Analytical and Bioanalytical Chemistry (v.395, #6)

is Professor at the Eberhard Karls University Tübingen working in analytical and physical chemistry. He has been chairman of the GDCh Division of Analytical Chemistry and chaired the Europt(r)ode VIII meeting. For the last 10 years, his main scientific interests have centred on research and development in the area of chemical and biochemical sensors with special focus on the characterisation of the interfaces of polymers and biomembranes by surface spectroscopic techniques, the application of spectral interferometry to monitor changes in the optical thickness of thin layers and the effects of Fresnel reflectivity at interfaces. Since 2002 he has been an editor of Analytical and Bioanalytical Chemistry. is Emeritus Professor of Analytical Chemistry at the Johannes Gutenberg University Mainz. His research interests lie in the development and application of analytical methods for the determination of trace elements and trace amounts of elemental species, using inductively coupled plasma mass spectrometry, thermal ionisation mass spectrometry, different types of optical atomic spectrometry, and electroanalysis as detection methods, and high-performance liquid chromatography, capillary electrophoresis and capillary gas chromatography as separation methods. He has received several awards, including the Clemens Winkler Medal of the German Society for Analytical Chemistry in 2004 for his scientific lifework and for continuous support of analytical chemistry in Germany. In 2007 he received the European Award for Plasma Spectrochemistry. He is a member of several national and international scientific societies and he was a member of the IUPAC Commission on Atomic Weights and Isotopic Abundances for 12 years and chairman from 1991 to 1995. Since 2002 he has been an editor of Analytical and Bioanalytical Chemistry.

Analytics swings! ANAKON 2009 by Markus Ehni; Peter Fechner; Dominik Furin; Stefanie Jaeger; Barbara Schwarz (1575-1576).

Statistical tests for limit value transgression—how to deliver unambiguous results by Karl Molt; Jürgen W. Einax; Michael Winterstein (1577-1582).
is Professor for Instrumental Analysis at the University Duisburg-Essen, Germany. He presents lectures on statistics in the bachelor/master course “Water Science” at this university. His main research interests lie in the areas of IR/NIR spectrometry for process analysis and chemometrics. is Professor of Analytical Chemistry at the Friedrich Schiller University of Jena, Germany, and Head of the Department of Environmental Analysis. His main areas of research include not only trace analytical problems in the environment, but also the application of chemometrics to environmental research. He is a member of the executive board of the Division Analytical Chemistry in the German Chemical Society and Chairman of the Working Group for Chemometrics and Laboratory Data Processing in this division. is the Division Manager of the WESSLING Laboratorien GmbH & Co. KG in Oppin (Germany), an Environmental Laboratory. He is chairman of the working group on chemometrics within the “DIN Normenausschuss Wasserwesen”.

The use of monolithic supports for a wide variety of applications has rapidly expanded during the past few years. The examples for applications of monoliths presented herein show that the chromatographic performance of bioreactors and affinity media prepared from monolithic media is superior to that of conventional particle-based systems. The ease of fabrication and modification combined with the long lifetime of the monolithic columns and their potential to be used in fully automated analytical systems make them attractive tools for an increasing number of applications.
Keywords: Monolithic column; Enzymatic digestion; Trypsin; Proteome analysis

Differential scanning calorimetry (DSC) is an effective analytical tool to characterize the physical properties of a polymer. DSC enables determination of melting, crystallization, and mesomorphic transition temperatures, and the corresponding enthalpy and entropy changes, and characterization of glass transition and other effects that show either changes in heat capacity or a latent heat. Calorimetry takes a special place among other methods. In addition to its simplicity and universality, the energy characteristics (heat capacity C P and its integral over temperature T—enthalpy H), measured via calorimetry, have a clear physical meaning even though sometimes interpretation may be difficult. With introduction of differential scanning calorimeters (DSC) in the early 1960s calorimetry became a standard tool in polymer science. The advantage of DSC compared with other calorimetric techniques lies in the broad dynamic range regarding heating and cooling rates, including isothermal and temperature-modulated operation. Today 12 orders of magnitude in scanning rate can be covered by combining different types of DSCs. Rates as low as 1 μK s−1 are possible and at the other extreme heating and cooling at 1 MK s−1 and higher is possible. The broad dynamic range is especially of interest for semicrystalline polymers because they are commonly far from equilibrium and phase transitions are strongly time (rate) dependent. Nevertheless, there are still several unsolved problems regarding calorimetry of polymers. I try to address a few of these, for example determination of baseline heat capacity, which is related to the problem of crystallinity determination by DSC, or the occurrence of multiple melting peaks. Possible solutions by using advanced calorimetric techniques, for example fast scanning and high frequency AC (temperature-modulated) calorimetry are discussed.
Keywords: Differential scanning calorimetry (DSC); Fast scanning; Temperature modulation (AC); Semicrystalline polymers; Crystallization; Melting

The oily product ZANTHIN® consists of natural astaxanthin, which is manufactured from the microalgae Haematococcus pluvialis by supercritical CO2 extraction. An HPLC method was developed to separate all of the components of the complex astaxanthin extract using a C30 column. The separation resulted in different isomers of astaxanthin accompanied by two other carotenoids. The main component consisted of astaxanthin singly esterified with several different fatty acids. C18:3, C18:2, C18:1 and C16:0 were identified as the most commonly occurring fatty acids. Doubly esterified astaxanthin was also found, although in lower concentrations compared to singly esterified astaxanthin. After performing a detailed fatty acid analysis by GC-MS, the peaks from the extract were assigned via HPLC-MS. A trans to cis transmutation of the all-trans compound was performed by thermal treatment in order to obtain an enrichment of cis isomers as the basis for unambiguous identification via NMR experiments. The all-trans as well as the 9- and 13-cis isomers of astaxanthin were characterized in detail by UV/Vis, 1H, and 1H,1H COSY NMR spectroscopy.
Keywords: Haematococcus pluvialis ; Astaxanthin esters; HPLC; LC-(APCI)MS; Trans/cis isomerization; NMR spectroscopy

Pathogen detection is important for health and safety reasons. Several outbreaks all over the world have shown the need for rapid, qualitative, quantitative, and, particularly, multianalyte detection systems. Hence, a multichannel flow-through chemiluminescence microarray chip for parallel detection of pathogenic bacteria was developed. The disposable chip made of acrylonitrile–butadiene–styrene (ABS) copolymer was devised as a support for a multiplexed sandwich immunoassay. Calibration and measurement was possible in one experiment, because the developed chip contains six parallel flow-through microchannels. Polyclonal antibodies against the pathogenic bacteria Escherichia coli O157:H7, Salmonella typhimurium, and Legionella pneumophila were immobilized on the chip by microcontact printing in order to use them as specific receptors. Detection of the captured bacteria was carried out by use of specific detection antibodies labelled with biotin and horseradish peroxidase (HRP)–streptavidine conjugates. The enzyme HRP generates chemiluminescence after adding luminol and hydrogen peroxide. This signal was observed by use of a sensitive CCD camera. The limits of detection are 1.8 × 104 cells mL−1 for E. coli O157:H7, 7.9 × 104 cells mL−1 for L. pneumophila, and 2.0 × 107 cells mL−1 for S. typhimurium. The overall assay time for measurement and calibration is 18 min, enabling very fast analysis. Figure Array principle
Keywords: Antibody microarray; Biosafety; Pathogenic bacteria; Multiplexed sandwich immunoassay; Chemiluminescence

