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Analytical and Bioanalytical Chemistry (v.379, #2)

Isotopic and nuclear analytical techniques for health and environment by M. Rossbach; P. De Regge; G.V. Iyengar (pp. 179-180).

A future for nuclear analytical techniques? Why not? by P. Bode (pp. 181-187).

The choices of universities and national research institutions in supporting scientific research are increasingly justified on the basis of, amongst others, the relevance that has to be reflected by external, preferably sustainable funding of the research programs. Many traditional fields of application such as environmental sciences do not offer a promising outlook in this respect. As a consequence, university research reactors face closure because of reallocations of university funds to more contemporary sciences such as molecular biology and nanotechnology. Therefore, laboratories operating nuclear analytical techniques (NAA, (TR)XRF, and PIXE) need to use their creativity in finding ways for participation in, for example, nanotechnology, cancer research, or genomics. This requires an open mind in terms of the opportunities, strengths, and weaknesses of the techniques, and a departure of technique-oriented research towards problem-oriented research in which other nuclear techniques can be used. The unique features of radiotracers, nuclear imaging, and nuclear beam techniques are discussed in view of the new areas mentioned above. Some examples of opportunities for nuclear analytical techniques in the above-mentioned fields are given.

Use of D–T-produced fast neutrons for in vivo body composition analysis: a reference method for nutritional assessment in the elderly by J. J. Kehayias (pp. 188-191).

Body composition has become the main outcome of many nutritional intervention studies including osteoporosis, malnutrition, obesity, AIDS, and aging. Traditional indirect body composition methods developed with healthy young adults do not apply to the elderly or diseased. Fast neutron activation (for N and P) and neutron inelastic scattering (for C and O) are used to assess in vivo elements characteristic of specific body compartments. Non-bone phosphorus for muscle is measured by the ³¹P(n,α)²⁸Al reaction, and nitrogen for protein via the ¹⁴N(n,2n)¹³N fast neutron reaction. Inelastic neutron scattering is used to measure total body carbon and oxygen. Body fat is derived from carbon after correcting for contributions from protein, bone, and glycogen. Carbon-to-oxygen ratio (C/O) is used to measure the distribution of fat and lean tissue in the body and to monitor small changes of lean mass. A sealed, D–T neutron generator is used for the production of fast neutrons. Carbon and oxygen mass and their ratio are measured in vivo at a radiation exposure of less than 0.06 mSv. Gamma-ray spectra are collected using large BGO detectors and analyzed for the 4.43 MeV state of carbon and 6.13 MeV state of oxygen, simultaneously with the irradiation. P and N analysis by delayed fast neutron activation is performed by transferring the patient to a shielded room equipped with an array of NaI(Tl) detectors. A combination of measurements makes possible the assessment of the “quality” of fat-free mass. The neutron generator system is used to evaluate the efficacy of new treatments, to study mechanisms of lean tissue depletion with aging, and to investigate methods for preserving function and quality of life in the elderly. It is also used as a reference method for the validation of portable instruments of nutritional assessment.

Keywords: Neutron activation; Neutron inelastic scattering; Muscle; Protein; Nitrogen; Aging; D–T

Prompt-gamma neutron activation analysis facility for in vivo body composition studies in small animals by I. E. Stamatelatos; K. Kasviki; S. Green; M. Gainey; J. Kalef-Ezra; A. Beddoe (pp. 192-197).

The design, calibration, dosimetry and performance evaluation of a prompt-gamma neutron activation analysis facility for in vivo body composition studies in small animals (i.e. rats or rabbits) is discussed. The system design was guided by Monte Carlo transport calculations using MCNP-4C code. A system was built and performance evaluation was made using a 185-GBq Pu-Be neutron source. Prompt-gamma rays produced by neutron capture reactions were detected by a combination of a NaI(Tl) scintillation and a HPGe semiconductor detectors. Nitrogen and chlorine were quantified by analysis of the 10.83-MeV and 6.11-MeV peaks, respectively. Appropriate corrections for the animal body size were determined. The facility described allows the in vivo determination of protein and extracellular space in sets of experimental animals.

