Method to reveal and determine origin of unknown substances in alcoholic drinks

FIELD: test equipment.

SUBSTANCE: proposed invention relates to gas chromatographic analysis and can be used in alcohol quality tests. Proposed method consists in that, additionally, water-spirit mix in the ratio of 60/40% by volume is prepared to a series of model samples based thereon to prepared by adding every component of analysed drink separately in said mix. Then model sample are analysed at the inlet assembly temperature of 180C, 250C and 310C. Note that unknown substance detected in model sample is qualified as artifact formed in analysis, while is it is absent from model samples, check sample is prepared by combining the entire series of model samples to be analysed at aforesaid 180C, 250C and 310C. Then mass spectra and chromatograms related therewith are analyzed and, if there is no revealed unknown substance in check sample, it is qualified as marker of nonfoods origin.

EFFECT: unambiguous identification of chemical compounds and fragments thereof as well as their origin, higher accuracy and faster identification.

4 tbl, 3 ex

 

The invention relates to gas chromatography analysis of various chemical compounds and can be used in the control of alcoholic beverages.

There is a method of analysis of liquid preparations based on vegetable raw material by chromatography, which involves removing the volatiles by distillation of the original sample vapor, the concentration of volatile substances by extraction with a low-boiling solvent followed by distillation of the solvent and finally the actual definition of the components by the methods of gas or liquid chromatography [1].

The disadvantage of this technical solution is the low information content of the data received, in particular chromatographic spectra, which prevents unambiguous identification of chemical compounds and their fragments in arbitrary combinations.

There is also known a method of chromatographic identification of components of complex mixtures of organic compounds, including passing the substance through a system of series-connected columns filled with different sorbent polarity, sampling after each column, detection at the detectors of various types and identification of the analyte by calculating the sensitivity coefficient and the relative retention data of two detectors [2].

The disadvantages of this method sleduyuschi complexity analysis procedures, as well as the probability of obtaining inaccurate results when calculating retention values of different columns.

There is also known a method for the identification of unknown substances by gas chromatography in combination with mass spectrometry. At the specified method record the chromatogram as a function of retention time and record the mass spectrum in the period of time corresponding to the release of substances from the column, and compared with the mass spectra of known substances in the database, then define the retention index and compare it with those from the database and identify the substance by the two parameters : the mass spectrum and retention index [3].

The disadvantage of this method despite the attractiveness of using index retention is a high probability of obtaining false results of the analysis, because the retention indices of the initially bound to a specific column with defined parameters and is often either not played or played back on other equipment with distortion, which can lead to inaccurate interpretation of results.

The closest analogue to the claimed technical solution is a way of performing mass spectral analysis of multicomponent systems, which consists in registration of mass spectra of the sample decks is nwalozie of mass spectra and their associated chromatograms of one substance and recognition by comparison with the reference spectrum of the substance, by comparing the intensities of peaks and retention time recognized substances with predefined parameters of the required substances confirming recognition [4].

The disadvantage of this method is the low threshold of the definition, namely, that it is not possible to determine the analyte at low concentrations, and the resulting high probability of obtaining false results of the analysis in this two-stage recognition.

The technical result, which directed the establishment of this invention is the provision of opportunities for unambiguous identification of chemical compounds and their fragments and determining the origin of these chemical compounds while increasing the accuracy and timeliness of the definition.

The technical result is achieved in that, in addition, prepare a water-alcohol mixture of 60/40 % by volume, based on it, develop a set of model samples by introducing a water-alcohol mixture each component of the investigated drink separately model and analyze the samples at the temperature of inlet node 180C, 250C and 310C, and detection in the model sample of an unknown substance qualify as an artifact formed during the analysis, and in the absence of it in modelin the x samples prepared control sample by combining the total number of model samples analyze it when the temperature of the inlet node 180C, 250C and 310C, recorded mass spectra and associated chromatogram and in the absence in the sample found an unknown substance it qualify as a marker of non-food origin.

It should be noted that the inventive method can also be carried out using analytical system HPLC-MS/MS, because the principal provisions of the proposed technical solutions are sample preparation, analyses in different modes of climate parameters on the temperature gradient, the choice of objects for analysis and subsequent identification of the designated substances by comparing the results of the analysis of baseline data of the reference substance.

As the study of alcohol beverage can be used the full range of alcohol-containing liquids.

The analytical system GC-MS can be used such as gas chromatography-mass spectrometer with quadrupole analyzer Agilent-5973, coupled with a gas chromatograph model Agilent-6890.

As accessories can be used:

- automatic shaker firm Glas-Col, USA for JJA;

- centrifuge brand Rotina 46R company Hettich (Germany), to obtain the contrast of the boundary surface between the organic and aqueous phases;

- VAK the smart hub firm Barnstead Inc.(CLUA) for evaporation of the organic extract;

- column type FFAP for chromatographic separation.

