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2023 Book Chapter: Chemometrics & Process Control (from: Springer Handbook for Advanced Catalyst Characterization)
  A book chapter describing the typical procedures in quantitative analysis of spectra along the common workflows. On-the-fly introduction of the fundamental methodology behind the most relevant chemometric methods, using real-life application cases. Valuable overview reading for the practical user!
2021 Inline Raman Spectroscopy of an Emulsion Copolymerization in an Industrial Pilot Plant Using Indirect Hard Modeling

Raman spectroscopy was used to determine the concentrations of monomers and polymers in the second stage of a two-stage emulsion polymerization process. Spectral hard modeling was applied to monitor inline the reaction in semi-batch operation in lab scale and pilot scale.


DOI: 10.1002/cite.202100114

2021 Inline Raman Spectroscopy and Indirect Hard Modeling for Concentration Monitoring of Dissociated Acid Species

Monitoring the concentration of dissociated carboxylic acid species in dilute aqueous solution was demonstrated. The dissociated acid species are quantified employing inline Raman spectroscopy in combination with Indirect Hard Modeling (IHM) and multivariate curve resolution (MCR).

  DOI: 10.1177/0003702820973275
2021 Standardization and Control of Grignard Reactions in a Universal Chemical Synthesis Machine using online NMR

A chemical synthesis platform was extended by online NMR spectroscopy to allow real-time adjustments of encoded reactions. The approach was demonstrated on Grignard reactions. Real-time process analytics and the use of a straightforward feedback control algorithm enable the synthesis in full automation.

  DOI: 10.1002/anie.202106323
2021 Method for Automated Generation of Indirect Hard Models using crossvalidation (MAGIC) for the spectral analysis of mixture spectra
  Indirect Hard Modeling (IHM) requires user decisions regarding the number of peak functions and model flexibility. A method for the Automatic Generation of Indirect Hard Models using Crossvalidation (MAGIC) is presented that jointly chooses the number of peak functions and peak parameter adjustments such that the crossvalidation error of calibration is minimized.
  DOI: 10.1016/j.chemolab.2021.104419
2021 Advanced Real?Time Process Analytics for Multistep Synthesis in Continuous Flow

The integration of four complementary process analytical technology tools (NMR, UV/Vis, IR and UHPLC) in the multistep synthesis of an active pharmaceutical ingredient (mesalazine) is reported. Advanced data analysis models were developed (IHM, deep learning and PLSR), to quantify the desired reactants. The automated flow system has been demonstrated by operating both steady state and dynamic experiments.

