CN114428074A - Detection system and detection method for water-soluble cyanide precursor in tobacco - Google Patents

Abstract

The invention provides a detection system and a detection method for a water-soluble cyanide precursor in tobacco, wherein the detection system for the water-soluble cyanide precursor in tobacco comprises a pretreatment module, a cyanide generation module, a separation module and a detection module which are sequentially connected; the pretreatment module comprises a reaction unit, and the reaction unit comprises a heating device. The invention provides a detection system for water-soluble cyanide precursors in tobacco for the first time, based on the detection system, the detection of the water-soluble cyanide precursors in the tobacco is successfully realized, the operation is simple, the detection result is accurate and stable, a new strategy is provided for evaluating the release amount of cyanide in cigarette smoke, and the detection system has important significance for controlling the quality of tobacco products.

Description

Detection system and detection method for water-soluble cyanide precursor in tobacco

Technical Field

The invention belongs to the technical field of tobacco product detection, and relates to a detection system and a detection method for a water-soluble cyanide precursor in tobacco.

Background

The content of cyanide in the flue gas is one of 7 indexes of the flue gas hazard index, and is an important index for evaluating the flue gas hazard. The content of cyanide in the smoke is influenced by the contents of more than ten chemical components such as protein, proline, asparagine, organic acid ammonium, nitrate and the like in the tobacco besides the influence of tobacco materials (mainly the influence of filter tip punching dilution rate and cigarette paper air permeability).

Controlling the focus and reducing the harm are always one of the key points of the tobacco industry. By designing a reasonable tobacco leaf formulation and adopting tobacco leaf modulation and processing technologies to improve the quality of tobacco leaves, the selective reduction of the cyanide release amount of cigarette smoke can be realized. In the research process, the content of more than ten kinds of smoke cyanide precursor components in the tobacco shreds is measured, and the method has important help for understanding and analyzing the cyanide content which can be released by the combustion of the tobacco shreds under different types and different grades of tobacco leaves, different tobacco leaf modulation and processing parameters and different tobacco leaf group formulas, can understand the influence of different raw materials or processes on the final quality of a product before the finished product cigarette is finished and the smoke is detected, and provides support data for developing precise product design and process adjustment. However, the method for determining the release amount of cyanide after combustion of the cut tobacco by measuring the content of the precursor in the cut tobacco greatly increases the detection workload and delays the research progress. Therefore, researchers adopt a cracking chromatography simulation detection method to estimate the content of cyanide in flue gas possibly generated by combustion of tobacco shreds, so that tens of detections are reduced to 1 detection, and the estimation in advance has practical operability. However, the method not only needs to adopt Py-GC/MS for detection, but also has many limitations in the aspects of operation complexity, detection repeatability, detection efficiency and the like, and has extremely high requirements on the operation of a human.

Therefore, a simple and feasible new strategy is developed to detect the content of the cyanide precursor in the tobacco product, and the method has important significance for controlling the quality of the tobacco product.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a detection system and a detection method for a water-soluble cyanide precursor in tobacco.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the invention provides a detection system for a water-soluble cyanide precursor in tobacco, which comprises a pretreatment module, a cyanide generation module, a separation module and a detection module which are sequentially connected; the pretreatment module comprises a reaction unit, and the reaction unit comprises a heating device.

The invention creatively provides a detection system for water-soluble cyanide precursors in tobacco, based on the detection system, the detection of the water-soluble cyanide precursors in the tobacco is successfully realized, the operation is simple, the detection result is accurate and stable, a new strategy is provided for evaluating the release amount of cyanide in cigarette smoke, and the detection system has important significance for controlling the quality of tobacco products.

Preferably, the pretreatment module comprises a first sample introduction unit, a reaction unit, a separation unit and a pressurization unit, wherein the first sample introduction unit is connected with the reaction unit in series and is connected with the pressurization unit in parallel through the separation unit.

Preferably, the first sample introduction unit comprises a liquid inlet device and a gas inlet device which are connected in sequence.

Preferably, the reaction unit comprises a blending device and a heating device which are connected in sequence.

Preferably, the heating coil in the heating device has 20-100 turns, such as 20 turns, 40 turns, 60 turns, 80 turns, 100 turns, etc., preferably 40-80 turns.

Preferably, the separation unit comprises a bubble separation device.

Preferably, the pressurizing unit comprises an air inlet device, a pressure regulating valve, a switch valve, an air buffer tube, a pressurizing device and a waste discharging device which are connected in sequence.

Preferably, the cyanide generation module comprises a second sample feeding unit, a digestion reaction unit and a distillation reaction unit which are connected in sequence.

Preferably, the second sample introduction unit comprises a re-feeding device, an air inlet device, a liquid inlet device and a blending device which are connected in sequence, and the re-feeding device is connected with the bubble separation device in the pretreatment module.

Preferably, the digestion reaction unit comprises a liquid inlet device, a uniform mixing device and an ultraviolet digestion device which are connected in sequence.

