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Analytical and Bioanalytical Chemistry (v.399, #5)

Speciation analysis in healthcare by H. Goenaga-Infante (pp. 1733-1734).

is currently Principal Scientist for the Chemical Measurement and Calibration Team at LGC Limited in Teddington, UK. Her research interests lie in trace element speciation analysis, metallomics research, combined use of elemental and molecular mass spectrometry, size-based element fractionation and the characterisation of ‘speciated’ reference materials and standards. She is a member of the International Advisory Board of the journals Analytical and Bioanalytical Chemistry and Metallomics.

Critical review or scientific opinion paper: Arsenosugars—a class of benign arsenic species or justification for developing partly speciated arsenic fractionation in foodstuffs? by Jörg Feldmann; Eva M. Krupp (pp. 1735-1741).

has been Professor at the University of Aberdeen and Chair for Environmental Analytical Chemistry since 2004. He obtained his PhD in 1995 from the University of Essen (Germany) and was a Feodor-Lynen Fellow (Alexander von Humboldt) at the University of British Columbia in Vancouver (Canada) before coming to Scotland in 1997 as a Lecturer at the University of Aberdeen. He is head of TESLA, the Trace Element Speciation Laboratory Aberdeen, as part of the newly founded Marine Biodiscovery Centre. He is member of the Advisory Boards of Environmental Chemistry and Analytical and Bioanalytical Chemistry and has published more than 130 scientific papers, mainly on element speciation analysis in environmental and biological systems, and has given more than 80 invited and plenary lectures at international conferences. The main focus of his research is on element speciation with an emphasis on the development of hyphenated mass spectrometry for studies of the molecular forms of arsenic and their behaviour in biology and the environment. obtained her PhD in Analytical Chemistry at the University of Essen, Germany, in 1999. She then moved to the CNRS for Bioinorganic Chemistry at the University of Pau, France, to work as a Post-Doctoral Fellow in the element-speciation group of O.F.X. Donard. From here she moved to the University of Aberdeen, Scotland, in 2005 and was, in 2008, appointed lecturer in Analytical and Environmental Chemistry within TESLA, the Trace Element Speciation Laboratory Aberdeen and the Aberdeen Centre for Environmental Sustainability (ACES). She is committee member of the Royal Society of Chemistry Analytical Division (Scotland). Her research is focused on element speciation and related method developments, now mainly focusing on mercury in the environment and life. She has published more than 30 scientific papers and given more than 15 invited lectures and workshops on international conferences and symposia. In this opinion paper the toxicokinetic behaviour of arsenosugars is reviewed and compared with that of inorganic arsenic and arsenobetaine. It is concluded that the arsenosugars are similar to inorganic arsenic in terms of metabolite formation and tissue accumulation. As a pragmatic means of generating uniform data sets which adequately represent the toxicity of arsenic in food we recommend reporting partly speciated arsenic concentrations in food commodities in three fractions: i) toxic inorganic arsenic as arsenate (after oxidation); ii) arsenobetaine as established non-toxic arsenic; and iii) potentially toxic arsenic, which includes arsenosugars and other organoarsenicals.

Keywords: arsenic; speciation; legislation; food analysis; metabolism; accumulation

Surveying selenium speciation from soil to cell—forms and transformations by Bente Gammelgaard; Matthew I. Jackson; Charlotte Gabel-Jensen (pp. 1743-1763).

The aim of this review is to present and evaluate the present knowledge of which selenium species are available to the general population in the form of food and common supplements and how these species are metabolized in mammals. The overview of the selenium sources takes a horizontal approach, which encompasses identification of new metabolites in yeast and food of plant and animal origin, whereas the survey of the mammalian metabolism takes a horizontal as well as a vertical approach. The vertical approach encompasses studies on dynamic conversions of selenium compounds within cells, tissues or whole organisms. New and improved sample preparation, separation and detection methods are evaluated from an analytical chemical perspective to cover the progress in horizontal speciation, whereas the analytical methods for the vertical speciation and the interpretations of the results are evaluated from a biological angle as well.