  DOI: 10.1002/anie.202016007
2020 Process analytical technology (PAT) as a versatile tool for real-time monitoring and kinetic evaluation of photocatalytic reactions
  Process analytical technology (PAT) was applied to disclose kinetic insights into photocatalytic reactions. The eosin Y catalyzed photooxidation of 4-methoxythiophenol (4-MTP) to bis(4-methoxyphenyl)disulfide (4-MPD) was monitored with Raman and UV/Vis spectroscopy.  The evaluation by indirect hard modelling approach (IHM) disclosed the contributions of rate limiting effects like the oxygen mass transport and the degradation of eosin Y.
  DOI: 10.1039/D0RE00256A
 2020 Artificial neural networks for quantitative online NMR spectroscopy
  Data augmentation procedure for the generation of synthetic (simulated) NMR spectra based on spectral hard modeling enables the development of data-driven models such as neural nets because the initial training dataset can be sized and distributed along various prediction variables arbitrarily.
  DOI: 10.1007/s00216-020-02687-5
2019 Kinetics of Formic Acid Decomposition in Subcritical and Supercritical Water - A Raman Spectroscopic Study
  In-situ Raman spectroscopy is used to produce real-time data and accurately quantify product yields of H2, CO2, and CO of the decomposition of formic acid in sub- or supercritical water. PEAXACT allowed for efficient analysis of the large data set.
  DOI: 10.1016/j.ijhydene.2019.10.070
2018 Investigating phase separation in amorphous solid dispersions via Raman mapping
  Phase-separation kinetics and the compositions of the two amorphous phases evolving due to amorphous solid dispersions were quantitatively determined for the first time using confocal Raman spectroscopy and Indirect Hard Modeling (IHM).
  DOI: 10.1016/j.ijpharm.2017.11.014
2018 Choosing Appropriate Solvents for the preparation of amorphous solid dispersions (ASD)
  ASDs are often used for formulating poorly water-soluble active pharmaceutical ingredients (APIs). Raman measurements were carried out and Indirect Hard Modeling (IHM) was used to quantify the API distribution in ASD films as well as to investigate the compositions in the films during drying.
  DOI: 10.1021/acs.molpharmaceut.8b00892
2018 Reliable spectroscopic process monitoring using an optimal acquisition time procedure determined by signal-to-noise ratio
  Monitoring chemical processes with optical spectroscopy involves a trade-off between high-frequency sampling to capture process dynamics and good signal-to-noise ratio (SNR). This contribution presents a strategy to maximize sampling frequency while maintaining a high SNR during in-line process monitoring using IHM.
  DOI: 10.1016/j.measurement.2018.02.061
2017 Robust analysis of spectra with strong background signals by First-Derivative Indirect Hard Modeling (FD-IHM)
  First-Derivative Indirect Hard Modeling (FD-IHM) is a form of the IHM-method using the derivative of peak-functions for fitting the derivative of a spectrum, which is robust against strong background signals.
  DOI: 10.1016/j.chemolab.2017.11.005
2016 In-line Monitoring of Monomer and Polymer Content During Microgel Synthesis Using Precipitation Polymerization via Raman Spectroscopy and Indirect Hard Modeling
  Indirect Hard Modeling (IHM) enables the quantitative analysis during microgel synthesis with Raman spectroscopy, having a model which is robust against changes in microgel particle size and temperature.
  DOI: 10.1177/0003702815626663
2015 Model-Based Recognition of Mid-Infrared Sensor Fouling in Paracetamol Crystallization
  API deposition on a fibre-optic ATR immersion probe for MIR spectroscopy is detected in a crystallization process, applying an intelligent Indirect Hard Modeling (IHM) approach for spectral analysis.
  DOI: 10.1002/ceat.201400585
2015 Automated data evaluation and modelling of simultaneous 19F– 1H medium-resolution NMR spectra for online reaction monitoring
  Benchtop NMR instruments are applied as online process analysers for the monitoring of reacting mixtures. Essential contribution of Indirect Hard Modeling to quantitative Data Analysis.
  DOI: 10.1002/mrc.4216
2013 Application of ATR-MIR Spectroscopy in the Pilot Plant – Scope and Limitations using the Example of Paracetamol Crystallizations
  MIR spectroscopic monitoring of an API crystallisation; successful method transfer from lab to pilot plant scale and compensation of perturbations through Indirect Hard Modeling.
  DOI: 10.1016/j.cep.2013.04.003
2013 Comprehensive monitoring of a biphasic switchable solvent synthesis