Progress in circular dichroism laser mass spectrometry by Christoph Logé; Alexander Bornschlegl; Ulrich Boesl (1631-1639).
Circular dichroism in ion yield has promising new potentials for chiral analysis. Our progress of its development is described here. Circular dichroism in ion yield is achieved by resonance-enhanced multiphoton ionization. The feasibility of circular dichroism spectroscopy and quantitative determination of circular dichroism by this method is demonstrated. Several excitation schemes have been applied using different types of lasers, which vary in wavelength and repetition rate. Progress to improve the statistical error and thus the lower limit of measurable circular dichroism is described. This is achieved by adding achiral compounds or racemic mixtures of chiral compounds to the sample gas as reference substances and ionizing them by the same laser pulse. Therefore, in the mass spectrum of every single laser pulse, ion signals of sample and reference species appear both being subject to the same kind of instrumental fluctuations (in particular of laser pulse energy). In another approach, a laser repetition rate of 200 Hz allowed averaging of large numbers of laser pulses. Figure Resonant Multiphoton Ionization & Circular Dichroism
Keywords: Circular dichroism; Enantiosensitive ionization; Laser mass spectrometry; Multiphoton ionization; Chiral ketones

PM-IRRAS mapping of ultrathin molecular films with high spatial resolution by Gerald Steiner; Valdas Sablinskas; Wolfgang Seidel; Reiner Salzer (1641-1650).
Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) is a very sensitive technique to characterize the degree of molecular ordering in thin films on metallic surfaces. This is the first report of the coupling of a PM-IRRAS microscope to a free electron laser (FEL), a light source of highest brilliance. Some FELs emit in the infrared region and permit the mapping of molecular properties at high lateral resolution. We studied the molecular orientation of octadecanephosphonic acid (OPA) attached to a gold surface with microstructured aluminum oxide islands on the gold. The spatial resolution achieved is 12 μm which corresponds to the diffraction limit of the infrared light used in this study. This is a substantial improvement compared to previous studies using a PM-IRRA accessory together with a commercial Fourier transform infrared spectrometer, where the lateral resolution is noise-limited rather than diffraction-limited. The spectral maps reveal that OPA is preferably attached to the aluminum oxide islands via the bidentate binding mode whereas the tridentate mode is dominating in case of OPA attached to the gold areas.
Keywords: PM-IRRAS; Mapping; Free electron laser; Self-assembly monolayer

The size distribution of 'gold standard' nanoparticles by Ralf Bienert; Franziska Emmerling; Andreas F. Thünemann (1651-1660).
The spherical gold nanoparticle reference materials RM 8011, RM 8012, and RM 8013, with a nominal radius of 5, 15, and 30 nm, respectively, have been available since 2008 from NIST. These materials are recommended as standards for nanoparticle size measurements and for the study of the biological effects of nanoparticles, e.g., in pre-clinical biomedical research. We report on determination of the size distributions of these gold nanoparticles using different small-angle X-ray scattering (SAXS) instruments. Measurements with a classical Kratky type SAXS instrument are compared with a synchrotron SAXS technique. Samples were investigated in situ, positioned in capillaries and in levitated droplets. The number-weighted size distributions were determined applying model scattering functions based on (a) Gaussian, (b) log-normal, and (c) Schulz distributions. The mean radii are 4.36 ± 0.04 nm (RM 8011), 12.20 ± 0.03 nm (RM 8012), and 25.74 ± 0.27 nm (RM 8013). Low polydispersities, defined as relative width of the distributions, were detected with values of 0.067 ± 0.006 (RM 8011), 0.103 ± 0.003, (RM 8012), and 0.10 ± 0.01 (RM 8013). The results are in agreement with integral values determined from classical evaluation procedures, such as the radius of gyration (Guinier) and particle volume (Kratky). No indications of particle aggregation and particle interactions—repulsive or attractive—were found. We recommend SAXS as a standard method for a fast and precise determination of size distributions of nanoparticles. Figure 1 A suspension of gold nanoparticles with a nominal diameter of 10 nm is positioned in a trap (acoustic levitator) for SAXS analysis with synchrotron radiation (droplet diameter is 2 mm). The measured scattering intensities (black line in right hand figure) are interpreted in terms of model functions (red line) for precise determination of the particles’ size distribution. Thank you.
Keywords: Small-angle scattering; Reference materials; Metrology; Nanoparticles

An approach to the spectral simulation of infrared hollow waveguide gas sensors by Andreas Wilk; Seong-Soo Kim; Boris Mizaikoff (1661-1671).
Optical simulations enable to model an entire chemical gas sensing platform based on hollow waveguides (HWGs) operating in the mid-infrared spectral regime using a three-dimensional representation of the sensor components and taking the spectral response to virtual analytes into account. Furthermore, a strategy for including the spectral response of dielectrically coated HWGs is demonstrated. Utilizing experimentally obtained spectroscopic data recorded at well-defined conditions, the complex refractive indices of selected target analytes (i.e., methane, butane, and isobutylene) have been derived based on a refined harmonic oscillator model. In turn, these parameters have enabled to directly assign the dielectric functions of these analytes to virtual objects representing the analyte within the modeled sensor setup. In a next step, spectroscopic sensor response functions have been simulated as absorbance spectra across selected wavelength regimes utilizing spectrally resolved ray-tracing techniques and have been compared to experimental data.
Keywords: 3D optical sensor simulation; Spectral ray tracing; Mid-infrared gas sensor; Optical sensor; Hollow waveguide; Dielectric function modeling

An extension of the unified equation of chromatography to directly access reaction rate constants k 1 of first-order reaction in on-column chromatography is presented. This extended equation reflects different response factors in the detection of the reaction educt and product which arise from structural changes by elimination or addition, e.g., under pseudo-first-order reaction conditions. The reaction rate constants k 1 and Gibbs activation energies $$ Delta G^{ e } $$ of first-order reactions taking place in a chromatographic system can be directly calculated from the chromatographic parameters, i.e., retention times of the educt E and product P ( $$ t_{ ext{R}}^{ ext{A}} $$ and $$ t_{ ext{R}}^{ ext{B}} $$ ), peak widths at half height (w A and w B), the relative plateau height (h p) of the conversion profile, and the individual response factors f A and f B. The evaluation of on-column reaction gas chromatographic experiments is exemplified by the evaluation of elution profiles obtained by ring-closing metathesis reaction of N,N-diallytrifluoroacetamide in presence of Grubbs second-generation catalyst, dissolved in polydimethylsiloxane (GE SE 30). Figure
Keywords: Chromatography; Electrophoresis; Dynamics; Kinetics; Catalysis; Metathesis

