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Abstract Protein-surfactant interactions have been explored for decades owing to their widespread application in the pharmaceutical, food, and cosmetics industries and their importance to biochemical systems. However, they require further study owing to their compositional complexity and the innate limitations of current analytical approaches. In this review, we briefly introduce a series of individual approaches used for the qualitative and quantitative investigation of protein-surfactant interactions, including absorbance- or emission-based spectroscopy, scattering-based spectroscopy, mass spectrometry, calorimetry, computation and microscopy. More importantly, we then compare and evaluate various combinations of these approaches and provide comprehensive critical assessments and comments regarding their application to the advanced study of protein-surfactant interactions at the molecular level. Graphical abstract Image 1 Highlights • Investigation of protein-surfactant interactions are important in chemistry. • Individual analytical approaches have limitations. • Overview of individual analytical approaches: cons and pros. • Combinations of current individual approaches to overcome their limitations. • Assessment of the efficiency and validity of combinations of analytical approaches. [ABSTRACT FROM AUTHOR]

Abstract The prospect of developing new bio-based products from lignin partially depends on the development of effective analytical techniques to characterize the end products from lignin degradation experiments. To date, the most utilized mass spectrometric technique for characterizing lignin oligomers has been negative ion mass spectrometry. Positive ion mass spectrometry remains a relatively unexplored approach for lignin sequencing. Here we report on the sequencing of lignin oligomers using lithium cationization positive ion electrospray followed by higher-energy collisional dissociation (HCD) tandem mass spectrometry on a high-resolution accurate-mass Orbitrap mass spectrometer. Thirteen synthetic lignin model oligomers containing β-O-4 and 4-O-α linkages were analyzed and sequenced based on their HCD tandem mass spectrometry fragmentation patterns. Proposed sequence-specific fragmentation pathways are provided. The method presented in this study provides a potential application of lithium cationization tandem mass spectrometry for the analysis of lignin degradation products. Graphical abstract Image 1 Highlights • Lithium forms stable adducts with lignin oligomers generating cations for positive ion mass spectrometry. • Tandem mass spectrometry of lithium-lignin precursors produces lithiated fragment ions. • The monolignol sequence of an oligomer can be determined from the tandem mass spectrum. • Lithium cationization provides an alternative means of lignin oligomer ionization that retains sequencing features. [ABSTRACT FROM AUTHOR]

Abstract In this review, an assessment of non-separative methods based on mass spectrometry used to analyse volatile organic compounds in the field of bioanalysis is performed. The use of non-separative methods based on mass spectrometry has been established as an attractive option for analysing compounds. These instrumental configurations are suitable for biomedical applications because of their versatility, rapid output of results, and the wide range of volatile organic compounds that can be determined. Here, techniques such as headspace sampling coupled to mass spectrometry, membrane introduction mass spectrometry, selected ion flow tube mass spectrometry, proton transfer reaction mass spectrometry, secondary electrospray ionization mass spectrometry and ion mobility mass spectrometry, are evaluated. Samples involving non-invasive methods of collection, such as urine, saliva, breath and sweat, are mainly considered. To the best of our knowledge, a comprehensive review of all the non-separative instrumental configurations applied to the analysis of gaseous samples from all matrices non-invasively collected has not yet been carried out. The assessment of non-separative techniques for the analysis of these type of samples can be considered a key issue for future clinical applications, as they allow real-time sample analysis, without patient suffering. Any contribution to the early diagnosis of disease can be considered a priority for the scientific community. Therefore, the identification and determination of volatile organic compounds related to particular diseases has become an important field or research. Graphical abstract Image 1 Highlights • Advantages and disadvantages of using different non-separative methods in bioanalysis are presented. • Potential of VOCs determination using methods based on mass spectrometry are discussed. • The use of samples involving non-invasive sample collection is a key issue for clinical applications. [ABSTRACT FROM AUTHOR]

