CN110988240A - Method for rapidly analyzing ethyl hexanoate in Luzhou-flavor liquor through two-channel gas chromatography - Google Patents

Abstract

The invention discloses a method for rapidly analyzing ethyl caproate in Luzhou-flavor liquor by using a two-channel gas chromatography, which is characterized in that after an internal standard is added into a liquor sample to be detected, DB-WAX (20m 0.180mm 0.30 mu m) is used as a separation column, nitrogen is used as carrier gas for flowing, and a hydrogen flame ionization detector is used for detecting after the sample is separated by a chromatographic column. The method adopts a double-channel detection method, namely two sample injection towers, two sample injection ports, two identical chromatographic columns, two identical detectors and a DB-WAX (20m 0.180mm 0.30 mu m) chromatographic column. The method is simple, convenient, short in time and accurate and reliable in data.

Description

Method for rapidly analyzing ethyl hexanoate in Luzhou-flavor liquor through two-channel gas chromatography

Technical Field

The invention relates to a method for rapidly analyzing ethyl caproate in strong aromatic Chinese spirits by using a two-channel gas chromatography, belonging to the technical field of liquor analysis.

Background

Luzhou-flavor liquor is a distilled liquor which is unique to China, and is listed as six famous distilled liquors in the world together with brandy, whiskey, vodka, rum and golden liquor. It is made up by using yeast and yeast as saccharification leaven and using starch as raw material through the processes of cooking, saccharification, fermentation, distillation, ageing and blending. The wine is clear and transparent, has pure texture, no turbidity, aromatic and rich flavor, is mellow, soft and soft, has strong pungency, is sweet and clean in mouth, has high alcohol content, has aftertaste after drinking, and has long aftertaste. The products are produced in all regions of China, and are most famous in Sichuan, Guizhou, Jiangsu, Shanxi, Anhui, Shanxi and the like.

The types of the aroma components of the white spirit are as follows: alcohols, esters, acids, aldehyde ketone compounds, acetals, aromatic compounds, nitrogen-containing compounds, furan compounds, and the like. The ethyl caproate is the main body fragrance of the strong aromatic Chinese spirits and has the effect of increasing the body fragrance. At present, single-channel gas chromatography is mainly adopted for quantitative analysis of ethyl caproate in white spirit, and a chromatographic column adopts a long column with the length of more than 30m, so that the time is long.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method for rapidly analyzing ethyl caproate in Luzhou-flavor liquor by using a dual-channel gas chromatography, so that ethyl caproate in liquor can be rapidly and accurately detected, and scientific and accurate basis is provided for rapidly analyzing ethyl caproate in Luzhou-flavor liquor.

The apparatus provided by the invention is GC7890 (double channels), and the chromatographic column is DB-WAX (20m 0.180mm 0.30 μm), a liquid transfer machine and an electronic analytical balance.

The invention discloses a method for rapidly analyzing ethyl caproate in Luzhou-flavor liquor by using a two-channel gas chromatography, which comprises the following steps of:

step 1: preparation of the internal Standard

Taking 1 branch of 5mL tertiary amyl alcohol (chromatographic purity), weighing the tertiary amyl alcohol with the mass of M mg on an electronic analytical balance, and using 60% absolute ethyl alcohol to make the volume constant to 200mL to obtain the tertiary amyl alcohol internal standard, wherein the concentration of the internal standard in a sample to be measured is M/250 x 1000 x 0.01mg/L (the concentration of an internal standard substance in a wine sample).

Step 2: drawing of ethyl caproate standard curve

Preparing standard working solutions with different mass concentrations by taking an ethyl hexanoate standard solution, respectively adding 10mL of the standard working solutions with different mass concentrations into 0.1mL of tertiary amyl alcohol internal standard, respectively taking 1.5mL of sample injection, detecting by using a hydrogen flame ionization detector, performing linear regression by using peak areas and corresponding mass concentrations of the ethyl hexanoate and the internal standard, and obtaining a standard curve, namely the standard curve of the ethyl hexanoate.

The concentration of the standard working solution with different mass concentrations is controlled at 500-2500mg/L, and the mass concentration is at least 5 different points.

Linear regression equation corresponding to ethyl caproate and related coefficient r²See table 1.

TABLE 1 Linear regression equation, correlation coefficient, detection limit, quantitation limit for ethyl hexanoate

And step 3: pretreatment of wine sample to be tested

And (3) taking 10mL of the wine sample to be detected into a 10mL colorimetric tube with a plug, adding 0.1mL of tertiary amyl alcohol internal standard, uniformly mixing to obtain a sample to be detected, and sampling.