Keywords: Selenium; Speciation; Liquid chromatography–inductively coupled plasma mass spectrometry; Liquid chromatography–electrospray ionization mass spectrometry; Review

Distribution and metabolism of selenohomolanthionine labeled with a stable isotope by Yasumi Anan; Takahiro Mikami; Yoshiro Tsuji; Yasumitsu Ogra (pp. 1765-1772).

The distribution and metabolism of selenohomolanthionine (4,4′-selenobis[2-aminobutanoic acid], SeHLan), a newly identified selenoamino acid in selenized Japanese pungent radish, were evaluated by administering ⁷⁷Se-labeled SeHLan at a dose of 25 μg/kg body weight in rats. Exogenous ⁷⁷Se of SeHLan was preferably distributed to the kidneys and remained in the intact form for up to 6 h after dosing. The accumulation in the kidneys is one of the specific characteristics of SeHLan, differing from other selenoamino acids, such as selenomethionine and Se-methylselenocysteine, which preferably accumulate in the pancreas. The intact form of SeHLan was detected in the serum and kidney supernatant but not in the urine, suggesting that the amount of exogenous Se that was distributed to the kidneys was within metabolic capacity. Indeed, the exogenous Se was converted into two urinary metabolites, Se-methylseleno-N-acetyl-galactosamine and trimethylselenonium. Exogenous Se was also detected in several selenoproteins, including selenoprotein P and extracellular glutathione peroxidase. SeHLan is expected to be a potential supplemental source of Se because its distribution differs from that of selenomethionine and Se-methylselenocysteine. Simultaneous detection of exogenous and endogenous Se metabolites using a stable isotope labeled Se compound.

Keywords: Selenohomolanthionine; Stable isotope; Selenium; Speciation; ICP-MS

Physicochemical characterisation of different welding aerosols by B. Berlinger; N. Benker; S. Weinbruch; B. L`Vov; M. Ebert; W. Koch; D. G. Ellingsen; Y. Thomassen (pp. 1773-1780).

Physicochemical properties important in exposure characterisation of four different welding aerosols were investigated. Particle number size distributions were determined by scanning mobility particle sizer (SMPS), mass size distributions by separation and weighing the individual size fractions of an 11-stage cascade impactor. The size distribution of the primary particles of agglomerates, chemical composition and morphology of the particles were examined by TEM. There were significant differences in the particle number size distributions of the different welding aerosols according to the SMPS determinations. The particle mass size distributions determined gravimetrically were, however, not really different. The dominant range with respect to mass was between 0.1 and 1 μm, regardless of the welding technique. Most of the primary particles in all different welding aerosols had diameters between 5 and 40 nm. All types of primary particles had a tendency to form chainlike agglomerates. A clear size dependence of the particle chemical composition was encountered in the case of manual metal arc welding aerosol. Small particles with diameters below 50 nm were mostly metal oxides in contrast to larger particles which also contained more volatile elements (e.g. potassium, fluorine, sodium, sulphur).

Keywords: Welding aerosol; Transmission electron microscopy; Scanning mobility particle sizer; Particle size distribution; Primary particles; Morphology

Arsenic speciation in clinical samples: urine analysis using fast micro-liquid chromatography ICP-MS by Jackie Morton; Elizabeth Leese (pp. 1781-1788).

Arsenic speciation is a subject that is developing all the time both from improvements in analytical techniques and from increases in toxicological understanding. Despite speciation methods being widely developed, arsenic speciation is not routinely offered as an analysis in clinical laboratory. The work in this paper describes a simple routine method for arsenic speciation that could be easily implemented in clinical laboratories. The method described, a new, fast analytical method for arsenic speciation, is reported using micro-liquid chromatography hyphenated to an inductively coupled plasma mass spectrometer (μLC-ICP-MS). The method uses a low-pressure delivery six-port valve with a 5 cm anion exchange column, which allows a fully resolved separation of five arsenic species (arsenobetaine [AB], arsenite [As³⁺], arsenate [As⁵⁺], mono-methylarsonic acid [MMA⁵⁺] and dimethylarsinic acid [DMA⁵⁺]) in urine in just 6 min. This fast analytical method offers an arsenic speciation method that is feasible for a laboratory that does not have the capability for a dedicated arsenic speciation LC-ICP-MS instrument. The micro-LC system is small, easy to install and is fully integrated with the ICP-MS software. The results reported here are from urine samples from 65 workers in a semiconductor work providing a sample for their routine biological monitoring to assess workplace exposure. Control samples from 20 unexposed people were also determined. Results show that the semiconductor workers exhibit very low levels of arsenic in their urine samples, similar to the levels in the controls, and thus are not significantly exposed to arsenic. Care must be taken when interpreting urinary arsenic species results because it is not always possible to differentiate between dietary and other external sources of exposure.

