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Three patients were enrolled, two as hemophiliacs, and one with acute EBV infection. Serial serum samples of each patient were tested with at least 3 different HIV antibody EIA tests, an immunofluo-rescent test and two western blots (WB). In the third case, PCR and reverse transcriptase enzyme activity measurement were also done. One of the regularly checked serum samples of hemophiliac patients was reactive with different HIV screening and confirmatory assays. Their next blood samples, two weeks and one month later, respectively, were negative with the same tests. In Case 3. two and a half years after the first examination, the EIA tests results changed to negative, but the WB was still indeterminate. In the case of the two hemophiliac patients, the patients may have been exposed to HIV containing blood products (before 1985), but were not infected. Regular treatment with factor VIII concentrate, in which HIV antigens may be present, can boost the immune response and results in transient seropositivity. In the case of the EBV infected patient, the transient HIV seropositivity may be the consequence of EBV induced proliferation of anti-HIV-antibody producing B cell clones. During our ten year HIV confirmatory practice we tested more than 40000 samples, from which transient seropositivity were observed only in the three cases summarized in this paper.

Chlorinated hydrocarbons (CHCs) were monitored using a recently presented infrared fiber-optic physico-chemical sensor consisting of an MIR transparent, polymer coated, silver halide fiber coupled to a commercial FTIR spectrometer. The aim of this study was to test the performance of this new fiber optic sensing device with respect to temperature dependence, simultaneous detection of several CHCs, sensitivity and dynamic response behavior. In addition the diffusion process of the CHCs into the polymer was analyzed in order to better understand and evaluate the obtained results. During the investigation of the temperature dependence of the sensor response to real trend could be observed in the temperature range of 0 to 22°C. The dynamic response of the sensor is in the minute range when experiencing an increase in concentration of the analyte while with a decrease in concentration, the response is relatively slow. The sensor enabled the detection of 10 environmentally relevant CHCs at concentrations of 1 to 50ppm. The simulation of the experimental diffusion data revealed Fick's 1st law diffusion for CHCs into the polymer layers. Finally the sensing device was validated with head space-gas chromatography (HSGC) analyses and showed good agreement with these already established methods. This work shows the great potential of IR fiber optic sensors as early warning systems for a variety of CHCs in water (“threshold alarm sensor”)

A new method of optical gas sensing is presented which uses evanescent waves of optical fibers. Gas detection can be done in a simple, flexible, and possibly distributed way using a single optical fiber as both the sensor with an active element of 10 cm and the transmission line for optical signals. The detection of several single gaseous species — such as hexane, trichloro-trifluoro-ethane, methane, acetone, etc. — as well as gaseous mixtures in a concentration range of 1–10% could be achieved with an average reproducibility of 2–3% with a chalcogenide fiber optic coupled to an IFS 88 Bruker spectrometer.

The importance of education and training grows with the complexity and practical need of a given subject. Especially in times of rapid evolution such as the introduction of new measurement principles and advanced computers into Analytical Chemistry (AC) a quick update of curricula is necessary. A basic equivalence of undergraduate curricula should be reached to stimulate the world wide exchange of students

As the analysis of glucose and urea is of special interest in the field of clinical and process analysis, an enzymatic FIA-FTIR system is presented, based on the reactions of glucose to gluconic acid using glucose oxidase as well as of urea to ammonium carbonate catalyzed by urease. The method is tested with standard solutions, with samples simulating the blood composition and with a variety of fruit juices and soft drinks. Whereas the systematic error is within few percent, as concluded from the slope of the calibration graph, the reproducibility of the method is up to now not satisfactory for routine applications in process analysis and has to be improved.

The response behavior of a polymer-coated mid-infrared fiber optical sensor for chlorinated hydrocarbons in water is evaluated practically and theoretically. The sensor response to the target analytes tri- and tetrachloroethylene obtained in a muddy waste water sample is shown to be unaffected by other trace organic pollutants. A theoretical model is presented which can be used to predict the response of this sensing device. The use of this model allows to simulate the sensor response not only for increasing chlorinated hydrocarbon concentrations, but rather for any change in its concentration in the surrounding medium. In addition, the asymmetric sensor response, depending on the direction of the concentration change and the lag time after a concentration change can be explained by digital simulations and are shown to occur due to diffusion processes in the membrane.