Mass spectrometry imaging (MSI) is a technique that can map analyte spatial distribution directly onto a tissue section. This enables the spatial correlation of molecular entities with a tissue morphology to be investigated. Analyte annotation in MSI is intrinsically linked to the mass accuracy of the data. Mass accuracy and analyte identification are determined by such factors as the experimental set up and the data processing workflow. We present an MSI data processing workflow that uses a label-free approach to compensate for mass shifts. The algorithms developed were designed to perform efficiently even for datasets much larger than computer's memory. Herein, we present the application of the developed processing workflow to a dataset with more than 13.000 pixels and ∼50.000 mass channels. We assessed the overall mass accuracy in the range m/z 400 to 1200 using silver and gold sputtered nanolayers. With our novel processing workflow we were able to obtain mass errors as low as 5 ppm using a TOF instrument. [ABSTRACT FROM AUTHOR]

Peak broadening in ion mobility (IM) is a relatively predictable process and abnormally broad peaks can be indicative of the presence of unresolved species. Here, we introduce a new ion mobility peak fitting (IM_FIT) software package for automated and systematic determination of traveling wave ion mobility (TWIM) unresolved species. To identify IM unresolved species, the IM_FIT software generates a trend line by plotting ions' mobility peak widths as a function of their arrival times. Utilizing user-defined thresholds, IM_FIT allows for automated and rapid detection of ions that deviate from the peak width trend line. To demonstrate the advantages of IM_FIT for automated detection of IM unresolved species, IM-mass spectrometry (IM-MS) data from a sample mixture containing polypropylene glycol and multiple peptides were analyzed. A total of 14 out of the 34 observed singly-charged IM peaks above 5% relative abundance ( i.e., signal-to-noise ratios above ∼200) were tagged as potentially co-eluting ions by IM_FIT. Subsequently, the 14 IM peaks tagged as potentially unresolved (presumably, peaks corresponding to co-eluting compounds), were further analyzed by automated IM deconvolution (AIMD), liquid chromatography-IM-MS (LC-IM-MS), and/or ultra-high resolution mass spectrometry. Using the aforementioned techniques, more than 85% of the tagged IM peaks (12 out of 14) were confirmed to contain co-eluting ions. As an additional new finding, IM_FIT facilitated the discovery of an unexpected sequence-scrambled y-type fragment ion. [ABSTRACT FROM AUTHOR]

A new side-reaction occurring during divergent synthesis of PAMAM dendrimers (generations G 0 –G 2 ) was revealed by mass spectrometric detection of defective molecules with a net gain of a single carbon atom as compared to expected compounds. Combining MS/MS experiments performed on different electrosprayed precursor ions (protonated molecules and lithiated adducts) with NMR analyses allowed the origin of these by-products to be elucidated. Modification of one ethylenediamine end-group of perfect dendrimers into a cyclic imidazolidine moiety was induced by formaldehyde present at trace level in the methanol solvent used as the synthesis medium. Dendrimers studied here were purposely constructed from a triethanolamine core to make them more flexible, as compared to NH 3 - or ethylenediamine-core PAMAM, and hence improve their interaction with DNA. Occurrence of this side-reaction would be favored by the particular flexibility of the dendrimer branches. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ambient mass spectrometry allows direct analysis of polymers and their additives. [•] Ambient sampling methods offer many advantages over classical mass spectrometry. [•] Capabilities, limitations, and future perspectives of each method are discussed. [Copyright &y& Elsevier]

Quantitative mass spectrometry analysis for multi-component gas phase reaction processes is a typical multi-input and multi-output (MIMO) nonlinear problem. Conventional calibration and analytical methods that are based on the common hypothesis of linearity of the detected signal and gas parameters, could result in misjudgment of the reaction mechanism and inaccuracy in the determination of the reaction kinetics. In the present work, theoretical derivations based on equivalent characteristic spectrum analysis (ECSA®), discrete mode experiments and continuous mode experiments were performed, and the nonlinearity of mass spectrometry was confirmed. It is only possible to determine the physical parameters such as flow rate and/or concentrations of gases by properly handling the nonlinearity of mass spectrometry. In such case comprehensive reaction mechanisms and even the kinetics of the process can be accurately characterized. Well-handled nonlinear mass spectrometry analysis ensures a reliable and highly accurate identification for the multi-component gas phase reaction processes, and ensures high signal-to-noise ratio for detecting the small-flow gases at a wide range of carrier gas flow. [Display omitted] • The MS nonlinearity between MI and MO signals is found and expounded firstly. • The MS nonlinearity is confirmed through theoretical derivation and experiments. • Taking the nonlinearity ensures the MS reliability, and high signal-to-noise ratio. • Using ECSA® it was possible to well interpret the nonlinearity. [ABSTRACT FROM AUTHOR]