Keywords: Arsenic speciation; Urine; Exposure; Workers; Controls

Capabilities of HPLC with APEX-Q nebulisation ICP-MS and ESI MS/MS to compare selenium uptake and speciation of non-malignant with different B cell lymphoma lines by Heidi Goenaga-Infante; Shireen Kassam; Emma Stokes; Christopher Hopley; Simon P. Joel (pp. 1789-1797).

The formation of intracellular dimethylselenide (DMSe) as a product of exposure of non-malignant (PBMCs) and lymphoma (RL and DHL-4) cell lines to methylseleninic acid (MSA) at clinical levels is suggested here for the first time. This was achieved by analysis of cell lysates by HPLC coupled to ICP-MS via APEX-Q nebulisation, enabling limits of detection for target methyl-Se species which are up to 12-fold lower than those obtained with conventional nebulisation. Methyl-Se-glutathione (CH₃Se-SG), although detected in lysates of cells exposed to MSA, was found to be a reaction product of MSA with glutathione. This was confirmed by HPLC-ESI MS (MS) analysis of lysates of control cells (unexposed to Se) spiked with MSA. The MS/MS data obtained by collision-induced dissociation fragmentation of the ion m/z 402 (for [M+H]⁺ ⁸⁰Se) were consistent with the presence of CH₃Se-SG. Formation of DMSe was not detected by HPLC-ICP-MS in these spiked lysates, and it was found to require live cells in cell media containing MSA. Interestingly, the ratio of DMSe to CH₃Se-SG was significantly higher in lymphoma cells exposed to MSA in comparison to non-malignant cells. Moreover, maximum Se uptake levels in lymphoma cell lines seemed to be reached much earlier (after 10 min of MSA exposure) than in non-malignant cells. Finally, the GC-TOF-MS speciation data obtained for cell headspace suggested that the major Se species (dimethyldiselenide) appeared to be present in lymphoma cell headspace at significantly higher concentrations than in non-malignant cell headspace after only 10 min of exposure to MSA. Evidence for the presence of dimethylselenidesulfide in lymphoma cell headspace is also provided for the first time.

Keywords: Selenium speciation; Non-malignant cell lines; Cancer cell lines; Intracellular dimethylselenide; APEX-Q nebulisation; Methylseleninic acid; Clinical levels; HPLC-ICP-MS; HPLC-ESI MS/MS

Enhanced extract preparation of native manganese and iron species from brain and liver tissue by J. Diederich; B. Michalke (pp. 1799-1806).

To date, no reference method for the extraction of labile Mn species from biological tissues is published which provides sufficient extraction efficiency combined with monitoring speciation. Here, an extraction method is reported using cryogenic conditions (+N) under inert gas atmosphere. Fresh brain and liver tissues were used, then stored either 1 day (+N) or 1 month in N_2liq (+N 1 m) to evaluate degradation effects during long-term storage. Both attempts were compared to a previous extraction method (−N) using neither N_2liq nor storage ability. Mn and Fe concentrations in extracts and pellets were determined with inductively coupled plasma (ICP)-atomic emission spectroscopy (AES) and compared to acid digests of the same sample. Element ratios of extracts/digest indicated the extraction efficiency, which was increased from 17% (−N) to 26% (+N) for Mn in brain or from 28% (−N) to 44% (+N) in liver extracts. For Fe species, the increase was only from 40% (−N) to 44% (+N) in brain but from 64% (−N) to 74% (+N) in liver. Size exclusion chromatography (SEC)-ICP-mass spectrometry (MS) was employed to screen for Mn and Fe species pattern in extracts. In brain, surplus extracted Mn (+N, +N 1 m) was assigned to organic Mn species, mainly from the 0.7–4 kDa fraction, while in the liver, it was seen in the 70–80 kDa fraction. Fe speciation was similar for −N and +N methods in brain extracts. In liver, higher amounts of Fe species were extracted from the 140–160 kDa fraction. Storage at −196 °C for 1 month did neither affect Mn speciation in brain nor in liver extracts. Fe species pattern showed a negligible shift (≤5%) from 140–160 to 70–80 kDa fraction in liver extracts stored 1 month in N_2liq. Separation of Mn species

