Selected publications reporting the application of MIR fibre optical sensors. Please access the original document by clicking on the DOI/URL link.

JabRef References output

QuickSearch:   Number of matching entries: 0.

AuthorTitleYearJournal/ProceedingsReftypeDOI/URL
Minnich, C. B., Greiner, L., Reimers, C., Uerdingen, M. & Liauw, M. A. Bridging the gap: A nested-pipe reactor for slow reactions in continuous flow chemical synthesis 2010 Chemical Engineering Journal   article DOIURL  
Abstract: A multi-purpose production facility for continuous ow operation of medium-fast to slow chemical reactions was realised. The reactor concept followed the typical three-stage sequence for numerous organic reactions: non-reactive mixing at low temperature, main conversion with selectivity control at medium temperature, and completion of the reaction at high temperature. For the first two stages, a static mixer for immediate mixing and a micro-structured heat exchanger for efficient heat transfer were utilised, respectively. A lack of equipment availability was experienced for the third stage, requiring reaction times in the hours range at well-defined flow conditions. In order to bridge this gap between (micro-)structured low-volume devices and traditional macro-scale equipment for long reaction times, a novel nested-pipe reactor design based on annular slit geometries was realised. These reactor modules provide reaction volumes between 0.25 and 8.0 L, depending on the width of the slit and the number of reactor modules connected in series. The entire unit was constructed as a compact, mobile, self-consistent device with a high degree of automation. As a representative process example, the solvent-free synthesis of the Ionic Liquid [EMIM]EtSO4 from N-methylimidazole and diethylsulfate was selected, since this reaction is characterised by high initial rates of reaction and heat release, and requires long reaction times in order to achieve high conversion. A characterisation of the residence time behaviour of the annular slit reactors was performed by means of fibre optical mid-infrared spectroscopy. Tracer experiments in step-change mode showed a well predictable response behaviour with a pronounced laminar contribution in the studied flow parameter range.
BibTeX:
@article{Minnich2010,
  author = {Minnich, Clemens B. and Greiner, Lasse and Reimers, Christian and Uerdingen, 

Marc and Liauw, Marcel A.},
  title = {Bridging the gap: A nested-pipe reactor for slow reactions in continuous flow chemical synthesis},
  journal = {Chemical 

Engineering Journal},
  year = {2010},
  volume = {In Press, Accepted Manuscript},
  pages = {--},
  url = 

{http://www.sciencedirect.com/science/article/B6TFJ-511K42B-2/2/b8b0ec853a3cff5c1aadbc5dcc326bdf},
  doi = {http://dx.doi.org/10.1016/j.cej.2010.09.004}
}
Minnich, C. B., Sipeer, F., Greiner, L. & Liauw, M. A. Determination of the Dispersion Characteristics of Miniaturized Coiled Reactors with Fiber-Optic Fourier Transform Mid-infrared Spectroscopy 2010 Industrial & Engineering Chemistry Research   article DOI  
Abstract: A miniaturized modularized tubular reactor setup designed for flexible small-scale experimentation under continuous flow conditions was investigated for its residence time behavior. Studies focused on the question of whether the coil shape of the tubular reactor segments beneficially affects the dispersion behavior of the system by inducing secondary flows in the dispersed plug flow pattern. In the studies, fiber-coupled sensors for the attenuated total reflectance technique were applied to measure concentration profiles of tracer substances by Fourier transform mid-infrared spectroscopy. Sensor flow cells with specifically structured flow geometries were designed in order to reduce the impact on the flow characteristics, and in this context they have proven to be superior to nonstructured flow cells. Quantitative evaluation of the measured spectra yielded good-quality time profiles of the tracer concentration that were subjected to a mathematical approximation with the well-established dispersion model by Taylor and Aris. In accordance with model predictions from literature, the axial dispersion coefficient is drastically reduced in coiled capillaries as compared to the coefficient in the Taylor−Aris case for straight tubes. Depending on the influence of the tube curvature and the flow properties, expressed by the product of the square Dean number and the Schmidt number, the reduction of the axial dispersion coefficient can be by up to a factor of 4. For chemical processes with critical requirements regarding selectivity, this can be of great advantage since the detrimental impact of axial back-mixing is effectively reduced.
BibTeX:
@article{Minnich2010a,
  author = {Minnich, Clemens B. and Sipeer, Frank and Greiner, Lasse and Liauw, Marcel A.},
  title = 

{Determination of the Dispersion Characteristics of Miniaturized Coiled Reactors with Fiber-Optic Fourier Transform Mid-infrared Spectroscopy},
  journal = 

{Industrial \& Engineering Chemistry Research},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {49},
  number = {12},
  pages = 