An application of FTIR-microspectroscopy for the study of the homogeneity of chemisorbed, thin silane layers on IR-transparent fibers and ATR-elements is presented. Furthermore a calibration method for the layer thickness based on ellipsometry is established and theoretical considerations, which refer to the occuring signal enhancement in the fiber compared to a flat substrate, are explained.

In this paper the discovery is presented that FTIR microspectroscopy is also suitable for the micro-analysis of very thin organic layers in the range of 3.6 to 36 nm on chalcogenide fibers. Theoretical confirmation using the raytracing method is given and the observation of ultra-thin coatings on fibers is made possible by a signal enhancement compared to planar substrates due to the geometry of the fiber.

The stability of silver halide fibers in artificial sea water (ASW) with and without a protective polymer coating and the influence of high salt concentrations on the sensor response was investigated. In contrast to bare silver halide fibers, the polymer coated fibers remain stable in contact with chloride solutions. This enables the application of a recently presented mid-IR fiber evanescent wave spectroscopy (FEWS) sensor system for the quantitative detection of chlorinated hydrocarbons (CHC) also in sea water.

The importance of education and training grows with the complexity and practical need of a given subject. Especially in times of rapid evolution such as the introduction of new measurement principles and advanced computers into Analytical Chemistry (AC) a quick update of curricula is necessary. A basic equivalence of undergraduate curricula should be reached to stimulate the worldwide exchange of students. This is underlined by the increasing role of Analytical Chemistry as problem solving science and as main source for reliable data needed in product- and environmental quality control often as basis for far reaching political decision, such as the setting of quality standards.

In the present work a silver-halide fiber was coated with low-density-polyethylene and used as a fiber optic Ir sensor for the detection of chlorinated hydrocarbons in water

The quantitative analysis of organic microsamples [vinylite (PVC-PVA) cellulose-nitrate and polyamide] on Al-foils was performed with good precision (rel. standard deviation 1.04% to 12.1%) after calibration of their main IR-bands with relative conductometric techniques. It was shown that the lower detection limit using the 15×Cassegrain objective was 1μm and that the linear range of the calibration curves was limited by a deviation of Beer's law atA>1.2 due to the “reststrahlen-effect”.

For the sample system of oil films in the range below 10 nm mean film thickness on aluminium foils, the advantages of recording IR-ATR spectra with a Fourier transform instrument are pointed out. The achievable high signal-to-noise ratio makes it possible also to determine the weak bands usually lost in the grating IR-ATR spectrum of the sample, allowing qualitative analysis of these thin films. It is also possible to get results concerning the structure and the reaction mechanism of adsorbed oil constituents (such as acids) on the aluminium foils investigated. Because in IR-ATR spectroscopy the interaction of the radiation with the sample is different in the plane of polarization and the plane perpendicular to it (this difference in interaction allows investigation of the orientation of ATR samples), the influence of the polarization ratio of the instrument on the IR-ATR spectra has been studied for both instruments. A strong influence of the surface roughness of the reflection elements was also found. A rough surface (especially of KRS-5 reflection elements, which are always scratched by previous samples) randomizes the dipole orientation of the radiation and causes a complicated mixture of the polarized spectra, even if a polarizer is used. Reflection elements made of germanium have a hard surface and do not randomize the orientation of the radiation. If no polarizer is used, it is again advantageous to use a Fourier transform instrument, because in grating instruments the polarization ratio is dependent on the position of the gratings.

An analysis of the present situation of Analytical Chemistry is performed, taking into consideration the difference to be observed between the large and further increasing importance of Analytical Chemistry in industrial research, development and quality control and the poor reputation of the subject at many universities. The main reason for the latter can be located in the existence of outdated curricula for Analytical Chemistry. Many chairs or departments of Analytical Chemistry leave the education in modern physical methods for separation and identification as well as Computer Based Analytical Chemistry (COBAC) and its applications to life-, environmental- and material sciences to other departments and restrict themselves to classical subjects. According to a survey of the “Working Party on Analytical Chemistry” of the “Federation of European Chemical Societes” (Chairman: Prof. Dr. E. Pungor) this holds true especially for universities without an own chair or department of Analytical Chemistry. Modern Analytical Chemistry, however, is definitively no longer an appendix of any other subject but the “interdisciplinary science of the generation of information about the composition and the structure of matter”. Furthermore Analytical Chemistry is the “key to solve problems related to material systems”. It is the — certainly difficult but fascinating — task of the professor of Analytical Chemistry to present together with his team the complex modern curricula (chemical analysis, biochemical analysis, chemometrics, analytical strategies, material analysis, clinical analysis, environmental analysis etc.) according to the principle of the reduction to the scientific basis.

