WO2023065811A1 - Method for measuring content of methanol in burst bead essential oil for cigarette - Google Patents

Abstract

A method for measuring the content of methanol in burst bead essential oil for a cigarette by using a fully vaporized headspace gas chromatography method, comprising the following steps: (1) after burst bead essential oil for a cigarette is subjected to ultrasonic treatment, putting the burst bead essential oil for a cigarette into a headspace bottle and sealing; (2) putting the headspace bottle in step (1) into a headspace sample injector, and measuring a signal value of methanol in the headspace bottle by means of a fully vaporized headspace gas chromatography method; and (3) substituting the signal value of methanol obtained in step (2) into a standard curve to obtain the content of methanol in the burst bead essential oil for a cigarette. The beneficial effect is that the measurement method is simple and convenient to operate and high in accuracy.

Description

A kind of determination method of methanol content in popcorn essential oil for cigarettes technical field

The invention relates to the technical field of detection of methanol content, in particular to a method for accurately measuring the content of methanol in popcorn essential oil for cigarettes by using full vaporization headspace gas chromatography.

Background technique

Methanol is an important organic raw material and is widely used in industry. Methanol is highly toxic. Once ingested by the human body, it will be metabolized into formic acid and formate that are harmful to the central nervous system. In severe cases, it will cause blindness, coma or even death. Therefore, in food, drinking water and air, the concentration of methanol has strict restrictions and must be below 5-10mg/kg. Popcorn essential oil for cigarettes is an important food additive. A large amount of chemical solvents such as ethanol, propylene glycol, and petroleum ether are used in the process of dissolution, extraction, and synthesis. These residual methanol may be brought into food. And then pose a serious threat to human health. In view of this, it is necessary to establish a rapid and accurate method for the determination of residual methanol content in popcorn essential oil for cigarettes, which has an important guiding role in ensuring food quality and reducing safety risks.

At present, the detection methods of the methanol content in the popcorn essential oil (oil phase) for cigarettes are mainly gas chromatography and high performance liquid chromatography. For gas chromatography, since the popcorn essential oil system for cigarettes contains high-boiling solvents such as caprylic acid glyceride (boiling point is 456 ° C), direct sampling detection will pollute the sampling system, and then affect the service life of the instrument; therefore, in order to reduce Risk, pretreatment steps such as extraction and separation with organic solvents are required before detection. These pretreatments are not only cumbersome and inefficient, but also affect the accuracy of detection results. Although high performance liquid chromatography has high separation efficiency and does not need to consider the high boiling point and difficulty of volatilization of caprylic acid glyceride, due to the lack of chromogenic groups in methanol, it is necessary to mix methanol with organic solvents to form stable derivatives with methoxy groups before detection. It is not only complicated and time-consuming, but also consumes more organic solvents. In addition, methods such as Raman spectroscopy, infrared spectroscopy, UV-visible spectroscopy, and spectrophotometry have also been used to measure the methanol content in the oil phase. Raman spectroscopy, infrared spectroscopy, and ultraviolet-visible spectroscopy are based on the determination of the characteristic peaks of the characteristic functional groups (methyl) in methanol to determine the methanol content. The main problem is that it will be affected by the complex matrix of the sample and the detection sensitivity is not high. ; and the principle of spectrophotometric method for measuring methanol is to oxidize methanol into formaldehyde, and formaldehyde reacts with chromogenic agents such as sulfite fuchsin, chromotropic acid, etc. to develop color and then carry out photometric measurement; obviously, the method is complicated and time-consuming to operate, and the detection The formaldehyde produced in the process is harmful to the human body. Therefore, it is necessary to develop a new detection method that can overcome the above shortcomings to measure the methanol content in the popcorn essential oil for cigarettes, and provide effective technical assistance for factory production and laboratory research.

The present invention is proposed to solve the above-mentioned problems.

Contents of the invention

In order to overcome the shortcomings and deficiencies of the prior art method for measuring methanol content in popcorn for cigarettes, the present invention provides a method for accurately measuring the content of methanol in popcorn essential oil system for cigarettes by using full vaporization headspace gas chromatography. The method of the invention has the advantages of fast detection speed, high result accuracy, simple and convenient operation, etc., and overcomes the disadvantages existing in the current determination of the methanol content in the oil phase system.