{5530--5535},
  doi = {http://dx.doi.org/10.1021/ie901094q}
}
Bentrup, U., Radnik, J., Armbruster, U., Martin, A., Leiterer, J., Emmerling, F. & Brückner, A. Linking Simultaneous In Situ WAXS/SAXS/Raman with Raman/ATR/UV–vis Spectroscopy: Comprehensive Insight into the Synthesis of Molybdate Catalyst Precursors 2009 Topics in Catalysis   other DOI  
Abstract: A new setup is presented which enables simultaneous wide- and small-angle X-ray scattering (WAXS/SAXS) and Raman spectroscopic experiments during the synthesis of Mo-based mixed oxide catalyst precursors at the μ-spot beamline at the Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung (BESSY). Furthermore, we report about the separate monitoring of the same reactions under comparable conditions by simultaneous combined ATR/UV–vis/Raman spectroscopic measurements. For testing the performance of both experimental setups two syntheses were described comprising the precipitation of metal molybdates by mixing solutions of metal nitrates and ammonium heptamolybdate. Additionally, the effect of H3PO4 admixture on precipitation was investigated. The combined evaluation of spectroscopic and WAXS/SAXS data allows the discrimination between different molybdate species appearing in solution and precipitate. Furthermore, these molybdate species could be assigned to separate phases of different crystallinity.
BibTeX:
@other{Bentrup2009,
  author = {Bentrup, Ursula and Radnik, Jörg and Armbruster, Udo and Martin, Andreas and Leiterer, Jork and Emmerling, 

Franziska and Brückner, Angelika},
  title = {Linking Simultaneous In Situ WAXS/SAXS/Raman with Raman/ATR/UV–vis Spectroscopy: Comprehensive Insight into the 

Synthesis of Molybdate Catalyst Precursors},
  journal = {Topics in Catalysis},
  publisher = {Springer Netherlands},
  year = {2009},
  volume = {52},
  number 

= {10},
  pages = {1350--1359},
  doi = {http://dx.doi.org/10.1007/s11244-009-9309-y}
}
Hbner, S., Bentrup, U., Budde, U., Lovis, K., Dietrich, T., Freitag, A., Kpper, L. & Jhnisch, K. An Ozonolysis-Reduction Sequence for the Synthesis of Pharmaceutical Intermediates in Microstructured Devices 2009 Organic Process Research & Development   article URL  
Abstract: The advantages of microstructured reactors were utilized in a two-step process for the preparation of intermediates of vitamin D analogues, which are known to be important compounds in bone and mineral metabolism. The reaction sequence consisting of an ozonolysis step of a double bond and a subsequent reduction was successfully performed in a microplant. Concerning the feasibility and optimization of the two reaction steps in different microreactors, ozonolysis and reduction have initially been investigated separately. A miniaturized ATR sensor was employed for online monitoring of the ozonolysis step. The overall process was then performed in a continuous manner. The utilization of microstructured devices allows for the realization of a safe and highly controlled multistep process with online analysis via FTIR.
BibTeX:
@article{Huebner2009,
  

author = {Hbner, Sandra and Bentrup, Ursula and Budde, Uwe and Lovis, Kai and Dietrich, Thomas and Freitag, Andreas and Kpper, Lukas and Jhnisch, Klaus},
  

title = {An Ozonolysis-Reduction Sequence for the Synthesis of Pharmaceutical Intermediates in Microstructured Devices},
  journal = {Organic Process Research 

\& Development},
  publisher = {American Chemical Society},
  year = {2009},
  volume = {13},
  number = {5},
  pages = {952--960},
  url = 

{http://dx.doi.org/10.1021/op9000669}
}
Kondepati, V. R., Kremer, C. & Kpper, L. Fibre-optic probes for infrared spectrometry: versatile applications within process monitoring and quality control. 2008 G.I.T. Laboratory Journal, Europe   article  
Abstract: According to the general trend in anal. chem., phys. methods will gain in importance within the areas of process and quality control. To comply with these applications, reagent-free and rapid spectroscopic procedures without any sample prepn. are required. In particular, IR spectra contain high information content with regard to identification of pure substances, as required, for example, for raw materials entering the factory premises or the anal. of complex mixt. samples for quality or process control. The available measurement techniques with fiber-optic probes allow the study of solid and liq. substances, but also of biol. aq. samples with components at per mille concns. and lower. [on SciFinder(R)]
BibTeX:
@article{Kondepati2008,
  author = {Kondepati, Venkata R. and Kremer, Claudia and Kpper, Lukas},
  title = {Fibre-optic probes for 

infrared spectrometry: versatile applications within process monitoring and quality control.},
  journal = {G.I.T. Laboratory Journal, Europe},
  publisher = 

{GIT Verlag GmbH \& Co. KG},
  year = {2008},
  volume = {12},
  number = {5-6},
  pages = {14--17}
}
Minnich, C. B., Buskens, P., Steffens, C., Buerlein, P. S., Butvina, L. N., Kpper, L., Leitner, W., Liauw, M. A. & Greiner, L. Highly Flexible Fibre-Optic ATR-IR Probe for Inline Reaction Monitoring 2007 Organic Process Research & Development   article DOI  
Abstract: Abstract: Near infrared (IR) applications have considerably profited from the use of flexible and robust fibre-optical probes. So far, a comparable technique for mid-IR was not available due to low stability and lack of robustness of the fibres. We report the use of a newly developed miniaturised diamond ATR-probe with high chemical resistance and pressure resistance based on robust fibre optics. The routine and convenient application in a glove box to highly air- and oxygen-sensitive reactions on a millilitre scale is reported, as well as the monitoring of a solventless reaction on a litre scale.
BibTeX:
@article{Minnich2007,
  author = {Minnich, Clemens B. and Buskens, Pascal and 