Model membranes have been prepared from PVC (65 mg), dioctyl sebacate (120 mg) and the crown ether BME-44 (4 mg) in 2 ml THF solution and analyzed by the molecular-specific surface technique Attenuated Total Reflectance (ATR) in the infrared region in order to better understand the complexation reactions at the interface between the membrane and aqueous solutions of NaCl, KCl, KSCN and NH4SCN. The information depth provided by this method was between 0.1 and 3 μm and could be changed by variation of the angle of incidence of the IR-radiation. The study of the reactions was carried out ex-situ (at the dried membrane surfaces) after contact times of 1 h with 0,1–2 M aqueous solutions and subsequent rinsing with H2O for 0–100 s. It was found that KSCN- and NH4SCN-contact results in significant complex formation with the membrane, whereas KCl and of course NaCl do not react in such a way (under diffusion of the complex into the bulk of the membrane). Through rinsing with H2O and variation of the angle of incidence experimental evidence was found that KCl forms a complex only in the outmost surface region of the membrane. This complex cannot penetrate into the membrane because of the lipophobic nature of Cl−. These findings support the “space-charge effect” model for the explanation of the potential generation since the electrochemical behaviour of the electrode membrane described is nearly equal for KCl and KSCN in low concentrations (−58.5 mV/decade) while it loses its sensitivity for KSCN (not for KCl) at higher concentrations.

In order to get more information about the complexation reaction between potassium-selective electrode membranes and aqueous solutions of KCl, KSCN, NaCl, NaSCN, NH4Cl and NH4SCN, model membranes have been analyzed by the molecular-specific surface technique Attenuated Total Reflection (ATR) in the infrared region, thus providing an information depth between 0.1 and 3 μm depending on the angle of incidence of the radiation. The membranes have been prepared by dissolving PVC, dioctylsebacate and crown ether BME-44 in differing amounts in THF and casting in a glass ring on a glass plate. It has been found that DOS is slightly enriched at the surface but the membranes are sufficiently stable. It has further been found that complex formation occurs in the surface region for SCN− as well as Cl−. Pretreated and subsequently rinsed samples have shown that Cl− is almost totally washed away. But in the case of the lipophilic SCN−1 anion, this diffuses into the bulk; rinsing results in a loss at the near-surface region only. A special diffusion experiment, in which only one side of the membrane was in contact with the solution, has shown that diffusion of KSCN through the membrane occurs at a very low rate with a diffusion constant of appr. 10−8 cm2/s.

In this paper the necessary experimental steps are described to obtain high quality IR-spectra from single crystal surfaces (approx. 1.5×2 mm) of N,N-dithiocarbamates with plane polarized radiation. The low spectral contrast to be obtained with such samples (A 1 cm−1 and variable ratios of band intensities for different polarization could be observed and used to perform reliable band assignments.

Flavor samples are complex mixtures with components of sometimes very similar chemical behavior (e.g. isomeres). As an approach towards their characterization an integrated analytical method on the basis of capillary gas-chromatography (HRGC) was applied consisting of two molecular specific techniques for component-identification in unknown samples: GC-FTIRS (GC-Fourier transform infrared spectrometry) and GC-MS (GC-mass spectrometry). In addition GC-retention indices-from simultaneous GC on two columns (nonpolar/polar) —were stored in a database for routine retrieval and quantitative monitoring. To correlate this information with sensory perception “sniffing chromatograms” were generated with the human nose as a high performance detector. Because of the high information contents of GC-FTIR spectra in this field a small but specific vapor-phase-FTIR flavor library was accumulated, which dramatically improved the “fast identification power” of GC-FTIRS alone.