  MIR and UV spectroscopic monitoring of a high pressure synthesis with simultaneous measurements in both active phases.
  DOI: 10.1039/c2an36044f
2012 Concentration Measurements in Ionic Liquid–Water Mixtures by Mid-Infrared Spectroscopy and Indirect Hard Modeling
  Quantitative characterization of binary mixtures of water and ionic liquids using Mid-IR spectroscopy in combination with Indirect Hard Modeling.
  DOI: 10.1366/11-06427
2011 Diffusion of poly(ethylene glycol) and ectoine in NIPAAm hydrogels with confocal Raman spectroscopy
  Characterisation of diffusion in hydrogels by measuring time- and space-resolved concentration profiles using confocal Raman spectroscopy
  DOI: 10.1007/s00396-011-2399-7
2010 Bridging the gap: A nested-pipe reactor for slow reactions in continuous flow chemical synthesis
  Characterisation of a novel pilot-scale reactor for continuous production of Fine Chemicals
  DOI: 10.1016/j.cej.2010.09.004
2009 Determination of the Dispersion Characteristics of Miniaturized Coiled Reactors with Fiber-Optic Fourier Transform Mid-infrared Spectroscopy
  Characterisation of a miniaturised continuous lab reactor
  DOI: 10.1021/ie901094q
2009 An Ozonolysis-Reduction Sequence for the Synthesis of Pharmaceutical Intermediates in Microstructured Devices
  Reaction monitoring of a pharmaceutical synthesis in a microstructured device
  DOI: 10.1021/op9000669
2009 Direct determination of the concentration dependence of diffusivities using combined model-based Raman and NMR experiments
  Determination of diffusion behaviour in multi-component system with Raman and NMR spectroscopy
  DOI: 10.1016/j.fluid.2008.10.012
2008 Identification of unknown pure component spectra by indirect hard modeling
  Hard Modeling Factor Analysis (HMFA): Calibration-free spectral analysis based on Indirect Hard Modeling
  DOI: 10.1016/j.chemolab.2008.05.002
2007 In situ monitoring of an isocyanate reaction by fiber-optic FT-IR/ATR-spectroscopy
  Reaction monitoring and kinetic studies of a polyurethane synthesis
  DOI: 10.1016/j.vibspec.2006.07.004
2007 Process monitoring and control in microreactors with ATR IR Spectroscopy
  Micro-structured flow cell for miniaturised fibre optical mid-infrared sensors
  DOI: 10.1002/cite.200750089
2007 Fully automated indirect hard modeling of mixture spectra
  Automated modelling of spectra with IHM: Validation with mid-infrared and Raman spectra
  DOI: 10.1016/j.chemolab.2007.11.004
2006 Highly Flexible Fibre-Optic ATR-IR Probe for Inline Reaction Monitoring
  Applications of fibre-optical spectroscopy in organic synthesis
  DOI: 10.1021/op0601767
2006 Combining reaction calorimetry and ATR-IR spectroscopy for the operando monitoring of ionic liquids synthesis
  A combination of fibre-optical spectroscopy with reaction calorimetry
  DOI: 10.1016/j.cattod.2006.12.007
2006 Mid-infrared monitoring of gas-liquid reactions in vitamin D analog synthesis with a novel fiber optical diamond ATR sensor
  Reaction monitoring in a vitamin synthesis
  DOI: 10.1002/ceat.200600110
2006 Ternary diffusivities by model-based analysis of raman spectroscopy measurements
  Elucidation of diffusion processes in complex systems
  DOI: 10.1002/aic.11021
2005 Method for quantitative determination of spatial polymer distribution in alginate beads using Raman spectroscopy
  Raman spectroscopy for the characterisation of polymer beads
  DOI: 10.1366/0003702053585363
2004 Indirect Spectral Hard Modeling for the analysis of reacting and interacting mixtures
  Indirect Hard Modeling (IHM): New model-based method for spectral analysis
  DOI: 10.1366/0003702041655368
2004 Automatic generation of peak-shaped models
  Automatic generation of peak-shaped models: Foundation for Indirect Hard Modeling
  DOI: 10.1366/0003702041655421
2003 Novel infrared optical probes for process monitoring and analysis based on next-generation silver halide fibers
  Recent developments in optical fibres for reaction monitoring
  DOI: 10.1007/s00216-003-1782-8
2003 Model-based measurement of diffusion using Raman spectroscopy
  Monitoring of multi-component diffusion with Raman spectroscopy
  DOI: 10.1002/aic.690490205
2002 Bio-analytical applications of mid-infrared spectroscopy using silver halide fiber-optic probes
  Applications from biomedical analytics
  DOI: 10.1016/S0584-8547(02)00103-9
2001 Novel developments in mid-IR fiber-optic spectroscopy for analytical applications
  Overview over new fibre-optical sensors for mid-infrared spectroscopy
  DOI: 10.1016/S0022-2860(00)00804-8