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Analytical and Bioanalytical Chemistry (v.362, #1)
The changing face of chemical derivatization in pharmaceutical and biomedical analysis by S. Görög (pp. 4-8).
The present and past use of chemical derivatization reactions is overviewed with emphasis on the present role of derivatization in chromatographic and electrophoretic methods with special respect to fluorogenic derivatization to increase the selectivity and sensitivity, chiral derivatization to transform enantiomeric pairs to easily separable diastereomers, and GC/GC-MS derivatization. Non-chromatographic derivatization is also discussed with emphasis on UV-VIS spectrophotometry, fluorimetry, and immunoassay methods. The up-to-dateness of derivatization methods with negative examples mainly from the field of UV-VIS analysis are also discussed. Finally, examples are given on how the experiences obtained in the course of old studies can be used to solve current problems with the aid of chemical derivatization.
Surface plasmon resonance within ion implanted silver clusters by G. Steiner; M. T. Pham; Ch. Kuhne; R. Salzer (pp. 9-14).
Surface plasmon resonance (SPR) belongs to the most sensitive indicators for changes in analyte concentrations or other sample properties, which depend on the refractive index in the medium. Surface plasmons represent collective electron oscillations in metal cluster or metal layers of diameter or thickness in the nanometer range. Such layers or clusters are used in many optical sensors in order to enhance the interaction between electromagnetic radiation and analyte. Clusters are preferred to enhance Raman scattering and IR absorption, whereas layers are used for SPR in the visible range. We tested the applicability of ion implanted clusters in order to enhance the stability of the metal coatings of the SPR sensor elements. A model based on the effective media theory was developed in order to enhance the sensor capabilities. The potential of the SPR with ion implanted metal clusters consists in durable resonance layers for biochemical sensors.
Surface enhanced infrared absorption spectroscopy (SEIRA) using external reflection on low-cost substrates by H. D. Wanzenböck; B. Mizaikoff; N. Weissenbacher; R. Kellner (pp. 15-20).
A novel approach for spectroscopic trace analysis is introduced by combining surface enhanced infrared absorption (SEIRA) spectroscopy with external reflection techniques on disposable inexpensive substrates. SEIRA-active surfaces produced by electrochemical deposition of silver on smooth metal surfaces and glass improve the sensitivity of IR reflection measurements significantly since the infrared absorption of organic substances such as p-nitrobenzoic acid is considerably increased in the vicinity of rough noble metal surfaces. The enhancement properties of thus prepared substrates are characterized and compared using IR-spectroscopy. These low-cost substrates used in single- and multiple external reflection arrangements, respectively, yield a significant increase of the detection level compared to conventional reflection absorption infrared spectroscopy (RAIRS) up to one order of magnitude. Hence, a notable step towards a wide-spread application of SEIRA in routine IR reflection analysis is presented.
Process control with mass-sensitive chemical sensors – Cyclodextrine modified polymers as coatings by F. L. Dickert; Matthias Tortschanoff; Karin Weber; Matthias Zenkel (pp. 21-24).
Chemical sensors can also be used for process control since they are able to follow concentration changes nearly instantaneously. The mass sensitive quartz-micro-balance (QMB), coated with cross-linked cyclodextrin cavities was applied to monitor the formation of the Grignard reagent. It was possible to detect the reactant chlorobenzene even in a saturated diethyl ether atmosphere down to some ppm (μL/L). This is equivalent to a molar ratio of 50000:1 of diethyl ether to chlorobenzene. The sensor characteristic is completely linear in the concentration range from 10 to 500 ppm (μL/L) chlorobenzene. As a practical application, the end point of the Grignard reaction can be determined in an accuracy of approximately 2% of the reagent supply. This was achieved by a direct on-line acquisition of the QMB frequency response or its derivative.
Classification and recognition of compounds in low-resolution open-path FT-IR spectrometry by Kohonen self-organizing maps by Husheng Yang; John D. Jegla; P. R. Griffiths (pp. 25-33).
