CN113588851A - Method for extracting and determining dithiocarbamate, determination device and application thereof - Google Patents

Abstract

The invention belongs to the field of detection and analysis, and in particular relates to a method for extracting dithiocarbamate compounds in a sample. Potassium mixture mixes, and centrifugation separates the supernatant as the extract containing dithiocarbamate compounds; Wherein, the volume ratio of water and hexafluoroisopropanol in the water-hexafluoroisopropanol mixed solution is ( 7～11): 1, the weight ratio of sodium chloride and dipotassium hydrogen phosphate in the sodium chloride-dipotassium hydrogen phosphate mixture is (0.4～1): 1. The invention also relates to a method, device and application for determining the content of various dithiocarbamate compounds in a sample. The method of the invention can accurately measure the content of various dithiocarbamate compounds in the sample, and has good repeatability and high precision.

Description

Method, measuring device and application for extracting and measuring dithiocarbamate

technical field

The invention belongs to the field of detection and analysis, in particular to a method for extracting dithiocarbamate compounds in a sample, and also relates to a method, device and application for determining the content of various dithiocarbamate compounds in a sample .

Background technique

Dithiocarbamate compounds (DTCs) are a class of fungicides that are widely used in the world. They can be used to control more than 400 kinds of pathogens in more than 70 crops. They are the earliest and widely used organic compounds in history. This type of fungicide has low cost and wide application, and is still widely used to control downy mildew, spot and scab caused by algae and deuteromycetes in crops such as fruit trees and vegetables. However, with the widespread application of dithiocarbamate compounds, it has been found that animals and plants that have applied it will produce a metabolite called hexamethylene thiourea (ETU) during the metabolic process, and ETU is carcinogenic, Teratogenic and mutagenic, can affect the function of the thyroid gland for a long time, and is listed in the manual by the US Occupational Safety and Health Administration as a carcinogen. In addition, dithiocarbamate compounds are moderately irritating to mammalian skin and respiratory organs, manifesting as itching, sore throat and trachea inflammation.

At present, there are many methods for analyzing the residues of dithiocarbamate pesticides in the world, including spectrophotometry, gas chromatography and liquid chromatography. The -CS ₂ functional group in the pesticide-like residues is reduced to carbon disulfide, and then the carbon disulfide content is detected by an instrument to obtain the content of the dithiocarbamate-like pesticide residues. However, dithiocarbamates are a class of compounds that include dimethyl dithiocarbamates (DMDCs, such as sodium carbamazepine, carbamazepine, carbamazepine, carbamazepine), ethylene dithiocarbamate Esters (EBDCs, such as sodium, mancozeb, mancozeb, mancozeb) and propylene dithiocarbamates (PBDCs, such as sodium prosen, mancozeb), etc., the general disulfide The toxicity of dithiocarbamate compounds is not large, but the toxicity of dithiocarbamate compounds containing heavy metal ions is significantly enhanced. It can be seen that different types of dithiocarbamate compounds have different toxicity, but the existing methods cannot distinguish them. The content of various dithiocarbamate compounds is detected, so the residual amount of the more toxic dithiocarbamate compounds cannot be accurately known.

Therefore, there is an urgent need for a method that can separately determine the content of various dithiocarbamate compounds in a sample.

SUMMARY OF THE INVENTION

One of the objects of the present invention is to provide a method for extracting dithiocarbamate compounds in a sample, which removes the interference of impurities through specific steps and has a high extraction rate for dithiocarbamate compounds; another aspect of the present invention The purpose is to provide a device for measuring the content of various dithiocarbamate compounds in a sample; another purpose of the present invention is to provide a method for measuring the content of various dithiocarbamate compounds in a sample by using the aforementioned device , the method can accurately determine the content of various dithiocarbamate compounds in the sample, with good repeatability and high precision.

To achieve the above object, a first aspect of the present invention relates to a method for extracting dithiocarbamate compounds in a sample, comprising the following steps:

Use water-hexafluoroisopropanol mixture to impregnate the sample, add sodium chloride-dipotassium hydrogen phosphate mixture to mix, centrifuge, and separate the supernatant as an extract containing dithiocarbamate compounds; - The volume ratio of water and hexafluoroisopropanol in the hexafluoroisopropanol mixture is (7~11):1 (eg 8:1, 9:1, 10:1), sodium chloride-dipotassium hydrogen phosphate The weight ratio of sodium chloride and dipotassium hydrogen phosphate in the mixture is (0.4~1):1 (for example, 0.5:1, 0.6:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1 ).

In some embodiments of the first aspect of the present invention, the sample is tobacco raw material and/or tobacco product, preferably tobacco raw material; more preferably, the sample is selected from flue-cured tobacco, burley tobacco and oriental tobacco.