And 4, step 4: detection of a wine sample to be tested

And (3) performing DB-WAX chromatographic column separation on 0.5-1.5mL of the sample to be detected after pretreatment in the step (3), detecting by using a hydrogen flame ionization detector to obtain a chromatogram of the sample to be detected, performing qualitative analysis on the sample to be detected according to retention time, and performing quantitative analysis according to a standard curve of ethyl caproate.

The detection conditions were set as follows:

the conditions of the gas chromatograph were:

a chromatographic column: DB-WAX (20m 0.180mm 0.30 μm)

Carrier gas: nitrogen with purity over 99.999%

Sample inlet temperature: 250 deg.C

Detector temperature: 300 deg.C

The split ratio is as follows: 30:1

Flow rate of carrier gas: 1.0mL/min

Mode (2): double sample inlet sample introduction

The column box temperature program was set as follows: initially 35 ℃ for 1min, at 15 ℃/min to 150 ℃ and at 25 ℃/min to 230 ℃ for 3 min.

The method of the invention carries out the following sensitivity tests: the sensitivity test comprises instrument sensitivity and method sensitivity, the instrument sensitivity is expressed by a detection limit, and the minimum concentration of a standard working solution with a signal-to-noise ratio of more than or equal to 3 is taken as the instrument detection limit; the sensitivity of the method is expressed by a quantitative limit, and the minimum concentration of the standard working solution with the signal-to-noise ratio of more than or equal to 3 is taken as the quantitative limit of the method. The relevant data obtained are shown in Table 1.

The following accuracy and reproducibility tests were performed on the method of the present invention: selecting a white spirit sample as a blank spirit sample, dividing the white spirit sample into 3 parts, respectively adding standard working solutions, performing pretreatment, performing a standard addition recovery experiment, and calculating the recovery rate; selecting a wine sample, dividing into 6 parts, respectively carrying out pretreatment, carrying out experiments, and judging the reproducibility of the analysis method by calculating the range of Relative Standard Deviation (RSD). The accuracy of the process is expressed in terms of recovery, see table 2, and the reproducibility of the process is expressed in terms of Relative Standard Deviation (RSD), see table 3. It can be seen that the recovery is between 80 and 120% with RSD < 10%.

TABLE 2

TABLE 3

The method uses GC7890 (double channels) for detection, the sensitivity meets the requirement of quantitative detection of wine samples, and meanwhile, the method has simple pretreatment, can analyze two samples at a time, and can quickly detect the content of ethyl caproate in wine.

The invention has the beneficial effects that:

1. the invention establishes a method for rapidly detecting ethyl caproate in wine by a gas chromatograph (dual-channel) method, can accurately perform qualitative and quantitative detection on ethyl caproate in wine, and provides scientific and accurate basis for detection of ethyl caproate in wine products.

2. The gas chromatograph (double-channel) has the advantages of simple and quick operation, time saving, high accuracy and good reproducibility.

3. The DB-WAX (20m 0.180mm 0.30 mu m) chromatographic column has good separation effect on ethyl caproate, short column length and short analysis time.

4. The method has simple pretreatment, reduces the use of laboratory consumables, and further saves the laboratory cost.

Drawings

The attached figure is a chromatogram for detecting a white spirit sample, wherein an internal standard (tertiary amyl alcohol) and ethyl caproate are marked, a front detector signal is shown in figure 1, and a rear detector signal is shown in figure 2.

Detailed Description

The technical solution of the present invention is further illustrated by the following specific examples.

In this embodiment, ethyl caproate in a Luzhou-flavor liquor is detected according to the following steps:

the instrument used was GC7890 (dual channel), the column was DB-WAX (20m 0.180mm 0.30 μm), pipette, electronic analytical balance.

The method comprises the following specific steps:

step 1: preparation of the internal Standard

Taking 1 piece of 5mL tertiary amyl alcohol (chromatographic purity), weighing the tertiary amyl alcohol with the mass of M mg on an electronic analytical balance, and metering the volume into a 200mL volumetric flask by using 60% absolute ethyl alcohol to obtain the internal standard with the concentration of M/250 x 1000 x 0.01mg/L in the sample to be measured.