Keywords: Manganese; Iron; Extraction; Speciation; Rat; Brain

Mohammed Zourob, Akhlesh Lakhtakia (Eds.): Optical guided-wave chemical and biosensors I and II, 1^st ed. by Lothar Leidner (pp. 1807-1808).

Lloyd R. Snyder, Joseph J. Kirkland, John W. Dolan: Introduction to modern liquid chromatography, 3rd ed. by Catherine A. Rimmer (pp. 1809-1810).

The 2010 Chemistry Nobel Prize to R.F. Heck, E. Negishi, and A. Suzuki for palladium-catalyzed cross-coupling reactions by Didier Astruc (pp. 1811-1814).

is Professor of Chemistry at the University of Bordeaux I and Member of the Institut Universitaire de France. He did his Ph.D. in Rennes with R. Dabard and his postdoctoral work at MIT with R. R. Schrock. He is the author among other works of Electron Transfer and Radical Processes in Transition-Metal Chemistry (VCH, 1995) and Organometallic Chemistry and Catalysis (Springer, 2007). His interests are in dendrimers and nanoparticles and their applications in catalysis, sensing, materials science, and nanomedicine. http://astruc.didier.free.fr/welcome.htm

Improved method for plasma ADMA, SDMA, and arginine quantification by field-amplified sample injection capillary electrophoresis UV detection by Angelo Zinellu; Salvatore Sotgia; Maria Franca Usai; Gianfranco Pintus; Luca Deiana; Ciriaco Carru (pp. 1815-1821).

Here, we describe an easy field-amplified sample injection capillary electrophoresis method with UV detection for the separation and detection of free plasma arginine and dimethylated arginines. The analytes were baseline-separated within 22 min by using 50 mmol/L Tris phosphate pH 2.3 as running buffer. The plasma samples were treated with acetonitrile/ammonia for protein elimination, the supernatants were dried, re-swollen in water and directly injected in the capillary without complex cleanup by solid phase extraction and/or tedious sample derivatization procedures. Due to the stacking effects of the electrokinetic injection, it was possible to operate a consistent on-line pre-concentration of the analytes before running the electrophoresis. This procedure allowed to reach a detection limit in the real sample of 10 nmol/L for dimethylated arginines and 20 nmol/L for arginine, thus improving about threefold our previous method, that required a more complicated pre-analytical procedure to concentrate samples. The recovery of plasma ADMA was 99–104% and inter-day CV was less than 3%. The assay performance was evaluated measuring the levels of arginine and its dimethyl derivatives in 50 subjects. The statistical tests for the methods comparison suggest that the data obtained by our new method and by our previous CE assay are similar.

Keywords: ADMA; SDMA; Capillary electrophoresis; FASI

Real-time electrical impedance-based measurement to distinguish oral cancer cells and non-cancer oral epithelial cells by Liju Yang; L. Renea Arias; Tonya S. Lane; Martez D. Yancey; Jaouad Mamouni (pp. 1823-1833).