Highlights: [•] MALDI mass spectrometry used for shrimp species identification. [•] Peak database constructed from six commercially important shrimp species. [•] 97% of samples were correctly identified at the species level. [ABSTRACT FROM AUTHOR]

Abstract: Many complex natural or synthetic products are analysed either by the GC–MS (gas chromatography–mass spectrometry) or HPLC–DAD (high performance liquid chromatography–diode-array detector) technique, each of which produces a one-dimensional fingerprint for a given sample. This may be used for classification of different batches of a product. GC–MS and HPLC–DAD analyses of complex, similar substances represented by the three common types of the TCM (traditional Chinese medicine), Rhizoma Curcumae were analysed in the form of one- and two-dimensional matrices firstly with the use of PCA (Principal component analysis), which showed a reasonable separation of the samples for each technique. However, the separation patterns were rather different for each analytical method, and PCA of the combined data matrix showed improved discrimination of the three types of object; close associations between the GC–MS and HPLC–DAD variables were observed. LDA (linear discriminant analysis), BP-ANN (back propagation-artificial neural networks) and LS-SVM (least squares-support vector machine) chemometrics methods were then applied to classify the training and prediction sets. For one-dimensional matrices, all training models indicated that several samples would be misclassified; the same was observed for each prediction set. However, by comparison, in the analysis of the combined matrix, all models gave 100% classification with the training set, and the LS-SVM calibration also produced a 100% result for prediction, with the BP-ANN calibration closely behind. This has important implications for comparing complex substances such as the TCMs because clearly the one-dimensional data matrices alone produce inferior results for training and prediction as compared to the combined data matrix models. Thus, product samples may be misclassified with the use of the one-dimensional data because of insufficient information. [Copyright &y& Elsevier]

Abstract: A rapid, but sensitive and selective method for simultaneous screening and quantification of toxic pyrrolizidine alkaloids (PAs) by ultra performance liquid-chromatography (UPLC) coupled with tandem mass spectrometry (MS/MS) on a tandem quadrupole mass spectrometer (TQ-MS) is described. This was accomplished by incorporating the precursor ion scan (PIS) acquisition and multiple reaction monitoring (MRM) acquisition in the same UPLC–MS/MS run. Notably, the developed PIS approach for detecting two pairs of characteristic product ions at m/z 120/138 or 168/150, allowed specific identification of toxic retronecine and otonecine types PAs. This PIS method is highly sensitive with over 10-fold sensitivity improvement upon previously published LC–MS method. Moreover, this new approach is suitable for high sample throughput and was applied to the screening and quantifying toxic PAs in 22 samples collected from seven Parasenecio species and four Senecio species. In addition, coupling the MRM with PIS approach generated quantitative results equivalent to those obtained by conventional MRM-only approach. This coupled MRM with PIS approach could provide both qualitative and quantitative results without the need of repetitive analyses. [ABSTRACT FROM AUTHOR]