Step 2: drawing of ethyl caproate standard curve

Preparing 5 standard working solutions with different mass concentrations from the ethyl hexanoate stock solution, wherein the concentration range is 500-2500mg/L, respectively adding 0.1mL of tertiary amyl alcohol internal standard into 10mL of the standard working solutions, respectively sampling about 1.5mL of the standard working solutions, detecting by using a hydrogen flame ionization detector, and performing linear regression by using peak areas and corresponding mass concentrations of the ethyl hexanoate and the internal standard to obtain a standard curve, namely the standard curve of the ethyl hexanoate.

And step 3: pretreatment of wine sample to be tested

And (3) taking 10mL of the wine sample to be detected into a 10mL colorimetric tube with a plug, adding 0.1mL of tertiary amyl alcohol internal standard, uniformly mixing to obtain a sample to be detected, and sampling.

And 4, step 4: detection of a wine sample to be tested

And (3) performing DB-WAX chromatographic column separation on 0.5-1.5mL of the sample to be detected after pretreatment in the step (3), detecting by using a hydrogen flame ionization detector to obtain a chromatogram of the sample to be detected, performing qualitative analysis on the sample to be detected according to retention time, and performing quantitative analysis according to a standard curve of ethyl caproate.

The detection conditions were set as follows:

the conditions of the gas chromatograph were:

a chromatographic column: DB-WAX (20m 0.180mm 0.30 μm)

Carrier gas: nitrogen with purity over 99.999%

Sample inlet temperature: 250 deg.C

Detector temperature: 300 deg.C

The split ratio is as follows: 30:1

Flow rate of carrier gas: 1.0mL/min

Mode (2): double sample inlet sample introduction

The column box temperature program was set as follows: initially 35 ℃ for 1min, at 15 ℃/min to 150 ℃ and at 25 ℃/min to 230 ℃ for 3 min.

The ethyl hexanoate content of the wine sample is shown in table 4 below:

TABLE 4 Ethyl hexanoate content of the wine samples

Claims (4)

1. A method for rapidly analyzing ethyl caproate in Luzhou-flavor liquor by using a two-channel gas chromatography is characterized by comprising the following steps of:

step 1: preparation of the internal Standard

Taking 1 piece of 5mL chromatographically pure tertiary amyl alcohol, weighing the mass of the tertiary amyl alcohol on an electronic analytical balance to be M mg, and using 60% absolute ethyl alcohol to fix the volume to 200mL to obtain a tertiary amyl alcohol internal standard;

step 2: drawing of ethyl caproate standard curve

Preparing standard working solutions with different mass concentrations by taking an ethyl hexanoate standard solution, respectively adding 10mL of the standard working solutions with different mass concentrations into 0.1mL of tertiary amyl alcohol internal standard, respectively taking 1.5mL of sample injection, detecting by using a hydrogen flame ionization detector, performing linear regression by using peak areas and corresponding mass concentrations of the ethyl hexanoate and the internal standard, and obtaining a standard curve, namely the standard curve of the ethyl hexanoate;

and step 3: pretreatment of wine sample to be tested

Taking 10mL of the wine sample to be detected, putting the wine sample into a 10mL colorimetric tube with a plug, adding 0.1mL of tertiary amyl alcohol internal standard, uniformly mixing to obtain a sample to be detected, and sampling;

and 4, step 4: detection of a wine sample to be tested

And (3) performing DB-WAX chromatographic column separation on 0.5-1.5mL of the sample to be detected after pretreatment in the step (3), detecting by using a hydrogen flame ionization detector to obtain a chromatogram of the sample to be detected, performing qualitative analysis on the sample to be detected according to retention time, and performing quantitative analysis according to a standard curve of ethyl caproate.

2. The method of claim 1, wherein:

in step 2, the concentration of the standard working solution with different mass concentrations is controlled to be 500-2500mg/L, and at least 5 points with different mass concentrations are taken.

3. The method of claim 1, wherein:

the detection conditions were set as follows:

the conditions of the gas chromatograph were:

a chromatographic column: DB-WAX (20m 0.180mm 0.30 μm)

Carrier gas: nitrogen with purity over 99.999%

Sample inlet temperature: 250 deg.C

Detector temperature: 300 deg.C

The split ratio is as follows: 30:1

Flow rate of carrier gas: 1.0mL/min

Mode (2): and injecting samples through double sample inlets.

4. The method of claim 3, wherein:

the column box temperature program was set as follows: initially 35 ℃ for 1min, at 15 ℃/min to 150 ℃ and at 25 ℃/min to 230 ℃ for 3 min.

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