Method for measuring agar gel strength through low-field NMR (nuclear magnetic resonance)

A technology of gel strength and agar, which is applied in the field of determination of agar gel strength and agar strength by using low-field NMR, can solve the problems of complex sample preparation process, poor accuracy and repeatability, and large external influence, and achieve The method of sample preparation is simple, the measurement result is accurate, and the effect of rapid detection

Active Publication Date: 2013-04-03
GUANGDONG OCEAN UNIVERSITY
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  • Summary
  • Abstract
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AI Technical Summary

Problems solved by technology

Although the constant pressure fracturing method is relatively simple and low in cost, it is time-consuming to measure, difficult to control the flow rate of water, the balance vibrates, the external influence is large, and the accuracy and repeatability are poor.
Texture analyzer or rheometer measurement method adopts automatic equipment, overcomes the error of manual oper

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0011] Example 1

[0012] Put 1.0 g of the agar powder sample with pH 7.0 into a 10mm diameter nuclear magnet tube, put the tube into an NMRI20-Analyst analyzer, the proton resonance frequency is 21.9MHz, and the measurement temperature is 30°C. Spin-spin relaxation time T 2 Use CPMG sequence to measure, the parameters used are: ζ-value (the time between 90° pulse and 180° pulse) is 100us, the number of repetition scans is 32, and the repetition interval time is 200ms, and the resulting graph is an exponential decay graph. Repeat the test 3 times for each sample, and perform fast inversion with inversion software to obtain the spin-spin relaxation time T 2 Is 0.490ms, using gel strength B and spin-spin relaxation time T 2 The corresponding linear relationship is: T 2 =0.446+3.60×10-5B, the calculated gel strength of agar is 1220g / cm 2 .

Example Embodiment

[0013] Example 2

[0014] Put 2.0 g of agar powder sample with a pH of 7.2 into a 15mm diameter nuclear magnet tube, put the tube into an NMRI20-Analyst analyzer, the proton resonance frequency is 22.1MHz, and the measurement temperature is 35°C. Spin-spin relaxation time T 2 Use CPMG sequence to measure, the parameters used are: ζ-value (the time between 90° pulse and 180° pulse) is 100us, the number of repetition scans is 64, and the repetition interval time is 210ms, and the resulting graph is an exponential decay graph. The test is repeated 4 times for each sample, and the inversion software is used for fast inversion to obtain the spin-spin relaxation time T 2 Is 0.497ms, using gel strength B and spin-spin relaxation time T 2 The corresponding linear relationship is: T 2 =0.446+3.60×10 -5 B, the calculated gel strength of agar is 1480g / cm 2 .

Example Embodiment

[0015] Example 3

[0016] Put 2.5 g of agar powder sample with a pH of 6.8 into a nuclear magnetic tube with a diameter of 15 mm, and put the tube into an NMRI20-Analyst analyzer. The proton resonance frequency is 22.4 MHz and the measurement temperature is 25°C. Spin-spin relaxation time T 2 Use CPMG sequence to measure, the parameters used are: ζ-value (the time between 90° pulse and 180° pulse) is 100us, the number of repetition scans is 128, and the repetition interval time is 220ms, and the resulting graph is an exponential decay graph. Repeat the test 5 times for each sample, and perform fast inversion with inversion software to obtain the spin-spin relaxation time T 2 Is 0.503ms, using gel strength B and spin-spin relaxation time T 2 The corresponding linear relationship is: T 2 =0.446+3.60×10 -5 B, the calculated gel strength of agar is 1620g / cm 2 .

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Abstract

The invention provides a method for measuring agar gel strength through low-field NMR (nuclear magnetic resonance). The method comprises the following steps of: putting a certain number of agar powder samples into a nuclear magnetic tube; putting the nuclear magnetic tube into an NMR analyzer; measuring the spin-spin relaxation time T2 by using a CPMG (carr purcell meiboom gill) array; testing every sample for 3 times repeatedly; performing quick inversion by using inversion software to obtain the spin-spin relaxation time T2, wherein a corresponding linear relationship of the gel strength B and the spin-spin relaxation time T2 is as follows: T2=0.446+3.60*10<-5>B. Compared with a constant-pressure fracturing method and a texture analyzer or rheometer measuring method of the conventional agar measuring method, the defects that a sample preparing process is complicated, the measuring time consumption is high, influence caused by external factors is relatively large and the like are overcome and the method provided by the invention has the advantages of simple sample preparing method, no damage to samples, quick detection, accurate measuring result, good repeatability and the like.

Description

technical field [0001] The invention relates to a method for measuring the strength of agar gel, in particular to a method for measuring the strength of agar gel by using low-field NMR, and belongs to the technical field of agar gel strength detection. Background technique [0002] Gel strength is the most important index to measure the quality of agar. Low-strength gel has excellent protection of the dispersion system, prevents diffusion and improves product texture; high-strength gel has excellent strength, Elasticity, resilience, relative transparency, relative permeability and reversibility, have extremely high application value. Therefore, it is particularly important to accurately and rapidly determine the gel strength of agar. [0003] At present, the gel strength determination methods of agar mainly include: constant pressure rupture method, texture analyzer or rheometer measurement and other methods. Although the constant pressure rupture method is relatively simp...

Claims

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Application Information

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IPC IPC(8): G01N24/08
Inventor 李思东问莉莉杨培强欧春艳杨磊刘莉莉李秋婵
Owner GUANGDONG OCEAN UNIVERSITY
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