CN110554107B - Method for analyzing triglyceride components in edible oil by high performance liquid chromatography-mass spectrometry - Google Patents

Abstract

The invention relates to a method for analyzing triglyceride components in edible oil by high performance liquid chromatography-mass spectrometry, which comprises the steps of dissolving an edible oil sample in an organic solvent, taking n-octane-isopropanol or n-heptane-isopropanol as a mobile phase, taking a porous graphite carbon column as a stationary phase, and adopting a high performance liquid chromatography-mass spectrometer for separation and analysis. Compared with the prior art, the invention has the advantages of low mobile phase toxicity, low ultraviolet background, simple and convenient operation, capability of separating isomers and high accuracy of separation and detection results. The method can be used for analyzing various triglyceride components in vegetable oil and animal oil, can be applied to identification of adulterated vegetable oil containing animal oil components, and is a direct and effective edible oil analysis method.

Description

A method for analyzing triglyceride components in edible oil by high performance liquid chromatography-mass spectrometry

technical field

The invention relates to the field of analysis and detection, in particular to a method for analyzing triglyceride components in edible oil by high performance liquid chromatography-mass spectrometry.

Background technique

Edible oils, including vegetable and animal oils, are mainly composed of various triglyceride (TAGs) components and lower amounts of diglycerides, free fatty acids (FAs), phospholipids and other minor components. Among them, triglycerides are the most important nutrients, also known as triacylglycerols (TAGs), accounting for about 95%-98%. They form an important part of the human diet, and their uncontrolled intake may contribute to coronary heart disease, dyslipidemia, and obesity. On the other hand, a healthy intake of fat can also reduce the incidence of cardiovascular disease.

At present, some manufacturers will mix low-cost edible oil with high-value edible oil in order to make a profit, and obtain corresponding income through adulteration. For example, olive oil is mixed with a certain amount of soybean oil or peanut oil, and animal oil is mixed with corn oil. In order to obtain huge profits, some lawbreakers will also use waste oil to pretend to be edible oil or mix waste oil into edible oil, which will pose a very unfavorable threat to people's health.

Using the differences in triglyceride composition in different edible oils, it is possible to identify different edible oils as well as adulterated edible oils. This requires separation and analysis of triglycerides in edible oils, especially the identification of triglyceride components with different isomers is the key to detecting adulterated edible oils.

Several analytical techniques are currently available for qualitative and quantitative triglyceride determination, ranging from classical spectroscopic methods such as infrared, Raman spectroscopy and nuclear magnetic resonance (NMR) to the more recent high temperature gas chromatography-mass spectrometry, high performance liquid chromatography (HPLC), and high-temperature gas-mass spectrometry (GC-MS) and liquid-mass spectrometry (LC-MS) techniques, among these techniques, HPLC and LC-MS based thereon have the potential to separate glycerol The ability of triester isomers is the most studied.

There are three types of HPLC-based methods: normal phase, reversed phase, and silver ion stationary phase. Among them, the selectivity of positive relative to different triglycerides is poor, and it is not used much. Reversed-phase HPLC using C18 or C8 stationary phase and non-aqueous mobile phase has become an important triglyceride separation system. At present, new technologies such as hydrophilic stationary phase, monolithic column, multi-column tandem, ultra-efficient stationary phase, and core-shell stationary phase liquid chromatography have been used in the separation and research of TAGs, which has rapidly improved people's understanding of the differences in TAGs in different oils. . Reversed-phase liquid chromatography is basically separated according to carbon number, and the separation ability of the same equivalent carbon number (ECN, total carbon number of acyl chain minus twice the number of double bonds) and isomers is not strong, even if multi-column series is used. Or ultra-efficient columns are still often difficult to obtain satisfactory separations. High temperature gas chromatography has a similar situation in the separation of TAG.

Silver ion HPLC can separate TAGs according to the number of double bonds through the interaction of silver ions on its stationary phase with carbon-carbon double bonds, which is an important supplement to reversed-phase liquid chromatography. Early silver ion HPLC was achieved by combining silver ions on a silica stationary phase, and the column life was short and not stable enough. The emergence of the second-generation silver ion stationary phase based on sulfonic acid ion exchange groups has made silver ion HPLC achieve rapid development in the separation of triglycerides. Dugo P et al. -POP/sn-PPO ratio is an indicator to identify 5% tallow incorporated in lard. However, the life and stability of this stationary phase column are still not ideal. The third-generation silver ion stationary phase based on sulfhydryl groups that appeared in 2012 has been significantly improved compared with the previous silver ion stationary phases based on sulfonic acid groups, and the service life after a single silverization has been greatly improved, and can be used for polyene fatty acids. Preparation, separation and purification, but the low column efficiency of silver ion column and the defects of column technology make related research still have certain obstacles.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for analyzing triglyceride components in edible oil by high performance liquid chromatography-mass spectrometry in order to solve the above problems, which has the ability to separate isomers, the accuracy of separation and detection results is high, the method is simple, and the operation is simple. Simple and convenient, can significantly improve the detection quality, and improve the accuracy of the detection effect.