Improving tritium exposure reconstructions using accelerator mass spectrometry by A. H. Love; J. R. Hunt; J. S. Vogel; J. P. Knezovich (pp. 198-203).

Direct measurement of tritium atoms by accelerator mass spectrometry (AMS) enables rapid low-activity tritium measurements from milligram-sized samples and permits greater ease of sample collection, faster throughput, and increased spatial and/or temporal resolution. Because existing methodologies for quantifying tritium have some significant limitations, the development of tritium AMS has allowed improvements in reconstructing tritium exposure concentrations from environmental measurements and provides an important additional tool in assessing the temporal and spatial distribution of chronic exposure. Tritium exposure reconstructions using AMS were previously demonstrated for a tree growing on known levels of tritiated water and for trees exposed to atmospheric releases of tritiated water vapor. In these analyses, tritium levels were measured from milligram-sized samples with sample preparation times of a few days. Hundreds of samples were analyzed within a few months of sample collection and resulted in the reconstruction of spatial and temporal exposure from tritium releases. Although the current quantification limit of tritium AMS is not adequate to determine natural environmental variations in tritium concentrations, it is expected to be sufficient for studies assessing possible health effects from chronic environmental tritium exposure.

Keywords: Tree rings; Tritiated; Water vapor; Groundwater

Non-exchangeable organically bound tritium (OBT): its real nature by F. Baumgärtner; W. Donhaerl (pp. 204-209).

Denaturation experiments show that the larger part of organically bound tritium (OBT) consists of “buried tritium” and is not bound to carbon, as has been traditionally assumed. The logistical growth analysis of hydrogen isotopes in dry plant matter reveals a larger rate of increase of OBT than organically bound hydrogen (OBH). This is reflected by tritium accumulation for 1.4 and 2 in the primary hydration shell and in the base-pairing hydrogens of DNA respectively. If tritons and protons are considered as quantum mechanical entities, the accumulative tritium transfer from water to the hydrogen bonds of biopolymers is generally valid. Growth experiments confirm the assumed rapid isotope exchange “in vivo”, which is not observed “in vitro” by denaturation.

Keywords: OBT; Tritium; Logistical growth analysis; Hydrogen isotope exchange; Hydrogen bonding; DNA; Radiation dose; In vivo

The internal comparator method by X. Lin; R. Henkelmann (pp. 210-217).

An internal comparator method is proposed which offers reliable instrumental neutron activation analysis (INAA) results for samples with an irregular geometry and/or measured at the closest position to the Ge detector. Because the selected internal comparator in the sample analyzed will receive exactly the same thermal neutron flux as the other components, this method can be applied to the INAA of materials suffering from thermal neutron self-shielding. To apply the internal comparator method, the k₀-method must be installed and the analytes, including the internal comparator, should be homogeneously distributed in the test portion.

Keywords: Internal comparator; Internal comparator method; k₀-method; k₀-instrumental neutron activation analysis

Elemental contents in Napoleon’s hair cut before and after his death: did Napoleon die of arsenic poisoning? by Xilei Lin; D. Alber; R. Henkelmann (pp. 218-220).

Whether or not Napoleon died of arsenic poisoning is an open question on which debate has been active since 1960. This work examined several of his hairs, cut at different times and in different places: two pieces cut the day after his death on the island of St. Helena (1821) and two pieces cut seven years earlier (1814) during his first exile on the island of Elba. INAA results show that all of the samples of Napoleon’s hair have an elevated arsenic concentration. These results disfavor the arsenic poisoning theory. Aside from arsenic, 18 other elements are reported, providing additional information for examining the arsenic poisoning theory.

Keywords: Napoleon ; Hair; Arsenic poisoning; INAA; k0-INAA

Metrological assessment of the high-accuracy RNAA method for determination of cobalt in biological materials by H. Polkowska-Motrenko; B. Danko; R. Dybczyński (pp. 221-226).