Calibration-free concentration determination of charged colloidal nanoparticles and determination of effective charges by capillary isotachophoresis by Ute Pyell; Wendelin Bücking; Carolin Huhn; Barbara Herrmann; Alexey Merkoulov; Joachim Mannhardt; Hartmut Jungclas; Thomas Nann (1681-1691).
Although colloidal nanoparticles show an electrophoretic heterogeneity under the conditions of capillary electrophoresis, which can be either due to the particle-size distribution and/or the particle shape distribution and/or the zeta-potential distribution, they can form correct isotachophoretic zones with sharp-moving boundaries. Therefore, the technique of isotachophoresis permits to generate plugs in which the co-ions and counter ions of the original colloidal solution are removed and replaced by the buffering counter ions of the leading electrolyte. It is shown that analytical isotachophoresis can be used to measure directly, without calibration, the molar (particle) concentration of dispersed ionic colloids provided that the transference number and the mean effective charge number of the particles (within the isotachophoretic zone) can be determined with adequate accuracy. The method can also be used to measure directly the effective charge number of biomacromolecules or colloidal particles, if solutions with known molar (particle) concentration can be prepared. The validity of the approach was confirmed for a model solution containing a known molar concentration of bovine serum albumin. Figure Isotachopherogram for CdSe/ZnS nanoparticles coated with BSA. Leading electrolyte: 10 mmol/L HCl titrated with BTP to pH = 8.60, terminating electrolyte: 10 mmol/L HEPPS titrated with BTP to pH = 8.00, fused-silica capillary 200 mm × 300 μm, I = 50 μA, injection 3 μL, ambient temperature
Keywords: Effective charge number of colloidal particles; Electrophoretic mobility; Isotachophoresis; Nanoparticles; Zeta potential

Electrodeposition polymers can be precipitated on electrode surfaces upon electrochemical-induced modulations of the pH value in the diffusion zone in front of the electrode. The formed polymer films can be used as immobilization matrices in amperometric biosensors. In order to rationally control the thus obtained biosensor properties, it is indispensable to develop strategies for the reproducible synthesis of electrodeposition polymers as well as methods for the non-manual and reproducible sensor fabrication. Based on instrumental developments such as a specifically designed parallel synthesizer with improved stirring and temperature control, an automatic pipetting robot for the preparation of the monomer mixtures and controlled removal of polymerization inhibitors, the reproducible synthesis of libraries of electrodeposition polymers was achieved. Moreover, the polymerization process could be monitored using in-line thermocouples, and it could be shown that the chosen strategies led to reproducible polymerization reactions. By adaptation of an electrochemical robotic system integrating a Au microtiter plate and automatic electrode cleaning by means of a polishing wheel reproducible biosensor fabrication using glucose oxidase as a model enzyme could be demonstrated. These results open the route for the rational development of biosensors and control of the sensor properties by choosing specifically designed electrodeposition polymers. Figure A parallel synthesizer with integrated thermoelements was designed for controlling the reproducible synthesis of simultaneously 8 electrodeposition polymers. An electrochemical robotic system was then employed for automatic fabrication of glucose biosensors and evaluation of their properties.
Keywords: Copolymerization; Electrodeposition paints; Reproducibility; Parallel synthesis; Biosensor

De-noising signals is a frequent aim achieved by signal processing in analytical chemistry. The purpose is to enable the detection of trace concentrations of analytes. The limit of detection is defined as the lowest amount of analyte that still causes signals greater than the background noise. Appropriate de-noising decreases only the noise and maintains the measurement signal, so that signal-to-noise ratios are enhanced. One adequate mean of signal processing for this purpose is wavelet transform, which still is not a common tool in analytical chemistry. In this paper, the ability of de-noising by wavelet transform is shown for measurements in anodic stripping voltammetry using a hanging mercury drop electrode. The calculation of limits of detection and signal-to-noise ratios on the basis of peak-to-peak noise is exercised to quantify the performance of de-noising. Furthermore, signal shape with regard of easing the application of base lines is discussed. Different wavelet functions are used, and the results are compared also to Fourier transform. Coiflet2 was found out to reduce noise by the factor of 330 and is proposed as the adequate wavelet function for voltammetric and similar signals.
Keywords: Wavelet transform; Limit of detection; Signal-to-noise ratio; Signal processing; Voltammetry

Analysis of autophosphorylation sites in the recombinant catalytic subunit alpha of cAMP-dependent kinase by nano-UPLC–ESI–MS/MS by Joerg Seidler; Melaku Adal; Dieter Kübler; Dirk Bossemeyer; Wolf D. Lehmann (1713-1720).
The catalytic subunit of recombinant wild-type cyclic adenosine monophosphate-dependent protein kinase A (PKA) has been analyzed by a combination of 1D gel electrophoresis, in-gel digestion by trypsin, chymotrypsin, or endoproteinase AspN, and nano-ultraperformance liquid chromatography–MS/MS. The MS/MS spectra were annotated by MASCOT and the annotations were manually controlled. Using Ga(III)-immobilized metal ion affinity chromatography (IMAC), in addition to the four established autophosphorylation sites of the catalytic subunit of recombinant PKA, pSer10, pSer139, pThr197, and pSer338, six new phosphorylated residues have been characterized–pSer14, pThr48, pSer53, pSer212, pSer259, and pSer325. The established phosphorylation sites all are part of a PKA consensus motif and were found to be almost completely modified. In contrast, the newly detected sites were only partially phosphorylated. For estimation of their degree of phosphorylation, a method based on signal intensity measurements was used. For this purpose, signal intensities of all phospho- and non-phosphopeptides containing a particular site were added for estimation of site-specific phosphorylation degrees. This addition was performed over all peptides observed in the different digestion experiments, including their different charge states. pThr48 and pSer259 are located within PKA consensus motifs and were observed to be phosphorylated at 20% and 24%, respectively. pSer14 and pSer53 are located within inverted PKA consensus motifs and were found to be phosphorylated around 10% and 15%, respectively. The sequence environments of pSer212 and pSer325 have no similarity to the PKA consensus motif at all and were observed to be phosphorylated at about 5% or lower. All newly observed phosphorylation sites are located at the surface of the native protein structure of the PKA catalytic subunit. The results add new information on the theme of site-specific (auto)phosphorylation by PKA. Figure Sequence of protein kinase A Ca (P00517) with highlighted autophosphorylation sites as determined by UPLC-MS/MS. The 4 known autophosphorylation sites are printed in blue and the 6 newly detected autophosphorylation are printed in red.
Keywords: Protein kinase A; Protein phosphorylation; Electrospray; Phosphorylation degree; LC–MS; Mass spectrometry