In some embodiments of the first aspect of the invention, the dipping and/or mixing is performed under vortexing conditions.

In some embodiments of the first aspect of the present invention, 2-10 mL of water-hexafluoroisopropanol mixture is used per gram of sample, such as 3 mL, 4 mL, 5 mL, 6 mL, 7 mL, 8 mL, 9 mL.

In some embodiments of the first aspect of the present invention, 1-8g of sodium chloride-dipotassium hydrogen phosphate mixture is used per gram of sample, such as 2g, 3g, 4g, 5g, 6g, 7g.

In some embodiments of the first aspect of the invention, the immersion is performed for 3 to 20 minutes, eg, 5, 7, 8, 10, 12, 15, 17, 19 minutes.

In some embodiments of the first aspect of the invention, mixing is performed for 1 to 10 minutes, eg, 2, 3, 4, 5, 6, 7, 8, 9 minutes.

In some embodiments of the first aspect of the present invention, centrifugation is performed at a rotational speed of 6000-16000 rpm, for example, the rotational speed is 8000 rpm, 10000 rpm, 12000 rpm, and 15000 rpm.

In some embodiments of the first aspect of the present invention, the centrifugation is performed for 2 to 10 minutes, such as 3 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes.

In some embodiments of the first aspect of the invention, the sample is submerged when the sample is dipped.

The second aspect of the present invention relates to a device for determining the content of various dithiocarbamate compounds in a sample, comprising a liquid chromatography, a microreactor, a gas-liquid separator and an inductively coupled plasma mass spectrometer connected in series; wherein,

The liquid chromatography is provided with a sample inlet and a sample outlet;

The microreactor includes a reducing agent storage tank, a reaction coil and a mixing coil; wherein, one end of the reaction coil is provided with a reducing agent inlet and a sample inlet, the other end is provided with a reaction product outlet, and the reducing agent inlet is connected with the reducing agent storage tank. , the sample inlet is connected with the sample outlet of the liquid chromatography; one end of the mixing coil is provided with a material liquid inlet and an inert gas inlet, and the other end is provided with a material outlet, and the material liquid inlet of the mixing coil is connected with the reaction product outlet of the reaction coil. ;

The gas-liquid separator includes a fat belly-shaped pipe with open upper and lower ends, the lower end is used as a waste liquid outlet, and the upper end is used as an air outlet. The injection port set on the plasma mass spectrometer is connected.

In some embodiments of the second aspect of the present invention, the microreactor further includes a peristaltic pump, and the reducing agent inlet of the reaction coil is connected to the reducing agent storage tank through the peristaltic pump.

In some embodiments of the second aspect of the present invention, the peristaltic pump has a double-flow channel structure, the reducing agent inlet of the reaction coil is connected to the reducing agent storage tank through a flow channel of the peristaltic pump, and the waste liquid outlet of the gas-liquid separator passes through the peristaltic pump. The other flow channel discharges the waste liquid.

In some embodiments of the second aspect of the present invention, the number of turns of the reaction coil is 1.5-5 times, preferably 2-3 times, the number of turns of the hybrid coil.

In some embodiments of the second aspect of the present invention, the reaction coil has 26 to 60 turns, preferably 30 to 50 turns.

In some embodiments of the second aspect of the present invention, the hybrid coil has 8 to 22 turns, preferably 10 to 20 turns.

In some embodiments of the second aspect of the present invention, threads are distributed on the inner wall of the reaction coil and/or the mixing coil.

In some embodiments of the second aspect of the present invention, the inner diameter of the pipeline of the mixing coil is 1-2 times, eg, 1.4 times, the inner diameter of the pipeline of the reaction coil.

In some embodiments of the second aspect of the present invention, the inner diameter of the pipeline of the reaction coil is the same as the inner diameter of the reducing agent inlet.

In some embodiments of the second aspect of the present invention, the inner diameter of the reducing agent inlet is 1.5-5 mm, preferably 2-4 mm, such as 2.5 mm.

In some embodiments of the second aspect of the present invention, the inner diameter of the waste liquid outlet is equal to the inner diameter of the reducing agent inlet.

