Compact and portable low-field pulsed NMR dispersion analyzer

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 said compatible and portable 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, and particle size by diffusion; and wherein said device has a total footprint area less than about 0.25 m 2 , 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 m 2 , 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 m 2 , 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 less than about 0.2 m 2 , 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 inhomogeneity of less than 1 part in 10 3 over a sample volume of 1.0 cm 3 ; 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 cm 3 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 cm 3 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 atomic concentration of Lithium, Fluorine, or Phosphorus from the signal intensity of the device of claim 1 .

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

18. 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, R 1 ave,ref or R 2 ave,ref , of one or more reference dispersions having known total particle surface area per unit volume of liquid, A ref T ;

ii) computing the proportionality constant, k AL , for the reference dispersion from the equation, R n ave,ref =k AL ref A T ref ; where n=1 or 2;

iii) determining an average NMR relaxation rate constants R 1 ave,sample or R 2 ave, sample of a sample dispersion whose surface area is to be determined;

iv) computing the total surface area of the sample dispersion, A T sample from the equation, R n ave, sample =k AL ref A T sample , where n=1 or 2, and

v) measuring and obtaining the relaxation times from the NMR output data stored in computer hardware using computational steps i)- iv) to determine the in-situ surface area of particles dispersed in a liquid of said in-situ surface.

19. The method according to claim 18 , wherein the relaxation times are measured with the device of claim 1 .