the sample with neither previous treatment nor manipulation. The results of the paired t-test revealed that there was no significant difference between the NIR method and the reference method. Besides, the prepreg could be analyzed one time within 20s without sample destruction. [Copyright &y& Elsevier]

Abstract: Structure generation and mass spectral classifiers have been incorporated into a new method to gain further information from low-resolution GC–MS spectra and subsequently assist in the identification of toxic compounds isolated using effect-directed fractionation. The method has been developed for the case where little analytical information other than the mass spectrum is available, common, for example, in effect-directed analysis (EDA), where further interpretation of the mass spectra is necessary to gain additional information about unknown peaks in the chromatogram. Structure generation from a molecular formula alone rapidly leads to enormous numbers of structures; hence reduction of these numbers is necessary to focus identification or confirmation efforts. The mass spectral classifiers and structure generation procedure in the program MOLGEN-MS was enhanced by including additional classifier information available from the NIST05 database and incorporation of post-generation ‘filtering criteria’. The presented method can reduce the number of possible structures matching a spectrum by several orders of magnitude, creating much more manageable data sets and increasing the chance of identification. Examples are presented to show how the method can be used to provide ‘lines of evidence’ for the identity of an unknown compound. This method is an alternative to library search of mass spectra and is especially valuable for unknowns where no clear library match is available. [Copyright &y& Elsevier]

Abstract: This study describes the application of confocal Raman microscopy to the detection and identification of drugs-of-abuse in situ on undyed natural synthetic fibres, and coloured textile specimens. Raman spectra were obtained from drug particles trapped between the fibres of the specimens. Pure samples of cocaine hydrochloride and N-methyl-3,4-methylenedioxy-amphetamine HCl (MDMA-HCl) were used in this study. Raman spectra were collected from drug particles of an average size in the range 5–15μm. Despite the presence of spectral bands arising from the natural and synthetic polymer and dyed textiles, the drugs could be identified by their characteristic Raman bands. If necessary, interfering bands could be successfully removed by spectral subtraction. Furthermore, Raman spectra were recorded from drug particles trapped between the fibres of highly fluorescent specimens. Interference from the fibres, including background fluorescence, was overcome by careful focusing of the confocal beam and the resulting spectra allow ready differentiation from interference from the fibres substrate bands. Spectra of several drugs-of-abuse on dyed and undyed clothing substrates were readily obtained within 3min with little or no sample preparation and with no alteration of the evidential material. [Copyright &y& Elsevier]

Abstract: Further consideration has been given to the reaction pathway of a model peroxyoxalate chemiluminescence system. Again utilising doubly labelled oxalyl chloride and anhydrous hydrogen peroxide, 2D EXSY 13C nuclear magnetic resonance (NMR) spectroscopy experiments allowed for the characterisation of unknown products and key intermediate species on the dark side of the peroxyoxalate chemiluminescence reaction. Exchange spectroscopy afforded elucidation of a scheme comprised of two distinct mechanistic pathways, one of which contributes to chemiluminescence. 13C NMR experiments carried out at varied reagent molar ratios demonstrated that excess amounts of hydrogen peroxide favoured formation of 1,2-dioxetanedione: the intermediate that, upon thermolysis, has been long thought to interact with a fluorophore to produce light. [Copyright &y& Elsevier]

Abstract: This article presents a method employing stir bar sorptive extraction (SBSE) with in situ derivatization, in combination with either thermal or liquid desorption on-line coupled to gas chromatography–mass spectrometry for the analysis of fluoxetine in plasma samples. Ethyl chloroformate was employed as derivatizing agent producing symmetrical peaks. Parameters such as solvent polarity, time for analyte desorption, and extraction time, were evaluated. During the validation process, the developed method presented specificity, linearity (R 2 >0.99), precision (R.S.D.<15%), and limits of quantification (LOQ) of 30 and 1.37pgmL−1, when liquid and thermal desorption were employed, respectively. This simple and highly sensitive method showed to be adequate for the measurement of fluoxetine in typical and trace concentration levels. [Copyright &y& Elsevier]

