JPH03115846A - Apparatus for measuring freshness of living body tissue - Google Patents

Abstract

PURPOSE:To measure freshness by fixing a specific standard specimen to a planar coil. CONSTITUTION:A specimen 2 having the peak of the phosphoric acid (<31>P) NMR spectrum of living body tissue, for example, having a peak at a position separated from a range of 20 - 5ppm such as creatine phosphate, sugar phosphate, ATP or ADP is received in a sphere having a diameter of 2mmphi to be fixed to a detecting planer coil 1. The coil 2 is a spiral one and the specimen 2 is set to the center of the coil 1 so as to separated by about 1mm from the coil 1. When this detector is used to a sample 3 to measure a phosphorus-NMR spectrum, simultaneously with the peak of inorg. phosphorix acid (<31>P) contained in the sample 3, the peak of the specimen 2 appears at a position separated from said peak. By calculating the chemical shift difference between both of them to measure pH from a pH titration curve, freshness can be accurately measured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a method for measuring the pH of biological tissues such as foods from the chemical shift of P-NMR spectra, and determining the freshness of foods from the PH value. This relates to a measuring device.

[Conventional technology]

In general, the freshness of biological tissues such as fresh foods is related to pH, and it is known that when freshness is high, the pH is around 6 to 7, but when freshness decreases, the pH decreases and becomes acidic. There is. Biological tissues contain phosphates CH, PO,]
Some [H, PO.

-], [HPO, ``-], etc., and the ratio of these components changes depending on the pH, so the chemical shift of the phosphoric acid (''P) NMR spectrum changes with a change in PH. Therefore, using creatine phosphate, which is contained in living tissue and has a stable NMR peak position, as a reference, we measured the chemical shift δ of 3+p in phosphoric acid with respect to creatine phosphate, as shown in Figure 4. A PH titration curve as shown in Figure 5 is obtained in advance by changing the pH of creatine phosphate and determining the chemical shift relative to creatine phosphate.The freshness is measured by determining the pH using the PH titration curve from the previously measured chemical shift. Ta.

Note that creatine phosphate, which serves as an internal standard, may disappear if the freshness of the living body deteriorates, or may not exist depending on the product, and in that case, freshness cannot be measured using creatine phosphate as a standard. Therefore, commercially available 85% H, PO, was used as a reference sample, and biological tissue and NM of 85% H, PO,
Each R spectrum was measured separately and 85% H=PO
Freshness has also been measured by determining the chemical shift of phosphoric acid in biological tissue using a scale in which the peak position of the NMR spectrum of No. 4 is expressed as Oppm.

These methods have been used to observe, for example, that the pH of diseased red blood cells is lower than normal ones, and have also been effective in determining the freshness of fresh foods such as fish and vegetables.

[Problem to be solved by the invention]

The freshness measurement method based on creatine phosphate contained in living tissue is based on the fact that the peak position of the NMR spectrum of creatine phosphate is stable and does not move, but as shown in Figure 6, when the pH becomes low, Accurate measurements could not be made because of the slight shift. Also, 85% H, PO,
In the method of measuring 85%H, PO, separately from the biological tissue, it is necessary to perform the measurement twice, and if the observation conditions for 85% H, PO, and the biological tissue are different for some reason, the horizontal axis of the chemical shift This may result in incorrect measurement.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a biological tissue freshness measuring device that can perform freshness measurement by determining the chemical shift between a standard sample and a biological tissue by measuring the degree of freshness.

[Means to solve the problem]

The present invention is an apparatus for measuring the freshness of living tissue by determining the pH from the chemical shift of the phosphoric acid ("P) NMR spectrum, which has a peak at a position far from the phosphoric acid ("P) NMR spectrum of the living tissue. The feature is that the standard sample is placed near the detection coil.

[Effect]

In the present invention, a standard sample is attached to an NMR detector,
- At the same time, the freshness of the biological tissue can be determined by determining the chemical shift difference between the spectra of the standard sample and the biological tissue and measuring the pH from the PH titration curve, since the measurement conditions for the standard sample and the biological tissue are the same. Accurate measurements can be made without chemical shift shifts.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a biological tissue freshness measuring device of the present invention, and FIGS. 2 and 3 are diagrams showing a freshness measuring method. In the figure, 1 is a detection carp J, 2 is a standard sample, and 3 is a sample.

As shown in the plan view of FIG. 1(a), hexamethylphosphoramide (HMPA) 2 is placed in a sphere of about 2 uφ and fixed to a planar coil l for detection.

The planar coil 1 is a spiral coil, and HMPA 2 is located at the center of the coil and is separated from the coil by about 1 uφ. HMPA is 28% when the beater of 85% H, PO, is set as Oppm. It has a chemical shift value of lppm, which is within the range of the phosphorus NMR spectrum of biological tissues.
It has a peak value at a position far from 0 to 5 ppm, and there is no overlapping force.Such a detector is shown in the side view of FIG.
When the phosphorus NMR spectrum was measured using one apple, as shown in Figure 2, inorganic phosphoric acid (
At the same time as the peak of ``P'', HMPA is placed at a distance from the peak
peaks appear at the same time. This peak position is 28. l
Read the chemical shift difference δ between the inorganic phosphoric acid peak and the HMPA peak according to the ppm. In the example shown, δ=25p
It is pm.

On the other hand, similarly measure the NMR spectra of several 85% H, PO4 aqueous solutions with different PH, read the chemical shift difference with HMPA, and obtain a PH titration curve as shown in Figure 3, and use this. PH for δ=25ppm
By reading, PH=4 can be determined, and freshness can be determined.

Although HMPA was used as the standard sample in the above example, peaks in the P-NMR spectrum of biological tissues, such as creatine phosphate, sugar phosphate, inorganic phosphate, ATP
, ADP, etc., which have a peak at a position away from the range of -20 to 5 ppm, can be used by being fixed to a planar coil instead of HMPA. 10mmφ~
In the case of a sample, such as blood or a tissue section, which is to be placed in a 25 mm diameter sample tube, the standard sample can be fixed in the sample tube using an ordinary blower "f" and phosphorus-NMR can be measured.

〔Effect of the invention〕

As described above, according to the present invention, since the standard sample is fixed to the planar coil, the peak of the standard sample can also be measured when measuring phosphorus-NMR of living tissue. It is possible to give an accurate chemical shift position to each peak according to the position when it is set as Oppm, and by reading the chemical shift difference between phosphoric acid and the standard sample, P
Freshness can be determined by determining pH from the H titration curve.

In addition, the intensity of high-energy compounds such as ΔTP and creatine phosphate tends to decrease with respect to the peak of the standard sample when freshness decreases, so it is also possible to compare the freshness of tissues by determining the relative intensity of these NMR peaks. It is possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of the biological tissue freshness measuring device of the present invention, FIGS. 2 and 3 are diagrams showing the freshness measuring method, and FIG. 4 is a diagram showing the chemical shift of phosphoric acid with respect to creatine phosphate. , FIG. 5 is a diagram showing a PH titration curve, and FIG. 6 is a diagram showing changes in chemical shift due to changes in PH of creatine phosphate. l...Detection coil, 2...Standard sample, 3...Sample. Applicant: JEOL Ltd.

Claims (1)

[Claims] (1) A device that measures the freshness of biological tissue by determining the pH from the chemical shift of the phosphoric acid (^3^1P) NMR spectrum, and is located at a position far from the phosphoric acid (^3^1P) NMR spectrum of the biological tissue. 1. A biological tissue freshness measuring device, characterized in that a standard sample having a peak is placed near a detection coil.