A METHOD FOR DETERMINING THE AMOUNT OF H2O IN A SAMPLE

Abstract

The application relates to a method of determining an amount of H.sub.2O in a sample, the method comprises performing at least one NMR measurement on the sample wherein the NMR measurement comprises applying the sample in an NMR spectrometer and performing a NMR reading of .sup.17O nuclei in the sample, the reading comprises obtaining .sup.17O NMR data and determine the amount of H.sub.2O in a sample by correlating the .sup.17O NMR data to calibration data. The application also relates to a system suitable for determination of an amount H.sub.2O in a sample, the system comprises a NMR spectrometer configured for performing a .sup.17O NMR reading of the sample to obtain .sup.17O NMR data, and a computer comprising calibrating data for calibrating the .sup.17O NMR data the computer being programmed to processing the .sup.17O NMR data to determining the amount of H.sub.2O in the sample.

Claims

1-41. (canceled)

42. A method of determining an amount of H.sub.2O in a sample, the method comprising: performing at least one NMR measurement on the sample wherein the NMR measurement comprises applying the sample in an NMR spectrometer; performing a NMR reading in a magnetic field of up to about 2.5 Tesla of .sup.17O nuclei in the sample, wherein the reading comprises obtaining .sup.17O NMR data and determining the amount of H.sub.2O in a sample by correlating the .sup.17O NMR data to calibration data.

43. The method of claim 42 wherein the NMR measurement comprises simultaneously subjecting the sample to said magnetic field B, and a plurality of pulses of radio frequency energy E (RF pulses) and receiving relaxation signals from the .sup.17O nuclei, wherein the RF pulses has a band width of up to about 1 KHz.

44. The method of claim 42 wherein the RF pulses has a band width of up to about 500 Hz.

45. The method of claim 42, wherein the exciting RF pulse or train of pulses has a field band width (Hz) and a pulse width (s) selected to provide the desired angle pulse selected from a 45 pulse, a 90 or a 180 pulse.

46. The method of claim 42, wherein the NMR measurement comprises simultaneously subjecting the sample to a magnetic field B, and a plurality of RF pulses, wherein the RF pulses comprise a plurality of exciting RF pulses and a plurality of refocusing RF pulses and the exciting RF pulses comprises at least one 90 pulse and the refocusing RF pulses comprises at least one 180 pulse.

47. The method of claim 42, wherein the NMR measurement comprises subjecting the sample to proton decoupling pulses and/or polarization pulses during at least a part of the NMR reading.

48. The method of claim 42, wherein the method comprising enhancing signal to noise of the data spectra by subjecting the sample to a pulse configuration providing polarization and/or proton decoupling of atoms of the H.sub.2O in the sample.

49. The method of claim 42, wherein the method comprising enhancing signal to noise of the data spectra by subjecting the sample to a pulse configuration comprising at least one of DEPT (Distortionless Enhancement by Polarization Transfer), DEPTQ (DEPT with retention of Quaternaries), HSQC (Heteronuclear Single Quantum Coherence), INEPT (Insensitive Nuclei Enhanced by Polarization Transfer), BIRD (Bilinear Rotation Decoupling pulses), TANGO (Testing for Adjacent Nuclei with a Gyration Operator) or NOE (Nuclear Overhauser Effect).

50. The method of claim 49, wherein the method comprising subjecting the sample to a pulse configuration comprising a) a DEPT-45 pulse sequence and b) a DEPT-90 pulse sequence and obtaining an NMR reading and a quantitative amount of excited .sup.17O nuclei from each sequence wherein the quantitative amount of excited .sup.17O nuclei by the DEPT-90 pulse sequence is subtracted from K1 times the quantitative amount of excited .sup.17O nuclei by the DEPT-45 pulse sequence and the result is multiplied by K2 to thereby determine the amount of H.sub.2O in the sample, wherein K1 is fixed and K2 is a constant determined by calibration on known samples comprising both organic and H.sub.2O bound oxygen.

51. The method of claim 42, wherein the method comprising subjecting the sample to a plurality of refocusing RF pulses comprising at least one train of refocusing RF pulses, wherein the refocusing RF pulse are applied with an echo-delay time of about 500 s or less after the exciting RF pulse(s).

52. The method of claim 42, wherein the NMR reading is performed in a magnetic field of up to about 1.5 Tesla.

53. The method of claim 42, wherein the method comprises determining the amount of H.sub.2O in a sample in form of a relative amount or in form of an absolute amount, wherein the sample size has a volume of at least about 1 mm.sup.3.