Abstract: A method for the separation of tetrachloroplatinate PtCl4 2−, and hexachloroplatinate PtCl6 2−, by solid-phase extraction, using a Dowex 1×10 anion exchange resin is proposed. The sequential elution and separation of PtCl4 2−, and PtCl6 2− is achieved using selective complexing agents. The eluates, containing Pt(II) and Pt(IV) were analyzed by inductively coupled plasma–atomic emission spectroscopy (ICP–AES). Recoveries of 102% for PtCl4 2− and 94% for PtCl6 2− and detection limit of 15ngg−1 were achieved. Using this method determination of Pt(II) and Pt(IV) in soil samples, spiked with different platinum species was performed. The comparison with GFAAS determination showed a very good agreement. [Copyright &y& Elsevier]

Abstract: The automated and robust identification of metabolites in a complex biological sample remains one of the greatest challenges in metabolomics. In our experiments, HSQC carbon–proton correlation NMR data with a model that takes intensity information into account improves upon the identification of metabolites that was achieved using COSY proton–proton correlation NMR data with the binary model of [Y. Xi, J.S. de Ropp, M.R. Viant, D.L. Woodruff, P. Yu, Metabolomics, 2 (2006) 221–233]. In addition, using intensity information results in easier-to-interpret “grey areas” for cases where it is not clear if the compound might be present. We report on highly successful experiments that identify compounds in chemically defined mixtures as well as in biological samples, and compare our two-dimensional HSQC analyses against quantification of metabolites in the corresponding one-dimensional proton NMR spectra. We show that our approach successfully employs a fully automated algorithm for identifying the presence or absence of predefined compounds (held within a library) in biological HSQC spectra, and in addition calculates upper bounds on the compound intensities. [Copyright &y& Elsevier]

Abstract: Multivariate curve resolution coupled to alternating least-squares (MCR-ALS) has been employed to model kinetic-spectroscopic second-order data, with focus on the achievement of the important second-order advantage, under conditions of extreme spectral overlapping among sample components. A series of simulated examples shows that MCR-ALS can conveniently handle the studied analytical problem unlike other second-order multivariate calibration algorithms, provided matrix augmentation is implemented in the spectral mode instead of in the usual kinetic mode. The approach has also been applied to three experimental examples, which involve the determination of: (1) the antiparkinsonian carbidopa (analyte) in the presence of levodopa as a potential interferent, both reacting with cerium (IV) to produce the fluorescent species cerium (III) with different kinetics; (2) Fe(II) (analyte) in the presence of the interferent Zn(II), both catalyzing the oxidation of methyl orange with potassium bromate; and (3) tartrazine (analyte) in the presence of the interferent brilliant blue, both oxidized with potassium bromate, with the interferent leading to a product with an absorption spectrum very similar to tartrazine. The results indicate good analytical performance towards the analytes, despite the intense spectral overlapping and the presence of unexpected constituents in the test samples. [Copyright &y& Elsevier]

Abstract: A new method based on accelerated solvent extraction (ASE) followed by ultra performance liquid chromatography (UPLC) analysis has been developed for the identification and quantification of major alkaloids in extracts of Coptis chinensis Franch. The UPLC system consisted of a dual detection system of photodiode array detector (PDA) and positive ion electrospray ionization-tandem mass spectrometry (ESI-MS/MS) in sequential configuration. The operational parameters of ASE including extraction solvent, extraction temperature, static extraction time and extraction cycles were optimized. UPLC analysis was performed on an ACQUITY UPLC BEH C18 column eluted by a mobile phase of acetonitrile spiked with a buffer solution consisting of 0.50% acetic acid and 20mmolL−1 ammonium acetate. A tandem quadrupole spectrometer operating in either full scan mode or in MS/MS mode for multiple reaction monitoring (MRM) was used for the identification and quantitative analysis of eight major alkaloids in C. chinensis Franch extracts. The samples were also analyzed on a high-performance liquid chromatography–electrospray ionization-time-of-flight mass spectrometry (HPLC-ESI-TOF-MS) system to confirm the identification results. Three of the eight major alkaloids, berberine, palmatine and jatrorrhizine were quantified by UPLC–PDA and UPLC–MS/MS. The results indicated that both UPLC–PDA and UPLC–MS/MS methods were simple, sensitive and reliable for the determination of alkaloids in C. chinensis Franch. Seven Huanglian samples from different locations were analyzed using the established methods. UPLC fingerprints based on the distribution of the eight major alkaloids can serve as a rapid and reliable method for the authentication and quality evaluation of traditional Chinese medicine (TCM) herbs. [Copyright &y& Elsevier]