Steffens, Christian and Buerlein, Patrick S. and Butvina, Leonid N. and Kpper, Lukas and Leitner, Walter and Liauw, Marcel A. and Greiner, Lasse},
  title = 

{Highly Flexible Fibre-Optic ATR-IR Probe for Inline Reaction Monitoring},
  journal = {Organic Process Research \& Development},
  year = {2007},
  volume = 

{11},
  number = {1},
  pages = {94--97},
  doi = {http://dx.doi.org/10.1021/op0601767}
}
Minnich, C. B., Kpper, L., Liauw, M. A. & Greiner, L. Combining reaction calorimetry and ATR-IR spectroscopy for the operando monitoring of ionic liquids synthesis 2007 Catalysis TodayOperando Spectroscopy   article DOI  
Abstract: For the routine application of ionic liquids in organic synthesis and catalysis, high purity is a key issue. Prerequisite for this is a reproducible synthesis procedure, so a detailed knowledge of kinetics and thermodynamics is required. We combined reaction calorimetry with ATR-IR spectroscopy based on fibre optics for the operando monitoring in order to achieve an appropriate characterisation of the established batch processes. Based on this a continuous process utilising micro-structured equipment was realised that avoids end-of-pipe workup.
BibTeX:
@article{Minnich2007b,
  author = {Minnich, Clemens B. and Kpper, Lukas 

and Liauw, Marcel A. and Greiner, Lasse},
  title = {Combining reaction calorimetry and ATR-IR spectroscopy for the operando monitoring of ionic liquids 

synthesis},
  booktitle = {Operando Spectroscopy},
  journal = {Catalysis Today},
  year = {2007},
  volume = {126},
  number = {1--2},
  pages = {191--195},
  

doi = {http://dx.doi.org/10.1016/j.cattod.2006.12.007}
}
Friebe, A. & Siesler, H. In situ monitoring of an isocyanate reaction by fiber-optic FT-IR/ATR-spectroscopy 2007 Vibrational SpectroscopyVIBRATIONAL SPECTROSCOPY - Dedicated to John van der Maas, Founding Editor   article DOI  
Abstract: This communication describes the application of a fiber-optic coupled FT-IR/ATR-probe to study the AlCl3 catalyzed reaction of phenyl isocyanate and phenol to diphenyl urethane in chloroform solution at variable temperatures and to derive the activation energy from the corresponding concentration profiles.
BibTeX:
@article{Friebe2007,
  author = {Friebe, A. and Siesler, H.W.},
  title = {In situ monitoring of an isocyanate 

reaction by fiber-optic FT-IR/ATR-spectroscopy},
  booktitle = {VIBRATIONAL SPECTROSCOPY - Dedicated to John van der Maas, Founding Editor},
  journal = 

{Vibrational Spectroscopy},
  year = {2007},
  volume = {43},
  number = {1},
  pages = {217--220},
  doi = {http://dx.doi.org/10.1016/j.vibspec.2006.07.004}
}
Minnich, C. B., Kpper, L., Kaever, M., Greiner, L. & Liauw, M. A. Process monitoring and control in microreactors with ATR IR Spectroscopy. 2007 Chemie Ingenieur Technik   article DOI  
BibTeX:
@article{Minnich2007a,
  author = {Minnich, C. B. and 

Kpper, L. and Kaever, M. and Greiner, L. and Liauw, M. A.},
  title = {Process monitoring and control in microreactors with ATR IR Spectroscopy.},
  journal = 

{Chemie Ingenieur Technik},
  publisher = {Wiley-VCH Verlag GmbH \& Co. KGaA},
  year = {2007},
  volume = {79},
  number = {9},
  pages = {1288--},
  doi = 

{http://dx.doi.org/10.1002/cite.200750089}
}
Bentrup, U., Kpper, L., Budde, U., Lovis, K. & Jhnisch, K. Mid-infrared monitoring of gas-liquid reactions in vitamin D analog synthesis with a novel fiber optical diamond ATR sensor. 2006 Chemical Engineering & Technology   article DOI  
Abstract: A novel mid-IR optical sensor enabling in situ ATR measurements was applied to investigate several steps of a vitamin D analog synthesis. The probe based on silver halide fibers coupled to a diamond prism was connected to a conventional FTIR spectrometer with internal MCT detector. All steps of the reaction were monitored by real-time in situ FTIR measurements. The steps carried out were the dissoln. of SO2 in a CH2Cl2/MeOH solvent mixt. as well as the addn. of SO2 to a vitamin D analog, the subsequent ozonation of the double bond in the SO2 addn. product, and the following redn. of the formed hydroperoxide with triphenylphosphine. The dissolving process of SO2 and the addn. of SO2 to the vitamin D analog were monitored by changing the characteristic νas(SO2) and νs(SO2) modes of dissolved and incorporated SO2. It was found that during ozonation of the SO2 addn. product the formation of hydroperoxide is accompanied by the simultaneous formation of the corresponding aldehyde identified by the typical ν(C=O) band at 1720 cm-1. Extended ozone exposure favors the formation of the corresponding acid detected by an addnl. carbonyl band at lower wavenumbers. During the reaction with triphenylphosphine the increasing intensity of the aldehyde band and the appearance of the ν(P=O) mode of the formed triphenylphosphine oxide indicate the progressive redn. of hydroperoxide. The hydroperoxide band disappears completely during the reaction whereas the νas(SO2) band remains unaffected. [on SciFinder(R)]
BibTeX:
@article{Bentrup2006,
  author = {Bentrup, Ursula and Kpper, Lukas and Budde, 