Of course, carrying out the claimed invention can be used, and other devices with characteristics similar to the above.

As the carrier gas can be used helium, nitrogen or hydrogen.

As internal standards (SU) use cyclohexanol or other suitable connection.

The ionization is carried out by electron impact in a vacuum. Detection of the detected substances is carried out in the registration mode full scan or selected ions.

Data processing is carried out with application of the automatic processing AMDIS and databases.

In principle, the detection and determination of unknown substances should be implemented in order to find new, previously unknown tokens, which may be responsible for the quality of alcoholic beverages or can be a witnesses of falsification liquor.

With regard to the implementation of the proposed technical solution, the authors, based on their knowledge and experience, I think it advisable to search in the following sequence:

- search and discovery of the unknown substance (GC-MS analysis of the samples analyzed liquor at the temperature gradient of 10C/min);

- yavlenie unknown substances as a product of decomposition of component(s) studied liquor (GC-MS analysis of a number of model samples of water-alcohol mixture + component investigated drink at the temperature of inlet node 180C, 250C and 310C);

- identification of the unknown substance as an impurity or degradation product of components of the control sample (GC-MS analysis of the control sample at the temperature of inlet node 180C, 250C and 310C).

The invention can be implemented as follows.

Previously, to create a database prepared samples of known beverage standards. Remove and register chromatographic and mass spectrometric characteristics of their (detects at least three characteristic ions of each component, determine the retention time, molecular mass precursor ions, characteristic ions, the lower limit of detection). From the data obtained form the base. Separately form the database laboratory background contamination and instrument background.

Prepare the internal standard solution, then hold the sample preparation, in which the sample liquor enter the internal standard solution to bring the pH of the sample to 9.0 solid buffer, conduct liquid-liquid extraction with a mixture of organic solvents of different polarity, the organic layer is evaporated to dryness in a stream of nitrogen, pererastayut in ethyl acetate and then the sample is introduced into the system GC-MS. Remove and register chromatographic and mass spectrometric characteristics of the sample. The results of the analysis comparing the database and identify the characteristics of an unknown substance (HB). Then check the probability of the presence of HB in each component analyzed liquor, which prepare a water-alcohol mixture of 60/40% vol. and on its basis the number of model samples of the composition of the water-alcohol mixture component analyzed alcoholic drink. Each sample is introduced into the system GC-MS, shoot and record chromatographic and mass spectrometric characteristics of the sample at the temperature of inlet node 180C, 250C and 310C and determine the presence of HB. Next, mix the whole number of model samples and thus obtained control sample is introduced into the system GC-MS, shoot and record chromatographic and mass spectrometric characteristics of the control sample when the temperature of the inlet node 180C, 250C and 310C. In the absence of the control sample was found an unknown substance it qualify as a marker of non-food origin.

For a better understanding of the invention can be illustrated by, but is not exhausted by the following specific examples of its implementation.

Example 1.

The identification of unknown substances in cognac.

A. Preparation and analysis of samples of the reference and the sample for the presence of volatile compounds.

As an internal standard using a solution of cyclohexanol in ethanol with a concentration of 0.1 vol.%. To 1 ml of the reference cognac add 30 l of the internal art is ngarta to a concentration of 28 mg/l and the sample is introduced into the system GC-MS with FFAP column.

Similarly prepare and analyze the sample studied brandy.

The analysis is performed by gas chromatography-mass spectrometry system Agilent 6890/5973N mass-selective detector (record the mass spectrum of the quadrupole and the mass spectrum of the ion trap). The process is conducted with the following parameters: temperature node of the input sample - 180C, analytical interface 190C. the Separation is performed on silica capillary column with a stationary phase (NP) HP-FFAP length 50 m, inner diameter 0.32 mm, film thickness of stationary phase 0.5 m. The flow rate of the carrier gas at 1.2 ml/min, the average linear velocity of carrier gas 32 cm/sec. The volume of injected sample 1 l dividing stream 1/10. Temperature program: 60C (4 min), 10C/min, 190C (40 min). The registration signal is carried out on total ion current (SCAN) in the mass range m/z 29 - 300 Amu retention Time of internal standard is to 4.52 minutes When using the GC-FID analysis is carried out in similar conditions. The retention time of internal standard is 9,27 min carrier Gas is nitrogen. Quantitative analysis is performed on the selected ions.

B. Preparation and analysis of samples of the reference and the sample for the presence of markers of age.

The sample reference brandy (3 ml) add 100 l of internal standard solution orthovision in ethanol, 2 mg/l), extracted with 3 ml of a mixture of hexane/diethyl the fir 1:1. The extract evaporated, add 100 l of ethyl acetate and 1 l of sample is introduced into the system GC-MS with column HP-5MS.

Similarly prepare and analyze the sample studied cognac. Remove and register chromatographic and mass spectrometric characteristics of the samples (detects at least three characteristic ions of each reference substance, determine the retention time, molecular mass precursor ions, characteristic ions, the lower the detection limit).

