2.2.7 Technique of definition of maintenance VK and CP in neftjah and asphaltenes method EPR

All measurements were made in identical conditions at ambient temperature on spectrometer EPR of type SE/X - 2544.
At measurement of maintenance CP and VK in neftjah the ampoule from a quartz glass with bore diameter = 6мм which was filled was used
Oil on all volume within spectrometer resonator EPR.
An ampoule of couples -
To it was fixed in the resonator centre. Intensity of a line of free stable radicals defined on amplitude of a single line in the centre of spectrum EPR (g = 2,003). For calculation of intensity of lines vanadilovyh complexes measured amplitude of a line +1/2, being on the neighbourhood with a line from CP in the field of weaker magnetic field. The site of an ampoule which is in area of shooting of data EPR, contains identical volume of oil. The difference in density neftej did not exceed 10 %. Intensity of signals CP and VK were measured in relative units of a spin (otn.sp.).
At definition of maintenance CP and VK in asphaltenes of oil objects ampoules from a molybdenic glass which did not yield an appreciable signal in spectrum EPR were used. For the purpose of exact installation of an ampoule with the sample the following approach was applied. In the spectrometer resonator the ampoule from a quartz glass with bore diameter = Zmm hardened. At removal of spectrums in this ampoule the adjusted ampoules from a molybdenic glass with the sample of asphaltenes were inserted. Ampoules densely filled with asphaltenes on height 13-14мм. The filling height stole up experimentally, thus the sample is located in the field of the maximum sensitivity of the resonator. Such way has allowed to fix precisely all investigated samples of asphaltenes in the centre of the resonator of spectrometer EPR and to achieve good reproducibility of signals in a spectrum.
As is known, one of the basic problems at measurement of quantity of the paramagnetic centres in oil objects is the standard choice. In our case the reception was used, allowing to avoid the errors connected with not by ideality of standards and absence of possibility of constant installation of a standard sample in the resonator of a spectrometer. At our measurements we have decided to refuse definition of absolute concentration, and you - waters built all on measurement of relative changes in spectrum EPR. For signal strength CP and VK amplitudes of corresponding lines in spectrum EPR as well as for neftej were taken over. Intensity of signals CP and VK all investigated asphaltenes paid off on weight of samples.
Thus, for a number of the investigated asphaltenes, values of maintenance CP and VK in relative units of a spin per unit mass asphaltenes (otn.spug) have been received. Maintenance CP follow-up recalculated taking into account various width of a signal. The correction factor made
Н/41 (Where N - width of signal CP in spectrum EPR of oil object). For neftej size of signals VK and CP multiplied by a correction factor representing the greatest signal of the standard in each separate series of shooting of spectrums.
In work [96] it is reported about research of types of complexes of vanadyl in neftjah and mineral oil by method EPR. The vanadium maintenance defined in the area of parallel orientation +5/2 which is on the brink of a spectrum
Also it is not imposed on a signal of radicals. The similar approach was applied and drugi -
G іі->і tt хг4+и are chosen
mi researchers [113]. For definition of the maintenance in V g
Lines of parallel orientation in the small fields, corresponding to transferrings
With a nuclear spin projection +5/2 and +3/2.
At calculation of quantity VK in asphaltenes we use a line +1/2, being on the neighbourhood with a line of a radical in the field of weaker magnetic field. The choice of the yielded line is not casual, since for all investigated samples of asphaltenes it is the most intensive line in spectrum EPR, and also the minimum distinction on width of this line in comparison with others is observed.
Comparison of maintenance VK and CP in svezhevydelennyh asphaltenes and evolved several years ago (from the same oil), shows practically identical values [101]. Thus, at the analysis of asphaltenes by means of method EPR there is a possibility to compare value of the maintenance of paramagnetic components as svezhevydelennyh, and before the received samples.
The note:
Sizes of abundance of the paramagnetic centres (VK and CP) in neftjah have units of measure — otn.sp., order of their maintenance makes 1018. However, in some cases, for the characteristic of maintenance VK and CP logarithms of sizes of their abundance (lgBK and IgCP) were used. Thus units of measure podlogarifmicheskih sizes remained former, and were designated - [otn.sp,] (in square brackets).
Similarly for asphaltenes - sizes of maintenance VK and CP have units of measure - otn.sp./g, order - 10, podlogarifmicheskie velichi thes were designated — [otn.sp./g].
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A source: Tagirzjanov, Marseilles Ilgisovich. ASPHALTENES VANADIJSODERZHASHCHIH neftej (on an example of oil objects of deposits of Tatarstan) the Dissertation on competition of a scientific degree of a Cand.Chem.Sci. Kazan - 2003. 2003

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