Extracts from deep-frozen Kiwi puree were investigated by an integrated method consisting of GC-FTIR and GC-MS for a reliable identification of the peaks detected and GC-sniffing to correlate this chemical information to sensory impression. Beneath trans-2-hexenal, that is responsible for the fresh, green scent, cyclohexarione was identified among a number of substances. By comparison of the FTIR-spectra to a specific vapor-phase-IR-library, that is presently accumulated in our group, most of the components could be identified. In particular 3 terpene-esters, linalyl-acetate, isobornylacetate anda-terpinyl-acetate were identified and found to be responsible for an overripe, terpene-like-off-flavor in stored Kiwi puree. In this field of unsaturated terpenes, esters and aldehydes the identification-capability of FTIR together with appropriate library-spectra exceeds that of mass-fragmentograms, especially for isomeric compounds, whereas the combined information of both techniques is needed for a reliable characterization of complex flavor-mixtures because of its complementary nature.

Untersuchungen uber die Eliminierung von Falschlichteinflussen auf das Resultat quantitativer IR-ATR-spektroskopischer Messungen wurden beschrieben. Zu diesem Zweck werden zunachst die Falschlichteinflusse als Funktion der Probengrose am Modellfall einer ATR-Meseinrichtung mit einem KRS-5-45°-Reflexionselement und Vinylite-Proben (PVC-PVA-Kopolymerisat, Schichtdicke 1,31 bzw. 5,91 g/m2) auf Aluminium bestimmt. Die Eliminierung des Falschlichtes ist neben der hier aus apparativen Grunden nicht zur Diskussion stehenden Methode der Fokussierung einerseits durch Anbringung von Schlitzblenden im Strahlengang vor dem Reflexionselement moglich und andererseits durch Ermittlung von Korrekturfaktoren fur die Berechnung der wahren aus der gemessenen Extinktion. Ohne Anbringung von Schlitzblenden liefern Proben mit einer Breite unter 12 mm bereits zu geringe Extinktionswerte, wahrend mit Blenden von 5 mm Schlitzbreite Proben bis zu 7 mm und mit Blenden von 3 mm Schlitzbreite Proben bis zu 5,5 mm Breite bei Montage der Probe am Anfang des Reflexionselementes maximale, falschlichtfreie Extinktionswerte (Probenlange 14,5 mm) ergeben. Die relative Standardabweichung betrug 3,34% bei 1,31 g/m2 Vinylite, Probengrose 14,5 x 14,5 mm mit Blende 5 mm. Beispiele fur die mestechnische bzw. rechnerische Korrektur der gemessenen Extinktionswerte wurden diskutiert. Werden IR-ATR-Spektren nach relativen Extinktionen ausgewertet (mit und ohne Blende 5 mm Schlitzbreite), so konnen Proben bis zu einer Breite von 5 mm herab ohne Falschlichtverluste herangezogen werden.

A systematic study has been carried out on the solvent and concentration dependence of the P=O stretching vibrationv(PO) of the model compoundEt 3PO in various aprotic and several CH-acidic solvents. Evidence has been found for the existence of dipole-dipole complexes in concentrated solutions ofEt 3PO in solvents of low acceptor numbers. In dilute solutions, however, the P=O stretching band generally occurs as a single symmetrical peak which shows that only one kind of solvate species is present in solution. In CH-acidic solventsEt 3PO is present in the form of hydrogen bonded complexes. Informations about the structure of these complexes have been obtained by means of spectrophotometric titrations. It has been shown that the wavenumbersv°(PO) obtained by extrapolation ofv(PO) values to zero concentration are linearly related to the acceptor numbers of the solvents, previously derived from31P-chemical shift measurements. The existence of this linear relationships proves that both parameters are linearly related to the strength of the intermolecular interactions and are virtually free from unspecific contributions such as magnetic anisotropy or vibrational coupling effects. The results of the present study show that the P=O stretching vibration ofEt 3PO represents an ideal probe for the investigation of solvent effects and solvation mechanisms.