54. The method of claim 42, wherein the sample size has a volume of at least about 1 cm.sup.3.

55. The method of claim 42, wherein the sample is selected from meat, meat powder, cheese, butter or corn, flour, skin, oil or wood.

56. The method of claim 42, wherein the method comprises determining dry matter in the sample.

57. The method of claim 42, wherein the method further comprises performing a NMR reading of .sup.13C nuclei in the sample and determine the amount of carbon in the sample.

58. The method of claim 42, wherein the method further comprises performing a NMR reading of .sup.1H nuclei in the sample and determine the amount of hydrogen in the sample.

59. The method of claim 58 wherein the method comprises determine the amount of H.sub.2O in a hydrocarbon gas stream.

60. The method of claim 42 wherein the method comprises determine the amount of H.sub.2O in two or three of liquid form, fluid form and gas form (vapor).

61. A system suitable for determination of an amount H.sub.2O in a sample according to claim 1, the system comprises a NMR spectrometer configured for performing a .sup.17O NMR reading of the sample to obtain .sup.17O NMR data, and a computer comprising calibrating data for calibrating the .sup.17O NMR data the computer being programmed to processing the .sup.17O NMR data to determining the amount of H.sub.2O in the sample wherein the NMR spectrometer comprises one or more magnets arranged to generate a magnetic field of up to about 2.5 Tesla.

Description

BRIEF DESCRIPTION OF EXAMPLES AND DRAWINGS

[0176] The invention is being illustrated further below in connection with a few examples and embodiment and with reference to the drawings in which:

[0177] FIG. 1 shows a diagram over the relationships between carbon/hydrogen ratio and gross heating value and carbon atoms.

[0178] FIG. 2 is a schematic drawing of an embodiment of a system of the invention for determining the amount of H.sub.2O in a sample.

[0179] FIG. 3 is a schematic drawing of another embodiment of a system of the invention for determining the amount of H.sub.2O in a sample.

[0180] FIG. 4 show a spectra obtained in example 1.

[0181] FIG. 5 show the basics of the CPMG pulse sequence.

[0182] FIG. 6 shows the phase response relationship OH, H.sub.2O and H.sub.3O groups the sample is being exposed to a DEPT NMR pulse sequence.

[0183] The diagram of FIG. 1 shows that there is a clear relationship between carbon/hydrogen ratio and gross heating value and carbon atoms in a fuel. This relationship is well known and is often applied to determine the gross heating value of a fuel and thereby to setting the value and price of the fuel. However the diagram does not take account of any possibly water in the fuel which results in a reduced heating value. By applying the method of the invention for determine the amount of H.sub.2O in a fuel sample the amount of water bound hydrogen can be deducted to thereby find the gross heating value with an increased accuracy. Since the NMR spectrometer may simultaneously determine the carbon content and the hydrogen content as described above, the total gross heating value can be found in a simple and cost effective manner. In an embodiment of the system the computer is programmed to calculate the gross heating value based on the data of the diagram and the NMR readings on a fuel sample.

[0184] The system of for determining the amount of H.sub.2O in a sample which is schematically shown in FIG. 2 comprises a NMR spectrometer 1 and an external computer 3 with a screenhere shown as a notebook connected to the NMR spectrometer 1. The NMR spectrometer 1 also comprises a not shown integrated computer. The calibration data may be contained in the notebook 3 or in the integrated computer or in both or partly in the notebook 3 and partly in the integrated computer. The measuring site of the NMR spectrometer 1 is indicated with the box 2. The system is advantageously connected to the internet as described above.

[0185] The system of for determining the amount of H.sub.2O in a sample which is schematically shown in FIG. 3 is a wheeled system and comprises a NMR spectrometer 11 and an external computer 12 with a screenhere shown as a notebook connected to the NMR spectrometer 11. The NMR spectrometer 1 also comprises a not shown integrated computer. The calibration data may be contained in the notebook 12 or in the integrated computer or in both or partly in the notebook 12 and partly in the integrated computer. The system further comprises a printer 16. The NMR spectrometer 11, the notebook 12 and the printer 16 are arranged on a carrier 15 with wheels 13 and a handle 12. The notebook may 12 be detached from the carrier 15. The system is advantageously connected to the internet as described above.