The paper summarizes work on the development of the high-accuracy RNAA method for the determination of trace amounts of cobalt in biological materials. The method is based on a combination of neutron activation with selective and quantitative isolation of the analyte in a state of high radiochemical purity by use of column chromatography followed by gamma-ray spectrometric measurements. The method was devised according to a set of rules, which were formulated to obtain high accuracy of the method. The procedure has been also equipped with several criteria as key factors in quality assurance. Qualification of the high-accuracy RNAA method as a primary ratio method has been demonstrated and its usefulness in the certification of the candidate reference materials tea leaves and mixed Polish herbs is presented.

Keywords: Radiochemical neutron activation analysis; Primary ratio method of measurement; Cobalt; Biological materials

Simultaneous determination of radionuclides separable into natural decay series by use of time-interval analysis by Tetsuo Hashimoto; Yukihisa Sanada; Yasuhiro Uezu (pp. 227-233).

A delayed coincidence method, time-interval analysis (TIA), has been applied to successive α–α decay events on the millisecond time-scale. Such decay events are part of the ²²⁰Rn→²¹⁶Po (T _1/2 145 ms) (Th-series) and ²¹⁹Rn→²¹⁵Po (T _1/2 1.78 ms) (Ac-series). By using TIA in addition to measurement of ²²⁶Ra (U-series) from α-spectrometry by liquid scintillation counting (LSC), two natural decay series could be identified and separated. The TIA detection efficiency was improved by using the pulse-shape discrimination technique (PSD) to reject β-pulses, by solvent extraction of Ra combined with simple chemical separation, and by purging the scintillation solution with dry N₂ gas. The U- and Th-series together with the Ac-series were determined, respectively, from alpha spectra and TIA carried out immediately after Ra-extraction. Using the ²²¹Fr→²¹⁷At (T _1/2 32.3 ms) decay process as a tracer, overall yields were estimated from application of TIA to the ²²⁵Ra (Np-decay series) at the time of maximum growth. The present method has proven useful for simultaneous determination of three radioactive decay series in environmental samples.

Keywords: Radionuclides; Natural decay series; Time-interval analysis (TIA); α-Spectrometry; Liquid scintillation counting (LSC); Pulse-shape discrimination technique (PSD)

Monitoring ground-level air for trace analysis: methods and results by J. Bieringer; C. Schlosser (pp. 234-241).

Trace analysis enables the sensitive detection of radionuclide concentrations in ground-level air in the range of microbecquerel per cubic meter (μBq m⁻³). Typical sampling intervals of less than one day up to a few days can be used in routine operation. Trace analysis measurements are performed in the framework of the German Integrated Measuring and Information system (IMIS) and the International Monitoring System (IMS) used for verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Within the environmental monitoring programmes of the German IMIS the Federal Office for Radiation Protection (BfS) performs measurements of aerosol-bound radionuclides and of radioactive noble gases in the atmosphere. Aerosols are collected on filters with high-volume air samplers and analysed by γ-spectrometry, α-spectrometry, and integral measurements of β-activity, with preceding radiochemical separation. Noble gas samples from 15 sites world-wide are analysed to observe the ⁸⁵Kr-release from nuclear fuel reprocessing plants and from seven sites in Germany to monitor the ¹³³Xe emitted from nuclear power plants. As part of the International Monitoring System (IMS) of the CTBT an automatic aerosol sampling and measuring system and an automatic noble gas sampling and measuring system will be operated by the BfS at Mount Schauinsland near Freiburg. Because of its expertise in noble gas measurements the BfS had been chosen to perform an intercomparison experiment in the BfS laboratory in Freiburg with several automatic noble gas sampling and measurement systems before their installation at IMS sites. To establish quality-assurance programmes for trace analysis performed for the German IMIS close collaboration between the involved German institutions has been established. First steps have been taken to expand cooperation to other European laboratories. Informal data exchange already occurs between trace-analysis laboratories in Europe (Ring of Five) and helps in cases of enhanced activity concentrations to get a rapid overview of the radiological situation and to identify possible sources.