A third aspect of the present invention relates to a method for determining the content of various dithiocarbamate compounds in a sample, comprising the steps of:

According to the method described in the first aspect of the present invention, an extract containing dithiocarbamate compounds is obtained;

Use the device described in the second aspect of the present invention to measure the extract to obtain a liquid chromatogram and a mass spectrum;

According to the ion peaks of mass 75.8-77.3 in the liquid chromatogram and mass spectrum, the content of carbon disulfide generated by various dithiocarbamate compounds in the extract was calculated, and then the various dithiocarbamate compounds in the sample were calculated. Content of acid ester compound;

Wherein, in the device,

The operating conditions of the liquid chromatography include: the chromatographic column is an FTFF chromatographic column; the column temperature is 3°C to 10°C (preferably 5°C to 8°C); the mobile phase is acetic acid with a concentration of 400 to 500mmol/L (for example, 450mmol/L). An ammonium aqueous solution, the ammonium acetate aqueous solution contains 0.01-0.07 mol/L sodium hydroxide (for example, 0.05 mol/L);

The operating conditions of the inductively coupled plasma mass spectrometer include: the detection mode of full scan integration; the plasma gas flow rate is 14-18L/min (for example, 16L/min); the auxiliary gas flow rate is 0.5-3L/min (for example, 1L/min); The sample lift rate is 0.5-1 mL/min (eg, 0.8 mL/min).

In some embodiments of the third aspect of the present invention, the types of dithiocarbamate compounds are qualitatively determined according to the retention times of different chromatographic peaks in the liquid chromatogram, and then quantitatively calculated in combination with the ion peaks with masses of 75.8 to 77.3 in the mass spectrum. The content of carbon disulfide produced by each dithiocarbamate compound in the extract.

In some embodiments of the third aspect of the present invention, the content of carbon disulfide generated by each dithiocarbamate compound in the extract is quantitatively calculated by the external standard method according to the ion peaks with mass numbers of 75.8 to 77.3 in the mass spectrum; preferably , the external standard is carbon disulfide.

In some embodiments of the third aspect of the present invention, the flow rate of the mobile phase of the liquid chromatography is 0.1-0.3 mL/min, preferably 0.2-0.25 mL/min.

In some embodiments of the third aspect of the present invention, the injection volume of the liquid chromatography is 10 μL.

In some embodiments of the third aspect of the present invention, the sample output flow rate of the liquid chromatography is equal to the mobile phase flow rate.

In some embodiments of the third aspect of the present invention, the forward power of the inductively coupled plasma mass spectrometer is 1100-1300W, for example, 1200W;

In some embodiments of the third aspect of the present invention, the sampling depth of the inductively coupled plasma mass spectrometer is 6-7 mm, for example, 6.5 mm.

In some embodiments of the third aspect of the present invention, the aperture of the sampling cone of the inductively coupled plasma mass spectrometer is 0.7-1.4 mm, for example, 1.0 mm.

In some embodiments of the third aspect of the present invention, the aperture of the scrambling cone of the inductively coupled plasma mass spectrometer is 0.5-1 mm, for example, 0.8 mm.

In some embodiments of the third aspect of the present invention, the data acquisition mode of the inductively coupled plasma mass spectrometry is a peak-hopping mode.

In some embodiments of the third aspect of the present invention, the dwell time of the inductively coupled plasma mass spectrometer is 20-40 ms, for example, 30 ms.

In some embodiments of the third aspect of the present invention, the number of acquisition points per unit mass of the inductively coupled plasma mass spectrometer is three.

In some implementations of the third aspect of the present invention, the data acquisition repetition times of the inductively coupled plasma mass spectrometry are three times.

In some embodiments of the third aspect of the present invention, the integration time of the inductively coupled plasma mass spectrometer is 0.100s.

In some embodiments of the third aspect of the present invention, in the device, the temperature of the pipeline of the reaction coil is 35°C to 50°C, preferably 40°C to 45°C.

In some embodiments of the third aspect of the present invention, in the device, the temperature of the pipeline of the mixing coil is 60°C to 75°C, preferably 65°C to 70°C.

In some embodiments of the third aspect of the present invention, in the device, the gas-liquid separator is maintained at 20°C to 40°C.

In some embodiments of the third aspect of the present invention, in the device, the flow rates of the reducing agent inlet and the waste liquid outlet are equal.

In some embodiments of the third aspect of the present invention, in the device, the reducing agent in the reducing agent storage tank is an acidic stannous chloride aqueous solution, preferably an acidic stannous chloride aqueous solution of 8-10 mol/L; more preferably , the pH value of the acidic stannous chloride aqueous solution is 6.6 to 6.8.

In some embodiments of the third aspect of the present invention, in the device, the flow rate of the reducing agent inlet is 9-10 mL/min, preferably 9.75-9.8 mL/min.

In some embodiments of the third aspect of the present invention, in the device, the flow rates of the sample inlet of the reaction coil and the sample outlet of the liquid chromatography are equal.

In some embodiments of the third aspect of the present invention, in the device, the flow rate of the inert gas inlet is 9.2-11 mL/min, preferably 9.9-10.1 mL/min.

