TY - CONF A1 - Guthausen, G. A1 - Zientek, Nicolai A1 - Maiwald, Michael A1 - Dalitz, F. T1 - Online measurements in a bypass: challenges and possibilities N2 - The design of sample flow cells, commonly used in online analytics and especially for medium resolution NMR spectroscopy (MR-NMR) in low magnetic fields, was experimentally and theoretically investigated by 1H-NMR and numerical simulations. The flow pattern was characterised to gain information about the residence time distribution and mixing effects. Both 1H-NMR imaging and spectroscopy were used to determine the characteristics of flow cells and their significance for on-line measurements such as reaction monitoring or hyphenated separation spectroscopy. The volume flow rates investigated were in the range from 0.1 to 10 ml/min, typically applied in the above mentioned applications. When compared to those commonly used in high-field NMR, the special characteristics of flow cells for MR-NMR were revealed by various NMR experiments and compared with CFD simulations. The influence of the design of the inlet and outlet on the flow pattern was investigated as well as the effect of the length of the cell. For practical use, a numerical estimation of the inflow length was given. In addition, it was shown how experiments on the polarisation build-up revealed insight into the flow characteristics in MR-NMR. T2 - Quantitative NMR Methods for Reaction and Process Monitoring (NMRPM) Symposium CY - Kaiserslautern, Germany DA - 15.01.2015 KW - Online NMR spectroscopy KW - Process analytical technology KW - Flow profiles KW - Online monitoring KW - Reaction monitoring PY - 2015 AN - OPUS4-36147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -