Method of chromatographic identification of components of complex mixtures of organic compounds

 

(57) Abstract:

Usage: in gas chromatography to determine the qualitative composition of multicomponent mixtures of organic compounds. The inventive method comprises passing an identifiable substance through a system of series-connected columns filled with different sorbent polarity, sampling after each column, getting the spectrum holding in the first non-destructive detector, the transmission of the sample at the second detector of a different type, the calculation according to the data from two detectors of the sensitivity coefficient and the relative retention and identification of the substance on the obtained values. On the second detector, the input connected to the output of the first detector, transmit sequentially samples from the first detector and shoot range of retention on the second detector. Sensitivity factor is chosen as the average value of the ratio of the areas of the corresponding peaks in the two spectra retention. table 1.

The invention relates to gas chromatography and can be used to determine the qualitative composition of multicomponent mixtures of organic compounds.

The known method DLNA United columns and remove chromatographic spectrum of the substance, which in this case is a set of relative values of retention, calculated by the given values of retention, and the combination of chromatographic peaks associated with a given substance. In this way it is possible to conduct both group and individual identification of substances through the spectrum and the set of relative valuesicharacteristic only for this matter. But very often the set of relative valuesifor different substances is close to its values. In this case, identification is difficult and requires additional criteria for the final classification of the substance to a particular class of compounds. Closest to the claimed method is a method for the identification of components of complex mixtures using chromatographic spectra, in which the identifiable substance is introduced into the system serially connected columns Packed with sorbents of different polarity, each of which has an output of first detector through the micro capillary and the detector signals are recorded as a spectrum of a substance that contains a number of peaks corresponding to the number of columns used. Next, the sample gets wholly in bufferno peak on the chromatogram. Next, calculate the retention indices of the analyte in each column, then determine the sensitivity coefficients. On the basis of data obtained by determining the retention indices of the coefficient of relative sensitivity of the two detectors, conduct identification by comparing the received data with reference [2]

The disadvantage of this method is that because of the dependence relationship of the signals of the two detectors (ratio of peak areas) from a ratio of the flow of carrier gas is difficult to obtain reliable information on the matter.

The technical result of the invention is the provision of reliability and accuracy of the information.

This is due to the fact that in the method of chromatographic identification of components of complex mixtures of organic compounds identifiable substance is passed through a system of series-connected columns Packed with sorbents of different polarity, and after each column divert part of the flow to the first (non-destructive) to the detector, on the chromatogram register first range of substances consisting of consecutive peaks, the number of which corresponds to the number ipeiroy second range of the same substance. For any spectrum calculated relative value of holding

,

which shows the retention time of the component in a separate column

n number of columns.

,

where i is the column number

retention time on the i-column

retention time on i-1 column.

The coefficient of relative sensitivity (Cotn) is defined as the average value of the corresponding coefficients calculated by the ratio of the areas of the corresponding peaks in the spectra obtained at different detectors.

Using a combination of iand KRelenables high accuracy and in a shorter time to conduct both group and individual registration.

Examples of specific implementation method.

Chromatographic spectra get five columns, made of stainless steel tube (length 2 m, internal diameter 2 mm). As stationary phases were used: Apiezon L, cryptochrome-methylsilicone oil (QF-1), pentagonally ether (PE), polyethylene glycol (mol. mass 20M (PET-20M), 1,2,3-Tris (cyanoethoxy)propane, applied to chromaton N-AW, graining 0,12 0,16 mm at 10 to 15% wt. The flow of carrier gas of nitrogen in sistemaren microcapillary. The signals of the detectors are recorded in the form of two spectra of substances consisting each of five peaks. Since the sensitivity of the detectors to various substances, the peak areas of the same substance, registered a flame ionization detector and katharometer different.

As an example, for identification were used, for example, two pairs of solutes: ethylbenzene hexane, o-xylene-heptane, which was introduced into the system. After passing each substance of the whole system, it turns out two of the chromatogram with the range I and range II, each of which consists of five peaks. By the values of the retention was calculated values of ri. The set of valuesicharacteristic only for these substances. However, a comparison of valuesiethylbenzene with valuesihexane shows that these values are very close. The calculation Cot (based on peak areas) shows that the values of Cot for hexane and ethylbenzene differ significantly: for Paksane Cotn=0,93, for ethylbenzene Cotn=1,32, for o-xylene Cotn= 0,98, and heptane, Cot=1,14. The measurement results are summarized in table 1.

Thus, the use of Corn along with setiallows control group and individualistic compounds, including the transmission of identifiable substance through a system of series-connected fibres filled with sorbents of different polarity, the sampling after each column, getting the spectrum holding in the first non-destructive detector, the transmission of the sample at the second detector of a different type, the calculation according to the data from two detectors of the sensitivity coefficient and the relative retention, identification of the substance on the received values, wherein the second detector, the input connected to the output of the first transmit sequentially samples from the first detector, remove a range of retention at the second detector and the sensitivity coefficient is chosen as the average value of the ratio of the areas of the corresponding peaks in the two spectra retention.

 

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