The present invention adopts full-vaporization headspace gas chromatography to measure the methanol content in the popcorn essential oil for cigarettes. The specific principle is: in a closed headspace bottle, when the equilibrium temperature of the headspace exceeds the boiling point of methanol, The methanol will be completely transferred from the liquid phase to the gas phase; the signal value of methanol is determined based on full vaporization headspace gas chromatography, and then the methanol content in the popcorn essential oil for cigarettes is calculated through the standard curve.

The present invention realizes through following technical scheme:

A method for accurately measuring the content of methanol in the popcorn essential oil for cigarettes by full-vaporized headspace gas chromatography, comprising the steps of:

①Put the puffed pearl essential oil for cigarettes into a headspace bottle after ultrasonic treatment and seal it; the conditions for ultrasonic treatment are preferably: 400w, time: 5min; the puffed pear essential oil for cigarettes can be liquid;

② Place the headspace vial of step ① in the headspace sampler, and measure the signal value of methanol in the headspace vial by full vaporization headspace gas chromatography;

③Substitute the methanol signal value obtained in step ② into the standard curve to obtain the methanol content in the essential oil for cigarettes.

Preferably, in step ②, the eluting time of the methanol peak is 0.668 min.

Preferably, the conditions of the headspace sampler in step ② are as follows: the initial equilibrium temperature is 105°C, the equilibrium time is 2min; The time to GC is 20s; the maximum injection volume is 40μL.

Preferably, gas chromatography operating conditions in step ②: hydrogen flame ion detector, carrier gas is nitrogen, flow rate is 25mL/min; combustible gas is hydrogen, flow rate is 30mL/min; assisted gas is oxygen, flow rate is 400mL/min; The detector temperature is 250°C, the split ratio is 2:1, and the detection time is 2min.

Preferably, the standard curve of step 3. is shown in the following formula: Y=A+BX; Wherein, Y is the GC signal value of methanol, i.e. the peak area, X is the concentration of the standard solution of methanol, the unit is mg/mL; A and B is a constant, A=-157.66, B=83.99.

More preferably, A is -157.66±21.91; B is 83.99±0.9197.

Beneficial effects of the present invention:

1. The method of the present invention utilizes full-vaporized headspace gas chromatography to measure the methanol content in the popcorn essential oil for cigarettes for the first time. The detection method of the invention is easy to operate and has high precision; the limit of quantification of methanol detection in the popcorn essential oil for cigarettes can reach 0.73 mg/mL. The detection method of the invention can detect in batches, thereby improving the efficiency; it overcomes the disadvantages of low detection sensitivity, cumbersome operation, low time-consuming efficiency, high organic solvent loss and the like in the prior art method.

2. The method of the present invention utilizes full-vaporized headspace gas chromatography to accurately measure the methanol content in the popcorn essential oil for cigarettes, avoids the influence of high-boiling solvents on the measurement results during direct sample injection, and has a wide range of applications.

3. The method of the present invention can accurately quantitatively analyze the methanol content in the popcorn essential oil for cigarettes, provide guidance for the determination of the methanol content in the oil phase, and play an important guiding role in ensuring food quality and reducing safety risks.

Description of drawings

Fig. 1 is the gas chromatogram of the volatile target substance in the popcorn essential oil for smoking with the temperature of the chromatographic column being 60°C.

Figure 2 is a graph showing the effect of headspace equilibration time on methanol signal value.

Fig. 3 is a graph showing the effect of the headspace equilibrium temperature on the methanol signal value.

Figure 4. The effect of headspace injection volume on toluene signal value.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Equipment and reagents used: DANI HS 86.50 PLUS, Italy type automatic headspace sampler, Agilent GC 8860, US type gas chromatograph (hydrogen flame ion detector, GS-Q type capillary column), headspace bottle ( 20.0ml), blue Teflon/blue silicone septa (with aluminum cap).