Keywords: Environmental monitoring; Trace analysis; Radionuclides; Aerosols; Noble gases; CTBT

Carbon sequestration and estimated carbon credit values as measured using ¹³C labelling and analysis by means of an optical breath test analyser by R. C. Hood; M. Khan; A. Haque; M. Khadir; J. P. Bonetto; R. Syamsul; L. Mayr; M. Heiling (pp. 242-246).

Recent developments in optical systems (isotope-selective non-dispersive infrared spectrometry) for breath testing have provided a robust, low-cost option for undertaking ¹³C analysis. Although these systems were initially developed for breath testing for Helicobacter pylori, they have an enormous potential as a soil science research tool. The relatively low cost of the equipment, US$15,000–25,000, is within the research budgets of most institutes or universities. The simplicity of the mechanisms and optical nature mean that the equipment requires relatively low maintenance and minimal training. Thus methods were developed to prepare soil and plant materials for analysis using the breath test analyser. Results that compare conventional mass spectrometric methods with the breath test analyser will be presented. In combination with simple ¹³C-plant-labeling techniques it is possible to devise methods for estimating carbon sequestration under different agronomic management practices within a short time frame. This enables assessment of the carbon credit value of a particular agronomic practice, which can in turn be used by policy makers for decision-making purposes. For global understanding of the effect of agricultural practices on the carbon cycle, data are required from a range of cropping systems and agro-ecological zones. The method and the approach described will enable collection of hard data within a reasonable time.

Keywords: Isotope; Soil; Enrichment; Cowpea; FANci

Assessment of drinking water radioactivity content by liquid scintillation counting: set up of high sensitivity and emergency procedures by R. Rusconi; A. Azzellino; S. Bellinzona; M. Forte; R. Gallini; G. Sgorbati (pp. 247-253).

In our institute, different procedures have been developed to measure the radioactivity content of drinking water both in normal and in emergency situations, such as those arising from accidental and terrorist events. A single radiometric technique, namely low level liquid scintillation counting (LSC), has been used. In emergency situations a gross activity screening is carried out without any sample treatment by a single and quick liquid scintillation counting. Alpha and beta activities can be measured in more than one hundred samples per day with sensitivities of a few Bq/L. Higher sensitivity gross alpha and beta, uranium and radium measurements can be performed on water samples after specific sample treatments. The sequential method proposed is designed in such a way that the same water sample can be used in all the stages, with slight modifications. This sequential procedure was applied in a survey of the Lombardia district. At first tap waters of the 13 largest towns were examined, then a more detailed monitoring was carried out in the surroundings of Milano and Lodi towns. The high sensitivity method for the determination of uranium isotopes was used to check the presence of depleted uranium in Lake Garda. Reduced equipment requirements and relative readiness of radiochemical procedures make LSC an attractive technique which can also be applied by laboratories lacking specific radiochemistry facilities and experience.

ELACH 6: Conference on electroanalytical applications and methods by Günter Trettenhahn (pp. 254-254).

Application of heated electrodes operating in a non-isothermal mode for interference elimination with amperometric biosensors by Carolin Lau; Sabine Reiter; Wolfgang Schuhmann; Peter Gründler (pp. 255-260).

Heated electrodes were applied for the non-isothermal operation of amperometric glucose biosensors based on glucose oxidase immobilised on the electrode surface by entrapment within a polymer layer. The localised deposition of the polymer film under simultaneous entrapment of the enzyme was achieved by an electrochemically induced pH-modulation in the diffusion zone in front of the electrode, thus altering the solubility of the polymer chains. This non-manual sensor preparation protocol could be successfully used for the modification of a novel indirectly heated electrode. The non-isothermal operating mode allows working at the optimum temperature of the enzyme sensors without any thermal distortion of the bulk solution. Increased surface temperature of the sensor thus accelerates transport as well as kinetic processes, resulting in an enhanced amperometric signal.In the presence of interfering compounds such as ascorbic acid, the proposed technique allows use of the diverging thermal impact on the sensing process, for different electrochemically active compounds, for a deconvolution of the amperometric signal at different electrode temperatures. A calculation method for determination of glucose in the presence of one interfering compound is presented as a basis for a calculative interference elimination.