The object of the present invention is achieved through the following technical solutions:

A method for analyzing triglyceride components in edible oil by high performance liquid chromatography-mass spectrometry. The edible oil sample is dissolved in an organic solvent, and n-octane-isopropanol or n-heptane-isopropanol is used as a mobile phase , and the porous graphite carbon column was used as the stationary phase, and the separation and analysis were carried out by high performance liquid chromatography-mass spectrometer.

Described organic solvent is n-hexane.

The specific steps are, dissolving the edible oil sample in n-hexane, and using a high performance liquid chromatography-mass spectrometer to separate and analyze the triglycerides in the edible oil sample, wherein the specific HPLC and MS conditions of the high performance liquid chromatography-mass spectrometer are as follows:

(1) HPLC conditions: flow rate 0.1-0.3mL/min; temperature 50～90℃; mobile phase n-octane-isopropanol or n-heptane-isopropanol ratio of 9:1 (v/v)～5 : 5(v/v), UV detection wavelength is 200nm～250nm;

(2) MS conditions: APCI mode, positive ion mode; mass range, 500-1100m/z; source temperature 200℃～350℃; desolvation line (DL) temperature 150℃～250℃; atomizing gas flow rate 2L/ min～7L/min; dry gas flow 3L/min～7L/min.

Preferably, the specific HPLC and MS conditions of the high performance liquid chromatography-mass spectrometer are as follows:

(1) HPLC conditions: flow rate 0.25mL/min; temperature 60°C; mobile phase n-octane-isopropanol (7:3); UV detection wavelength 215nm;

(2) MS conditions: APCI mode, positive ion mode; mass range, 500-1100m/z; source temperature 300°C; desolvation line (DL) temperature 200°C; atomizing gas flow rate 2.5L/min; drying gas flow rate 5L/min.

The temperature of the porous graphite carbon column is 50-90°C.

The edible oil sample was dissolved in n-hexane and diluted to 0.1-1.0 mg/mL with mobile phase.

The high performance liquid chromatography-mass spectrometer adopts LCMS-2020 liquid mass spectrometer.

The porous graphitic carbon column adopts Hypercarb column.

The edible oil samples include vegetable oil and animal oil.

Compared with the prior art, the beneficial technical effects of the present invention are:

High performance liquid chromatography using graphitized carbon column and mass spectrometry method, with n-octane-isopropanol or n-heptane-isopropanol as mobile phase, has the ability to separate isomers, and the separation and detection results are accurate It has high performance, simple method and simple operation, which can significantly improve the detection quality and the accuracy of the detection effect.

The mobile phase of the invention has low toxicity, low ultraviolet background and simple operation. The method can analyze various triglyceride components in vegetable oil and animal oil, and can be applied to the identification of adulterated vegetable oil containing animal oil components. An efficient method for the analysis of edible oils.

When realizing the separation of SPO/SOP of triglyceride acyl position isomers, the problem of toluene contamination in the mobile phase limits its wide application. This patent adopts a graphitized carbon chromatographic column, and proposes a new environment-friendly n-octane-isopropanol or n-heptane-isopropanol system as the mobile phase, which realizes the detection of SPO, a common triglyceride acyl position isomer in edible oil. The separation of /SOP components has good practical application ability, combined with the study of characteristic components in edible oil, it can be used for the identification of adulterated vegetable edible oil.

Description of drawings

Fig. 1 is the mass spectrometry separation figure of corn oil;

Fig. 2 is the mass spectrometry separation figure of soybean oil;

Fig. 3 is the mass spectrometry separation figure of lard;

Fig. 4 is the mass spectrometry separation diagram of incorporating lard in corn oil;

A corn oil, B corn oil+0.1% lard, C corn oil+0.5% lard, D corn oil+1% lard

Fig. 5 is the mass spectrometry separation diagram of incorporating lard in soybean oil;

A soybean oil, B soybean oil + 0.1% lard

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Equipment and materials used in the examples:

The equipment is LCMS-2020 liquid mass spectrometer (Shimadzu, Japan), Hypercarb column (100mm×2.1mmID, particle size 5μm) (Thermo Fisher Scientific, USA);

The materials are n-octane and isopropanol as mobile phases, corn oil, soybean oil and lard as raw materials.

The specific HPLC and MS conditions of the high performance liquid chromatography-mass spectrometer are as follows:

(1) HPLC conditions: flow rate 0.1-0.3mL/min; temperature 50～90℃; mobile phase n-octane-isopropanol or n-heptane-isopropanol ratio of 9:1 (v/v)～5 : 5(v/v), UV detection wavelength is 200nm～250nm;

(2) MS conditions: APCI mode, positive ion mode; mass range, 500-1100m/z; source temperature 200℃～350℃; desolvation line (DL) temperature 150℃～250℃; atomizing gas flow rate 2L/ min～7L/min; dry gas flow 3L/min～7L/min.