Celiac disease (CD) is a permanent gastrointestinal disorder characterized by the intolerance to a group of proteins called gluten present in wheat, rye, barley, and possibly oats. The only therapy is a strict lifelong gluten-free diet. The standard method for gluten determination in foods produced for CD patients is the R5-enzyme-linked immunosorbent assay (ELISA) as proposed by the recent Codex Alimentarius Draft Revised Standard. This test is based on the determination of prolamins, the alcohol-soluble proteins of gluten, and is available as a sandwich ELISA for intact proteins and as a competitive ELISA for gluten-derived peptides. While the suitability of the sandwich ELISA including a wheat prolamin (gliadin) reference for calibration has been shown by various studies and a ring test, the competitive ELISA still lacks a convenient reference for the quantitation of gluten peptides in fermented cereal foods (e.g., sourdough products, starch syrup, malt extracts, beer). Therefore, the aim of the present study was to prepare a suitable reference for the quantitation of partially hydrolyzed gluten in fermented wheat, rye, and barley products. The prolamin fractions from barley (hordein) and rye (secalin) were isolated from corresponding flours by means of a modified preparative Osborne fractionation. The prolamin fraction from wheat was obtained as reference gliadin from the Prolamin Working Group. The prolamin fractions were successively digested by pepsin and trypsin or pepsin and chymotrypsin procedures, which have been used for CD-specific toxicity tests on cereal storage proteins for many years. The protein/peptide content (N × 5.7) of the prolamin fractions and digests, which was the basis for the calculation of the gluten content by means of ELISA, varied between 67.1% and 96.0%. The prolamin fractions and enzymatic digests were then tested for their response in both sandwich and competitive assays. Intact prolamins responded similarly in both ELISA showing no important differences between the cereals. In the case of digested proteins, however, the sandwich ELISA was considerably less sensitive than the competitive ELISA. The former provided approximately 40% and the latter 70% of the signal intensity obtained with the intact prolamins. Thus, the combination of the competitive ELISA and the enzymatic digests of prolamin fractions as reference was considered to be an adequate system for the analysis of partially hydrolyzed gluten. The limit of detection using a peptic-tryptic hordein digest as reference was 2.3 µg prolamin equivalent per milliliter, and the limit of quantitation was 6.7 µg prolamin equivalent per milliliter. This system was applied for the determination of gluten equivalents in five commercial beverages based on fermented cereals. Figure Schematic representation of a competitive ELISA (top) and examples for the measurement of the prolamin content of different samples and references (bottom)
Keywords: Celiac disease; Gluten-free diet; Gluten content; ELISA

Developmental aspects of amperometric ATP biosensors based on entrapped enzymes by Cornelia Weber; Estelle Gauda; Boris Mizaikoff; Christine Kranz (1729-1735).
A novel concept for a dual-enzyme-based microbiosensor for the detection of adenosine-5′-triphosphate (ATP) was developed. The employed enzymes pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) and hexokinase were entrapped, using pH-shift-induced precipitation of electrodeposition paint (EDP) at platinum microelectrodes (diameter of 25 µm). PQQ-GDH is known showing a superior activity for glucose conversion at the relevant conditions (low oxygen concentration) for ATP detection in targeted biomedical studies. For immobilizing the two enzymes PQQ-GDH and hexokinase, the deposition conditions of EDP Resydrol AY498w/35WA were adapted to ensure high immobilization rates. Prior to ATP sensing, the conversion of glucose, which is the co-substrate for both enzymatic reactions, was optimized. Optimization was targeted towards ATP measurements in biomedical environments by optimizing the PQQ-GDH sensor for glucose. Therefore, different mediators were tested regarding their electron transfer rate and their compatibility with the enzyme: free-diffusing N-methylphenazonium methyl sulfate (PMS) and ferrocenemethanol, and an immobilized chromium hexacyanoferrate layer at platinum electrode. Free-diffusing ferrocenemethanol reveals high sensitivity towards glucose of 1.5 ± 0.4 nA/mM. In a next step, hexokinase was co-entrapped in the polymer film resulting in a sensitivity of up to 290 pA/µM.
Keywords: ATP; Microbiosensor; PQQ-glucose dehydrogenase; Hexokinase; Resydrol

Analytical approach for characterization of cadmium-induced thiol peptides—a case study using Chlamydomonas reinhardtii by Anja Bräutigam; Dirk Schaumlöffel; Gerd-Joachim Krauss; Dirk Wesenberg (1737-1747).
Phytochelatins (PC) were described earlier to play a role in metal detoxification in Chlamydomonas reinhardtii but were not clearly identified. The focus of this case study was to identify PC synthesized by C. reinhardtii exposed to Cd. Only low intracellular concentrations of cadmium (85 nmol g−1 fresh weight) were sufficient to cause significant changes in thiol peptide pools. Thus, results showed a progressive decline of the glutathione content, accompanied by an induction of phytochelatins. Not only canonic phytochelatins but for the first time also the iso-phytochelatins CysPC n and PC2Ala were identified in this unicellular green alga using electrospray ionization quadrupole time-of-flight tandem mass spectrometry. Additionally, CysPC n desGly, PC n desGly, CysPC n Glu, and PC2Glu were found throughout MS analysis. Also, low abundant PCs could be detected due to the high sample preconcentration combined with little sample amounts (0.3 μL min−1) necessary for electrospray. Identified PCs had a maximum number of 5 γ-glutamyl cysteine (γ-GluCys) units. Thiol peptides of higher molecular masses suggesting PC n with n > 5 could be identified as intermolecular oxidation products of smaller PCs. Thiols may easily be oxidized. Therefore, PCs were reduced prior to MS analysis. Dithiothreitol and tris(2-carboxyethyl) phosphine were compared concerning their reduction effort. Figure Chlamydomonas reinhardtii synthesizes isoforms of phytochelatins.
Keywords: Cadmium; Chlamydomonas ; Thiols; Iso-phytochelatins; DTT; TCEP