Keywords: Heated electrodes; Glucose biosensor; Interference; Ascorbic acid

Hydrodynamics with heated microelectrodes by Peter Gründler; Andreas Beckmann (pp. 261-265).

Voltammetry with continuously heated microelectrodes yields well-defined sigmoidal current-voltage curves. Unlike hydrodynamic electrodes, the surface temperature of a heated electrode can be adjusted arbitrarily within a certain range. Inside a thermal layer, a virtually stagnant diffusion layer of constant thickness δ _diff exists. δ _diffis independent of temperature within a certain range. On the basis of this theory, equations are derived which play a similar role to, for instance, the Levich equation for the rotating disk electrode. Reasonable agreement of the derived relationship with the results from voltammetric experiments is obtained.

Keywords: Heated electrodes; Voltammetry; Reversible redox couples; Theory; Diffusion-limited current

In-situ FTIR investigations on the reduction of vinylene electrolyte additives suitable for use in lithium-ion batteries by H. J. Santner; C. Korepp; M. Winter; J. O. Besenhard; K.-C. Möller (pp. 266-271).

Lithium-ion batteries operate beyond the thermodynamic stability of the aprotic organic electrolyte used and electrolyte decomposition occurs at both electrodes. The electrolyte must therefore be composed in a way that its decomposition products form a film on the electrodes which stops the decomposition reactions but is still permeable to the Li⁺ cations which are the charge carriers. At the graphite anode, this film is commonly referred to as a solid electrolyte interphase (SEI). Aprotic organic compounds containing vinylene groups can form an effective SEI on a graphitic anode. As examples, vinyl acetate (VA) and acrylonitrile (AN) have been investigated by in-situ Fourier transform infrared (FTIR) spectroscopy in a specially developed IR cell. The measurements focus on electrolyte decomposition and the mechanism of SEI formation in the presence of VA and AN. We conclude that cathodic reduction of the vinylene groups (i.e., via reduction of the double bond) in the electrolyte additives is the initiating and thus a most important step of the SEI-formation process, even in an electrolyte which contains only a few percent (i.e. electrolyte additive amounts) of the compound. The possibility of electropolymerization of the vinylene monomers in the battery electrolytes used is critically discussed on the basis of the IR data obtained.

Keywords: Lithium-ion batteries; Electrolyte additives; Solid electrolyte interphase, SEI; In-situ FTIR; Electrochemical polymerization

Dilatometric and mass spectrometric investigations on lithium ion battery anode materials by M. R. Wagner; P. R. Raimann; A. Trifonova; K.-C. Möller; J. O. Besenhard; M. Winter (pp. 272-276).

Lithium ion batteries operate beyond the thermodynamic stability of the aprotic organic electrolyte used. In 1 M LiClO₄ propylene carbonate electrolyte, with and without the addition of ethylene sulfite as a film forming electrolyte additive, we have used in situ electrochemical dilatometry and on-line electrochemical mass spectrometry to study the volume expansion/contraction of graphitic anodes and the formation of propylene gas, which both can occur during the graphite anode reduction (charge) process. The combination of both methods allows us to get insights into the respective electrolyte reduction mechanisms. The results indicate that the major failure mechanisms of graphitic anodes in pure PC electrolyte can be attributed to the intercalation of solvated lithium ions and the formation of propylene gas, which causes the graphite particles to exfoliate and crack.

Keywords: Lithium ion batteries; Solid electrolyte interphase (SEI); Dilatometry; Electrochemical mass spectrometry; Solvent co-intercalation

Sonoelectroanalysis: investigation of bismuth-film-modified glassy carbon electrodes by Craig E. Banks; Jaanus Kruusma; Michael E. Hyde; Abdollah Salimi; Richard G. Compton (pp. 277-282).

