METHOD FOR DETERMINING GROUP COMPOSITION OF OIL PRODUCTS USING NMR RELAXOMETRY Russian patent published in 2024 - IPC G01N24/08 

FIELD: physics; chemistry.

SUBSTANCE: application for determination of group composition of oil products by means of NMR relaxometry. Substance of the invention consists in the fact that three test tubes are taken with control samples of known weight, which are 25%, 50% and 75% aqueous solutions of deuterium oxide D₂O, and use them to perform single calibration of amplification factor of NMR relaxometer with frequency of proton resonance of not less than 20 MHz so that unit of signal amplitude is equal to value of signal from 1 mg of distilled water, which enables to exclude repeated measurement of the reference sample during each measurement of the analysed sample; further, to obtain a representative homogeneous sample, the container with the oil product sample is held at temperature of 40±0.2 °C for at least 30 minutes, then, if the sample viscosity is less than 100 mm²/s, then the container with the sample is intensively shaken by hand for 2–3 minutes, if the viscosity of the sample is more than 100 mm²/s, then the contents of the container with the sample are mixed with spatula for 2–3 minutes; then an empty glass test tube with diameter of 10 mm for a sample is weighed with an accuracy of not less than ±1.0 mg, the prepared homogenised sample is placed using a dispenser into a glass test tube to height of 15 mm, with possibility of providing maximum filling in resonance area of measuring coil of NMR relaxometer, further, the test tube filled with the sample is weighed with an accuracy of not less than ±1.0 mg and the weight of the sample is determined from the difference in the masses of the filled and empty test tubes; further, the test tube with the sample is thermostated for at least 15 minutes at a temperature of T=40±0.2 °C; further, the NMR relaxometer is adjusted, namely, the measurement parameters are entered to measure the free induction decay signal: recording frequency — 1 MHz, recording time — 6 ms, number of accumulations — 16, repetition time — 6 s; test tube with prepared sample is placed in NMR relaxometer and measurement process is started, as a result of which free induction decay signal is recorded with minimum "dead time" equal to 10 mcs; then performing mathematical processing of results.

EFFECT: providing the possibility of creating a simple-to-implement, fast and efficient method of analysing the group composition of oil products.

1 cl, 1 dwg