In some embodiments of the third aspect of the present invention, the inert gas is a nitrogen-helium gas mixture. Preferably, the volume ratio of nitrogen and helium in the mixed gas is 1:(5-10), for example, 1:8.

In some embodiments of the third aspect of the present invention, the analysis mode of inductively coupled plasma mass spectrometry is quantitative analysis.

A fourth aspect of the present invention relates to a method for determining the content of toxic dithiocarbamate compounds in a sample, comprising the steps of:

Determine the content of various dithiocarbamate compounds in the sample according to the method described in the third aspect of the present invention;

The contents of toxic dithiocarbamate compounds were summed.

In some embodiments of the fourth aspect of the present invention, the sample is tobacco raw material and/or tobacco product, preferably tobacco raw material, more preferably selected from flue-cured tobacco, burley tobacco and oriental tobacco.

The fifth aspect of the present invention relates to the application of the device according to the second aspect of the present invention in determining the content of various dithiocarbamate compounds in a sample.

In some embodiments of the fifth aspect of the present invention, the sample is tobacco raw material and/or tobacco product, preferably tobacco raw material, more preferably selected from flue-cured tobacco, burley tobacco and oriental tobacco.

In some embodiments of the present invention, the dithiocarbamate compounds are selected from the group consisting of Mancozeb, Mancozeb, Mancozeb, Mancozeb, Mancozeb, Mancozeb, Mancoride, Femex, Mancozeb, One or more of Prosenzinc, Famex, and Famex.

The beneficial effects obtained by the present invention:

1. The method of the present invention for extracting dithiocarbamate compounds in a sample can remove the interference of impurities and improve the extraction rate of dithiocarbamate compounds.

2. The method and device for determining the content of various dithiocarbamate compounds in the sample of the present invention can accurately measure the content of various dithiocarbamate compounds in the sample, with good repeatability and high precision.

Description of drawings

In order to make the content of the present invention easier to be understood clearly, the present invention will be described in further detail below according to specific embodiments of the present invention and in conjunction with the accompanying drawings, wherein:

Fig. 1 is a schematic diagram of an embodiment of the device for measuring the content of various dithiocarbamate compounds in a sample according to the present invention;

Fig. 2 is the liquid chromatogram of test sample in embodiment 2;

Among them: A is liquid chromatography, B is microreactor, C is gas-liquid separator, D is inductively coupled plasma mass spectrometry, 1 is reducing agent storage tank, 2 is peristaltic pump, 3 is reaction coil, 4 is mixing coil, 5 is the reducing agent inlet, 6 is the sample inlet, 7 is the reaction product outlet, 8 is the feed liquid inlet, 9 is the inert gas inlet, 10 is the material outlet, 11 is the fat part, 12 is the waste liquid outlet, and 13 is the outlet. Air port, 14 is the feed port.

Detailed ways

The embodiments of the present invention will be clearly and completely described below with reference to the examples. Obviously, the described examples are only a part of the examples of the present invention, but not all of the examples. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Fig. 1 is a schematic diagram of an embodiment of the device for measuring the content of various dithiocarbamate compounds in a sample according to the present invention;

The device includes a liquid chromatograph A, a microreactor B, a gas-liquid separator C, and an inductively coupled plasma mass spectrometer D that are connected in series. The liquid chromatograph A and the microreactor B can be placed horizontally, and the gas-liquid separator C can be placed vertically. ;in,

The liquid chromatography A is provided with a sample inlet and a sample outlet;

The microreactor B includes a reducing agent storage tank 1, a peristaltic pump 2, a reaction coil 3 and a mixing coil 4; one end of the reaction coil 3 is provided with a reducing agent inlet 5 and a sample inlet 6 in parallel, and the other end is provided with a reaction product outlet 7. , the reducing agent inlet 5 is connected with the reducing agent storage tank 1 through the peristaltic pump 2, and the sample inlet 6 is connected with the sample outlet of the liquid chromatography A; one end of the mixing coil 4 is provided with a material liquid inlet 8 and an inert gas inlet 9, The other end is provided with a material outlet 10, and the material liquid inlet 8 of the mixing coil 4 is connected with the reaction product outlet 7 of the reaction coil 3;

The gas-liquid separator C includes a fat belly-shaped pipe with open upper and lower ends, the lower end is used as a waste liquid outlet 12, the upper end is used as an air outlet 13, and the fat belly part 11 is provided with a feed port 14 and is connected with the discharge port 10 of the mixing coil. , the air outlet 13 is connected with the sample inlet of the inductively coupled plasma mass spectrometer D; the peristaltic pump 2 is a dual flow channel device, and the waste liquid outlet 12 is connected with another flow channel of the peristaltic pump 2 through a hose with the same diameter as the waste liquid outlet 12, Control the flow rate of the waste liquid outlet 12 and the reducing agent inlet 5 to be the same by the peristaltic pump 2;