Abstract: The solubility and molar absorptivity of trans- and cis-resveratrol isomers in aqueous solvents are poorly described. This study aimed to develop and describe a new simple method for the determination of trans- and cis-resveratrol concentrations in aqueous solutions. Up to 300μM trans-resveratrol was dissolved in water by sonication for 2h. Cis-resveratrol was obtained by exposing a 100-μM trans-resveratrol aqueous solution to sunlight for 8h, followed by HPLC separation and analysis by mass spectrometry (resveratrol oxidation products were absent). Accurate values for UV absorbance in water were , ɛ 286nm =23400M−1 cm−1 for trans-resveratrol and , ɛ 304nm =9515M−1 cm−1 for cis-resveratrol. These values allowed us to propose formulae to assess the trans-/cis-resveratrol ratio in water, using a simple and reliable UV–vis spectrophotometric method. Statistical analysis revealed no significant difference between our UV method and the commonly used HPLC method. All these data are transferable to 150mM NaCl and 10mM phosphate buffer solutions, which could be particularly useful for cell culture, ex vivo and in vivo studies. [Copyright &y& Elsevier]

Abstract: In the present study the qualitative and quantitative determination of diterpenoids in commercial distilled gin was carried out. This widely consumed juniper-based spirit is aromatized using Juniper (Juniperus communis) berries. Although juniper reportedly contains several diterpenic compounds, no studies have addressed the diterpenic composition of juniper-based spirits or beverages. With this objective, here we followed a multilevel factorial experimental design to optimize a direct immersion-solid phase microextraction (DI-SPME) method coupled to gas chromatography/mass spectrometry and analyzed eight commercial brands of gin. With total concentrations ranging from 10 to 190μgL−1, manool, manoyl oxide and trans-totarol were the most abundant diterpenoids of the 10 identified or tentatively identified at variable but not negligible concentrations in the distilled gin samples. The diterpenic composition allowed the brands to be differentiated. This indicates that these compounds contribute to the sensory characteristics of the distinct commercial brands, thus guaranteeing the authenticity and consequently the quality of the product. [Copyright &y& Elsevier]

Abstract: A new method using microwave digestion combined with inductively coupled plasma-mass spectrometry (ICP-MS) was studied to analyze the elemental composition of a variety of komatiites samples. Microwave digestion consisted in two-stage heating and pressurizing acid treatments for maximum dissolution of the samples. We report here different quality control measurements (external and internal calibration, monitoring of reference materials) which involve standard deviation calculations and recovery examinations in order to test the precision and accuracy of the analytical procedure. Data for 17 elements (Na, P, K, T, V Cr, Mn, Co, Ni, Cu, Zn, Zr, Pb, Al, F, Ca and Mg) in eight komatiite samples and two USGS basalt reference samples (BCR-2 and BHVO-2) are presented. We evaluate our new digestion and instrumental procedure. The element concentration obtained for BCR-2 and BHVO-2 agreed well with the certified values, the relative standard deviations were lower than 5% and recoveries were good. Our analytical results demonstrate that it reproduces accurately the concentrations of minor and trace elements in komatiites. The ease of digestion of the samples and the speed (less than 12h) to digest the komatiite material makes this technique an efficient method to be used easily and routinely for preparing and analyzing komatiites samples for multiple elements determination. [Copyright &y& Elsevier]

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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: Laser desorption ionization mass spectrometry (LDI-MS) was performed on selected azaborolinyl zirconium complexes in order to study them as potential industrial polyolefin catalyst compounds. UV–vis absorption data in conjunction with negative and positive ionization analyses revealed the mechanistic workings of the compounds when such single-site catalysts function in olefin polymerization reactions. Results presented highlight the many benefits of LDI-MS in the study of single-site zirconium azaborolinyl catalyst complexes including minimal sample preparation, the absence of matrix/pH/solvation effects, a lower degree of fragmentation as compared to EI ionization, high sensitivity and the ability to observe interesting and unique gas phase chemistry including ring slippage, and distinctive metal coordination and oxidation states. The extreme lability of the chlorine ligands was apparent, as well as the reactivity of the resulting zirconium metal center as demonstrated by the appearance of numerous similar four-coordinate zirconium species along with di-chloro-bridged dimers. LDI-MS permits analysis at low molecular weights, improving spectral characterization of these zirconium complexes. [Copyright &y& Elsevier]