In this study, electrical impedance-based measurements were used to distinguish oral cancer cells and non-cancer oral epithelial cells based on their cellular activities on the microelectrodes in a real-time and label-free manner. CAL 27 and Het-1A cell lines were used as the models of oral cancer cells and non-cancer oral epithelial cells, respectively. Various cellular activities, including cell adhesion, spreading, and proliferation were monitored. We found that both the kinetics of cell spreading and the static impedance-based cell index were feasible to distinguish the two cell types. At each given cell number, CAL 27 cell spreading produced a smaller cell index change rate that was 60–70% of those of Het-1A cells. When cells were fully spread, CAL 27 cells generated a cell index more than four times greater than that of Het-1A cells. Since cell spreading and attachment occurs in the first few hours when they were cultured on the microelectrodes, this impedance-based method could be a rapid label-free and non-invasive approach to distinguish oral cancer cells from non-cancer oral epithelial cells. Cell viability analysis was performed along with the impedance-based analysis. Confocal microscopic imaging analysis showed the difference in cell morphology and the thickness of cell monolayers between the two cell types.

Keywords: Impedance measurement; Real-time; Electrodes; Oral cancer cells; Non-cancer oral epithelial cells; Cellular activity

Simultaneous quantification and qualification of synacthen in plasma by Ayman Chaabo; Jacques de Ceaurriz; Corinne Buisson; Jean-Claude Tabet; Françoise Lasne (pp. 1835-1843).

Tetracosactide (Synacthen), a synthetic analogue of adrenocorticotropic hormone (ACTH), can be used as a doping agent to increase the secretion of glucocorticoids by adrenal glands. The only published method for anti-doping control of this drug in plasma relies on purification by immunoaffinity chromatography and LC/MS/MS analysis. Its limit of detection is 300 pg/mL, which corresponds to the peak value observed 12 h after 1 mg Synacthen IM administration. We report here a more sensitive method based on preparation of plasma by cation exchange chromatography and solid-phase extraction and analysis by LC/MS/MS with positive-mode electrospray ionization using 7–38 ACTH as internal standard. Identification of Synacthen was performed using two product ions, m/z 671.5 and m/z 223.0, from the parent [M + 5H]⁵⁺ ion, m/z 587.4. The recovery was estimated at 70%. A linear calibration curve was obtained from 25 to 600 pg/mL (R ² > 0.99). The lower limit of detection was 8 pg/mL (S/N > 3). The lower limit of quantification was 15 pg/mL (S/N > 10; CV% < 20%). The performance of the method was illustrated by an 8-h kinetic analysis of plasma samples from nine subjects submitted to IM injections of either Synacthen® (five subjects) or Synacthen® Depot, the slow-release form of the drug (four subjects). Concentrations of Synacthen between 16 and 310 pg/mL were observed. A sensitive method for quantitation of Synacthen in plasma is proposed for anti-doping control analyses.

Keywords: Synacthen; Tandem mass spectrometry; Doping; Excretion study

Potential of poly(styrene-co-divinylbenzene) monolithic columns for the LC-MS analysis of protein digests by Michiel H. M. van de Meent; Sebastiaan Eeltink; Gerhardus J. de Jong (pp. 1845-1852).

Two polystyrene-based capillary monolithic columns of different length (50 and 250 mm) were used to evaluate the effects of column length on gradient separation of protein digests. A tryptic digest of a 9-protein mixture was used as a test sample. Peak capacities were determined from selected extracted ion chromatograms, and tandem mass spectrometry data were used for database matching using the MASCOT search engine. Peak capacities and protein identification scores were higher for the long column with all gradients. Peak capacities appear to approach a plateau for longer gradient times; maximum peak capacity was estimated to be 294 for the short column and 370 for the long column. Analyses with similar gradient slope produced a ratio of the peak capacities of 3.36 for the long and the short column, which is slightly higher than the expected value of the square root of the column length ratio. The use of a longer monolith improves peptide separation, as reflected by higher peak capacity, and also increases protein identification, as observed from higher identification scores and a larger number of identified peptides. Attention has also been paid to the peak production rate (PPR, peak capacity per unit time). For short analysis times, the short column produces a higher PPR, while for analysis times longer than 40 min, the PPR of the 250-mm column is higher.

Keywords: Capillary LC; Mass spectrometry; Peak capacity; Monoliths; Protein digests

Chip electrophoresis of active banana ingredients with label-free detection utilizing deep UV native fluorescence and mass spectrometry by Stefan Ohla; Philipp Schulze; Stefanie Fritzsche; Detlev Belder (pp. 1853-1857).