In this embodiment, the reaction coil is 30 to 50 turns;

In this embodiment, the hybrid coil is 10 to 20 turns;

In this embodiment, threads are distributed on the inner walls of the reaction coil and the mixing coil;

In this embodiment, the inner diameter of the pipeline of the mixing coil is 1.4 times the inner diameter of the pipeline of the reaction coil;

In this embodiment, the inner diameter of the pipeline of the reaction coil is the same as the inner diameter of the reducing agent inlet;

In this embodiment, the inner diameter of the reducing agent inlet is 2.5 mm;

In this embodiment, the inner diameter of the waste liquid outlet is equal to the inner diameter of the reducing agent inlet.

The present invention also relates to a system for determining the content of various dithiocarbamate compounds in a sample, including dipping equipment, mixing equipment, sedimentation separation equipment and the device shown in Figure 1; wherein,

The dipping device is provided with a feeding port and a discharging port, and the feeding port is used for adding a sample and a water-hexafluoroisopropanol mixed solution;

The mixing equipment is provided with a feed port, an auxiliary agent inlet and a material discharge port, the feed port of the mixing equipment is connected with the discharge port of the impregnation equipment, and the auxiliary agent inlet is used for adding sodium chloride-dipotassium hydrogen phosphate mixture;

The settling separator is provided with a feed port, which is connected with the discharge port of the mixing device. The upper part of the settling separator is provided with a supernatant liquid outlet, which is connected to the liquid chromatograph in the device. connected to the injection port;

In this embodiment, the system further includes a vortex shaker, and the dipping equipment and the mixing equipment are located in the vortex shaker.

Example 1

(1) Weigh 2g of flue-cured tobacco sample in 50mL centrifuge tube, add 10mL water-hexafluoroisopropanol mixture (volume ratio is 10:1), vortex for 8min, then add 4g sodium chloride-dipotassium hydrogen phosphate Mix the powder (weight ratio 0.75:1), vortex for 2 min, centrifuge at 10,000 rpm for 5 min, and take the supernatant as the sample to be tested.

(2) adopt the device shown in Figure 1 to detect the sample to be tested, and the operating conditions of the device are as follows:

①Operating conditions of liquid chromatography A: the chromatographic column is an FTFF column (specification is 4.6mm*150mm); the column temperature is 5～8℃; the mobile phase is 450mmol/L ammonium acetate aqueous solution (containing 0.05mol/L sodium hydroxide) ; The flow rate of the mobile phase is 0.2-0.25mL/min; the injection volume is 10μL; the sample flow rate of liquid chromatography A is equal to the flow rate of the mobile phase;

②The operating conditions of the microreactor B: the reducing agent is 8-10mol/L acidic stannous chloride aqueous solution (pH value is 6.6-6.8); the flow rate (double channel) of the peristaltic pump 2 is 9.8-9.75mL/min; the reaction coil The pipeline of 3 is kept at 40-45°C; the flow rate of the sample inlet 6 of the reaction coil 3 is equal to the sample flow rate of the liquid chromatography A; the pipeline of the mixing coil 4 is kept at 65-70°C; the inert gas is nitrogen-helium Mixed gas (volume ratio 1:8); the flow rate of the inert gas inlet 9 is 9.9 to 10.1 mL/min;

③Operating conditions of the gas-liquid separator C: the gas-liquid separator C is placed under the constant temperature of 20-40°C (accuracy 2°C);

④Operating parameters of inductively coupled plasma mass spectrometry D:

Table 1 Operating parameters of inductively coupled plasma mass spectrometry

According to the retention time of different chromatographic peaks in the chromatogram, the types of dithiocarbamate compounds in the sample to be tested were qualitatively identified, and the mass 75.8-77.3 ion peaks in the mass spectrum corresponding to each dithiocarbamate compound were obtained. the peak area.

(3) Calculation and results

Preparation of carbon disulfide series standard solution: dilute carbon disulfide standard with isooctane to obtain carbon disulfide stock solution with a concentration of 10 μg/mL; accurately pipette 0.05mL, 0.1mL, 0.2mL, 0.5mL, 1mL, 2mL, 5mL of carbon disulfide reserve solution respectively The solution was transferred to a different 25mL volumetric flask, and the volume was adjusted with isooctane to obtain a series of standard solutions of carbon disulfide. The concentration range of the carbon disulfide series standard solutions should cover the expected detected levels.