Moglichkeiten und Grenzen der Anwendung der Infrarotspektroskopie mittels abgeschwachter Totalreflexion (IR-ATR-Spektroskopie) zur Oberflachenanalyse organischer Filme und Schichten ergeben sich durch theoretische Uberlegungen bezuglich der Auswirkung von Einfallswinkel des Messtrahls auf die Probe, der Wellenlange der verwendeten Strahlung, der Brechungsindices von Reflexionselement und Probe sowie von Falsch- und Streulicht auf die Extinktion der Mesbanden. Mit KRS-5-Reflexionselementen (60°) lassen sich demnach Eindringtiefen von 0,4 bis 1,6μm (fur den Aufnahmebereich 3,5 bis 13μm und Nachweisgrenzen fur organische Beschichtungen auf Aluminium im Nanometerbereich ermitteln. Die praktische Anwendbarkeit wird durch einige aktuelle Beispiele bewiesen.

The adsorption of 3-aminopropyltriethoxysilane (3-APTS) on germanium crystals was investigated using Attenuated Total Reflection (ATR) spectroscopy. Ethanol, which is produced by the hydrolysis of 3-APTS in water, adsorbs on germanium prior to 3-APTS. This can be checked by the CH3-modes at 1150 cm−1 and 2975 cm−1. The structure differences between chemisorbed and physisorbed 3-APTS can be observed by the shift of the Si-O-Si bands of the silane molecules. The asymmetric and symmetric stretch bands for chemisorbed 3-APTS occurs at 1096 cm−1 and 1022 cm−1, whereas, the bands for physisorbed 3-APTS are found at 1115 cm−1 and 1038 cm−1. The amino groups of physisorbed 3-APTS display two strong bands at 1566 cm−1 and 1485 cm−1 which result from amino groups strongly hydrogen bonded to free silanols. The deformation modes of the amino groups in chemisorbed layers can be found at 1609 cm−1 and 1512 cm−1, which is due to the deformation modes of the free amino groups. A controlled chemisorption is important for the development of chemical IR-sensors [15].

The fundamental importance of scientific research for the preservation and restoration of works of art is uncontestable. The methods described in this paper, such as light microscopy, microchemical tests, emission spectroscopy, chromatography, scanning electron analysis, electron microprobe analysis and infrared spectroscopy, are of special significance in this filed. Nevertheless a better understanding of the problems that arise out of new special questions of art history can be obtained only by the right interpretation of the data obtained by scientific methods.

An IR-spectroscopic study has been carried out on the solvation state of the model compoundEt 3PO in the solvents methanol, ethanol, propanol, 2-propanol, butanol, 1,2-ethanediol, 1,3-propanediol, water, acetic acid, and formamide. With the exception of formamide (where only one solvate species was detected) the spectra show the presence of two basic types of solvate complexes, which derive from hydrogen bonded complexes withprimary coordination numbers of one and two, respectively. In water there is evidence that higher coordinated solvates (withprimary solvation numbers of two and three) are formed. Detailed informations about the structure of these complexes were obtained by spectrophotometric titrations, which show that extensive outer-sphere interactions are taking place in the neat solvents. For solvents, where only one kind of solvate species is present, an excellent correlation was found between solvent acceptor numbers and the wavenumbersv(PO) of the P=O stretching vibration ofEt 3PO. By contrast, acceptor numbers of protic solvents usually represent average values, which are determined by the relative concentrations and31P-chemical shifts of the individual solvates present in solution. By means of the wavenumbersv(PO) of these solvates and the linear correlation mentioned above, it has become possible to calculate refined acceptor number values termed “Individual Acceptor Numbers”, which characterize the acceptor properties of protic solvents as a function of the solvation numbers of the substrates under consideration. It is shown, that the use of these individual acceptor numbers in linear energy relationships allows a significantly improved unified description of solvent effects on chemical reactions and physical processes in aproticand protic solvents.

The vibrational spectra [IR and Raman) of a number of N,N-diethyldithiocarbamate complexes have been recorded in the solid state (500–30 cm"1) and in solution (500–250 cm"1). The spectra of the solids have been analysed by the correlation method and compared with X-ray diffraction data and those of the solutions by the group-theoretical approach in order to study the changes in the effective symmetry upon dissolution. The analytically important complexes of the closed-shell ions [Zn(II), Cd(II) and Hg(II)] as well as the open-shell ions Ni(II) and Cu(II) have revealed enhanced symmetry upon dissolution produced by removing the intermolecular contacts which exist in the crystals. The Te(II) and Pb(II) complexes seem to retain their molecular symmetry upon dissolution. The findings of this integrated approach are important for analytical chemistry since the studied compounds are used exclusively in solution for enrichment, separation and determination, and X-ray data on solids cannot in general be transferred to describe molecular structures in solution.