[0186] The CPMG pulse sequence is illustrated in FIG. 5. CPMG pulse sequence begins with a 90 pulse followed by a series of 180 pulses. The first two pulses are separated by a time period , whereas the remaining pulses are spaced 2 apart. Echoes occur halfway between 180 pulses at 2, 4 . . . 2n, where n is the echo number. TE stand for echo spanning and it equals to 2. Spin echo amplitudes are decaying with the time constant T.sub.2.

[0187] FIG. 6 shows the phase response relationship OH, H.sub.2O and H.sub.3O groups the sample is being exposed to a DEPT NMR pulse sequence where curve 20 is the OH curve, curve 21 is the H.sub.2O curve and curve 22 is the H.sub.3O.

EXAMPLE 1

Tap Water

[0188] A NMR spectrometer with spectrometer frequency range of about 8.71 was used. The magnetic field generated was about 1.5 Tesla and the domain spectra generated had a frequency width per ppm of about 73 Hz/ppm.

[0189] A tap water sample was acquired in an oblong sampling cuvette with an inner diameter of 8 mm. The cuvette was filled to a level of 100 mm and the sample was arranged in the measuring site of the spectrometer.

[0190] The sample was subjected to a plurality of .sup.17O NMR readings by subjecting it to a plurality of cycles of a CPMG sequence of 40 times per second for 90 minutes. The pulse width for the 90 and 180 pulse was set to 25 s. The echo delay was 150 s and there were 24 echoes with 300 s between each echo for each cycle.

[0191] The T2 was determined to be about 8 ms and T1 was determined to be several times larger than T2.

[0192] FIG. 4 show a spectra for the accumulated data and it can be seen that a clear and strong .sup.17O signal was determined.

EXAMPLE 2

Meat Sample

[0193] The NMR spectrometer of example 1 is used.

[0194] A meat sample of about 2 cm.sup.3 (211) is arranged in the measuring site of the spectrometer.

[0195] The sample is subjected to a plurality of .sup.17O NMR readings by subjecting it to a plurality of cycles of a CPMG sequence for about 2 minutes. The 90 pulses are soft pulses of about 1000 Hz and the 180 refocusing is set to a pulse width of 25 s.

[0196] The obtained NMR data is processed to obtain a frequency domain spectrum ranging over about 500 ppm and the T1 and T2 is determined.

[0197] From the NMR data the water bound .sup.17O is determined without signal from the organic bound oxygen and the total amount of H.sub.2O in the meat sample is determined.

EXAMPLE 3

Sewage Sample

[0198] The NMR spectrometer of example 1 is used.

[0199] A sewage sample is arranged in an oblong sampling cuvette with an inner diameter of 8 mm. The cuvette is filled to a level of 100 mm and the sample is arranged in the measuring site of the spectrometer.

[0200] The sample is subjected to a plurality of .sup.17O NMR readings by subjecting it to a plurality of cycles of a CPMG sequence for about 2 minutes followed by cycles of a DEPT sequence for 2 minutes. The 90 and the 45 pulses are soft pulses of about 300 Hz and the 180 refocusing is set to a pulse width of 25 s.

[0201] The obtained NMR data is processed to obtain a frequency domain spectrum ranging over about 300 ppm and the T1 and T2 is determined.

[0202] From the NMR data the water bound .sup.17O is determined and the total mass of H.sub.2O in the sewage sample is determined and withdrawn from the total sewage sample mass to thereby determine the dry weight and the dry matter is determined as well.

EXAMPLE 3

Wood Sample

[0203] The NMR spectrometer of example 1 is used.

[0204] A wood sample of about 5 cm.sup.3 is obtained from a building which has been subjecting to flooding. The sample is arranged in the measuring site of the spectrometer.

[0205] The sample is subjected to a plurality of .sup.17O NMR readings by subjecting it to a plurality of cycles of a CPMG sequence for about 10 minutes followed by cycles of a HSQC sequence for 10 minutes. The 90 and the 45 pulses are soft pulses of about 300 Hz and the 180 refocusing is set to a pulse width of 25 s.

[0206] The obtained NMR data is processed to obtain a frequency domain spectrum ranging over about 300 ppm and the T1 and T2 is determined.

[0207] From the NMR data the water bound .sup.17O is determined and the total mass of H.sub.2O in the wood sample is determined and simultaneously the pH value is determined. By determine the amount of H.sub.2O the degree of the damage can be determined very fast. The pH value may show if the building has been attacked by fungus.