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1. WO2007106765 - ANALYSEUR DE DISPERSIONS RMN A IMPULSIONS A CHAMP FAIBLE COMPACT ET PORTABLE

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[ EN ]

What is claimed is:
1. A compact and portable device for the analysis of dispersions by low- field pulsed NMR comprising: an NMR probe module, a means for generating radio frequency and magnetic field gradient pulses, a signal processor, and a master controller; wherein the device measures one or more
characteristics of the phases or particles comprising the dispersion selected from the group consisting of surface area, solid/liquid ratio, particle size by diffusion, and elemental analysis; and wherein the device has a total footprint area less than about 0.25 m2, an elevation less than about 0.45 m, a weight less than 20 kg, and an operating power demand less than 500 W.

2. The device according to claim 1 wherein the
characteristic of the phases or particles being measured is the total surface area.

3. The device according to claim 1 wherein the total footprint area is less than 0.2 m2, the maximum elevation is less than 0.3 m, and the operating power demand is no more than 150 W.

4. The device according to claim 1 wherein the NMR probe module, the means for generating radio frequency and magnetic field gradient pulses, the signal processor and the master controller are integrated into a single cabinet having a total footprint area less than about 0.25 m2, an elevation less than about 0.45 m, a weight less than 20 kg, and an operating power demand less than 500 W.

5. The device according to claim 4 wherein the cabinet has a total footprint area is less than about 0.2 ra2, the maximum elevation is less than about 0.3 m, and the operating power demand is no more than about 150 W.

6. The device according to claim 1 wherein the NMR probe module comprises a magnet and yoke assembly having adjustable faces, said magnet maintaining a magnetic field directed across the chamber having a field strength between 0.2 and 0.5 Tesla and a magnetic field inhomogeniety of less than 1 part in 103 over a sample volume of 1.0 cm3; a means for
transmitting radio frequency pulses and detecting magnetic response from the dispersion; and a means for transmitting magnetic field gradient pulses.

7. The device according to claim 6 wherein the yoke assembly has 3 -fold symmetry and is comprised of three arms fitted with adjustable alignment screws

8. The device according to claim 6 wherein the magnet comprises samarium cobalt or neodymium- iron-boron.

9. The device according to claim 6 wherein the magnet is an electromagnet.

10. The device according to claim 1 wherein the pulse generator comprises a selectable means for generating a radio frequency pulse of about 10 W up to about 200 W to a sample volume of 1.0 cm3 at frequencies between about 1 and about 20 MHz over a duration of about 5 to about 20 μs; and a
selectable means for generating a magnetic field gradient pulse that generates a magnetic field gradient across a sample volume of up to 1.0 cm3 of up to about 1 Tm"1.

11. The device according to claim 1 wherein the master controller comprises a field programmable logic array capable of timings accurate to better than +/- 1 microsecond and providing RF pulses of about 1 μs to about 1000 μs with rise and fall times less than 1 μs, and sequence pulsing having a step size less than 0.1 μs with 0, 90, 180, and 270 degree phase shifts .

12. The device according to claim 1 wherein the radio frequency pulses are generated by the discharge of one or more capacitors.

13. The device according to claim 1 wherein magnetic response detecting means is sensitive to 10"6 Tesla over a length of 5 mm.

14. A method of using the portable device according to claim 1 to measure the surface area and/or particle size and/or volume fraction of liquid of a dispersion comprising finely divided liquid, gas, or solid particles dispersed in a fluid phase.

15. The device according to claim 1 that further provides a user with a series of predetermined actions or steps through hard-wired or software algorithms whereby the measurement of one or more characteristics of the phases or particles comprising the dispersion selected from the group consisting of surface area, solid/liquid ratio, particle size, and elemental analysis is accomplished according to a set protocol .

16. A method for determining the in-situ surface area of particles dispersed in a liquid using low field NMR relaxation times, said method comprising the steps of:
i) determining an average NMR relaxation rate constants, Riave,ref Qr ^ave.ref ^ of one or more reference
dispersions having known total particle surface area per unit volume of liquid, Arefτ;
ii) computing the proportionality constant, kAL, for
the reference dispersion from the equation, Rnave'ref = kAL ref Aτref;, where n = 1 or 2 ;
iii) determining an average NMR relaxation rate
constants Rlave < samPle Or R2ave' sample of a sample
dispersion whose surface area is to be determined;
and
iv) computing the total surface area of the sample
dispersion, Aτsample from the equation, Rnave' sample = kAL ref sample ( whe re n = ! o r 2 .

17. The method according to claim 16, wherein the relaxation times are measured with the device of claim 1.

18. A method for determining the atomic concentration of Lithium, Fluorine, or Phosphorus from the signal
intensity of the device of claim 1.

19. A method for determining surfactant adsorption isotherms from the measured NMR relaxation rate constants using the device of claim 1.