The possibility of using one- and two-dimensional Kohonen self-organizing maps (SOMs) to recognize similarities in low-resolution vapor-phase infrared spectra without any additional information, i.e., in an unsupervised mode, has been investigated. Full-range vapor-phase FT-IR reference spectra were first used to train the networks and the trained networks were then used to classify the reference spectra into several groups. The feasibility of reducing the spectral range to be consistent with the atmospheric windows used in open-path FT-IR spectrometry was also studied. Kohonen networks are shown to be relatively immune to the presence of noise. An example of using a trained Kohonen map to recognize the presence of selected compounds in field-measured open-path FT-IR spectra is given.
Multi-frequency S2FTIR PA spectral depth profiling by use of sinusoidal phase modulation and harmonic demodulation up to 2250 Hz (10th harmonic) by Haochuan Wang; Eric B. Phifer; R. A. Palmer (pp. 34-40).
Multi-frequency phase modulation for step-scan Fourier transform infrared photoacoustic spectroscopy (S2FTIR PAS) is demonstrated using a single frequency sinusoidal modulation of the interferometer movable mirror with modulation amplitude 5.2 λHe-Ne. A digital signal processing (DSP) lock-in amplifier is used to demodulate the photoacoustic response at the fundamental phase modulation frequency and its harmonic frequencies. Because the phase modulation is sinusoidal and of the appropriate amplitude, all the even and odd harmonics (up to the 10th harmonic) can be detected with good signal-to-noise ratio (SNR). Applications of this multi-frequency phase modulation approach for photoacoustic depth profiling are demonstrated by the study of a simple two-layered polymer sample. The sampling depth multiplexing advantage (as compared to that obtained with other types of phase modulation) is clearly demonstrated with the analysis of the phase and magnitude of signals at the fundamental frequency and all the harmonic frequencies. This is the first report of using the sinusoidal phase modulation method to easily obtain multi-frequency and high-frequency light modulation for FTIR PAS depth profiling. Although these data have been obtained sequentially, it would be possible (with considerable economy of time) to obtain them simultaneously by use of the internal digital signal processing capability of the instrument.
Speciation of activators in electroluminescent thin films: an EXAFS study of cerium and terbium doped strontium sulfide by Yves Charreire; Robert Cortes; E. Nykänen; L. Niinistö; P. Soininen; Markku Leskelä (pp. 41-50).
Extended X-ray absorption fine structure (EXAFS) was used to determine the local structure of the luminescent centers in Tb3+ and Ce3+ -doped strontium sulfide thin films deposited by Atomic Layer Epitaxy (ALE). The rare earths were observed to enter mainly the substitutional sites but at the same time a part of the atoms form RES clusters (RE = rare earth). The presence of both substitutional sites and RES clusters has been observed for the first time in this study for rare earths in II–VI compounds.
Surface enhanced infrared absorption observed with attenuated total reflection (ATR-SEIRA): modeling the optical response by A. Röseler; E. H. Korte (pp. 51-57).
The gain in sensitivity due to Surface Enhanced Infrared Absorption (SEIRA) when analyzing an adsorbate on a metal island film was calculated for the ATR configuration under full consideration of the anisotropy of the film. Modeling the islands as spheroids coated with the dielectric adsorbate leads to such extraordinarily high refractive indices and low absorption indices as experimentally observed and to an enhancement of the absorption bands of the coating. Simulation of the ATR reflectance indicated further enhancement as a result of the optical properties of the island film. The predicted total level of enhancement was about one order of magnitude superior to what commonly is found in experiments. This was attributed to percolation of the metal islands which almost inevitably occurred in practice: the resulting lateral conductivity was found to have a strongly decreasing effect on the enhancement.
Coupling continuous flow systems to instruments based on discrete sample introduction by M. Valcárcel; Mercedes Gallego; Angel Ríos (pp. 58-66).