Comprehensive analysis of the substitution pattern in dextran ethers with respect to the reaction conditions by Antje Vollmer; Kristin Voiges; Christian Bork; Kathrin Fiege; Katja Cuber; Petra Mischnick (1749-1768).
Dextrans from Leuconostoc ssp., α-1,6-linked glucans branched at O-3, were O-methylated in DMSO with lithium dimsyl and methyl iodide under various conditions. Methyl substituent distribution was comprehensively studied in the terminal, internal, and branched glucosyl units and along and over the dextran macromolecules. The order of reactivity was O-2 > O-4 ≥ O-3. The methyl pattern in the glucosyl units significantly deviates from a random distribution with enhanced amounts of un- and trisubstituted moieties. This deviation was found to proceed on macromolecular level by means of ESI-MS of perdeuteromethylated and partially depolymerized methyl dextrans. Heterogeneity was much more pronounced than for methyl amylose prepared under comparable conditions. DS gradients in and over the material are discussed with respect to dextran structure and the mechanism of Li dimsyl alkylation. For comparison, cyanoethyl dextrans were prepared by sodium hydroxide catalyzed addition of acrylonitrile. Monomer analysis of cyanoethyl dextrans revealed that this thermodynamically controlled reaction gave a random substitution pattern with 48% of cyanoethyl groups at O-2, 33% at O-4, and 19% at O-3. Figure Analysis of the monomer pattern of methyl dextran and comparison with a random model
Keywords: Biomaterials; GC; Mass spectrometry; Polymers

A novel analytical tool for quantification of estrogenicity in river water based on fluorescence labelled estrogen receptor α by Alexander Fabian Le Blanc; Christiane Albrecht; Tomas Bonn; Peter Fechner; Günther Proll; Florian Pröll; Mats Carlquist; Günter Gauglitz (1769-1776).
A novel combined procedure for estrogen-affinity purification and labelling of estrogen receptor α ligand-binding domain with Cy™ 5.5 cystein reactive dye was established. By using this procedure, mainly functional proteins are recovered. It can be easily adapted to a large variety of other proteins for which ligand-coated affinity materials are available. The labelled receptor was used in a total internal reflection fluorescence-based binding inhibition assay for determination of the impact of pollutants in river water on the receptor. The great advantage compared to conventional methods is that the total effect on the receptor is measured instead of concentrations of single compounds and that even currently unknown ligands are found as well. Therefore, the obtained signal is related to the response of the organism, which is exposed to the water. The limit of detection was found to be 0.139 nM of estradiol equivalents. The assay also provides a highly sensitive tool for pharmaceutical research and can be adapted to diagnostic applications. Figure Schematic illustration of the combined affinity purification and labelling procedure for ERα-LBD. a E2-derivatised sepharose gel. b ERα-LBD bound to E2–sepharose; other components from the bacterial lysate are removed in the following washing steps. c Labelling with Cy™ 5.5 followed by carboxymethylation. Excess of reagents as well as denatured protein material are removed by washing. d Elution of the receptor without addition of ligand
Keywords: Estrogen receptor α; Advanced protein labelling; Endocrine-disrupting chemicals (EDC); River water; Environmental monitoring; Response-related analytics

Wafers with varying concentrations of diphenhydramine hydrochloride (DPH-HCl) as active pharmaceutical ingredient (API) were prepared and their near infrared (NIR) and Raman spectra recorded. The purpose of this study was to compare the suitability of these two vibrational spectroscopic techniques for the quantification of DPH-HCl in pharmaceutical wafers. Partial least squares (PLS1) calibration models with different data pretreatments were tested. Both NIR and Raman spectroscopy proved to be suitable to predict DPH-HCl contents at lower concentration ranges. At higher concentrations, interference by crystallization processes was observed. For investigating the general applicability of the quantification methods, two commercially available products were examined.
Keywords: Raman spectroscopy; Near infrared spectroscopy; Active pharmaceutical ingredient (API) quantification; Pharmaceutical wafers; Thin strips; Crystallization; Process analytical technology (PAT)

Determination of the polar pesticide degradation product N,N-dimethylsulfamide in aqueous matrices by UPLC–MS/MS by Sebastian Kowal; Peter Balsaa; Friedrich Werres; Torsten C. Schmidt (1787-1794).
This study presents a fast, sensitive, and robust method for the determination of the polar pesticide degradation product N,N-dimethylsulfamide (DMS) in water based on ultraperformance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). To provide a robust analysis method, the use of an internal standard for both natural waters and model water was examined in order to compensate for matrix effects. The relative standard deviation was found to be ±15% (n = 10) and the limit of detection was 10 ng/L by direct injection in the UPLC–MS/MS system. The only sample preparation step required is the addition of the internal standard. The chromatographic analysis of one sample takes 4 min and thus is applicable for economic routine laboratory work. More than 600 samples of drinking water, surface water, and groundwater have been examined successfully with this method in the Rhine and Ruhr region of North Rhine Westphalia (Germany). Approximately 65% of analyzed samples contained measurable amounts of DMS at concentrations up to 63 µg/L. Figure Overview of N,N-dimethylsulfamide (DMS) concentrations in various environmental water samples
Keywords: Pesticides; Water; Degradation products; LC–MS/MS; Ion suppression; Matrix effects

Real-time trace detection of security-relevant compounds in complex sample matrices by thermal desorption–single photon ionization–ion trap mass spectrometry (TD-SPI-ITMS) Spectrometry (TD-SPI-ITMS) by Elisabeth Schramm; Jasper Hölzer; Michael Pütz; Rasmus Schulte-Ladbeck; Rainer Schultze; Martin Sklorz; Andreas Ulrich; Jochen Wieser; Ralf Zimmermann (1795-1807).
For the detection of security-relevant substances at low concentrations in complex matrices, coupling of thermal desorption–single photon ionization–ion trap mass spectrometry (TD-SPI-ITMS) was successfully tested. The main advantage of taking solid samples with a wipe pad followed by thermal desorption is the low detection limit by enhanced vapor pressure. Single photon ionization is a soft ionization technique which reduces the target ion fragmentation and shields bulk components with high ionization energies (IE) like nitrogen yielding to clearly arranged mass spectra with significant high mass peaks. To obtain low false-positive and false-negative rates, especially necessary for security-relevant substances, the ion trap mass spectrometer allows identification of signals with MS/MS studies. In this concept, the soft ionization technique fits well with the MS/MS studies, as peaks with high masses are generated yielding significant MS/MS fragments. For the ionization, photon energies between about 8 eV (155 nm) and 12 eV (103 nm) were generated with electron-beam-pumped rare gas excimer lamps (EBEL). Depending on the rare gas used, light with different photon energy is generated, adapted to the substances of interest. So, even most narcotics, having relatively low IEs, can be ionized with 8.4 eV photons without massive fragmentation. For most explosives, photons with higher energy must be used as their IEs are higher. In this work, a mobile setup with a commercial ion trap mass spectrometer has been developed and tested. Even a first real-scenario measurement campaign was accomplished successfully proving the field-suitability of the system.
Keywords: Single photon ionization; Security-relevant substances; Ion trap mass spectrometry; Trace detection; MS/MS; Excimer light source