Uwe and Lovis, Kai and Jhnisch, Klaus},
  title = {Mid-infrared monitoring of gas-liquid reactions in vitamin D analog synthesis with a novel fiber optical 

diamond ATR sensor.},
  journal = {Chemical Engineering \& Technology},
  publisher = {Wiley-VCH Verlag GmbH \& Co. KGaA},
  year = {2006},
  volume = {29},
  

number = {10},
  pages = {1216--1220},
  doi = {http://dx.doi.org/10.1002/ceat.200600110}
}
Ring, A., Schreiner, V., Wenck, H., Wittern, K., Kpper, L. & Keyhani, R. Mid-infrared spectroscopy on skin using a silver halide fibre probe in vivo 2006 Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI)   article  
Abstract: BACKGROUND/AIM: Mid-infrared spectroscopy is a versatile method for in vivo investigation of skin after topical treatment with skin care products. METHODS: FTIR-spectrometer (Bruker Optics) with a flexible silver halide fibre probe (Infrared Fiber Sensors). RESULTS: Absorbance spectra from 700 to 3000 cm(-1) have been recorded to gain information about proteins (amide-I and amide-II vibrations at 1650 and 1550 cm(-1)), esters (1740 cm(-1)), carboxylic acid (1710 cm(-1)), polyalcohols (1050 cm(-1)) and hydrocarbons (CH(n) vibrations at 2800-3000 cm(-1)). CONCLUSIONS: Using the particular light guide, we were able to measure for the first time the effects of lip care products on lips directly. Furthermore, water binding and glycerol content of the skin could be determined simultaneously, as well as the replenishment of lipids by lipid-enriched bath oil.[on SciFinder (R)]
BibTeX:
@article{Ring2006,
  author = {Ring, A. and Schreiner, V. and Wenck, H. and Wittern, K.P. and Kpper, L. and Keyhani, R.},
  

title = {Mid-infrared spectroscopy on skin using a silver halide fibre probe in vivo},
  journal = {Skin research and technology : official journal of 

International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for 

Skin Imaging (ISSI)},
  year = {2006},
  volume = {12},
  number = {1},
  pages = {18--23}
}
Kpper, L., Gulmine, J. V., Janissek, P. R. & Heise, H. M. Attenuated total reflection infrared spectroscopy for micro-domain analysis of polyethylene samples after accelerated ageing within weathering chambers. 2004 Vibrational Spectroscopy   article DOI  
Abstract: Elucidation of the chem. changes that take place during the aging of polyethylene by weathering can be accomplished by IR spectroscopy. Accelerated aging was applied to the most representative low-d. polyethylene (LDPE) found in markets today. The samples were exposed to UV- and xenon-arc radiation of varying duration and temp. cycles. The structural changes in the material surface were analyzed by SEM and chem. compn. was studied by FTIR spectroscopy. By varying the crystal material in the conventional attenuated total reflection (ATR) expts. it was possible to analyze distinct layers from the surface. Micro-domain anal. was made possible by using a novel ATR microprobe based on a silver halide fiber of circular cross-section with an outer diam. of 700 μm. Layers at larger depth were reached by cross-sectioning the LDPE-samples and measuring the concn. profiles of oxidn. products down to 500 μm with a spatial resoln. lesser than 15 μm. The main chem. modifications were from carbonyl formation of various kinds identifiable in the ATR-FTIR spectra of degraded polyethylene samples. [on SciFinder(R)]
BibTeX:
@article{Kpper2004,
  author = {Kpper, L. and Gulmine, J. V. and Janissek, P. R. and Heise, H. 

M.},
  title = {Attenuated total reflection infrared spectroscopy for micro-domain analysis of polyethylene samples after accelerated ageing within weathering 

chambers.},
  journal = {Vibrational Spectroscopy},
  publisher = {Elsevier Science B.V.},
  year = {2004},
  volume = {34},
  number = {1},
  pages = 