The interfaces between low-pressure continuous sample treatment systems and high-level information instruments such as gas chromatographs, capillary electrophoresis equipment and graphite furnace atomic spectroscopic instruments, which are characterized by conventional discrete sample introduction devices, are presented. The present and future developments are discussed of (directly) linking real samples and those analytical equipments with the main objective of avoiding or minimizing manually implemented preliminary operations of the analytical process.
Flow injection microscopy as a tool for two-parameter monitoring of cellular responses by Ilkka Lähdesmäki; J. Ruzicka (pp. 67-72).
Flow Injection Fluorescence Microscopy (FIFM) has been further developed to become a useful tool for a multiparametric study of the response of living cells to a biochemical stimulus. Rather than recording several parameters simultaneously, the multiparametric measurements are carried out in a sequential fashion: internal Ca-concentration and pH of Chinese Hamster Ovary cells were alternately monitored in subsequent runs where the cells were exposed to carbachol. Delivery of carbachol onto the cells was carried out by the flow injection apparatus in the FIFM setup. Fluorescent indicators fura-2 and BCECF had been loaded into the cells to provide the Ca- and pH dependent signals, respectively. The fluorescent signals were detected by means of the fluorescent microscope domain of the FIFM setup. Comparison of the temporal dependence of the response curves shows differences in the two responses. The experimental evidence is supported by a novel functional tracer test that is used to characterize the kinetics of cell-stimulation interaction.
Optical sensors for dissolved sulfur dioxide by Achim Stangelmayer; I. Klimant; Otto S. Wolfbeis (pp. 73-76).
Colorimetric sensing membranes for the determination of sulfur dioxide were developed and characterized. These films can be used for sensing trace amounts of sulfur dioxide both in the gas phase and in aqueous solutions. Lipophilic pH indicator ion pairs were immobilized in hydrophobic gas-permeable silicone and phenyl substituted ormosil. On exposure to SO2 the films undergo a visually detectable color change from blue to yellow. No cross-sensitivity to pH and CO2 was observed. Response times depend on the thickness of the sensing membranes, the indicator concentration in the film as well as on the respective SO2 concentration. Membranes with response times of < 1 min (t90) were developed. The sensitivity to sulfur dioxide depends on the pKa of the indicator. An increase in the pKa results in a lower detection limit. The new optical SO2 sensors are chemically and mechanically stable and are easy to manufacture. The storage stability of the membranes is at least 7 months if stored in the dark.
Simultaneous determination of trace-levels of alloying zinc and copper by semi-mercury-free potentiometric stripping analysis with chemometric data treatment by Jens E. T. Andersen; E. H. Hansen (pp. 77-83).
Assays of copper and zinc in brass samples were performed by semi-mercury free potentiometric stripping analysis (S-MF PSA) using a thin-film mercury covered glassy-carbon working electrode and dissolved oxygen as oxidizing agent during the stripping step. The stripping peak transients were resolved by chemometrics, which enabled simultaneous determination of both the copper and the zinc concentrations, thereby eliminating the conventional necessary pretreatment of the sample solution, such as initial addition of Ga(III) or solvent extraction of copper. The brass samples were diluted by factors in the range 2 · 104– 5 · 105 which resulted in quantification of the copper and of zinc contents comparable to the specified values within 10%. On the basis of the chemometric treatment, an empirical expression is deduced relating the stripping time to the recorded potential.
Matrix isolation Raman spectroscopy, semiempirical calculations and normal coordinate analysis of strained systems Part I: 2,3-Diazabicyclo[2.2.1]hept-2-ene by D. Gernet; W. Kiefer (pp. 84-90).