Monitoring carbamazepine in surface and wastewaters by an immunoassay based on a monoclonal antibody by Arnold Bahlmann; Michael G. Weller; Ulrich Panne; Rudolf J. Schneider (1809-1820).
The pharmaceutical compound carbamazepine (CBZ) is an emerging pollutant in the aquatic environment and may potentially be used as a wastewater marker. In this work, an enzyme-linked immunosorbent assay (ELISA) for the detection of carbamazepine in surface and sewage waters has been developed. The heterogeneous immunoassay is based on a commercially available monoclonal antibody and a novel enzyme conjugate (tracer) that links the hapten via a hydrophilic peptide (triglycine) spacer to horseradish peroxidase. The assay achieves a limit of detection of 24 ng/L and a quantitation range of 0.05–50 μg/L. The analytical performance and figure of merits were compared to liquid chromatography–tandem mass spectrometry after solid-phase extraction. For nine Berlin surface water samples and one wastewater sample, a close correlation of results was observed. A constant overestimation relative to the CBZ concentration of approximately 30% by ELISA is probably caused by the presence of 10,11-epoxy-CBZ and 2-hydroxy-CBZ in the samples. The ELISA displayed cross-reactivities for these compounds of 83% and 14%, respectively. In a first screening of 27 surface water samples, CBZ was detected in every sample with concentrations between 0.05 and 3.2 μg/L. Since no sample cleanup is required, the assay allowed for the determination of carbamazepine with high sensitivity at low costs and with much higher throughput than with conventional methods. Figure Left: Results from surface water analysis by carbamazepine ELISA; Right: Structure of the enzyme conjugate synthesized
Keywords: Carbamazepine; ELISA; Antibody; Immunoassay; Surface water; LC–MS/MS; Pharmaceuticals

Fluorescent polyacrylamide nanoparticles for naproxen recognition by Alejandro Lapresta-Fernández; Piotr J. Cywinski; Artur J. Moro; Gerhard J. Mohr (1821-1830).
We present the synthesis of fluorescent acrylamide nanoparticles (FANs) capable of recognizing non-steroidal anti-inflammatory drugs (NSAIDs) in buffered aqueous solutions. Within this important group, we selected naproxen, one of the 2-arylpropionic acids (profens), due to its use for the treatment of moderate pain, fever, and inflammation. The nanosensors were prepared under mild conditions of inverse microemulsion polymerization using aqueous acrylamide as the monomer and N,N′-methylenebisacrylamide as the cross-linker, employing the surfactants polyoxyethylene-4-lauryl ether (Brij®30) and sodium bis(2-ethylhexyl)sulfosuccinate in hexane. Furthermore, a fluorescent monomer, (E)-4-[4-(dimethylamino)styryl]-1-[4-(methacryloyloxymethyl)benzyl]pyridinium chloride (mDMASP) has been synthesized and incorporated into the nanoparticles. The nanosensors exhibit a broad absorbance at around 460 nm and a structureless fluorescence band with maximum at 590 nm in 0.5 M phosphate buffer (pH = 7.2). The recognition process is performed on the basis of ionic interactions which are monitored by the fluorescence increase at 590 nm upon addition of different concentrations of naproxen. The FANs show a size distribution in the range of 20–80 nm, with a hydrodynamic diameter of 34 nm. In order to assess the selectivity of the FANs, a systematic study was conducted on the effect produced by drugs and biomolecules that could interfere with the analysis of naproxen.
Keywords: Acrylamide nanoparticles; Naproxen determination; Fluorescent nanosensors; Inverse microemulsion polymerization

Electrokinetic sample extraction and enrichment is introduced as a newly developed concept for the analysis of substances in sludge-type or paste-like matrices. It is based on electrokinetic transport phenomena as electromigration and electroosmosis occurring when an electrical field is applied to the fresh, wet samples. Problems usually associated to sample drying can be avoided, e.g., losses of volatile analytes or contamination. We have designed and built a suitable apparatus for electrokinetic sample extraction and enrichment. Appropriate operating conditions (field strength, buffer composition, concentration, and volume) were identified in experiments with an artificial sludge model and real-world lake sediments. A proof of principle of the method was provided by the electromigrative extraction and online enrichment on a solid-phase sorbent disk of an azo dye from a diatomaceous earth slurry. Electroosmotic extraction and enrichment of a cyanobacterial hepatotoxin at trace levels was finally investigated as an application example using lake sediments. Rather clean extracts were obtained even with high organic content sediment samples, as shown by high-performance liquid chromatography with diode array detection. Figure Schematic representation of the principles of electrokinetic sample extraction and enrichment.
Keywords: Extraction; Electroosmosis/electromigration; Wet sludge-type samples; Sediments; Evans Blue; Microcystin-RR

Capillary electrophoresis (CE) was used to separate polycyclic aromatic sulfur heterocycles (PASHs), a class of compounds that occurs in fossil fuels and refined products of petroleum. An electric charge was introduced into the compounds through methylation or phenylation of the sulfur atom. Separations of standard PASHs that are expected to be present in industrially desulfurized fuels showed that CE possessed a higher resolution than reversed phase liquid chromatography. The CE method can separate all the monomethylbenzothiophenes; this is not achieved in capillary gas chromatography. A linear relationship was found between migration time and the calculated volume of the compounds. The PASHs in deeply desulfurized diesel were separated after preconcentration, and the electropherogram was compared with the chromatograms from GC and HPLC. Finally, derivatized PASHs are often enantiomeric and the enantiomers can be separated if a suitable cyclodextrin is added to the running buffer.
Keywords: Capillary electrophoresis; Polycyclic aromatic sulfur heterocycles; Diesel fuel; Methyl thiophenium salts; Cyclodextrins; Enantiomeric separation

Chemical causes of the typical burnt smell after accidental fires by Katharina Heitmann; Hubertus Wichmann; Müfit Bahadir (1853-1865).
The components responsible for the typical burnt smell that occurs after accidental fires (e.g. in buildings) were identified. For this purpose, samples of odorous materials were taken from different real fire sites. Their volatile fractions were analysed by means of thermal desorption, headspace analysis and solid-phase microextraction (SPME) combined with gas chromatography–mass spectrometry (GC/MS). Measurements performed with SPME gave the highest number of analytes as well as the highest signal intensities. A divinylbenzene/carboxen/polydimethylsiloxane SPME fibre was found to be the most suitable for this task. To distinguish the odour-active compounds from the ca. 1,400 identified volatiles concentrated by SPME, an olfactory detection port was attached to the GC/MS and the column effluent was assessed by panellists. The results revealed that eleven odorous compounds were present in most of the investigated samples: acetophenone, benzyl alcohol, 4-ethyl-2-methoxyphenol, 2-hydroxybenzaldehyde, 2-hydroxy-5-methylbenzldehyde, 2-methoxyphenol, 2-methoxy-4-methylphenol, 2-methylphenol, 3-methylphenol, 4-methylphenol and naphthalene. Their odour activities were confirmed in additional olfactory experiments, and the relative ratios of these eleven compounds were determined. Based on these ratios, standard solutions that presented an intense odour with typical characteristics of the burnt smell were produced.
Keywords: Accidental fire; Burnt smell; Olfactory detection; GC/MS-O; SPME