{63--72},
  doi = {http://dx.doi.org/10.1016/j.vibspec.2003.05.002}
}
Heise, H. M., Kpper, L. & Butvina, L. N. Mid-infrared attenuated total reflection spectroscopy of human stratum corneum using a silver halide fiber probe of square cross-section and adhesive tape stripping. 2003 Journal of Molecular Structure   article DOI  
Abstract: Mid-IR fiber probes allow an extended use of attenuated total reflection (ATR) measurements for topical in vivo skin anal., which were otherwise not possible with conventional sample compartment accessories. Evanescent wave spectroscopy using a flexible fiber-optic probe from silver halide fibers of square cross-section was employed for stratum corneum characterization and keratinocyte quantification on adhesive tapes. Such a method of quantifying the amt. of keratin, which can be repetitively removed from the skin surface by adhesive tape application, is essential for the study of substances topically applied and penetrating into the horny layer. For calibration, the wt. of keratinocytes was detd. using an ultramicro-balance. Best results were obtained with difference spectroscopy and the evaluation of the amide I absorption band intensity (correlation coeff. r=0.983). Lowest amts. per cm2 were reached for the range down to 5 μg/cm2. The heterogeneity in the surface d. of keratinocytes clinging to the tape was investigated by microscopy, and the thickness of some individual keratinocytes was tested by ATR-microspectroscopy and at. force microscopy. [on SciFinder(R)]
BibTeX:
@article{Heise2003,
  author = 

{Heise, H. M. and Kpper, L. and Butvina, L. N.},
  title = {Mid-infrared attenuated total reflection spectroscopy of human stratum corneum using a silver 

halide fiber probe of square cross-section and adhesive tape stripping.},
  journal = {Journal of Molecular Structure},
  publisher = {Elsevier Science B.V.},
  

year = {2003},
  volume = {661-662},
  pages = {381--389},
  doi = {http://dx.doi.org/10.1016/j.molstruc.2003.07.019}
}
Heise, H. M., Kpper, L. & Butvina, L. N. Novel infrared optical probes for process monitoring and analysis based on next-generation silver halide fibers. 2003 Analytical and Bioanalytical Chemistry   article DOI  
Abstract: Mid-IR spectroscopy proved to be a powerful method for the study of various samples and chem. media as found in different industrial processes. In general, the anal. of such samples takes advantage of the fact that multiple analytes can be quantified simultaneously and rapidly without the need for addnl. reagents. When compared to near-IR spectroscopy, for which quartz fiber probes can be successfully applied, the application of previously used mid-IR fiber materials was restricted due to deficiencies with regard to their optical transmission and mech. properties. Progress in the quality of IR transparent silver halide fibers and their extrusion with different cross sections enabled the authors to construct several flexible fiber-optic probes of different geometries which are particularly suitable and inert for process monitoring. Transmission and attenuated total reflection measurement techniques have mainly been employed for the anal. of liq. and gaseous media. One larger field, for which results are reported, is chem. reactor monitoring. Other applications are concerned with bio-reactor monitoring, or quasi-continuous measurements for the food industry. IR spectroscopic cosmetic assays for detg. the chem. compn. of skin-care formulations are a further promising field of application, for which an example is given. [on SciFinder(R)]
BibTeX:
@article{Heise2003a,
  author = {Heise, H. M. and Kpper, L. and Butvina, L. 

N.},
  title = {Novel infrared optical probes for process monitoring and analysis based on next-generation silver halide fibers.},
  journal = {Analytical and 

Bioanalytical Chemistry},
  publisher = {Springer-Verlag},
  year = {2003},
  volume = {375},
  number = {8},
  pages = {1116--1123},
  doi = 

{http://dx.doi.org/10.1007/s00216-003-1782-8}
}
Heise, H. M., Kpper, L. & Butvina, L. N. Bio-analytical applications of mid-infrared spectroscopy using silver halide fiber-optic probes. 2002 Spectrochimica Acta, Part B: Atomic Spectroscopy   article  
Abstract: IR-spectroscopy has proved to be a powerful method for the study of various biomedical samples, in particular for in-vitro anal. in the clin. lab. and for non-invasive diagnostics. In general, the anal. of biofluids such as whole blood, urine, microdialyzates and bioreactor broth media takes advantage of the fact that a multitude of analytes can be quantified simultaneously and rapidly without the need for reagents. Progress in the quality of IR silver halide fibers enabled us to construct several flexible fiber-optic probes of different geometries, which are particularly suitable for the measurement of small biosamples. Recent trends show that dry film measurements by mid-IR spectroscopy could revolutionize anal. tools in the clin. chem. lab., and an example is given. IR diagnostic tools show a promising potential for patients, and minimal-invasive blood glucose assays or skin tissue pathol. in particular cannot be left out using mid-IR fiber-based probes. Other applications include the measurement of skin samples including penetration studies of vitamins and constituents of cosmetic cream formulations. A further field is the micro-domain anal. of biopsy samples from bog mummified corpses, and recent results on the chem. of dermis and hair samples are reported. Another field of application, for which results are reported, is food anal. and bio-reactor monitoring. [on SciFinder(R)]
BibTeX:
@article{Heise2002,
  author = {Heise, H. M. and Kpper, L. and Butvina, L. 