The inductively coupled plasma mass spectrometry in item (2) was used to detect the carbon disulfide series standard solution, and the operating parameters were as ④ in item (2), and the standard was prepared according to the concentration of carbon disulfide and the peak area of the ion peak with a mass number of 75.8 to 77.3 in the mass spectrum. Working curve.

Substitute the peak areas of the ion peaks with mass numbers from 75.8 to 77.3 in the mass spectrum corresponding to each dithiocarbamate compound in the sample to be tested into the standard working curve and calculate to obtain each dithiocarbamate in the sample to be tested. The content of carbon disulfide generated by the compound, and then the content of dithiocarbamate compounds in the flue-cured tobacco sample was calculated according to the following formula.

formula:

X represents the content of dithiocarbamate compounds in the tobacco sample, in mg/kg;

c represents the content of carbon disulfide generated by each dithiocarbamate compound in the sample to be tested, in μg/mL;

V represents the volume of the sample to be tested, in mL;

s represents the conversion factor of carbon disulfide and each dithiocarbamate compound, as shown in Table 2;

m represents the mass of the tobacco sample, in g;

w represents the moisture mass content of the tobacco sample, %W/W.

Table 2 Conversion factors of various dithiocarbamate compounds

The contents of various dithiocarbamate compounds in the flue-cured tobacco samples of this example are shown in Table 3.

Table 3 Contents of various dithiocarbamate compounds in flue-cured tobacco samples

Dithiocarbamate compounds Content (mg/kg) Prosenzinc 0.056 Amtrak 0.063 Mancozeb 0.031

(4) Average spike recovery and precision

To 2g flue-cured tobacco samples, add 50 mg of Prosenzinc standard product, 50 mg of Mancozeb standard product, and 50 mg of Mancozeb standard product to obtain a spiked sample; according to the method in (1)-(3), detect the content of the spiked sample. Various dithiocarbamate compound levels were then calculated for spike recoveries.

The assay was repeated 6 times, and the average spike recovery and RSD were calculated.

The results are shown in Table 4.

Table 4

It can be seen from Table 1 that the detection method of the present invention has a high recovery rate of standard addition, which meets the actual detection requirements, indicating that the method of the present invention has high accuracy; and the detection method of the present invention has good repeatability.

Example 2

(1) Weigh 3.5g burley tobacco sample in 50mL centrifuge tube, add 15mL water-hexafluoroisopropanol mixture (volume ratio is 9:1), vortex for 10min, then add 5g sodium chloride-phosphoric acid Dipotassium hydrogen mixed powder (weight ratio 0.8:1) was vortexed for 3 min, centrifuged at 10000 rpm for 7.5 min, and the supernatant was taken as the sample to be tested.

(2) use a detection device to detect the sample to be tested, the structure of the detection device and each operating condition are the same as item (2) in Example 1; the chromatogram of the sample to be tested in this embodiment is shown in Figure 2, each chromatographic peak Desen sodium, propsenzinc and deseniron are represented in turn from left to right.

(3) Calculation and results

The calculation method is the same as item (3) in Example 1. The calculated contents of various dithiocarbamate compounds in the Burley tobacco samples are shown in Table 5.

Table 5 Contents of various dithiocarbamate compounds in Burley tobacco samples

Dithiocarbamate compounds Content (mg/kg) Prosenzinc 0.124 Desentie 0.239 Dyson sodium 0.096

(4) Average spike recovery and precision

Add 10 mg of Prosenzinc standard product, 10 mg of Dyseniron standard product, and 10 mg of Dysenic sodium standard product to 3.5g of Burley tobacco samples to obtain a spiked sample; detect according to items (1)-(3) in Example 1 The contents of various dithiocarbamate compounds in the spiked samples were then calculated for spike recoveries.

The above assay was repeated 6 times, and the average spiked recovery and RSD were calculated.

The results are shown in Table 6.

Table 6

It can be seen from Table 6 that the detection method of the present invention has a high recovery rate of standard addition, which meets the actual detection requirements, indicating that the accuracy of the method of the present invention is high; and the detection repeatability of the method of the present invention is good.

Example 3

(1) Weigh 5g oriental tobacco sample in a 50mL centrifuge tube, add 20mL water-hexafluoroisopropanol mixture with a volume ratio of 10:1, vortex for 10min, then add 6g sodium chloride-dipotassium hydrogen phosphate Mix the powder (weight ratio 0.85:1), vortex for 4 min, centrifuge at 10000 rpm for 9 min, and take the supernatant as the sample to be tested.

(2) A detection device is used to detect the sample to be tested, and the structure and operation conditions of the detection device are the same as those of item (2) in Example 1.

(3) Calculation and results

The calculation method is the same as item (3) in Example 1. The contents of various dithiocarbamate compounds in the oriental tobacco samples were calculated as shown in Table 7.