CCD camera image analysis for mapping solute concentrations in saturated porous media by Stefanie Jaeger; Markus Ehni; Christina Eberhardt; Massimo Rolle; Peter Grathwohl; Guenter Gauglitz (1867-1876).
This paper presents an optical approach, based on the use of a low-cost charge-coupled device (CCD) camera, for the quantitative determination of solute concentrations in saturated porous media. The method is applied to evaluate tracer experiments carried out in a laboratory model tank. The CCD photos deliver RGB values which are transferred into concentrations for the evaluation of vertical concentration profiles over the whole tank area. A specially developed evaluation procedure, including internal referencing for noise reduction, considers the colour of the adjacencies of the evaluated spots and scattering effects. The CCD data evaluation technique is accompanied by conventional sampling and absorption measurements and by numerical flow and transport simulations. This non-invasive technique allows a direct mapping of the concentration distribution without any disturbance of the solute plume. Therefore, it turns out to be an important tool for a detailed investigation of fundamental processes (e.g. transverse dispersion) determining the solute (e.g. contaminant) transport in porous media. Figure CCD camera set-up for solute concentration mapping in saturated porous media
Keywords: Optical sensor; Imaging; Porous media; Colour tracer; Numerical modelling

In this study, a method for the determination of organic micro-pollutants, i.e. personal care products such as synthetic musk fragrances, household bactericides, organophosphate flame retardants and plasticizers, as well as phthalates in sludge, has been developed. This method is based on lyophilisation and accelerated solvent extraction followed by clean-up steps, i.e. solid phase extraction and size exclusion chromatography. The determination is performed by gas chromatography coupled to mass spectrometry. Stable isotope-labelled compounds such as musk xylene (MX D15), tri-n-butylphosphate (TnBP D27) and triphenylphosphate (TPP D15) were used as internal standards. Recovery rates were determined to be 36–114% (with typical relative standard deviation of 5% to 23%) for the target compounds. The limit of detection was 3–30 ng g−1, and the limit of quantification was 10–100 ng g−1 dry matter.
Keywords: Personal care products; Musk fragrances; Triclosan; Household bactericides; Organophosphates; Phthalates

Electrochemical reduction of the iodinated contrast medium iomeprol: iodine mass balance and identification of transformation products by Christian Zwiener; Thomas Glauner; Jochen Sturm; Michael Wörner; Fritz H. Frimmel (1885-1892).
Potentiostatic-controlled electrochemical reduction of iomeprol was used to deiodinate iomeprol (IMP), a representative of the iodinated X-ray contrast media. The reduction process was followed by product analysis with liquid chromatography-electrospray ionization-tandem mass spectrometry and ion chromatography-inductively coupled plasma-mass spectrometry. The identification is mainly based on the interpretation of the mass fragmentation. The product analysis showed a rather selective deiodination process with the successive occurrence of IMP-I, IMP-2I, IMP-3I, and a transformation product (TP), respectively. The TP was formed from IMP-3I by a further cleavage of an amide bond and release of a (C = O)CHOH group from the side chain of IMP. The iodine mass balance on the basis of IMP and iodide showed a gap of about 26% at the beginning of the electrolysis process which could be completely closed by taking the intermediates IMP-I and IMP-2I into consideration. This means that the major intermediates and the TPs were considered and that the reduction process is a rather selective one to remove organically bound iodine from X-ray contrast media. An attractive application area would be the electrochemical deiodination of X-ray contrast media in urine of patients or hospital effluents. Mass fragmentation of iomeprol and its deiodination products
Keywords: Electrolysis; Cathodic dehalogenation; Iodine mass balance; Mass-spectrometric fragmentation

DC- and RF-GD-OES measurements of adsorbed organic monolayers on copper by Denis Klemm; Volker Hoffmann; Klaus Wetzig; Jürgen Eckert (1893-1900).
Our direct current (DC)- and radiofrequency glow discharge optical emission spectroscopy (RF-GD-OES) measurements of adsorbed organic monolayers were inspired by the work of Shimizu et al., who presented the first example of depth profile analysis of an adsorbed monolayer by RF-GD-OES in 2004. The great potential of RF-GD-OES for analyses of layers with thicknesses in the subnanometer range was surprising. Shimizu et al. discussed not only the qualitative detection of atoms of the organic monolayer (C, H, N, S), but also the determination of the different orientation of the molecules relative to the surface due to a significant peak sequence. This latter assumption was questioned in the analytical community. We intend to demonstrate the potential of the GD-OES technique for surface analysis in terms of reliability and reproducibility by using an advanced vacuum instrumentation and presputtering with silicon. It will be shown that comparable measurements can be reproduced not only with RF-GD-OES but, above all, also with DC-GD-OES. The experimental steps to adsorb thiourea molecules on a copper substrate are described in detail. Further experiments with other organic molecules, e.g. benzotriazole (BTA) or benzothiazole (BTH), disprove the predicted correlation between the orientation of the molecules relative to the surface and the occurrence of peak separation. Ultimately, a quantification of compounds of the organic monolayer in the case of adsorbed thiourea is achieved. Figure DC-GD-OES surface depth profiles of an adsorbed monolayer of thiourea
Keywords: GD-OES; Thiourea; Benzotriazole; Benzothiazole; Monolayer; Copper; Thin films; Depth profiling

Speciation of BC x N y films grown by PECVD with trimethylborazine precursor by Olaf Baake; Peter S. Hoffmann; Andreas Klein; Beatrix Pollakowski; Burkhard Beckhoff; Marina L. Kosinova; Nadeshda I. Fainer; Veronica S. Sulyaeva; Valentina A. Trunova; Wolfgang Ensinger (1901-1909).
Films of BC x N y were produced in a plasma-enhanced chemical vapor deposition process using trimethylborazine as precursor and with H2, He, N2, and NH3, respectively, as auxiliary gas. These films deposited on Si(100) wafers or fused quartz glass substrates were characterized chemically by X-ray photoelectron spectroscopy and by synchrotron radiation-based total-reflection X-ray fluorescence combined with near-edge X-ray absorption fine structure. Independent of the auxiliary gas, the B–N bonds are dominating. Furthermore, B–C and N–C bonds were identified. Oxygen, present in the bulk (in contrast to the surface layer of some nanometers, where molecular oxygen and/or water are absorbed) as an impurity, is bonded to boron or to carbon, respectively. The relation of boron and nitrogen changes with the character of the auxiliary gas: c B/c N ≈ 4:3 (for H2 and He) and c B/c N ≈ 1 (for N2 or NH3). Furthermore, physical properties such as the refractive index and the optical band-gap energy were determined.
Keywords: Boron carbonitride; Synthesis; PECVD; XPS; NEXAFS