Ein neues Verfahren zur Untersuchung von Elektrodenoberflachen im Kontakt mit Elektrolytlosungen wird beschrieben. Die Methode der inneren Vielfachreflexionsspektroskopie im infraroten Spektralbereich (ATR-FT-IR-Spektroskopie) erlaubt bei Verwendung eines schnell registrierenden Fourier-Transform-Spektrometers den Nachweis von Reaktionszwischen- und Endprodukten direkt an der Elektrodenoberflache. Am Beispiel der Reaktionen der Eisen- und Cadmiumelektrode in stark alkalischen Losungen werden die Moglichkeiten und Grenzen dieses Verfahrens erlautert.

From visual inspection by light microscopy it is likely that structural modifications are coexisting in microdomains of e.g.a-oxofuran acetamide, salicylic acid hydrazide and benzotriazole-5-carbonic acid methyl ester. An isolation of these phases is, however, not easy and a direct analysisin situ requires a non-destructive method of molecular specific microanalysis. Using FTIR-microscopy the samples prepared as thin film by cooling from the molten stage on an Al-mirror could be characterized as heterogeneous (lateral resolution 20μm). The IR-spectra of the different microphases could be recorded for the first timein situ. Any conventional sample preparation technique (KBr-disk or dissolution) would destroy the important information about the microphase composition. A mere comparison of the micro-FTIR-spectra shows clearly the difference between the microphases. By using step scanning and image processing devices also invisible microphases can be detected (FTIR-microprobe). FTIR-microscopy can be successfully used to investigate temperatureinduced microphase transitions. Examples for D,L-norleucine, oxeladin citrate and 2-chloro-ethane-amine hydrochloride are given also.

Es wird ein neues Verfahren zur IR-ATR-spektroskopischen Dickenbestimmung von dunnen organischen Filmen beschrieben und der konventionellen Methode unter Verwendung empirisch ermittelter Eichkurven gegenubergestellt. Das neue Verfahren beruht auf der Auswertung der Abhangigkeit der gemessenen Extinktion von den Probenparametern Schichtdicke, Brechungsindex und Extinktionskoeffizient, sowie von Parametern der Aufnahmeanordnung (Material und Geometrie des Reflexionselementes, sowie Polarisationsgrad). Anhand eines Modellfalles (Vinylite-Schichten, ein PVC-PVA-Copolymerisat auf Aluminiumfolien) werden die Einflusse der variablen Parameter auf das Analysenresultat untersucht und Moglichkeiten und Grenzen der Anwendung diskutiert. Im Fall glatter Aluminiumoberfiachen ergeben sich untere Nachweisgrenzen von 1,2 nm und 3 nm fur Banden mit Absorptionskoeffizienten von 43, 4 mm−1 bzw. 11,4 mm−1. Die obere Grenze (Beginn der Nichtlinearitat) liegt bei 400 nm. Typische Variationskoeffizienten betragen etwa 5%. Die Ubereinstimmung der nach dem neuen Verfahren berechneten Werte mit den tatsachlichen ist zufriedenstellend. Bei bekannter Filmdicke im Linearbereich, oder wenn diese groser ist als die Eindringtiefe, ist auch die Bestimmung des Gehaltes von Komponenten der Probe ohne Verwendung von Eichkurven moglich.

Reliable assignments of most of the bands of vibrational molecular spectra suffer from ambiguous interaction of atomic displacements. Various experimental methods must be used to ascertain the assignment. By means of dichroic measurements of vibrational bands additional information can be obtained to reach this goal. Thus FT-IR ATR spectra of single crystals of Cd(DEDTC)2 were recorded. If the molecular site with respect to the crystallographic cell is taken into account, the symmetry of certain vibrational modes can be determined. For aC 2h factor group of the monoclinic cell it is possible to distinguish betweenA u andB u symmetry species by the different dichroic ratios of the vibrational bands. This method supports vibrational assignment being verified by force constant refinement calculations. As a result a correlation between molecular site, symmetry and dichroic ratios of vibrational modes of single crystals is presented.