Application of Gas Chromatography in Liquor Industry

The detectors currently selected in gas chromatographs used in the liquor industry are mostly hydrogen flame detectors. Therefore, the analysis columns and analysis methods commonly used in the liquor industry are mainly described here.

one. Column selection

1. The packed column method is now the most widely used analytical method in a liquor factory. It uses the DNP column successfully developed by Inner Mongolia Light Industry. This method has been listed in the national standard for the control of ethyl acetate content in ethyl caproate and flavour-type liquors in Luzhou-flavor liquor. Packed column method uses constant temperature control, relatively low requirements on the instrument, good stability, easy to manipulate, generally used for routine testing and production quality control.

It adopts direct injection. It can analyze dozens of components such as alcohols, aldehydes, and esters at a time (see Figure 1). The analysis time is usually about thirty-five minutes (Luzhou-flavor liquor).

Disadvantages are: Can not detect the content of organic acids in liquor 2. Slim tube method (1) Large-caliber capillary column In the 1990s, the large-caliber capillary column analysis method introduced by the Lanzhou Institute of Chemical Industry. Since one direct injection can analyze the alcohol, aldehyde, ester, acetic acid, butyric acid and other 20 components in liquor, the analysis time is short, and the use of stigmatic injection, constant temperature manipulation, relatively low requirements for the instrument, Therefore, it has been well applied in the liquor industry.

The disadvantage is that this column of ethyl acetate and n-propanol, acetal and n-butanol is more difficult to separate, and if the time required to analyze the hexanoic acid is relatively long, it is generally only analyzed ethyl hexanoate.

(2) Fine-bore capillary technology The technique of using the cross-linked capillary column PEG-20M for the analysis of trace flavor components in white spirits was developed in 1991 by Hu Guodong and other senior engineers of the National Food Inspection Center. It has been widely used in major white spirits and liquor industries. . It directly injects samples and analyzes forty components such as alcohols, aldehydes, esters and acids in liquors, especially acids. Eight acids including caproic acid can be analyzed to solve the problems that have plagued the liquor industry for decades. Can't directly analyze the history of acids. Now with the continuous development of capillary column technology, high-grade fatty acids have been analyzed by direct injection with a capillary column. This negative gas chromatograph has become increasingly popular in the study of aroma components, liquor mixing, and quality control in liquor plants. Much effect.

The fine-bore capillary method has high requirements on the instrument. The instrument must be equipped with a capillary shunt system, and the temperature of the program is good and the stability is good.

The disadvantage is that ethyl acetate and acetal do not separate well. There is now an import column that can solve this problem, but the column is expensive.

two. Calculation method
The commonly used calculation method in the liquor industry is the internal standard method, which overcomes the errors caused by incorrect sample injection and inaccurate measuring instruments, and makes the quantitative results more correct.

Since both the packed column method and the large bore method use the constant temperature column head injection, only one kind of internal standard solution (butyl acetate) can be added, and the fine diameter method requires a split injection and the program warms up to reduce the instrument volume. The error caused by shunting is usually added to three internal standard solutions (tert-amyl alcohol, n-amyl acetate, 2-ethyl-n-butyric acid).

1. Packed Column Method and Large-Aperture Method Sample Configuration 1) Preparation of 2% Internal Standard Solution (Butyl Acetate) 60 ml of absolute ethanol (preferably non-fusel oil-ethanol) was prepared and dissolved in distilled water to 100 ml.

Take 2ml of butyl acetate, add it to a 100ml volumetric flask, dissolve it to 100ml with 60% ethanol solution, and turn it into 2% butyl acetate internal standard solution. Mix it.

2) The preparation of wine samples (internal standard volume 35.25mg/100ml)

Take 10ml of white wine sample to be tested, put it into a volumetric flask, add 0.2ml internal standard solution, and mix well. Injection 2. Capillary column sample configuration 1) Preparation of 2% internal standard solution Take anhydrous ethanol (preferably non-fusel oil, ethanol) 60ml, dissolve it with distilled water to 100ml, and wait.

Take 2 mL of tert-amyl alcohol, n-amyl acetate, and 2-ethyl-n-butyric acid, add them to a 100-mL volumetric flask, dissolve to 100 mL with 60% ethanol, and make up 2% of the internal standard solution. Mix it.

2) Preparation of Samples Take 10ml white wine samples to be tested, put them into a volumetric flask, add 0.1ml internal standard solution, and mix them. Injection.

The quantification of the sample is generally performed by a data processor or chromatographic workstation. Since this is the most commonly used quantitative method, it is not described here.

The application of gas chromatograph in the liquor industry has experienced rapid development in the past decade. This is inseparable from the unremitting efforts of liquor research staff. Now the major distillery companies are aware of the role of gas chromatographs. For example, there are dozens of chromatographs in Wuliangye Distillery and several chromatographs in medium-sized distillery companies. As the country pays more attention to quality, more enforcement efforts have been made. The small winery also realized the importance of the gas chromatograph. Now the national standard of alcohol is also written in gas chromatography, and will be enforced, I believe that with the continuous development and improvement of gas chromatography technology, gas chromatography will become more and more widely used in the liquor industry.