Micro-particles containing actinides are of interest for risk assessments of contaminated areas, nuclear forensic analyses, and IAEA as well as Euratom safeguards programs. For their analysis, secondary ion mass spectrometry (SIMS) has been established as the state-of-the-art standard technique. In the case of actinide mixtures within the particles, however, SIMS suffers from isobaric interferences (e.g., 238U/238Pu, 241Am/241Pu). This can be eliminated by applying resonance ionization mass spectrometry which is based on stepwise resonant excitation and ionization of atoms with laser light, followed by mass spectrometric detection of the produced ions, combining high elemental selectivity with the analysis of isotopic compositions. This paper describes the instrumental modifications for coupling a commercial time-of-flight (TOF)-SIMS apparatus with three-step resonant post-ionization of the sputtered neutrals using a high-repetition-rate (kHz) Nd:YAG laser pumped tunable titanium:sapphire laser system. Spatially resolved ion images obtained from actinide-containing particles in TOF-SIMS mode demonstrate the capability for isotopic and spatial resolution. Results from three-step resonant post-ionization of bulk Gd and Pu samples successfully demonstrate the high elemental selectivity of this process.
Keywords: SIMS; Resonance ionization; Micro-particles; Actinides

The concentration of platinum group elements (PGE) in the environment has increased significantly in the last 20 years mainly due to their use as catalysts in automotive catalytic converters. The quantitation of these metals in different environmental compartments is, however, challenging due to their very low concentrations and the presence of interfering matrix constituents when inductively coupled plasma-mass spectrometry (ICP-MS) is used for analysis. Previously, the research focus was on the analysis of platinum (Pt) and rhodium (Rh). However, due to the increasing use of palladium (Pd) in automotive catalytic converters, quantitation of this element in airborne particulate matter (PM) is also needed. Compared to Pt and Rh, measurements of Pd using ICP-MS are plagued by greater molecular interferences arising from elements such as copper (Cu), zinc (Zn) strontium (Sr), yttrium (Y), and zirconium (Zr). The aim of this study was to evaluate the applicability of reductive co-precipitation procedures using both mercury (Hg) and tellurium (Te) for the pre-concentration of Pd from airborne PM. Furthermore, helium (He) was tested as a collision gas for isotope dilution-inductively coupled plasma-quadrupole-mass spectrometry (ID-ICP-Q-MS) to measure Pd in the Hg and Te precipitates. Airborne PM samples (PM10) were collected from Neuglobsow (Brandenburg, north-eastern Germany) and Deuselbach (Rhineland-Palatinate, south-western Germany), considered to represent background levels, and from the city Frankfurt am Main (Hesse, Germany), a high-traffic area. Samples were first digested with aqua regia in a high-pressure asher (HPA) at 320 °C and 130 bar prior to the application of reductive co-precipitation procedures. The method was validated with road dust reference material BCR-723 and the CANMET-CCRMP reference material TDB-1 and WPR-1. In airborne PM collected at the background areas Neuglobsow and Deuselbach, Pd was detected with median concentrations values of 0.5 and 0.6 pg/m3, respectively. Much higher median concentration values of 14.8 pg Pd/m3 (detection limit = 0.01 pg Pd/m3) were detected in samples collected in the city of Frankfurt am Main. Results have shown that Hg co-precipitation depletes the concentrations of interfering matrix constituents by at least one order of magnitude more, compared to Te co-precipitation, making it a more effective method for the isolation and pre-enrichment of Pd from airborne PM prior to analysis. The use of a He gas flow of 120 ml/min in the plasma further minimized interferences, particularly those arising from CuAr+, YO+, and ZrO+ during the determination of Pd. The results demonstrate that Hg co-precipitation and the use of He collision gas, in combination with isotope dilution, are highly effective methods for the quantitation of Pd in airborne PM using ICP-MS. Figure Palladium concentration in air [pg/m3] (min–max, 25–75%, median) calculated from PM10 in urban area (Frankfurt am Main) and rural area (Deuselbach and Neuglobsow)
Keywords: Mercury co-precipitation; Collision gas; ID-ICP-Q-MS; Platinum group elements; Palladium

Detoxification of mercury species—an in vitro study with antidotes in human whole blood by Stefan Trümpler; Sascha Nowak; Björn Meermann; Gerhard A. Wiesmüller; Wolfgang Buscher; Michael Sperling; Uwe Karst (1929-1935).
To investigate the effects of mercury species intoxication and to test the efficiency of different commonly applied antidotes, human whole blood and plasma surrogate samples were spiked with inorganic mercury (Hg2+) and methylmercury (MeHg+, CH3Hg+) prior to treatment with the antidotes 2,3-dimercaptopropan-1-ol (British Anti Lewisite), 2,3-dimercaptosuccinic acid (DMSA), and N-acetylcysteine (NAC). For mercury speciation analysis in these samples, liquid chromatography was coupled to either inductively coupled plasma mass spectrometry (ICP-MS) or electrospray ionisation time-of-flight mass spectrometry (ESI-TOF-MS). Adduct formation between mercury species and physiological thiols (cysteine and glutathione) was observed as well as the release of glutathione under treatment with the antidotes DMSA and NAC.
Keywords: Mercury; Methylmercury; Speciation analysis; Human whole blood; Antidotes; Intoxication

Detection of angiotensin II type 1 receptor ligands by a cell-based assay by Matthias Grießner; Patrick Bröker; André Lehmann; Eva Ehrentreich-Förster; Frank F. Bier (1937-1940).
This work describes a cell-based assay that does not depend on radioactivity or laboratory animals for the detection of ligands of angiotensin II type 1 receptor (AT1R). The assay makes use of stable transfected Chinese hamster ovary cells (CHO-AT1R) expressing the AT1R. A sequential saturation assay principle was used in which receptor binding sites of the CHO-AT1R cells are blocked by the analyte in a concentration-dependent manner. Afterwards, TAMRA-angiotensin II, a fluorescence-labeled ligand, was added to bind to the remaining free binding sites of the receptor. In consequence, the fluorescence signal determined is inversely proportional to the concentration of the analyte.
Keywords: Angiotensin receptor; Biosensor; Chinese hamster ovary cells; Biochip; Sartans; Angiotensin II type 1 receptor ligands cell-based assay