Bismuth-modified glassy carbon electrodes have been investigated for their suitability in sonoelectroanalysis. The stability of the bismuth film to the application of ultrasound was assessed via voltammetric and atomic force microscopy (AFM) studies which revealed little ablation at powers up to an intensity of 130 W cm⁻² delivered from a 25-kHz sonic horn. Furthermore, bismuth-film-modified glassy carbon electrodes were evaluated for the sonoelectroanalytical quantification of zinc and cadmium. Detection limits of 2×10⁻⁷ M and 6×10⁻⁹ M respectively were found after a 60-s deposition time via an acoustically assisted deposition protocol.

Keywords: Sonoelectroanalysis; Bismuth film; Ultrasound; Stripping voltammetry; Zinc; Cadmium

Electrochemical investigations of baicalin and DNA–baicalin interactions by Ziyi Sun; Zhong Ma; Wenjun Zhang; Xiaoyue Wang; Chunhai Fan; Genxi Li (pp. 283-286).

Baicalin is an anti-HIV drug purified from the traditional Chinese medicinal plant Scutellaria Baicalensis Georgi. Baicalin has proven to be electroactive at pyrolytic graphite (PG) electrodes. We thus studied its interaction with DNA via the electrochemical approach. We observed that the peak currents corresponding to the baicalin reduction–oxidation (redox) reaction significantly decrease upon the addition of DNA. With complementary ultraviolet/visible (UV/Vis) spectroscopic evidence, we suggest that baicalin binds to DNA through intercalation. This feature has enabled baicalin to discriminate between double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA).

Keywords: Cyclic voltammetry; Interaction; Baicalin; DNA; Pyrolytic graphite

Pulsed amperometric detection of DNA with an ssDNA/polypyrrole-modified electrode by Almira Ramanaviciene; Arunas Ramanavicius (pp. 287-293).

Pulsed amperometric detection (PAD) of target DNA with platinum electrodes modified by single-stranded DNA (ssDNA) entrapped within polypyrrole (ssDNA/Ppy) is reported for the first time. Single-stranded DNA 20-mers complementary to the target DNA were used to construct the DNA biosensors. Polymerase chain reaction (PCR) amplified bovine leukaemia virus (BLV) provirus DNA was used as target DNA. Electrochemical impedance spectroscopic (EIS) investigation of ssDNA/Ppy before and after incubation in target DNA-containing sample revealed significant changes in terms of an imaginary (Z″) vs. a real (Z′) component. The PAD results were in good agreement with EIS investigations. The PAD method was selected, because it does not require such sophisticated equipment as it is used to perform EIS and the results obtained can be more easily estimated. Optimum conditions for performing PAD and evaluating an analytical signal were elaborated. No label-binding step was necessary for detection of target DNA in PCR-amplified amplicons and detection time was reduced by as much as 30–35 min. The changes of PAD signals were at least 6–7 times higher if ssDNA/Ppy-modified electrodes instead of blank Ppy-modified electrodes were incubated in the target DNA solutions. If ssDNA/Ppy modified electrodes were incubated in non-complementary (control) DNA solution changes in PAD signals were smaller than those detected after incubation in complementary (target) DNA-containing solution by a factor of at least 6–8.

Keywords: DNA biosensor; Pulsed amperometric detection; Polypyrrole; Retrovirus

Voltammetry of lead cations on a new type of silver composite electrode in the presence of other cations by Tomáš Navrátil; Světlana Šebková; Miloslav Kopanica (pp. 294-301).

A new type of silver composite electrode was examined, prepared from silver, graphite powder, and methacrylate resin. The effects of the presence of various cations (cadmium, copper, bismuth, thallium), anions (chlorides), surface-active substances (Triton X-100), and oxygen on the anodic-stripping voltammetric determination of lead were studied. It was found that the effect of underpotential deposition at the composite electrode differs from that produced at a metallic silver electrode, mainly at low concentrations of the deposited metal. The use of this type of silver composite electrode in differential pulse anodic-stripping voltammetry enables direct determination of lead in natural water samples without elimination of surface-active substances (LOD about 3 μg L⁻¹).