The Raman wavenumbers of 2,3-diazabicyclo[2.2.1]hept-2-ene (DBH), isolated in a low-temperature matrix, are presented and assignments for all vibrational fundamentals are proposed. The molecular structure of DBH is calculated by means of semi-empirical quantum-mechanics and a normal coordinate analysis of the strained bicyclic system is performed in internal coordinates using a valence force field. A detailed description of a homemade matrix isolation setup is given.
Infrared intensities of liquids XXII: Optical and dielectric constants, molar polarizabilities, and integrated intensities of liquid benzene-d6 at 25 °C between 5000 and 450 cm–1 by J. E. Bertie; C. Dale Keefe (pp. 91-108).
This paper presents accurate infrared absorption intensities of liquid benzene-d6 at 25 °C, between 5000 and 450 cm–1. The results are presented as graphs and tables of the real, n, and imaginary, k, refractive index spectra, which are also called the optical constant spectra. The real refractive index is shown between 8000 and 450 cm–1. The absolute errors in the k values are estimated to be ∼3% below, and up to 60%, above, 4700 cm–1, with those in the n values ∼0.25% throughout. The Beer-Lambert molar absorption coefficient spectra, E m(˜ν), and the complex dielectric constant spectra, ɛ′(˜ν) and ɛ″(˜ν), were calculated from the optical constant spectra. To correct for macroscopic dielectric effects, the complex molar polarizability spectra, α′m(˜ν) and α″m(˜ν), were calculated from the dielectric constant spectra under the Lorentz local field. The properties of bands in these different spectra are compared. The imaginary molar polarizability spectra were fitted convincingly to 208 Classical Damped Harmonic Oscillator bands, and the areas under the corresponding ˜να″m bands gave the integrated intensities C j . These were assigned as far as possible and are tabulated. The transition dipole moments of well assigned transitions, and for the infrared-active fundamentals, under the double harmonic approximation, the dipole moment derivatives with respect to the normal coordinates, were calculated from the values of C j , and are presented. This appears to be the first extensive measurement of the infrared absorption intensities of liquid benzene-d6. The results are compared with literature data for liquid and gaseous benzene-d6.
Near-infrared light-fiber spectroscopic reaction monitoring of the synthesis of diphenylurethane by K. Dittmar; H. W. Siesler (pp. 109-113).
The extension from the mid-infrared (MIR) to the near-infrared (NIR) region alongside the introduction of light-fiber optics has had a significant impact on vibrational spectroscopy for chemical quality- and process-control. In the present contribution the application of NIR light-fiber spectroscopy to the remote monitoring of the synthesis of diphenylurethane shall demonstrate the potential of this analytical technique.
Enhanced stability of RIfS-sensors for the determination of hydrocarbons in water by covalent immobilisation by D. Nopper; G. Gauglitz (pp. 114-119).
This paper presents two different methods to enhance the stability of the bonding between thin polymer layers and glass substrates. With these stabilised polymer layers the detection of hydrocarbons in waste waters using Reflectometric Interference Spectrometry (RIfS) is possible. The sensors could be used between 30 and 60 days in continuous measurements. In calibration measurements with regular fuel dissolved in deionised water, all sensors showed a linear correlation between the signal and the concentration in the examined range from 0 to 50 mg/L. A detection limit of 1.95 mg/L regular gasoline in water (for RTV 3140 layers) could be found. River water as matrix for regular fuel caused no changes in the response behaviour of the sensors, only an off-set value occurred. Even raw aqueous phases from industrial interceptors could be investigated without any pre-treatment.
Microwave assisted extraction of organochlorine pesticides from sediments and its application to contaminated sediment samples by I. Silgoner; R. Krska; E. Lombas; O. Gans; E. Rosenberg; M. Grasserbauer (pp. 120-124).