Abstract: A rapid analytical method for quantifying 17 ginsenosides in rat urine by ultra performance liquid chromatography (UPLC) coupled to electrospray ionization mass spectrometry (ESI-MS) is described. All analytes were extracted by solid-phase extraction optimized to obtain good recovery and quantified using digoxin as an internal standard. ESI-MS was optimized for different cone voltages at positive ionization mode to allow simultaneous analysis of all analytes in a relatively short time. Qualitative methodological considerations, including the linear range, precision, limit of quantification, limit of detection, recovery and sensitivity are also provided. [Copyright &y& Elsevier]

Abstract: The use of gestagens in animal fattening is prohibited within the European Union. Recently, the use of spectrometric methods for the detection and confirmation of banned substances was made obligatory. Therefore, conventional high-performance liquid chromatographic (HPLC) methods have been superseded. It has been possible to couple a previously described HPLC method for the determination of acetyl-gestagens in kidney fat to tandem mass spectrometry (LC-MS/MS). The decision limits CCα and the detection capability CCβ are found to be below the minimum required performance limit (MRPL) established for medroxyprogesterone acetate (MPA) at 1μgkg−1. The calculated values for CCα are as follows: megestrol acetate (MGA)—0.15μgkg−1, melengesterol acetate (MLA)—0.15μgkg−1, chlormadinone acetate (CMA)—0.37μgkg−1 and for medroxyprogesterone acetate (MPA)—0.24μgkg−1. The CCβ values for these compounds have been determined as 0.19, 0.19, 0.47 and 0.32μgkg−1, respectively. [Copyright &y& Elsevier]

Abstract: In animal production, it is consolidated the synthesis and the illegal use of growth promoters of new generation, able to skip routine screening and confirmatory analysis. In this work it is reported the nuclear magnetic resonance (NMR) and the mass spectrometry identification of a probable new adrenergic drug found in a feed premix. The substance was selectively purified on alpha 1 acid glycoprotein affinity columns; then its structure was first achieved by recording the 13C NMR spectrum that gave the total number of carbons of the molecule, successively sorted by DEPT experiments into quaternary, CH, CH2, and CH3 groups. However, the complete assignments of all resonances were derived from the bi-dimensional analysis and the crucial indications from the 1H–13C reverse experiments. Further characterisation was performed by atmospheric pressure chemical ionisation both in positive and negative ion mode, matching the molecular ion and the fragmentation pattern with those of most recently described new adrenergic agonists. After the loss of a ter-butylic group, the structure shows an internal symmetry along with the presence of Chlorine clusters. The proposed formula of the compound, the 8,8′-diamino-9,9′-dichloro-1-terbutyl-1,1′,4,4-tetrahydro-5H,5′H-2,2′-bi-1-benzazepine-5,5′-dione, partially resembles that of Zilpaterol for the presence of a heterocyclic ring; Further work is in progress to characterise the structure–activity relationship. [Copyright &y& Elsevier]

Abstract: This study deals with an automated data analysis strategy to pinpoint potential unknown compounds in full scan mass spectrometry (MS) experiments. Three examples of an untargeted metabolomics approach to contaminant analysis are given. By comparing a plant-oil based hormone cocktail to 90 plant oil samples ca. 25 compounds specific to the hormone cocktail could be detected. Five of these compounds were confirmed as steroid hormones. A comparison of a drink water sample from a farm to distillated water showed the presence of contaminants specific to this drink water sample. A grass sample, which was known to give a false positive result in a DR-CALUX bioassay, was unexpectedly shown to contain an abnormal level of chrysene, which was obviously not eliminated during clean-up. [Copyright &y& Elsevier]

Abstract: The applicability of the headspace coupled to mass spectrometry for evaluation of the sensory quality of virgin olive oil samples is presented. The volatiles of the oil are directly transferred from the sample vial to the detector without chromatographic separation. The mass spectrum obtained can be considered as a fingerprint of the oil sample and can be used for classification purposes. After a training step with samples previously qualified following the official method, a classification model was created using the supervised technique soft independent modeling of class analogy (SIMCA). Eight negative (rancid, winey-vinegary, muddy sediment, hay-wood, vegetable water, earthy, fusty and musty-humidity) and three principal positive attributes (fruity, bitter and pungent) have been included in this study. With them, a classification model consisting of two main classes (extra- and lampante-virgin olive oil) was constructed. In addition, the unsupervised technique cluster analysis permited the discrimination among oils with different negative attributes. The proposed procedure has been applied to the classification of commercial samples (as extra- or lampante-virgin olive oils) and the results were compared with those provided by the expert''s panel with acceptable correlation. [Copyright &y& Elsevier]