Keywords: Silver composite electrode; Voltammetry; Metals; Lead; Copper; Cadmium; Thallium; Bismuth; Chlorides; Underpotential Deposition Effect (UDP)

Capacitive chemical sensor for fenvalerate assay based on electropolymerized molecularly imprinted polymer as the sensitive layer by Ji-Lai Gong; Fu-Chun Gong; Ying Kuang; Ge-Ming Zeng; Guo-Li Shen; Ru-Qin Yu (pp. 302-307).

A capacitive chemical sensor for fenvalerate is reported. By using ac impedance measurements the sensor has been based on the decrease in capacitance caused by the analyte used as the template in the formulation of an electropolymerized molecularly imprinted polymer as receptor layer. Improvement of the insulating properties of the sensor was investigated in detail. The capacitive sensor was prepared by a deposition of a self-assembled monolayer of 2-mercaptobenzimidazole (2-MBI) before electropolymerization of 2-MBI and subsequent treatment with n-dodecanethiol to eliminate pinholes and defects in the polymerized 2-MBI film. From the calibration curve concentrations of fenvalerate up to 9 μg mL⁻¹ could be detected with a linear determination range up to 5 μg mL⁻¹ and a detection limit of 0.36 μg mL⁻¹. No significant interference was observed from common pyrethroid insecticides.

Keywords: Fenvalerate; Electropolymerized polymer; Electrochemical impedance spectroscopy; Capacitive sensor

Determination of piribedil in pharmaceutical formulations by micellar electrokinetic capillary chromatography by Ceren Yardımcı; İncilay Süslü; Nuran Özaltın (pp. 308-311).

A fast and simple micellar electrokinetic capillary chromatographic method was developed for the analysis of piribedil in pharmaceutical formulations. The effects of buffer concentration, buffer pH, sodium dodecyl sulphate (SDS) concentration, organic modifier, applied voltage and injection time were investigated. Optimum results were obtained with a 50 mM borate buffer at pH 8.0 containing 50 mM SDS by using a fused silica capillary (50 μm internal diameter, 72 cm effective length). The sample was injected hydrodynamically for 4 s at 50 mbar pressure and the applied voltage was +30 kV. The detection wavelength was set at 205 nm. Diflunisal was used as an internal standard. The analysis was performed at 25 °C and the total run time was 14 min. The method was suitably validated with respect to linearity range, limit of detection and quantification, precision, accuracy, specificity and robustness. The linear calibration range was 5–100 μg mL⁻¹ and the limit of detection was determined as 1 μg mL⁻¹. The method developed was successfully applied to the determination of piribedil in pharmaceutical formulations. The results were compared with a spectrophotometric method reported in the literature and no significant difference was found statistically.

Keywords: Piribedil; Capillary electrophoresis; Micellar electrokinetic chromatography; Pharmaceuticals

Compact program resolves overlapping voltammetric peaks by Jordan D. Dimitrov (pp. 312-317).

A simple self-contained program designed to separate overlapping peaks from electrochemical analyses is presented. Combining an original interactive way to define initial parameter estimates with nonlinear curve fitting based on the simplex method of optimization, it allows the user to resolve voltammograms consisting of 2 to 5 analytical peaks raised on a straight base line. The program provides highly intuitive interface, easy operation, and straightforward result documentation. A free package including the program, three data files and user instructions is available on request.

Keywords: Electroanalytical chemistry; Overlapping peaks; Resolve peaks; Curve fitting; Simplex method

The impact of chromatography and mass spectrometry on the analysis of protein phosphorylation sites by Martin Zeller; Simone König (pp. 318-318).

Joint European Stable Isotope Users group Meeting. JESIUM 2004 (pp. 319-319).

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Analytical and Bioanalytical Chemistry (v.379, #2)