N.},
  title = {Bio-analytical applications of mid-infrared spectroscopy using silver halide fiber-optic probes.},
  journal = {Spectrochimica Acta, Part B: 

Atomic Spectroscopy},
  publisher = {Elsevier Science B.V.},
  year = {2002},
  volume = {57B},
  number = {10},
  pages = {1649--1663}
}
Heise, H. M., Voigt, G., Lampen, P., Kpper, L., Rudloff, S. & Werner, G. Multivariate calibration for the determination of analytes in urine using mid-infrared attenuated total reflection spectroscopy. 2001 Applied Spectroscopy   article DOI  
Abstract: The reagent-free multicomponent anal. of components in urine using mid-IR spectroscopy possesses many attractions. A population of 67 individual urine samples from children and adults, collected over 24 h, was analyzed for urea, creatinine, uric acid, glucose, total protein, phosphate, and sulfate by using clin. ref. methodol. The urine pH value was potentiometrically measured by a glass electrode. Partial least-squares (PLS) calibration models were calcd. over optimized, component-specific ranges from attenuated total reflection spectra of the urine samples measured by a micro-Circle cell. Apart from glucose and total protein, for which the spread in urine sample concns. was too small, calibrations were successful for metabolites such as urea, creatinine, and uric acid. Addnl., concns. of sulfate and phosphate anions, which show significant mid-IR absorption bands, could also be quantified. The acid secreted with the urine influences the equil. between di- and monobasic phosphate in this biofluid, which is used as the spectroscopic basis for the pH assay presented here. The anal. performance of the ref. methods is discussed with regard to evaluating the limitations of the spectroscopic assay. Addnl., aq. solns. of individual urine components with a spread of concns. similar to those found in native urine samples were analyzed by using PLS calibrations. [on SciFinder(R)]
BibTeX:
@article{Heise2001a,
  author = {Heise, H. M. and Voigt, G. and Lampen, P. and Kpper, L. and Rudloff, S. and Werner, G.},
  title = {Multivariate 

calibration for the determination of analytes in urine using mid-infrared attenuated total reflection spectroscopy.},
  journal = {Applied Spectroscopy},
  

publisher = {Society for Applied Spectroscopy},
  year = {2001},
  volume = {55},
  number = {4},
  pages = {434--443},
  doi = 

{http://dx.doi.org/10.1366/0003702011951948}
}
Heise, H. M., Kpper, L., Pittermann, W. & Butvina, L. N. New tool for epidermal and cosmetic formulation studies by attenuated total-reflection spectroscopy using a flexible mid-infrared fiber probe. 2001 Fresenius' Journal of Analytical Chemistry   article DOI  
Abstract: The potential of mid-IR attenuated total-reflection spectroscopy for dermatol. studies has been increased by the development of a flexible fiber-optic probe from silver halide material. Such a tool significantly eases epidermal surface characterization. Spectra of human forearm skin and of bovine udder skin (BUS-model), which is used as a substitute for in-vivo tests on man, were compared, and as an example low concns. of vitamin E acetate (α-tocopherol acetate) in the stratum corneum were measured after topical skin application. Depth profiling was enabled by repeated steps of tape stripping and subsequent skin measurement. The IR methodol. is rapid and can be applied to small areas of skin. It is also sufficiently sensitive for anal. of a large variety of cosmetic formulations and dermatopharmaca. Discrimination of vehicle formulations is possible because of the large information content of mid-IR spectra. [on SciFinder(R)]
BibTeX:
@article{Heise2001,
  author = {Heise, H. M. and Kpper, L. and Pittermann, W. and Butvina, L. N.},
  title = 

{New tool for epidermal and cosmetic formulation studies by attenuated total-reflection spectroscopy using a flexible mid-infrared fiber probe.},
  journal = 

{Fresenius' Journal of Analytical Chemistry},
  publisher = {Springer-Verlag},
  year = {2001},
  volume = {371},
  number = {6},
  pages = {753--757},
  doi = 

{http://dx.doi.org/10.1007/s002160100927}
}
Kpper, L., Heise, H. M., Bechara, F. & Stucker, M. Micro-domain analysis of skin samples of moor-mummified corpses by evanescent wave infrared spectroscopy using silver halide fibers. 2001 Journal of Molecular Structure   article DOI  
Abstract: IR microscopy plays an important role in chem. micro-domain anal. of inhomogeneous materials. A simple exptl. arrangement based on fiber optics, employing bent silver halide fibers of sub-millimeter diam. cross-section, was used for IR attenuated total reflection (ATR) measurements with a min. spot size of 20 x 60 μm2. It was applied for the anal. of skin specimens and hair samples of mummified corpses, preserved under bog conditions. The dessicated dermis samples looked leather-like, but were rather brittle, so that micro-ATR measurements by a fiber probe were appropriate. Comparable ATR results were obtained using an IR microscope. Compn. along perpendicular dermis sections was evaluated by comparison with spectra from ref. materials. Natural dermis samples are mainly composed of collagen, primarily of type I and III, which was still found in the mummies' skin. The surfaces of the skin samples displayed chem. changes from moor constituents, while the center of the dermis cross-section consisted of unmodified collagen. Keratin in hair samples was also well preserved apart from surface changes, which had been caused by the bog chem. in these samples and are clearly manifested in the IR spectra. [on SciFinder(R)]
BibTeX:
@article{Kpper2001,
  author = {Kpper, L. and Heise, H. M. and Bechara, F.-G. and Stucker, M.},
  title = {Micro-domain 

analysis of skin samples of moor-mummified corpses by evanescent wave infrared spectroscopy using silver halide fibers.},
  journal = {Journal of Molecular 

Structure},
  publisher = {Elsevier Science B.V.},
  year = {2001},
  volume = {565-566},
  pages = {497--504},
  doi = 