Abstract: Hemoglobin-based oxygen carriers (HBOCs) are blood substitutes based on hemoglobin of either bovine or human origin and they can potentially be misused in elite sports to improve endurance performance. Recently, three methods have been proposed in doping control analysis to allow HBOCs screening and identification by application of electrophoresis, size-exclusion chromatography coupled with HPLC and LC coupled with tandem mass spectrometry (LC/MSMS). In view of the Athens 2004 Olympic Games, modifications were introduced in order to increase the specificity of these methods. The sample preparation protocols of the electrophoretic and SEC–HPLC methods were modified with the introduction of sequential ultra filtration steps to remove all heme containing material below 100kDa, thus leaving only HBOCs material for analysis. Furthermore, a modification of the LC/MSMS methodology was introduced to allow full scan MS–MS spectra of peptide segments arising from the tryptic digestion of bovine HBOCs. These relatively simple methodological modifications have major impact, as far as time and cost effectiveness is concerned in doping control procedures, because they provide a useful tool in order to identify which suspect samples from the initial visual screening are due to hemolysis and exclude them from further analysis. [Copyright &y& Elsevier]

Abstract: Accurate bacterial identification is important in diagnosing disease and in microbial forensics. Coxiella burnetii, a highly infective microorganism causative of the human disease Q fever, is now considered a U.S. category B potential bioterrorism agent. We report here an approach for the confirmatory identification of C. burnetii at the strain level which involves the combined use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and supervised pattern recognition via Partial Least Squares-Discriminant Analysis (PLS-DA). C. burnetii isolates investigated in this study included the following prototype strains from different geographical and/or historical origins and with different antigenic properties: Nine Mile I, Australian QD, M44, KAV, PAV, Henzerling, and Ohio. After culture and purification following standard protocols, linear MALDI-TOF mass spectra of pure bacterial cultures were acquired in positive ion mode. Mass spectral data were normalized, baseline-corrected, denoised, binarized and modeled by PLS-DA under crossvalidation conditions. Robustness with respect to uncontrolled variations in the sample preparation and MALDI analysis protocol was assessed by repeating the experiment on five different days spanning a period of 6 months. The method was validated by the prediction of unknown C. burnetii samples in an independent test set with 100% sensitivity and specificity for five out of six strain classes. [Copyright &y& Elsevier]

Abstract: The aim of this study was to evaluate the performance characteristics of the recently developed super elastic solid-phase microextraction (SPME) fibers. The fiber needle, plunger and fiber core are manufactured with a special type of flexible alloy that exhibits excellent shape memory and tensile strength. This material makes the assemblies more robust, permitting several hundreds of analyses in a sequence, which is one of the ways to improve the robustness and sample throughput of automated SPME methods. The design and size of the needle utilized in the new fiber assemblies is discussed here, as well as the use of a septum-free injector replacement and a low-volume direct injection glass liner placed in the GC inlet. Deionized water and pump oil samples spiked with target volatile compounds (McReynold''s probes and toluene) were used for the purposes of the presented study. A fully automated SPME sample preparation technique was combined with the GC–TOFMS system for the chromatographic separation and identification/quantification of the target analytes. [Copyright &y& Elsevier]

Abstract: The present article aims to develop a new extraction procedure to improve the determination of quinolones in chicken muscle. This new determination method was validated using liquid chromatography–ultraviolet detection (LC–UV) and liquid chromatography–mass spectrometry detection (LC–MS), which has special bearing on stability studies. The results obtained by using the method were compared with the results obtained with a previous methodology. The new extraction procedure presents a sensitivity low enough to determine concentration of these drugs below the permissible maximum residue limits (MRL) in chicken muscle and is less time consuming than the previous methodology. [Copyright &y& Elsevier]