Table 7 Contents of various dithiocarbamate compounds in oriental tobacco samples

Dithiocarbamate compounds Content (mg/kg) Fumei Zinc 0.387 Dyson Magnesium 0.166 Prosenzinc 0.028

(4) Average spike recovery and precision

To 5g oriental tobacco sample, add 25mg of standard product of fumei zinc, 25mg of standard product of magnesium d'ysen, and 25mg of standard product of zinc of prosen, to obtain a standard sample; according to (1)-(3) in Example 1, detect the standard product of standard product The content of various dithiocarbamate compounds in the sample was calculated, and then the spike recovery was calculated.

The above assay was repeated 6 times, and the average spiked recovery and RSD were calculated.

The results are shown in Table 8.

Table 8

It can be seen from Table 8 that the detection method of the present invention has a high recovery rate of standard addition, which meets the actual detection requirements, indicating that the method of the present invention has high accuracy; and the detection method of the present invention has good repeatability.

Comparative ratio

Substitute the water-hexafluoroisopropanol mixed solution in Example 1 with an equal volume of water-methanol mixed solution (volume ratio 10:1), the rest are the same as in Example 1, and, according to (4) in Example 1 A standard addition recovery experiment was carried out (the amount of addition was the same as that in Example 1), and the obtained average standard addition recovery rate was shown in Table 9.

Substitute the water-hexafluoroisopropanol mixed solution in Example 1 with an equal volume of water-ethanol mixed solution (volume ratio 10:1), and the rest are the same as in Example 1, and, according to Section (4) in Example 1 A standard addition recovery experiment was carried out (the amount of addition was the same as that in Example 1), and the obtained average standard addition recovery rate was shown in Table 9.

Table 9 Average spike recovery results

Combining with Table 4 and Table 9, it can be known that compared with the method of the comparative example, the method of the present invention has higher recovery rate and higher accuracy.

Obviously, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation manner. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. And the obvious changes or changes derived from this are still within the protection scope of the present invention.

Claims (10)

1. A method for extracting dithiocarbamate compounds from a sample, comprising the steps of:

dipping a sample by adopting a water-hexafluoroisopropanol mixed solution, adding a sodium chloride-dipotassium hydrogen phosphate mixture for mixing, carrying out centrifugal treatment, and separating out supernate to be used as an extracting solution containing the dithiocarbamate compound; wherein the volume ratio of water to hexafluoroisopropanol in the water-hexafluoroisopropanol mixed solution is (7-11): 1, and the weight ratio of sodium chloride to dipotassium hydrogen phosphate in the sodium chloride-dipotassium hydrogen phosphate mixture is (0.4-1): 1.

2. The method of claim 1, characterized by one or more of the following:

A. the sample is a tobacco raw material and/or a tobacco product, preferably a tobacco raw material; more preferably, the sample is selected from flue-cured tobacco, burley tobacco and flavoured tobacco;

B. dipping and/or mixing under vortex shaking conditions;

C. 2-10 mL of water-hexafluoroisopropanol mixed solution is adopted for each gram of sample;

D. 1-8 g of a sodium chloride-dipotassium hydrogen phosphate mixture is adopted for each gram of sample;

E. dipping for 3-20 minutes;

F. mixing for 1-10 minutes;

G. centrifuging at the rotating speed of 6000-16000 rpm;

H. and (4) centrifuging for 2-10 minutes.

3. A device for measuring the content of various dithiocarbamate compounds in a sample comprises a liquid chromatogram, a micro-reactor, a gas-liquid separator and an inductively coupled plasma mass spectrum which are connected in series in sequence; wherein,

the liquid chromatogram is provided with a sample inlet and a sample outlet;

the micro-reactor comprises a reducing agent storage tank, a reaction coil and a mixing coil; wherein, one end of the reaction coil is provided with a reducing agent inlet and a sample inlet, and the other end is provided with a reaction product outlet, the reducing agent inlet is connected with a reducing agent storage tank, and the sample inlet is connected with a sample outlet of the liquid chromatogram; one end of the mixing coil is provided with a feed liquid inlet and an inert gas inlet, and the other end of the mixing coil is provided with a discharge hole;

the gas-liquid separator comprises a fat belly type pipe with an open upper end and an open lower end, the lower end is used as a waste liquid outlet, the upper end is used as a gas outlet, the fat belly part is provided with a feed inlet which is connected with a discharge port of the mixing coil, and the gas outlet is connected with a sample inlet arranged on the inductively coupled plasma mass spectrometer.

4. The apparatus of claim 3, wherein the microreactor further comprises a peristaltic pump, and the reducing agent inlet of the reaction coil is connected to a reducing agent storage tank via the peristaltic pump.