{http://dx.doi.org/10.1016/S0022-2860(00)00935-2}
}
Kpper, L., Heise, H. M. & Butvina, L. N. Novel developments in mid-IR fiber-optic spectroscopy for analytical applications. 2001 Journal of Molecular Structure   article DOI  
Abstract: Mid-IR spectroscopy using the attenuated total reflection (ATR) technique plays an important role in anal. chem. Among others, silver halide fibers are promising for the development of remote sensor probes. Studies on long-term stability under various storage conditions were carried out, which demonstrate excellent stability for appropriately encased fibers. For the 1st time, fibers of square cross-section shape are presented and their advantages for IR spectroscopic applications in comparison to fibers of circular cross-section are demonstrated. Various probes, employing such fibers, were developed for measurements of liq. and inhomogeneous solid samples. A short, u-shaped fiber was directly coupled to an MCT-detector, enabling ATR-measurements of solid samples with a min. spot size of 20 μm × 60 μm. Using the same optical setup, lowest concn. detection limits were achieved for aq. solns. For routine anal. of liq. samples, two types of probes were developed using silver halide fibers of square cross-section. One ATR-probe contained an exchangeable, u-shaped piece of fiber, whereas the 2nd probe was made of a fiber coupled diamond micro-prism; the latter is esp. advantageous for small sample vols. to be measured or when extreme chem. inertness of the ATR-crystal is required. Measurements of different beverages were performed with high spectral reproducibility. For routine anal. demanding ultimate sensitivity, exchangeable sensor elements with an Ag2S coating were tested successfully to give an ATR-absorption enhancement by more than a factor of 10 compared to uncoated fibers. [on SciFinder(R)]
BibTeX:
@article{Kpper2001a,
  author = {Kpper, L. and Heise, H. M. and Butvina, L. N.},
  title = {Novel developments 

in mid-IR fiber-optic spectroscopy for analytical applications.},
  journal = {Journal of Molecular Structure},
  publisher = {Elsevier Science B.V.},
  year = 

{2001},
  volume = {563-564},
  pages = {173--181},
  doi = {http://dx.doi.org/10.1016/S0022-2860(00)00804-8}
}
Kpper, L., Heise, H. M., Lampen, P., Davies, A. N. & McIntyre, P. Authentication and quantification of extra virgin olive oils by attenuated total reflectance infrared spectroscopy using silver halide fiber probes and partial least-squares calibration. 2001 Applied Spectroscopy   article DOI  
Abstract: IR attenuated total reflectance spectroscopy has been assessed for the anal. of extra virgin olive oil samples from various Mediterranean sites and their adulteration by sunflower oil. Two different silver halide fiber-optic probes were sep. tested for the mid-IR spectroscopic measurement of pure olive oil samples and these same oils adulterated with sunflower oil. One fiber-optic probe contained an exchangeable U-shaped section of the silver halide fiber, whereas the 2nd probe consisted of a fiber-coupled diamond crystal, which performed slightly less well than the whole fiber probe. The optimum std. error of prediction for the sunflower oil concns. in spiked olive oil samples, obtained by optimized partial least-squares (PLS) calibration models and leave-one-out cross-validation, was 1.2% by wt. with the use of a special variable selection strategy based on a pairwise consideration of significant resp. min. and maxima of the optimum PLS regression vector, calcd. for broad spectral intervals, Calibration robustness was proven by also using packages of 10 randomly selected samples within a further cross-validation for calcg. independent prediction values. The implications for product monitoring are discussed. [on SciFinder(R)]
BibTeX:
@article{Kpper2001b,
  author = {Kpper, Lukas 

and Heise, H. Michael and Lampen, Peter and Davies, Antony N. and McIntyre, Peter.},
  title = {Authentication and quantification of extra virgin olive oils by 

attenuated total reflectance infrared spectroscopy using silver halide fiber probes and partial least-squares calibration.},
  journal = {Applied 

Spectroscopy},
  publisher = {Society for Applied Spectroscopy},
  year = {2001},
  volume = {55},
  number = {5},
  pages = {563--570},
  doi = 

{http://dx.doi.org/10.1366/0003702011952361}
}
Butvina, L. N., Dianov, E. M., Lichkova, N. V., Zavgorodnev, V. N. & Kpper, L. Crystalline silver halide fibers with optical losses lower than 50 dB/km in broad IR region. 1999 Proceedings of SPIE-The International Society for Optical Engineering   article  
Abstract: For the 1st time cryst. Ag halides optical fibers with optical losses <50 dB/km in broad region from 9-14 μm were fabricated by an extrusion process. The optical loss mechanism essential to lowest absorption in Ag halides materials and fibers as intraband absorption by free holes in valence band are proposed. The cryst. fibers with Rayleigh type λ-4 optical scattering were obtained. The IR region near 13 μm in AgBrI fibers with optical losses <10 dB/km was discovered. Nonaged, stable IR polycryst. Ag halides optical fiber cables with losses, <1 dB/m in region from 3-20 μm are presented. Various applications of developed ATR and reflection remote FTIR sensors, based on low losses Ag halides fibers are discussed. [on SciFinder(R)]
BibTeX:
@article{Butvina1999,
  author = 