In the present work, we report on a rapid and straightforward approach for the determination of biologically active compounds in bananas applying microchip electrophoresis (MCE). For this purpose, we applied label-free detection utilizing deep UV fluorescence detection with excitation at 266 nm. Using this approach, we could identify dopamine and serotonin, their precursors tryptophan and tyrosine and also the isoquinoline alkaloid salsolinol in less than 1 min. In bananas, after 10 days of ripening, we additionally found the compound levodopa which is a metabolite of the tyrosine pathway. Quantitative analysis of extracts by external calibration revealed concentrations of serotonin, tryptophan, and tyrosine from 2.7 to 7.6 μg/mL with relative standard deviations of less than 3.5%. The corresponding calibration plots showed good linearity with correlation coefficients higher than 0.985. For reliable peak assignment, the compounds were also analyzed by coupling chip electrophoresis with mass spectrometry. This paper demonstrates exemplarily the applicability of MCE with native fluorescence detection for rapid analysis of natural compounds in fruits and reveals the potential of chip-based separation systems for the analysis of complex mixtures.

Keywords: Neuroactive banana ingredients; Microfluidic chip; Nanoelectrospray MS; Native fluorescence detection; Real world sample

Electrochemistry-mass spectrometry for mechanistic studies and simulation of oxidation processes in the environment by Th. Hoffmann; D. Hofmann; E. Klumpp; S. Küppers (pp. 1859-1868).

Electrochemistry (EC) coupled to mass spectrometry (MS) has already been successfully applied to metabolism research for pharmaceutical applications, especially for the oxidation behaviour of drug substances. Xenobiotics (chemicals in the environment) also undergo various conversions; some of which are oxidative reactions. Therefore, EC-MS might be a suitable tool for the investigation of oxidative behaviour of xenobiotics. A further evaluation of this approach to environmental research is presented in the present paper using sulfonamide antibiotics. The results with sulfadiazine showed that EC-MS is a powerful tool for the elucidation of the oxidative degradation mechanism within a short time period. In addition, it was demonstrated that EC-MS can be used as a fast and easy method to model the chemical binding of xenobiotics to soil. The reaction of sulfadiazine with catechol, as a model substance for organic matter in soil, led to the expected chemical structure. Finally, by using EC-MS a first indication was obtained of the persistence of a component under chemical oxidation conditions for the comparison of the oxidative stability of different classes of xenobiotics. Overall, using just a few examples, the study demonstrates that EC-MS can be applied as a versatile tool for mechanistic studies of oxidative degradation pathways of xenobiotics and their possible interaction with soil organic matter as well as their oxidative stability in the environment. Further studies are needed to evaluate the full range of possibilities of the application of EC-MS in environmental research.

Keywords: Degradation; Xenobiotics; Environment; Electrochemistry; Mass spectrometry

An inexpensive thread-based system for simple and rapid blood grouping by David R. Ballerini; Xu Li; Wei Shen (pp. 1869-1875).

This study investigates the use of thread as a flexible and low-cost substrate for the rapid grouping of blood. The use of a capillary substrate such as thread for blood grouping utilises the sensitivity of the flow resistance of large particles in narrow capillary channels to separate agglutinated red blood cells (RBCs) from plasma. Large and discrete particles formed in a continuous liquid phase do not provide capillary wicking driving force and fall behind the capillary wicking front, leading to their separation from the wicking liquid. The capillary substrate therefore provides a very promising but different mechanism for the separation of the agglutinated RBCs and the blood serum phase compared to most existing blood grouping methods. The principle of chromatographic separation is also exploited in this study via the use of suitable dyes to enhance the visual detection of the agglutinated RBCs and the serum phase; surprising and encouraging outcomes are obtained. Using a thread-based device, the ABO and Rh groups can be successfully determined with only 2 μL of whole blood from a pricked finger tip within 1 min and without pre-treatment of the blood sample. It is hoped that a new, inexpensive, rapid and simple method may provide an easy-to-use blood grouping platform well suited to those in developing or remote regions of the world. Figure The use of a single-step thread-based blood testing device

Keywords: Blood typing; Thread-based; Point of care; Microfluidic; Low-cost; Developing regions

Differentiation of Panax quinquefolius grown in the USA and China using LC/MS-based chromatographic fingerprinting and chemometric approaches by Jianghao Sun; Pei Chen (pp. 1877-1889).

