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4. Application of a Novel Disposable Flow Cell for Spectroscopic Bioprocess Monitoring.

Author

Steinwedel, Tobias, Raithel, Philipp, Schellenberg, Jana, Kortmann, Carlotta, Gellermann, Pia, Belz, Mathias, and Solle, Dörte

Subjects
BIOTECHNOLOGICAL process monitoring, CHO cell, MODULAR construction, LIGHT sources, ULTRAVIOLET-visible spectroscopy
Abstract

The evaluation of the analytical capabilities of a novel disposable flow cell for spectroscopic bioprocess monitoring is presented. The flow cell is presterilized and can be connected to any kind of bioreactor by weldable tube connections. It is clamped into a reusable holder, which is equipped with SMA-terminated optical fibers or an integrated light source and detection unit. This modular construction enables spectroscopic techniques like UV-Vis spectroscopy or turbidity measurements by scattered light for modern disposable bioreactors. A NIR scattering module was used for biomass monitoring in different cultivations. A high-cell-density fed-batch cultivation with Komagataella phaffii and a continuous perfusion cultivation with a CHO DG44 cell line were conducted. A high correlation between the sensor signal and biomass or viable cell count was observed. Furthermore, the sensor shows high sensitivity during low turbidity states, as well as a high dynamic range to monitor high turbidity values without saturation effects. In addition to upstream processing, the sensor system was used to monitor the purification process of a monoclonal antibody. The absorption module enables simple and cost-efficient monitoring of downstream processing and quality control measurements. Recorded absorption spectra can be used for antibody aggregate detection, due to an increase in overall optical density. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Pollutant monitoring with fibre optics in the deep ultraviolet

Author

Belz, Mathias

Subjects
535, TD Environmental technology. Sanitary engineering
Abstract

This thesis reports on work carried out in the development of ultraviolet fibre-optic based absorption sensor systems, including those with the newly available ultraviolet improved silica fibres having low attenuation in the 200 nm to 250 nm wavelength region. Several approaches to optimize the optical design of such sensor systems, their sensitivity and stability are discussed. These fibre-optic sensor systems may be used for remote on-line and real-time analysis of process and water quality, enabling a separation of monitoring equipment from the sensor cell, which thus may be situated in a potentially hazardous environment. The effect of temperature variations on wavelength stability and dark output of inexpensive spectrometer modules, potentially useful for field applications, and the subsequent effect on the accuracy of absorption measurements, as well as the sensitivity of such spectrometer modules at wavelength below 250 nm, is investigated. Further, the performance of a remote fibre-optic sensor system, based on a reflectance cell with an optical pathlength of 1 cm, to measure nitrate concentrations in the wavelength region between 200 nm and 250 nm, is reported. Finally, to improve the sensitivity of such ultraviolet sensor systems, the performance of two fibre-coupled sensor cells with increased optical pathlengths has been investigated. The first sensor cell, based on an aluminium coated fused silica capillary cell, having an optical pathlength of 43 em, is demonstrated in the construction of a residual chlorine sensor. The second sensor cell, a capillary cell with an inner coating of Teflon AF, uses the low refractive index and the high transparency of Teflon AF in the ultraviolet to form a liquid-core waveguide (LeW). This sensor cell has an optical pathlength of 203 mm, extending the use of long pathlength cells to the 200 nm to 250 nm wavelength region. Its performance is illustrated when applied to monitoring low concentrations of nitrates, chlorine and acetylsalicylic acid.