Abstract: A label-free aptasensor for platelet-derived growth factor (PDGF) protein is reported. The aptasensor uses mixed self-assembled monolayers (SAMs) composed of a thiol-modified PDGF binding aptamer and 6-mercaptohexanol (MCH) on a gold electrode. The SAMs were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) before and after binding of the protein using [Fe(CN)6]3−/4−, a redox marker ion as an indicator for the formation of a protein–aptamer complex. The CVs at the PDGF modified electrode showed significant differences, such as changes in the peak currents and peak-to-peak separation, before and after binding of the target protein. The EIS spectra, in the form of Nyquist plots, were analyzed with a Randles circuit while the electron transfer resistance R ct was used to monitor the binding of the target protein. The results showed that, without any modification to the aptamer, the target protein can be recognized effectively at the PDGF binding aptamer SAMs at the electrode surface. Control experiments using non-binding oligonucleotides assembled at the electrode surfaces also confirmed the results and showed that there was no formation of an aptamer–protein complex. The DPV signal at the aptamer functionalized electrode showed a linearly decreased marker ion peak current in a protein concentrations range of 1–40nM. Thus, label-free detection of PDGF protein at an aptamer modified electrode has been demonstrated. [Copyright &y& Elsevier]

Abstract: This work presents a new and simple strategy for solving matrix effects using combination of H-point curve isolation method (HPCIM) and H-point standard addition method (HPSAM). The method uses spectrophotometric multivariate calibration data constructed by successive standard addition of an analyte into an unknown matrix. By successive standard addition of the analyte, the concentrations of remaining components (interferents) remain constant and therefore give constant cumulative spectrum for interferents in the unknown mixture. The proposed method firstly extracts such spectrum using H-point curve isolation method and then applies the obtained cumulative interferents spectrum for determination of analyte by H-point standard addition method. In order to evaluate the applicability of the method a simulated as well as several experimental data sets were tested. The method was then applied to the determination of paracetamol in pharmaceutical tablets and copper in urine samples and in a copper alloy. [Copyright &y& Elsevier]

Abstract: Most traditional chromatographic separation criteria or response functions are defined on chromatograms recorded by single-channel detectors, e.g. a spectrometer measuring the absorbance at a single wavelength or a thermal conductivity detector. When the peaks are seriously overlapped, usually there is a lack of the information concerning the total number of chemical components, overlap degree of the peaks and peak purity. Such information characterizes some crucial aspects of separation process and lack of it will lead to an inaccurate and misleading evaluation of separation quality as well as some computational ambiguity for many traditional response functions. In contrast, hyphenated chromatography–(multi-channel) spectroscopy instruments together with chemometric methods will largely increase the information content available in chromatographic detection. Such information, if properly used, can cast a new light on evaluation of chromatographic separation quality. The main objective of this article is to review chemometric methods devoted to estimation of the number of chemical components, determination of elution sequence and assessment of peak purity. Some newly defined response functions or separation criteria based on extracted information by chemometric methods are also introduced. The methods reviewed are limited to those for treating two-way data obtained by hyphenation of high-performance liquid chromatography with multi-channel detectors. We prefer to provide a comprehensive view of such methods rather than present a full list of all the methods developed. Further details of some important methods are touched upon in favor of employment and understanding of them by researchers not very familiar with chemometrics. [Copyright &y& Elsevier]

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]