Method for quantitating liquid-state <31>P nuclear magnetic resonance (phosphorus-31 NMR) by use of methylenediphosphonic acid (MDP) external standard method

Abstract

The invention relates to a method for quantitating liquid-state <31>P nuclear magnetic resonance (phosphorus-31 NMR) in an environment sample by taking methylenediphosphonic acid (MDP) as external standard. Before testing, a glass capillary tube in which an MDP aqueous solution is encapsulated and a nuclear magnetic tube filled with a monopotassium phosphate solution with determined concentration form a coaxial sleeve pipe system, and the correction coefficient of the sleeve pipe system is calculated; during testing, an alkaline extracting agent is used for dissolving a sample, then sustained oscillation and centrifugation are carried out to obtain leaching liquid, and the leaching liquid is frozen and dried; obtained powder is dissolved into a heavy solution, and the dissolved solution together with the glass capillary tube is transferred into the nuclear magnetic tube, and the concentrations of all phosphorus fractions are calculated according to the peak area ratio of MDP on the <31>P NMR spectrogram and a phosphorus compound to be detected. The capillary tube containing the MDP solution is used as the liquid-state 31P NMR external standard for determining the phosphorus concentration of the environment sample, interference of co-existing ions can be avoided, no overlapping with the chemical shifting of the characteristic peak is caused, the step of measuring total phosphorus in the heavy solution by a plasma spectrometer method or a chemical method is omitted, and the method is suitable for measuring and analyzing phosphorus fractions in multiple environment samples.

Description

technical field [0001] The present invention relates to 31 Determination of the content of phosphorus components in environmental samples by P nuclear magnetic resonance, especially involving a method for quantifying liquids using methylene diphosphonic acid external standard method 31 Methods of P NMR. Background technique [0002] Phosphorus (P) is one of the macroelements in the soil, a nutrient element necessary for the growth and development of organisms, and a limiting element that may cause eutrophication of water bodies (lakes, reservoirs, rivers, etc.). The average content of phosphorus in the earth's crust is 1.2g kg -1 , 95% of which exist in apatite minerals. An in-depth understanding of the content of phosphorus components in various environmental samples is of great significance for clarifying the biogeochemical cycle of phosphorus. According to the different extraction capabilities of the extractants for phosphorus, traditional chemical classification meth...

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Problems solved by technology

However, unlike the H spectrum, the use of 31 P NMR has a longer relaxation time in the determination of phosphorus components in environmental samples, which affects 31 There are many factors on the peak area on the P NMR spectrum, and the chemical shift deviation is relatively large. The selection of external standards in the test has a great influence on the test results.

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