Published
1998

14. Water-core waveguide for pollution measurements in the deep ultraviolet

Author

Dress, Peter, Belz, Mathias, Klein, Karl F., Grattan, Kenneth T.V., and Franke, Hilmar

Subjects
Waveguides -- Usage, Pollution -- Measurement, Ultraviolet spectroscopy -- Usage, Astronomy, Physics
Abstract

A fiber optic system for water analysis with high transparency in the deep-UV region ([Lambda] [greater than or equal to] 190 nm) is presented. The system consists of special UV-improved silica fibers and a liquid-core waveguide (LCW) as an optical cell. The apertures of both light guides, the silica fiber and the LCW, are matched. The optical losses of the device are investigated experimentally and compared with theory, especially with a standard free-space geometry. The performance of the system with respect to UV absorption spectroscopy is demonstrated for nitrate and chlorine pollution in pure water. For a 203-mm-long LCW the detection limits have been determined to be as low as 22 [[micro]gram]/L for nitrate and 26 [[micro]gram]/L for chlorine.

Published
1998

15. Determining CDOM Absorption Spectra in Diverse Aquatic Environments Using a Multiple Pathlength, Liquid Core Waveguide System

Author

Miller, Richard L, Belz, Mathias, DelCastillo, Carlos, and Trzaska, Rick

Subjects
Optics
Abstract

We evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, aCDOM, and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values and showed a linear response across all four pathlengths. Values of aCDOM measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of aCDOM for MPLCW measurements was 0.002 - 231.5 m-1. At low CDOM concentrations spectrophotometric aCDOM were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples.

Published
2001

16. Determining CDOM Absorption Spectra in Diverse Coastal Environments Using a Multiple Pathlength, Liquid Core Waveguide System. Measuring the Absorption of CDOM in the Field Using a Multiple Pathlength Liquid Waveguide System

Author

Miller, Richard L, Belz, Mathias, DelCastillo, Carlos, and Trzaska, Rick

Subjects
Oceanography
Abstract

We evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, a(sub CDOM), and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values (r > 0.99) and showed a linear response across all four pathlengths. Values of a(sub CDOM) measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of a(sub CDOM) for MPLCW measurements was 0.002 - 231.5/m. At low CDOM concentrations (a(sub 370) < 0.1/m) spectrophotometric a(sub CDOM) were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples. The maximum deviation in replicate MPLCW spectra was less than 0.001 absorbance units. The portability, sampling, and optical characteristics of a MPLCW system provide significant enhancements for routine CDOM absorption measurements in a broad range of natural waters.

Published
2000

25. Measurements of CDOM absorption spectra using different Instruments and techniques: A round robin exercise and extensive field data set

Author

NOVAK Michael, MANNINO Antonio, NELSON Norm, D'SA Eurico, MILLER Richard, WERDELL P.j., DEL VECCHIO Rosanna, DEL CASTILLO Carlos, CHAVES Joaquin, BERTHON Jean-Francois, BOSS Emmanuel, TZORTZIOU Maria, NEELEY Aimee, FREEMAN Scott, BRICAUD Annick, ROTTGERS Rudiger, MATSUOKA Atsushi, BELZ Mathias, and BLOUGH Neil

Abstract

The optical measurement of Chromophoric Dissolved Organic Matter (CDOM) throughout the open-ocean and coastal regions has played a crucial role in the development of Ocean Color algorithms. However many spectrophotometric instruments equipped with 10cm cells are not sensitive enough to measure light attenuation from CDOM in open ocean or case 1 waters. One solution is to significantly increase the optical path length, which gives the photons of light a greater probability of being absorbed before reaching the detector. Liquid waveguide capillary cells (LWCC), integrating cavity absorption meters (ICAM), and Wetlabs absorption attenuation meters have all become prominent instruments in the community for making long path length measurements. However limitations arise due to the loss of light from scattering, spectral offsets caused by temp and salinity offsets, and cell contamination with subsequent micro-bubble formation. An extensive round robin comparison was carried out with versions of all these instruments at NASA Goddard Space Flight Center in the fall of 2013. It was part of an ongoing CDOM workshop with an international committee. Many new insights pertaining to the methodology and results of the measurements will be presented along with an extensive field data set of LWCC measurements., JRC.H.1-Water Resources

Published
2014

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