{Butvina, Leonid N. and Dianov, Eugeni M. and Lichkova, N. V. and Zavgorodnev, V. N. and Kpper, Lukas.},
  title = {Crystalline silver halide fibers with 

optical losses lower than 50 dB/km in broad IR region.},
  journal = {Proceedings of SPIE-The International Society for Optical Engineering},
  publisher = 

{SPIE-The International Society for Optical Engineering},
  year = {1999},
  volume = {3849},
  number = {Infrared Optical Fibers and Their Applications},
  

pages = {181--188}
}
Heise, H. M., Kpper, L. & Butvina, L. N. Attenuated total reflection mid-infrared spectroscopy for clinical chemistry applications using silver halide fibers. 1998 Sensors and Actuators, B: Chemical   article DOI  
Abstract: The quant. anal. of biotic fluids can be carried out using attenuated total reflection mid-IR spectroscopy based on silver halide fibers, because good optical throughput can be achieved esp. in the fingerprint region of the mid-IR spectral range. The advantages and prospects of this technique using biofluids or dry films, obtained from such aq. solns., are discussed in the context of developing routine assay methodol. for the anal. of biofluids submitted to the clin. lab. for anal. Accessories developed from such fibers are simple and less expensive than conventional equipment using classical IR waveguides. Examples are also given for fiber application in gas anal. [on SciFinder(R)]
BibTeX:
@article{Heise1998,
  author = {Heise, H. M. and Kpper, L. and Butvina, L. N.},
  title = {Attenuated total reflection 

mid-infrared spectroscopy for clinical chemistry applications using silver halide fibers.},
  journal = {Sensors and Actuators, B: Chemical},
  publisher = 

{Elsevier Science S.A.},
  year = {1998},
  volume = {B51},
  number = {1-3},
  pages = {84--91},
  doi = {http://dx.doi.org/10.1016/S0925-4005(98)00231-7}
}
Heise, H. M., Bittner, A., Kpper, L. & Butvina, L. N. Comparison of evanescent wave spectroscopy based on silver halide fibers with conventional ATR-IR spectroscopy. 1997 Journal of Molecular Structure   article  
Abstract: With improved optical and mech. properties of cryst. silver halide fibers, the development of novel accessories, in particular of flow-through cells with an inner vol. of a few microliters or disposable sensor parts for sample measurement, is possible. These features enable process monitoring, for example, when only minute sample vols. at low flow rates are available such as in the case of in vivo blood glucose sensing using microdialysis. The performance of some fiber-optic sensors based on evanescent field absorption is compared with that of conventional attenuated total reflection spectroscopy equipment for studying microsamples of biofluids. [on SciFinder(R)]
BibTeX:
@article{Heise1997,
  author = {Heise, H. M. and 

Bittner, A. and Kpper, L. and Butvina, L. N.},
  title = {Comparison of evanescent wave spectroscopy based on silver halide fibers with conventional ATR-IR 

spectroscopy.},
  journal = {Journal of Molecular Structure},
  publisher = {Elsevier},
  year = {1997},
  volume = {410-411},
  pages = {521--525}
}
Butvina, L., Dianov, E., Lichkova, N., Kpper, L., Plotnichenko, V. & Savgorodnev, V. Silver halide crystalline fibers with optical losses 50 dB/km at the CO2-laser wavelength. 1995 Proceedings of SPIE-The International Society for Optical Engineering   article  
Abstract: For the first time cryst. fibers with optical losses 0.05 dB/m at 10.6 μm, 0.2 dB/m at 5-6 μm and 0.7 dB/m at 2.94 μm were fabricated from solid soln. AgClBrI by hot extrusion. Optical losses and numerical aperture for fibers were measured throughout IR spectra. Power delivery of CO2-, Er3+-lasers were studied. Fibers with diam. 0.5, 0.7 mm are able to deliver linearly at least up to 80 W power of continuous-wave CO2 laser. Fibers demonstrate stable delivery of 40 W power for 200 h. Fibers non damage by 0.5 J/pulse in msec pulse operation of Er3+ laser at 2.94 μm. Fibers have low mode mixing and low bending losses. Mech. properties are the same like for ordinary AgClBrI strong soln. fibers. Fibers have long shell-life. Clad cryst. AgClBrI fibers with optical losses 0.2 dB/m at 10.6 μm and diam. 0.7/0.9 mm were fabricated. Clad fibers have numerical aperture 0.3- 0.5. Clad fiber stable deliver 20 W power of continuous-wave CO2 laser on the distance 2 m with total transmission 73% for 200 h. [on SciFinder(R)]
BibTeX:
@article{Butvina1995,
  author = {Butvina, L.N. and Dianov, E.M. and 

Lichkova, N.V. and Kpper, L. and Plotnichenko, V.G. and Savgorodnev, V.N.},
  title = {Silver halide crystalline fibers with optical losses 50 dB/km at the 

CO2-laser wavelength.},
  journal = {Proceedings of SPIE-The International Society for Optical Engineering},
  year = {1995},
  volume = {2631},
  pages = 

{150--5}
}

Created by JabRef on 11/10/2010.