A method was established and optimized for rapid and reproducible analyses of 17 organochlorine pesticides in sediments employing microwave assisted extraction followed by gas chromatographic separation with mass spectrometric detection using a computer optimized temperature program. For optimization, 5 g portions of sediment were spiked with a standard solution of the 17 analytes in isooctane at ∼50 ng/g for each pesticide and extracted in a microwave oven for 30 min at 100 °C using three different solvents. The best recoveries between 74% and 99% (RSD = 1.0–10.2%) were obtained with tetrahydro furan. The time consuming and laborious clean-up using liquid/liquid-extraction and two column-chromatographic steps was replaced by a one step liquid/solid-extraction, showing the same or even better performance in terms of recovery and reproducibility. Calibration plots were linear for all analytes and MDLs were in the range from 2–9 ng/g. To show the environmental applicability, the method was employed for the analysis of naturally contaminated sediments from the Netherlands (SETOC 701). The results were compared with the results obtained in our lab with ultrasonic extraction and supercritical fluid extraction and corresponded well with the median of results obtained from different interlaboratory comparison studies.
The effect of sample preparation on metal determination in soil by FAAS by Zofia Kowalewska; E. Bulska; A. Hulanicki (pp. 125-129).
Different methods for the determination of several metals in soils by flame atomic absorption spectrometry (FAAS) were investigated. Different procedures for total dissolution of soil: I – HF+HClO4, H3BO3, HCl digestion (conventional heating), II – HF+HClO4, H3BO3 digestion followed by fusion with LiBO2 (conventional heating) and III – HF+HCl+HNO3, H3BO3 digestion (microwave heating), as well as a leaching procedure with HNO3+HClO4, HCl were tested and compared. For quality assessment, the certified reference material S-1 soil was used. For most of the investigated metals, the best accuracy and precision were achieved when the procedure I or III were used. The developed procedure was applied to the analysis of soil samples from crude oil refinery and dump of petroleum origin wastes regions.
A rapid automated method for wine analysis based upon sequential injection (SI)-FTIR spectrometry by R. Schindler; R. Vonach; B. Lendl; R. Kellner (†) (pp. 130-136).
A new process control methodology for the simultaneous determination of sugars, alcohols and organic acids in wine based on multivariate evaluation of mid-IR transmission spectra of wine samples is presented. In addition to ethanol several lower level wine components (glucose, fructose, glycerol, citric-, tartaric-, malic-, lactic- and acetic acid) were determined. To establish a multivariate calibration model a set of 72 calibration solutions was prepared and measured, using a novel, fully automated sequential injection (SI) system with Fourier transform infrared (FTIR) detection. The resulting spectra were evaluated using a partial least square (PLS) model. The developed PLS model was then applied to the analysis of real wine samples containing 79–91 g L–1 ethanol, 5.9–8.1 g L–1 glycerol, 0.4–6.9 g L–1 glucose, 1.5–7.5 g L–1 fructose, 0.3–1.6 g L–1 citric acid, 1.0–1.7 g L–1 tartaric acid, 0.02–3.2 g L–1 malic acid, 0.4–2.8 g L–1 lactic acid and 0.15–0.60 g L–1 acetic acid, yielding results which were in good agreement with those obtained by an external reference method (HPLC-IR). The short analysis time (less than 3 min) together with high reproducibility makes the newly developed method applicable to process control and screening purposes (average of the standard deviations calculated from four repetitive measurements of six different real samples: ethanol: 0.55 g L–1, glycerol: 0.037 g L–1, glucose: 0.056 g L–1, fructose: 0.036 g L–1, citric acid: 0.020 g L–1, tartaric acid: 0.010 g L–1, malic acid: 0.052 g L–1, lactic acid: 0.012 g L–1 and acetic acid: 0.026 g L–1).
Comparative study of reflectance cells for PLS-FTIR determination of sugars in soft drinks by S. Garrigues; F. J. Rambla; M. de la Guardia (pp. 137-140).