The sample solution of popcorn essential oil for cigarettes containing different methanol contents is commercially available.

Determination of full vaporization of methanol:

Add 15 μL of smoked pearl essential oil sample to a glass vial (1 mL), place the glass vial at the bottom of the headspace vial, seal it, and detect the methanol signal value (A ₁ ) in the gas phase after 3 min. After running, immediately take out the glass vial and place it in a new headspace vial, and detect the methanol signal value (A ₂ ) in the sample vial after sealing; measure the signal value ratio (R%) twice, that is, A ₂ /A ₁ , It can be used as a parameter to evaluate the total vaporization efficiency of methanol. The smaller the R value, the more complete the mass transfer of methanol. Table 1 shows the R value results obtained by three parallel tests. It can be seen from the table that if R<1.94, methanol is close to full-vaporization mass transfer, which shows that it is feasible to use full-vaporization technology to determine the methanol content in popcorn essential oil for cigarettes.

Table 1

The headspace sampler conditions were as follows:

The equilibrium temperature is 105°C, the equilibrium time is 2min, the pressurization time of the headspace bottle is 15s, the depressurization time is 15s, the filling time of the quantitative loop is 10s, the transfer line time is 20s, the injection purge time is 20s, and the pressurization pressure is 1bar.

Gas chromatography operating conditions:

Hydrogen flame ion detector (FID), the inlet pressure is 22.47psi, the inlet temperature is 250°C, the split ratio is 2:1, the detector temperature is 250°C, the detection time is 2min, and the hydrogen flow rate is 30mL /min, the oxygen flow rate of the assisted gas is 400mL/min, the make-up flow is 25mL/min; the detector temperature is 250°C.

Determination of gas chromatography conditions:

Pipette 15 μL of sample into a 20.0 mL headspace vial, and immediately seal it with a PTFE/silicone septum and an aluminum cap; place the sample vial in a headspace sampler for FE HS-GC detection. Figure 1 is a gas chromatogram of a sample of cigar bead extract when the oven temperature is 60°C. It can be seen from Figure 1 that methanol and other volatile substances can be better separated at a lower oven temperature, and the methanol retention time is 0.668min. Therefore, the temperature of the chromatographic column selected in the present invention is 60°C.

Determination of headspace equilibration time:

Pipette 15 μL of sample into a 20.0 mL headspace vial, and immediately seal it with a PTFE/silica gel septum and an aluminum cap; then analyze and detect at different headspace equilibration times to obtain the curve shown in Figure 2. It can be seen from Figure 2 that when the headspace equilibration time is 2 minutes, the signal value of methanol in the headspace bottle tends to be stable. Therefore, the present invention selects the equilibration time as 2 minutes.

Determination of Headspace Equilibrium Temperature:

Pipette 15 μL of the sample into a 20.0 mL headspace vial and immediately seal it with a PTFE/silicone septum and an aluminum cap. Then analyze and detect at different headspace equilibrium temperatures, and obtain the curve shown in Fig. 3 . It can be seen from Figure 3 that when the temperature is lower than 105°C, the signal value of methanol increases with the increase of temperature. It can be seen that appropriately increasing the equilibrium temperature can improve the detection sensitivity; if the temperature continues to rise, the signal value of methanol decreases, the reason is that the temperature is too high. High, the high pressure generated by water vapor will reduce the concentration of methanol per unit volume; in addition, if the temperature is too high, air leakage is prone to occur during headspace sampling. Considering the detection sensitivity and safety, the present invention selects the equilibrium temperature as 105°C.

Determination of injection volume:

Use a pipette gun to pipette samples of different volumes (5-100 μL) into 20.0 mL headspace vials, and immediately seal them with PTFE/silica gel septum and aluminum cap; display curve. It can be seen from Figure 4 that the linear variation range between the GC signal of methanol and the sample volume is 0-40 μL. Therefore, the maximum injection volume of the present invention to determine the residual methanol in the popcorn essential oil for cigarettes is 40 μL.