5. The device of claim 4, wherein the peristaltic pump is of a double-channel structure, the reducing agent inlet of the reaction coil is connected with the reducing agent storage tank through one channel of the peristaltic pump, and the waste liquid outlet of the gas-liquid separator discharges waste liquid through the other channel of the peristaltic pump.

6. The device according to any one of claims 3 to 5, characterized by one or more of the following:

a. the number of the reaction coils is 26-60;

b. the number of the mixed coils is 8-22;

c. the inner wall of the reaction coil and/or the mixed coil is distributed with a thread;

d. the inner diameter of the pipeline of the mixing coil is 1-2 times of the inner diameter of the pipeline of the reaction coil;

e. the inner diameter of the pipeline of the reaction coil is the same as that of the reducing agent inlet;

f. the inner diameter of the reducing agent inlet is 1.5-5 mm.

7. A method for determining the amount of each dithiocarbamate compound in a sample, comprising the steps of:

obtaining an extract containing a dithiocarbamate compound according to the method of claim 1 or 2;

measuring the extract using the device of any one of claims 3 to 6, resulting in a liquid chromatogram and a mass spectrum;

calculating the content of carbon disulfide generated by various dithiocarbamate compounds in the extracting solution according to the liquid chromatogram and the ion peak with the mass number of 75.8-77.3 in the mass spectrogram, and then calculating the content of various dithiocarbamate compounds in the sample;

wherein, in the device, the first and second electrodes are arranged in a circular arc shape,

the operating conditions of liquid chromatography include: the chromatographic column is an FTFF chromatographic column; the column temperature is 3-10 ℃; the mobile phase is an ammonium acetate aqueous solution with the concentration of 400-500 mmol/L, and the ammonium acetate aqueous solution contains 0.01-0.07 mol/L sodium hydroxide;

the operating conditions of the inductively coupled plasma mass spectrometer include: a detection mode of full scanning integration is adopted; the flow rate of plasma gas is 14-18L/min; the auxiliary gas flow is 0.5-3L/min; the sample lifting rate is 0.5-1 mL/min.

8. The method of claim 7, characterized by one or more of the following:

1) the flow rate of a mobile phase of the liquid chromatogram is 0.1-0.3 mL/min;

2) the sample size of the liquid chromatogram is 10 mu L;

3) the sample flow rate of the liquid chromatogram is equal to the flow rate of the mobile phase;

4) the forward power of the inductively coupled plasma mass spectrum is 1100-1300W;

5) the sampling depth of the inductively coupled plasma mass spectrum is 6-7 mm;

6) the aperture of a sampling cone of the inductively coupled plasma mass spectrum is 0.7-1.4 mm;

7) the aperture of an intercepting cone of the inductively coupled plasma mass spectrum is 0.5-1 mm;

8) the data acquisition mode of the inductively coupled plasma mass spectrometry is a peak jump mode;

9) the residence time of the inductively coupled plasma mass spectrum is 20-40 ms;

10) in the device, the temperature of a pipeline of the reaction coil is 35-50 ℃;

11) in the device, the temperature of the pipeline of the mixing coil is 60-75 ℃;

12) in the device, the gas-liquid separator is kept at 20-40 ℃;

13) in the device, the flow rates of a reducing agent inlet and a waste liquid outlet are equal;

14) in the device, a reducing agent in a reducing agent storage tank is an acidic stannous chloride aqueous solution, and is preferably an acidic stannous chloride aqueous solution of 8-10 mol/L;

15) in the device, the flow rate of a reducing agent inlet is 9-10 mL/min;

16) in the device, the flow rate of a sample inlet of a reaction coil is equal to that of a sample outlet of the liquid chromatogram;

17) in the device, the flow rate of an inert gas inlet is 9.2-11 mL/min;

18) the inert gas is a nitrogen-helium gas mixture, and preferably, the volume ratio of nitrogen to helium in the gas mixture is 1 (5-10).

9. A method for determining the amount of a toxic dithiocarbamate compound in a sample, comprising the steps of:

determining the amount of each dithiocarbamate compound in the sample according to the method of claim 7 or 8;

summing the contents of toxic dithiocarbamate compounds;

preferably, the sample is a tobacco material and/or a tobacco product, more preferably a tobacco material, further preferably selected from the group consisting of flue-cured tobacco, burley tobacco and flavoured tobacco.

10. Use of the device of any one of claims 3 to 6 for determining the content of various dithiocarbamate compounds in a sample;

preferably, the sample is a tobacco material and/or a tobacco product, more preferably a tobacco material, further preferably selected from the group consisting of flue-cured tobacco, burley tobacco and flavoured tobacco.

Images