American ginseng (Panax quinquefolius) is one of the most commonly used herbal medicines in the world. Discriminating between P. quinquefolius grown in different countries is difficult using traditional quantitation methods. In this study, a liquid chromatographic mass spectrometry fingerprint combined with chemometric analysis was established to discriminate between American ginseng grown in the USA and China. Fifteen American ginseng samples grown in Wisconsin and 25 samples grown in China were used. The chromatographic fingerprints, representing the chemical compositions of the samples, made it possible to distinguish samples from the two locations. In addition, it was found that some ginsenosides varied widely from P. quinquefolius cultivated in these two countries. P. quinquefolius grown in the USA is higher in ginsenoside R_c, ginsenoside R_d, quinquenoside III/pseudo-ginsenoside RC₁, malonyl ginsenoside R_b1, and ginsenoside R_b2, but lower in ginsenoside R_b1 compared with P. quinquefolius grown in China. These ginsenosides may be responsible for the class separation seen using fingerprinting and chemometric approaches.

Keywords: American ginseng; Fingerprint; Chemometrics; Liquid chromatography–mass spectrometry; Panax quinquefolius

Effects of surface water on gas sorption capacities of gravimetric sensing layers analyzed by molecular descriptors of organic adsorbates by Iwao Sugimoto; Kouta Mitsui; Masayuki Nakamura; Michiko Seyama (pp. 1891-1899).

The gas sorption capacities of sputtered carbonaceous films are evaluated with quartz crystal resonators. These films are sensitive to 20 ppm organic vapors and exhibit structure-dependent responses. Films derived from synthetic polymers are hydrophobic, whereas films derived from biomaterials are amphiphilic or hydrophilic. Polyethylene (PE) film has an extremely high sorption capacity for a wide range of vapors. Transient sorption responses are investigated using a humidified carrier by employing carboxylic acid esters, whose aliphatic groups are systematically changed. Small esters with a higher affinity to water induce negative U-shaped responses from amphiphilic films derived from biomaterials. On the other hand, polymeric films exhibit positive exponential response curves. Even if the concentrations are decreased, the response intensities are enhanced with the incremental expansion of carbon chains of aliphatic groups. Only fluoropolymer film shows the opposite tendency. The modeling of quantitative structure property relationships has indicated that the sorption capacities of the PE film to the carboxylic acid esters are fundamentally governed by electrostatic interactions. The intermolecular attractive forces are basically attributable to interactions between the positively polarized sites in esters and the negatively polarized/charged sites in PE film.

Keywords: Surface water; Thin film; Quartz crystal microbalance (QCM); Quantitative structure property relationships (QSPR)

Dispersive liquid–liquid microextraction based on the solidification of a floating organic droplet for simultaneous analysis of diethofencarb and pyrimethanil in apple pulp and peel by YiWen Zhou; LinTao Han; Jing Cheng; Feng Guo; XiaoRan Zhi; HaiLi Hu; Gang Chen (pp. 1901-1906).