Calibration of assay methods and determination of quantitation limits:

In this method, a simple external standard method is used for calibration. Pipette 15 μL of the sample into a 20.0 mL headspace vial and immediately seal it with a PTFE/silicone septum and an aluminum cap. Then analyze and detect after equilibrating at 105°C for 2 minutes. According to the obtained data, the standard curve between the methanol GC signal value (A) and the methanol concentration (C) in the headspace vial can be obtained, as shown in formula (1):

A=-157.66(±21.91)+83.99(±0.9197)C(n=7, ^R2 =0.9994) (1)

In the formula: A is the GC signal value (ie peak area) of methanol in the headspace vial, and C is the concentration of methanol in the standard solution (unit: mg/mL).

The limit of quantitation (LOQ) of methanol detection by this method can be calculated by the following formula:

Where: a, s, and Δa are the intercept, slope, and standard deviation of the intercept in formula (1), respectively. From the formula (2), it can be calculated that the quantitative limit of the method for the detection of methanol in the popcorn essential oil for cigarettes is 0.73 mg/mL.

Method reproducibility and accuracy:

The reproducibility evaluation of the method of the present invention is to carry out 3 repeated experiments on 4 different paper samples, and compare the detection results to obtain the relative standard deviation value of the detection results. The reproducibility test results of the method of the present invention are shown in Table 2. It can be seen from Table 2 that the relative standard deviations of the method for different samples of popcorn essential oil for cigarettes are all less than 3.89%. Therefore, it can be considered that the method of the present invention has good reproducibility for detecting residual methanol in the popcorn essential oil for cigarettes.

Table 2

The accuracy evaluation of the method of the present invention is to add 10-80 μL of pure methanol solution to 10mL sample (methanol content in the sample is 1.94mg/mL), respectively, to obtain a spiked sample solution. At the same time, the non-spiked popcorn essential oil sample with a methanol content of 1.94 mg/mL was used as a reference object to detect the net contribution of the added standard, and the results are shown in Table 3. It can be seen from Table 3 that the recovery rate of the method of the present invention for detecting the methanol content in the popcorn essential oil for cigarettes is between 97.8% and 101%, which shows that the method has good accuracy.

table 3

From the above results, it can be seen that the method of the present invention can accurately quantitatively analyze the methanol content in the popcorn essential oil for cigarettes; the detection method is easy to operate and has high precision.

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments. What are described in the above-mentioned embodiments and the description only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention also has Variations and improvements are possible, which fall within the scope of the claimed invention. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (5)

1. A kind of assay method of methanol content in quick-fried pearl essential oil for cigarettes, is characterized in that, comprises the steps:

   ① After ultrasonic treatment, the essential oil for cigarettes is placed in a headspace bottle and sealed;

   ② Place the headspace vial of step ① in the headspace sampler, and measure the signal value of methanol in the headspace vial by full vaporization headspace gas chromatography;

   ③Substitute the methanol signal value obtained in step ② into the standard curve to obtain the methanol content in the essential oil for cigarettes.
2. The method according to claim 1, wherein the conditions of the headspace sampler in step ② are as follows: the initial equilibrium temperature is 105° C., and the equilibrium time is 2 minutes; the vibration condition is set as violent oscillation; the pressurization time of the headspace bottle is 15s, the filling time of the quantitative loop is 10s, and the transfer time to GC is 20s; the maximum injection volume is 40μL.
3. The method according to claim 1, characterized in that, in step 2., gas chromatography operating conditions: hydrogen flame ion detector, carrier gas is nitrogen, and the flow rate is 25mL/min; the combustible gas is hydrogen, and the flow rate is 30mL/min; The gas is oxygen, the flow rate is 400mL/min; the detector temperature is 250°C, the split ratio is 2:1, and the detection time is 2min.
4. The method according to claim 1, wherein the standard curve of step 3. is shown in the following formula: Y=A+BX; wherein, Y is the GC signal value of methanol, i.e. the peak area, and X is the value of the standard solution of methanol The unit of concentration is mg/mL; A and B are constants, A=-157.66, B=83.99.
5. The method according to claim 4, wherein A is -157.66±21.91; B is 83.99±0.9197.

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