Sample Temperature Control

Precisely control the temperature of  sample tubes and flow set ups

Sample Temperature Control

Precisely control the temperature of  sample tubes and flow set ups

The Spinsolve 43 MHz systems  can be equipped with a unique temperature control system that allows to control the temperature with out the need of additional nitrogen or dry air supply. This is achieved by adjusting the magnet temperature instead of using a gas flow approach, which reduces the sample volume and sensitivity. The variable temperature option does not compromise resolution, sensitivity or stability.

Features:

  • System and magnet design that allows to adjust the temperature of the magnet
  • Precise temperature control for static samples as well as online setups
  • Works with standard 5 mm tubes and flow cell without sensitivity loss
  • No requirement to re-calibrate at different temperatures
  • No need of nitrogen or dry air supply
  • Temperature range : RT to 60 °C
  • Frequency: 43 MHz
  • Available as Standard and Ultra version
  • Available with diffusion gradient

Precise temperature control

MeOD-NMR Thermometer: MeOD spectra acquired at different temperatures between 28°C and 60° C. The observed chemical shift differences are in excellent agreement with the calibration values of the NMR thermometer.

Excellent system stability

By utilizing the multi-layer temperature control of the Spinsolve series the system stability is not compromised over the whole temperature range.

Graph: 100 superimposed vegetable oil spectra taken over a period of  20 h at 60°C. Spectra were acquired without any reshimming between measurements.

Reaction kinetics study

The appearance of the ester peak and the disappearance of the alcohol peak can be easily followed. The four graphs on the right show the concentrations obtained through the integration of the ester and the alcohol as a function of time for different temperatures.

 

As  trifluoro acetic acid was used in high excess the reaction follows a pseudo first order kinetics, which is demonstrated by linear dependence of the logarithm of the ethanol concentration on time. From the slopes of the linear fit the reaction rate constants can be extracted. Rate constant are given in the table in the center. Furthermore, when plotting the logarithm of the rate constant against  T -1 and applying the Arrhenius equation the activation energy of the reaction can be determined via the slope of the linear dependence. This is demonstrated in the graph on the right hand side. 1

Improving resolution

The linewidth in the NMR spectrum does not only depend on the homogeneity of the magnetic field, but as well on sample properties like the viscosity as well. High viscous samples do have shorter relaxation times resulting in broad lines. With increasing sample temperature the viscosity gets smaller and the lines in NMR spectrum get narrower. The example shows spectra of a vegetable oil taken at 28° C and 60° C respectively. It can be clearly seen how the linewidth improves at 60°C and the J-coupling patterns become visible.

The systems with the sample temperature control feature can as well be equipped with a pulsed field gradients. This enables one for example to run temperate dependent self-diffusion studies. The graph on the left shows data received from  pulsed field gradient stimulated echo measurements on ionic liquid samples with different Li-Ion concentrations. Such type of mixtures are used in Li-Ion batteries, where the self diffusion coefficients can contribute to study transport characteristics in batteries. The graph on the right shows the concentration dependence of the diffusion coefficient for different temperatures. It can be seen than the self diffusion coefficients increase with the temperature and decreases with the Li concentration.