A comparative study has been carried out between a horizontal Attenuated Total Reflectance (h-ATR) cell and a Cylindrical Internal Reflection (CIR) cell (CIRCLE cell). Both cells were employed for the determination of glucose, fructose, sucrose and total sugar in soft drinks and fruit juices using absorbance measurements at two resolution values (4 and 8 cm–1). Data were processed by Partial Least Squares regression (PLS). Using a resolution of 4 cm–1, mean relative errors of prediction from 0.6% to 1.3% were obtained using the horizontal-ATR and from 0.6% to 2.8% using the CIRCLE cell resulting in a limit of detection from 0.03% in the case of sucrose to 0.21% for total sugar for the h-ATR and from 0.06% for sucrose to 0.13% for glucose using the CIRCLE cell. Both cells provided appropriate figures of merit, but the analytical sensitivity obtained using the h-ATR cell was three times higher than that obtained using the CIRCLE cell.
Multivariate calibration for near-infrared spectroscopic assays of blood substrates in human plasma based on variable selection using PLS-regression vector choices by H. M. Heise; A. Bittner (pp. 141-147).
A multicomponent assay for the blood substrates of total protein, glucose, total cholesterol, triglycerides and urea in human EDTA-plasma by FT-IR spectroscopy is described based on near-infrared spectra of human plasma recorded in a 1 mm quartz transmission cell. Partial least-squares was applied for multivariate calibration taking into account absorbance or logarithmized single beam spectra. Further data reduction was applied using the pairwise selection of spectral variables suggested by the weights of the optimum full spectrum PLS-regression vector. The standard errors of prediction for protein, cholesterol, triglycerides, glucose and urea are calculated by cross-validation for the population of 124 plasma samples of different patients. These values are compared for full spectrum and reduced spectral variable set regression.
Using thermodesorption-GC/cryocondensation-FT-IR for the measurement of biogenic VOC emissions by J. Geiger; T. Hoffmann; J. Kahl; D. Klockow; E. H. Korte; W. Schrader (pp. 148-154).
For the investigation of terpene emissions from plants a thermodesorption-GC/cryocondensation-FT-IR system was used to complement GC/MS measurements. FT-IR spectra allow to obtain structural information on functional groups, especially if they contain oxygen. Measurements of the release of volatile organic compounds from pine trees (Pinus sylvestris L.) and lavender show the potential of GC/FT-IR to detect and quantify terpenes down to the pg-level. One major advantage of the system is the cryocondensation step on a ZnSe-slide, which allows to scan the substances repeatedly with higher scan number and/or resolution to improve the signal-to-noise ratio.
Determination of human serum albumin and γ-globulin in a control serum solution by near-infrared spectroscopy and partial least squares regression by Koichi Murayama; Keiichi Yamada; Roumiana Tsenkova; Y. Wang; Y. Ozaki (pp. 155-161).
Near infrared (NIR) spectra in the 1300– 1850 nm region were measured for control serum solutions containing both albumin and γ-globulin of various concentrations. Partial least squares two (PLS2) regression was applied to the NIR spectra to determine simultaneously the concentrations of both proteins. For albumin, the correlation coefficient (R) of 0.988, the standard error of calibration (SEC) of 1.61 g/L, the standard error of prediction (SEP) of 1.29 g/L, the relative standard deviation (RSD) of 0.026 and the ratio of standard deviation of reference data in prediction to SEP (RPD) of 12.2 were obtained. For γ-globulin, the corresponding values were 0.997, 1.36 g/L, 1.35 g/L, 0.0365 and 8.66, respectively. The regression coefficients (RCs) of PLS factors were compared between albumin and γ-globulin, and the observed differences in the RCs were discussed based upon the differences in the hydration between albumin and γ-globulin. In order to explore the effects of various metabolites such as glucose, and cholesterol on the chemometrics models, the RCs for albumin and γ-globulin in the control serum solutions were also compared with those for albumin and γ-globulin in phosphate buffer solutions previously studied. The results of our experiments show that NIR spectroscopy with the use of PLS2 regression has considerable promise in nondestructive determination of the concentrations of blood serum proteins.
ETAAS determination of aluminium and copper in dialysis concentrates after microcolumn chelating ion-exchange preconcentration by Svetlana Knežević; R. Milačič; Marjan Veber (pp. 162-166).
A procedure was developed for the preconcentration and determination of aluminium and copper in dialysis concentrates at the ng cm–3 level. The preconcentration was achieved on microcolumns filled with Chelex-100 resin adjusted to a pH of 4.0. Five repetitive cycles of the sample through the column ensured a sufficient contact time for quantitative retention of aluminium and copper ions. The retained ions were eluted with HNO3 (0.5 mol dm–3). Aluminium and copper were determined in the eluate by Zeeman ETAAS using the standard addition technique. The procedure was performed under clean room conditions (class 10,000), The reliability of the results was evaluated by recovery tests, using dialysis concentrates spiked with aluminium and copper. The recoveries obtained ranged from 86 to 106% for aluminium and from 92 to 97% for copper. Using the recommended procedure, the LOD of aluminium and copper in dialysis concentrates (preconcentration factor 2) was found to be 0.5 ng cm–3 and 0.2 ng cm–3, respectively.
Flow injection chemiluminescence determination of medazepam by S. M. Sultan; Ala’ddin M. Almuaibed; A. Townshend (pp. 167-169).
A new flow injection chemiluminescence method for the assay of medazepam is explored. The method involves the use of permanganate in sulfuric acid for the oxidation of medazepam with the emission of chemiluminescence detected by a photomultiplier tube. A simplex procedure was employed for optimising the conditions for high sensitivity detection, which were found to be 1.03 × 10–3 mol L–1 permanganate, 0.153 mol L–1 sulfuric acid and 3.43 mL min–1 flow rate. The linear calibration range was 3.7 × 10–5 to 1.7 × 10–3 mol L–1. The detection limit (3σ) and the sample throughput were 1.85 × 10–5 mol L–1 and 100 per hour, respectively. The relative standard deviation for 5 replicate determinations of 1.9 × 10–4 mol L–1 medazepam was 0.15%. Common excipients (starch, glucose, maltose, lactose) used in pharmaceutical preparations had no effect.
Analytical characterisation of pigments on pre-Roman pottery by means of spectroscopic techniques Part I: white coloured shards by G. E. De Benedetto; F. Catalano; L. Sabbatini; P. G. Zambonin (pp. 170-175).
This paper is part of a systematic archaeometric investigation aimed at the characterisation of the pigments and related materials (ligand, colour substrate) used in decoration of pottery excavated in the archaeological zone of Canosa (Puglia, Italy). Shards found in thirteen different tombs have been analysed; in this paper samples exhibiting a white colouration have been selected. Both surface (XPS) and bulk (FT-IR) spectroscopies were used which gave complementary information and enabled white pigments to be divided into two groups. Moreover, X-ray diffraction was used in some cases to further support some spectral assignments. The molecular specificity of FT-IR, when applied to the analysis of both pigments and ceramic body, allowed the identification of the various constituents and, hence, provided indirect information on the end-use of the original wares. The potential of the combined use of different spectroscopies to obtain valuable information on both painting materials and technical aspects is shown.
An enzyme-immunoassay for the detection of the mycotoxin zearalenone by use of yolk antibodies by H. Pichler; R. Krska; A. Székács; M. Grasserbauer (pp. 176-177).
The development of an enzyme-immunoassay (ELISA) for the detection of the Fusarium mycotoxin zearalenone (ZON) is described. In contrast to the common antibody isolation from mammal serum, chicken were immunized in order to isolate specific antibodies from the egg yolk. Five weeks after the start of the immunization a titer of 1:76 000 resulted from three injections without any adverse effects for the animals. Utilizing the indirect competitive assay format ZON could be detected in a concentration range between 10 and 200 μg/L.