Abstract: The Raman and mass spectra of 1,4-diphenylbuta-1,3-diene and several of its monomethyl and dimethyl homologues are reported and discussed, with a view to developing a spectroscopic protocol for detecting the presence and position of a methyl group in these compounds. Raman spectroscopy and mass spectrometry are shown to provide complementary information, by which the four available monomethyl homologues may be readily distinguished from each other and 1,4-diphenylbuta-1,3-diene itself. The utility of these 1,4-diarylbutadienes as model compounds for carotenoids and related materials, which may serve as indicators of extinct or extant extraterrestrial life, is considered. [Copyright &y& Elsevier]

Abstract: A quadrupole inductively coupled plasma mass spectrometer (Q-ICP-MS) equipped with a dynamic reaction cell (DRC) and coupled with a desolvating nebulization system (APEX-IR) was employed to determine 17 elements (Al, As, Ba, Cd, Co, Cr, Li, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, V, and Zr) in blood samples. Ammonia (for Al, Cr, Mn, and V) and O2 (for As and Se) were used as reacting gases. Selection of the best flow rate of the gases and optimization of the quadrupole dynamic bandpass tuning parameter (RPq) were carried out, using digested blood diluted 1+9 with deionized water and spiked with 1μgL−1 of Al, Cr, Mn, V and 5μgL−1 of As and Se. Detection limits were determined in digested blood using the 3σ criterion. The desolvating system allowed a sufficient sensitivity to be achieved to determine elements at levels of ngL−1 without detriment of signal stability. The accuracy of the method was tested with the whole blood certified reference material (CRM), certified for Al, As, Cd, Co, Cr, Mn, Mo, Ni, Pb, Sb, Se, and V, and with indicative values for Ba, Li, Sn, Sr, and Zr. The addition calibration approach was chosen for analysis. In order to confirm the DRC data, samples were also analyzed by means of sector field inductively coupled plasma mass spectrometry (SF-ICP-MS), operating in medium (m/Δm =4000) and high (m/Δm =10,000) resolution mode and achieving a good agreement between the two techniques. [Copyright &y& Elsevier]

Abstract: We present an analytical procedure based on laser ablation mass spectrometry (LAMS) in order to detect and quantify arsenic and calcium in soil samples and we analyze the diverse factors that influence the precision of LAMS, such as laser fluence and matrix effect. The results indicate that a Zn matrix is a good choice for the analysis of those metals in soil samples. This work also provides a method for the direct determination of As in soil samples whose concentrations are lower than 100ppm with a 70ppm minimum detection limits (MDL). [Copyright &y& Elsevier]

Abstract: Wax sculptures contain several materials from both organic and inorganic nature. These works of art are particularly fragile. Determining their chemical composition is thus of prime importance for their preservation. The identification of the recipes of waxy pastes used through time also provides valuable information in the field of art history. The aim of the present research was to develop a convenient analytical strategy, as non-invasive as possible, that allows to identify the wide range of materials involved in wax sculptures. A multi-step analytical methodology, based on the use of complementary techniques, either non- or micro-destructive, was elaborated. X-ray fluorescence and micro-Raman spectroscopy were used in a non-invasive way to identify inorganic pigments, opacifiers and extenders. The combination of structural and separative techniques, namely infrared spectroscopy, direct inlet electron ionisation mass spectrometry and high temperature gas chromatography, was shown to be appropriate for unravelling the precise composition of the organic substances. A micro-chemical test was also performed for the detection of starch. From this study it has been possible to elucidate the composition of the waxy pastes used by three different sculptors at the end of the 19th century. Complex and elaborated recipes, in which a large range of natural substances were combined, were highlighted. [Copyright &y& Elsevier]