The results of analysis in the study brandy (see Table 1) found two substances identified as not characteristic of brandy.

Table 1
Retention timeMass spectrumContentEstimated substance*
24,56 min103, 116, 1458 ng/ltriacetin
26,75 min31, 43, 60, 1726 ng/l
* - was found in the database

Next, prepare a water-alcohol (cognac alcohol relevant excerpts) a mixture of SOS is ava 60/40% vol. and on the basis of the above-mentioned mixture to prepare a number of samples of the individual components of the reference brandy, including:

water-alcohol mixture + ethylhexenal

water-alcohol mixture + diethylcarbamoyl

water-alcohol mixture + ethyllactate

water-alcohol mixture + vanilla

water-alcohol mixture + sucrose

water-alcohol mixture + eugenol

Each sample is introduced into the system GC-MS, shoot and record chromatographic and mass spectrometric characteristics of the sample at the temperature of inlet node 180C, 250C and 310C.

When analyzing samples of water-alcohol mixture + sucrose found an unknown substance with the following parameters: retention time 26,75 min; characteristic ions 31, 43, 60, 172. Specified substance, therefore, is a product of thermal decomposition of sucrose in the injector of the chromatograph. Database substance defined as a dimer of 1,3-dihydroxyacetone. A full analysis of the components of the reference brandy individually and in the aggregate, have not revealed the presence of the other unknown substances. On the basis of the data determined that the specified substance is triacetin. It is known that triacetin is an indispensable component of artificial flavorings. According to the analysis of triacetin is regarded as a marker of non-food origin.

Example 2

The identification of unknown substances in the vodka.

Preparation of reference samples and analyzed vodkas are as in Example 1. Analysis of lead, as in part B of Example 1.

Resolutionality presented in Table 2.

Table 2
Retention timeMass spectrumContentEstimated substance*
33,85122, 105, 7713,0
40,76212, 194, 167, 1058,5
45,02234, 120, 867,6

Next, prepare the reference water-alcohol mixture of 60/40% vol. (in accordance with the formulation of the investigational vodka) and analyze the sample, as in example 1. In the control sample of unknown substances were not detected. On the basis of data found in the study vodka unknown substances are benzoic acid, benzoyl benzoate and lidocaine, respectively, and are the products of thermal decomposition of bitrex - denaturing additives to alcohols and qualify the results of the analysis as markers of non-food origin.

Example 3.

The identification of unknown substances in the vodka.

Preparation of reference samples and analyzed vodkas are, as the Example 2. Analysis of lead, as in part B of Example 1.

The results of the analysis are presented in Table 3.

Table 3
Retention timeMass spectrumContentEstimated substance*
39,45222, 177, 14934,7

In the control sample of an unknown substance was found. On the basis of data found in the study vodka unknown substance is diethylphthalate.

At the same time, diethylphthalate and other esters of phthalic acid are typical representatives of laboratory contamination (injectors, dishes, etc. and therefore qualified for the determination of origin found dimethylphthalate required to carry out an audit of determining the level of laboratory contamination. The analysis is conducted at the following parameters: 100C (1 min), 35C/min, 300C (20 min), column HP-5MS.

The results of the laboratory analysis of contaminants are presented in Table 4.

The results of the analysis to qualify detected in the studied vodka unknown substance - dimethylphthalate - qualify as a marker of episunago origin, denaturing additive to alcohol.

As can be seen from the description and examples of the method, the proposed solution provides the ability to uniquely identify chemical compounds and their fragments, allows you to set the origin of these chemical compounds while increasing the accuracy and timeliness of the definition.

Sources of information

1. EN 2093822 C1, MCL G01N 30/04, publ. 1997

2. EN 2069363 C1, MCL G01N 30/02, publ. 1996

3. WO 2004/104571, MCL G01N 30/00, publ. 2004

4. EP 1846757 A2, MCL G01N 30/86, publ. 2007 - the nearest equivalent.

The method of detection and origin identification of unknown substances in alcoholic beverages, which prepare the sample studied drink, put her GC/MS analysis, record mass spectra and their associated performance and conduct recognition components are compared with a database of reference analytical characteristics of the beverage, characterized in that it additionally prepare a water-alcohol mixture of 60/40% by volume, based on it, develop a set of model samples by introducing a water-alcohol mixture each component of the investigated drink separately model and analyze the samples at the temperature of inlet node 180C, 250C and 310With, and if it is detected in the model sample of an unknown substance qualify as an artifact, is resouses in the analysis, in the absence of it in the model samples are prepared control sample by combining the total number of model samples, analyze it when the temperature of the inlet node 180C, 250C and 310C, recorded mass spectra and associated chromatogram and in the absence in the sample found an unknown substance it qualify as a marker of non-food origin.



 

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