Porous graphite carbon column column temperature is 50 ~ 90 ℃.

Example 1

2 μL of corn oil (0.5 mg/mL) was injected into LC-MS, and the specific HPLC and MS conditions of high performance liquid chromatography-mass spectrometer were as follows: (1) HPLC conditions: flow rate 0.25 mL/min; temperature 60 ° C; flow Phase n-octane-isopropanol (7:3); UV detection wavelength 215nm; (2) MS conditions: APCI mode, positive ion mode; mass range, 500-1100m/z; source temperature 300℃; desolvation line (DL) temperature 200°C; atomizing gas flow 2.5L/min; drying gas flow 5L/min. The separation effect of corn oil was monitored in Scan mode, as shown in Figure 1, 14 triglycerides could be separated and characterized with the signal-to-noise ratio S/N>3.

Example 2

2 μL of soybean oil (0.5 mg/mL) was injected into LC-MS, and the separation effect of soybean oil was monitored in Scan mode. As shown in Fig. 2, 14 triglycerides could be separated and characterized with the signal-to-noise ratio S/N>3.

Example 3

2 μL of lard (0.5 mg/mL) was injected into LC-MS, and the separation effect of lard was monitored in Scan mode. As shown in Figure 3, 20 triglycerides could be separated and characterized with a signal-to-noise ratio S/N>3.

Example 4

The corn oil was mixed with 1% lard, 0.5% lard and 0.1% lard respectively, and the injection volume was 10 μL. Monitoring is performed in SIM mode. The results showed that the signal-to-noise ratio of SPO contained in corn oil was small, and the signal-to-noise ratio of SPO in corn oil increased after adding 0.1%-1% lard. Therefore, the incorporation of lard in corn oil can be identified, and the spectrum is shown in Figure 4.

Example 5

Soybean oil was spiked with 0.1% lard, and the injection volume was 6 μL. Monitoring is performed in SIM mode. The results showed that the signal-to-noise ratio of SPO contained in soybean oil was small, and the signal-to-noise ratio of soybean oil mixed with 0.1% lard was significantly increased. Therefore, the incorporation of lard in soybean oil can be identified, and the spectrum is shown in Figure 5.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (5)

1. A method for analyzing triglyceride components in edible oil by high performance liquid chromatography-mass spectrometry is characterized in that an edible oil sample is dissolved in an organic solvent, n-octane-isopropanol or n-heptane-isopropanol is used as a mobile phase, a porous graphite carbon column is used as a stationary phase, and a high performance liquid chromatography-mass spectrometer is used for separation and analysis;

the organic solvent is n-hexane;

the porous graphite carbon column adopts a Hypercarb column, the specification is 100 mm multiplied by 2.1 mm ID, and the particle size is 5 mu m;

the method comprises the specific steps of dissolving an edible oil sample in n-hexane, and separating and analyzing triglyceride in the edible oil sample by using a high performance liquid chromatography-mass spectrometer, wherein the specific HPLC and MS conditions of the high performance liquid chromatography-mass spectrometer are as follows:

(1) HPLC conditions: the flow rate is 0.1-0.3 mL/min; the temperature is 50-70 ℃; the ratio of mobile phase n-octane-isopropanol or n-heptane-isopropanol is 9: 1-5: 5, v/v, the ultraviolet detection wavelength is 200-250 nm;

(2) MS conditions: APCI mode, positive ion mode; the mass range is 500-1100 m/z; the source temperature is 200 ℃ and 350 ℃; desolvation Line (DL) temperature 150-; the flow rate of the atomized gas is 2-7L/min; the flow rate of the drying gas is 3-7L/min.

2. The method for analyzing triglyceride composition in edible oil by high performance liquid chromatography-mass spectrometry as claimed in claim 1, wherein the specific HPLC and MS conditions of the high performance liquid chromatography-mass spectrometer are as follows:

(1) HPLC conditions are as follows: the flow rate is 0.25 mL/min; the temperature is 60 ℃; the ratio of the mobile phase n-octane to the isopropanol is 7:3, v/v; ultraviolet detection wavelength is 215 nm;

(2) MS conditions: APCI mode, positive ion mode; the mass range is 500-1100 m/z; the source temperature is 300 ℃; desolvation Line (DL) temperature 200 deg.C; the flow rate of the atomized gas is 2.5L/min; the flow rate of the drying gas was 5L/min.

3. The method for analyzing triglyceride components in edible oil by high performance liquid chromatography-mass spectrometry as claimed in claim 1, wherein the edible oil sample is dissolved in n-hexane and diluted to 0.1-1.0 mg/mL by mobile phase.

4. The method for analyzing triglyceride composition of edible oil by HPLC-MS of claim 1, wherein the HPLC-MS is LCMS-2020 liquid mass spectrometer.

5. The method for analyzing triglyceride composition of edible oil by HPLC-MS as claimed in claim 1, wherein the edible oil sample comprises vegetable oil and animal oil.

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