Abstract: Per-O-methylation of carbohydrates is an important sample preparation step in structural analysis of complex carbohydrates, which has generated considerable interest as shown by thousands of citations in the last 10 years. This article provides a critical overview of the per-O-methylation methods applied for structural analysis of carbohydrates by mass spectrometry. The understanding of the O-methylation mechanism can help the researchers to apply the adequate O-methylation method and can generate new ideas in the effort of improving this reaction. The per-O-methylation of carbohydrates is relied upon stepwise reactions. The parameters that affect the reaction are discussed for the most important methods and are critically commented for each reaction step. The limits of each method are emphasized. The improvements of the per-O-methylation reaction are described in detail with their advantages and disadvantages and some illustrative examples are given. The methods that give complete O-methylation in non-hazardous conditions with high yields within minutes at room temperature with a very low amount of side-products are especially highlighted. [Copyright &y& Elsevier]

Abstract: Closed-vessel microwave digestion of nine standard reference plant materials (NIST, BCR, IAEA) and a laboratory standard of plant material with different Si contents assisted by HNO3 +H2O2 (procedure A), HNO3 +H2O2 +HF+H3BO3 (procedure B) and HNO3 +H2O2 +HBF4 (procedure C) were used to determine the recovery of 36 elements by ICP-MS: Ag, Al, As, Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, Ge, In, La, Li, Mn, Mo, Nd, Ni, Pb, Pr, Rb, Sb, Se, Sn, Sr, Th, Tl, U, V, W, Y, Zn. Additions of HF+H3BO3 and HBF4 in procedures B and C exceeded by 10% (B1, C1) and 100% (B2, C2) the equivalent concentrations of Si in the samples determined by ICP-OES. Most recoveries of certified elements (e.g., Al*, Cu, Mo*, Rb*, Sb*, Th) decreased significantly (* p ≤0.05) with increasing Si content in plant reference materials digested by procedure A, while the recoveries from procedures B and C decreased insignificantly only for Mo and Sb. Digestions B and C gave significantly higher recoveries of Al, Sb, W and REEs, which were tighter to the reference values of these elements. A similar effect was found for Cu, Fe, Li, Ni, Sn, Th, Tl, V, Zn, Ba, Rb and Sr recoveries in samples with Si contents exceeding 2000μgg−1. If the Si content in plant samples is less than 10mgg−1, digestion of 0.5g of plant samples through 0.05mL of HF and 0.5mL of 4% H3BO3 or 0.1mL of HBF4 is recommended to get satisfactory results for most of the elements. For materials with Si content exceeding 10mgg−1 the weight of the sample for digestion should be reduced to 0.25g. However, the operation of potential interferences should be taken into account and eliminated through correction equations and adequate dilution of the samples. [Copyright &y& Elsevier]

Abstract: A knowledge base for identification of residual solvents in pharmaceuticals has been established using gas chromatograph–mass spectrometry (GC–MS) and gas chromatograph–Fourier transform infrared spectrometry (GC–FTIR). Sixty solvents were studied according to the guideline for residual solvents regulated by the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). The standard mass spectra library, the limit of detection (LOD) mass spectra library, the standard vapor-phase infrared spectra library, and the limit of detection (LOD) vapor-phase infrared spectra library were established and constituted the knowledge base. Using the knowledge base, the problem of qualitation, which was the difficulty of determining residual solvents, can be resolved. [Copyright &y& Elsevier]

Abstract: High-performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC/ESI–MS/MS) was used to identify C-21 steroidal glycosides with immunological activities in roots of Cynanchum chekiangense. In the MS/MS spectra, fragmentation reactions of the [M+Na]+ were recorded to provide structural information about the glycosyl and aglycone moieties. To further confirm the fragments structures, off-line Fourier transform ion cyclotron resonance tandem mass spectrometry (FT-ICR–MS/MS) was also performed. In the study, four known steroidal glycosides cynascyroside C, chekiangensosides A and B, glaucoside H, and four novel steroidal glycosides chekiangensosides C, D, E and chekiangensoside A isomer were identified based on mass spectral data, NMR spectral data and standards. This is the first report on identifying steroidal glycosides in roots of C. chekiangense by HPLC/ESI–MS/MS directly, which could save time and material consuming efforts in traditional phytochemistry analysis. [Copyright &y& Elsevier]