A method for analysis of diethofencarb and pyrimethanil in apple pulp and peel was developed by using dispersive liquid–liquid microextraction based on solidification of a floating organic droplet (DLLME-SFO) and high-performance liquid chromatography with diode-array detection (HPLC–DAD). Acetonitrile was used as the solvent to extract the two fungicides from apple pulp and peel, assisted by microwave irradiation. When the extraction process was finished, the target analytes in the extraction solvent were rapidly transferred from the acetonitrile extract to another extraction solvent (1-undecanol) by using DLLME-SFO. Because of the lower density of 1-undecanol than that of water, the finely dispersed droplets of 1-undecanol collected on the top of aqueous sample and solidified at low temperature. Meanwhile, the tiny particles of apple cooled and precipitated. Recovery was tested for a concentration of 8 μg kg⁻¹. Recovery of diethofencarb and pyrimethanil from apple pulp and peel was in the range 83.5–101.3%. The repeatability of the method, expressed as relative standard deviation, varied between 4.8 and 8.3% (n = 6). Detection limits of the method for apple pulp and peel varied from 1.2–1.6 μg kg⁻¹ for the two fungicides. Compared with conventional sample preparation, the method has the advantage of rapid speed and simple operation, and has high enrichment factors and low consumption of organic solvent. Figure Chromatogram of apple pulp (a) and spiked apple pulp (b) at the concentration level of 0.4 μg g⁻¹ for two fungicides obtained by using DLLME-SFO combined with HPLC-DAD. Peak identification: 1-Diethofencarb, 2- Pyrimethanil

Keywords: Diethofencarb; Pyrimethanil; Floating organic droplet; Apple analysis

Quantitative nuclear magnetic resonance for additives determination in an electrolytic nickel bath by Miren Ostra; Carlos Ubide; Maider Vidal (pp. 1907-1915).

The use of proton nuclear magnetic resonance (¹H-NMR) for the quantitation of additives in a commercial electrolytic nickel bath (Supreme Plus Brilliant, Atotech formulation) is reported. A simple and quick method is described that needs only the separation of nickel ions by precipitation with NaOH. The four additives in the bath (A-5(2X), leveler; Supreme Plus Brightener (SPB); SA-1, leveler; NPA, wetting agent; all of them are commercial names from Atotech) can be quantified, whereas no other analytical methods have been found in the literature for SA-1 and NPA. Two calibration methods have been tried: integration of NMR signals with the use of a proper internal standard and partial least squares regression applied to the characteristic NMR peaks. The multivariate method was preferred because of accuracy and precision. Multivariate limits of detection of about 4 mL L⁻¹ A-5(2X), 0.4 mL L⁻¹ SPB, 0.2 mL L⁻¹ SA-1 and 0.6 mL L⁻¹ NPA were found. The dynamic ranges are suitable to follow the concentration of additives in the bath along electrodeposition. ¹H-NMR spectra provide evidence for SPB and SA-1 consumption (A-5(2X) and NPA keep unchanged along the process) and the growth of some products from SA-1 degradation can be followed. The method can, probably, be extended to other electrolytic nickel baths. Figure Typical NMR spectrum of a nickel electrodeposition bath along the process showing characteristic peaks of additives (A-5(2X), SPB, SA-1), NPA) in blue and by-products in red.

Keywords: qNMR; Ni electroplating; Additives determination; Process analysis

Lactose does not interfere with the analysis of sialic acids as their 1,2-diamino-4,5-methylenedioxybenzene derivatives by Véronique Spichtig; Philippe Rohfritsch; Sean Austin (pp. 1917-1922).

In 2007, Martin et al. developed a method for the analysis of sialic acids by HPLC following 1,2-diamino-4,5-methylenedioxybenzene (DMB) derivatisation (Martín et al., Anal Bioanal Chem 387:2943–2949, 2007). Within the article, the authors noted that lactose interfered with the analysis, giving erroneously high results when lactose-containing products were analysed. Such an observation is important when analysing milk-based products, yet was contradictory to the observations of Nakamura et al. (Chem Pharm Bull 35(2):687–692, 1987) who demonstrated that DMB was specific for α-keto acids and did not react with simple sugars such as glucose or lactose. In order to clarify the situation, this phenomenon was investigated and it was confirmed that lactose does not interfere with the analysis. However, it was found that most commercial preparations of lactose do contain small amounts of sialic acids, either as the free monosaccharide or bound to lactose in the form of 3′- and 6′-sialyllactose.

Keywords: Sialic acid; DMB; N-acetylneuraminic acid; HPLC; Fluorimetry; Infant formula

Erratum: Recent advances in analytical and bioanalysis applications of noble metal nanorods by Ilaria Mannelli; Maria-Pilar Marco (pp. 1923-1923).

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Analytical and Bioanalytical Chemistry (v.399, #5)