Preferably, the number of the coils in the ultraviolet digestion device is 20-120, such as 20 turns, 40 pounds, 60 turns, 80 turns, 100 turns, 120 turns and the like, and preferably 40-100 turns.

Preferably, the distillation reaction unit comprises a liquid inlet device and a distillation device which are connected in sequence.

Preferably, the number of turns of the coil in the distillation apparatus is 5-40, such as 5, 10, 20, 30 etc., preferably 5-10.

Preferably, the separation module includes a separation reaction unit, a waste unit, and an absorption unit.

Preferably, the waste discharge unit comprises a condensing device and a waste discharge device which are connected in sequence.

Preferably, the absorption unit comprises a condensing device, a liquid inlet device and a bubble discharging device which are connected in sequence.

Preferably, the separation reaction unit comprises a vapor-liquid separation device which is connected with the distillation device in the cyanide generation module, the condensation device in the waste discharge unit and the condensation device in the absorption unit at the same time.

Preferably, the detection module comprises a third sample feeding unit, a color development reaction unit and a detection unit which are connected in sequence.

Preferably, the third sample feeding unit comprises a re-feeding device, an air inlet device, a liquid inlet device and a blending device which are connected in sequence, and the re-feeding device is connected with a bubble discharge device in the separation module.

Preferably, the color reaction unit comprises a liquid inlet device, a blending device and a heating device.

Preferably, the coil in the heating device has 10-80 turns, such as 10 turns, 20 turns, 40 turns, 60 turns, 80 turns, etc., preferably 20-40 turns.

Preferably, the detection unit comprises a cuvette and a waste.

In a second aspect, the present invention provides a method for detecting a water-soluble cyanide precursor in tobacco, the method including the step of detecting the water-soluble cyanide precursor in tobacco by using the detection system of the first aspect, the method including the steps of:

(1) pretreatment: injecting the tobacco sample solution to be detected into a pretreatment module for heating treatment to obtain a pretreatment solution;

(2) cyanide formation: the pretreatment solution enters a cyanide generation module to react to obtain cyanide generation solution;

(3) separation: separating the cyanide generated liquid by a separation module to obtain cyanide ion solution;

(4) and (3) detection: and detecting the content of cyanide ions in the cyanide ion solution in a detection module to obtain the content of water-soluble cyanide precursors in the tobacco.

The invention creatively provides a method for detecting the water-soluble cyanide precursor in the tobacco, which has the advantages of simple operation, high stability, high precision and high accuracy, provides a new strategy for evaluating the cyanide release amount of the cigarette smoke, and has important significance for controlling the quality of tobacco products.

Preferably, the preparation method of the tobacco sample solution to be tested comprises the following steps: mixing the tobacco sample with a solvent, and filtering to obtain the tobacco extract;

preferably, the solvent comprises pure water or an acidic aqueous solution;

preferably, the hydrogen ion concentration in the acidic aqueous solution is 0.005 to 1mol/L, such as 0.005mol/L, 0.01mol/L, 0.05mol/L, 0.1mol/L, 0.2mol/L, 0.4mol/L, 0.5mol/L, 0.6mol/L, 0.8mol/L, 1mol/L, etc., preferably 0.05 to 0.2 mol/L.

Preferably, the mixing is at a temperature of 15-40 ℃, e.g., 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃ etc., and the mixing is for a time of 20-60min, e.g., 20min, 30min, 40min, 50min, 60min, etc.

Preferably, the mixing is by any one or a combination of at least two of oscillation, vortexing, or sonication.

Preferably, the pretreatment of step (1) comprises: injecting the tobacco sample solution to be detected, the strong acid solution and the gas into the detection system through the first sample introduction unit, mixing and heating to obtain the pretreatment solution.

Preferably, the concentration of hydrogen ions in the strong acid solution is 1 to 3mol/L, such as 1mol/L, 1.2mol/L, 1.5mol/L, 1.7mol/L, 2mol/L, 2.2mol/L, 2.5mol/L, 2.7mol/L, 3mol/L, and the like.

Preferably, the strong acid comprises any one of hydrochloric acid, sulfuric acid or phosphoric acid or a combination of at least two of the hydrochloric acid and the sulfuric acid, the phosphoric acid and the hydrochloric acid, the phosphoric acid and the sulfuric acid, and the like, and any other combination can be used.

Preferably, the gas comprises nitrogen or air.

Preferably, the heating temperature is 95-125 deg.C, such as 95 deg.C, 100 deg.C, 105 deg.C, 110 deg.C, 115 deg.C, 120 deg.C, 125 deg.C, preferably 95-115 deg.C.

Preferably, the cyanide formation of step (2) comprises: injecting the pretreatment liquid, the alkaline diluent and the gas obtained in the step (1) into a detection system through a second sample injection unit, mixing, adding a sulfamic acid solution, performing ultraviolet digestion, adding a distillation reagent, and distilling to obtain a cyanide generation liquid.

Preferably, the concentration of hydroxide ions in the alkaline diluent is from 0.5 to 2mol/L, such as 0.5mol/L, 1.0mol/L, 1.5mol/L, 2mol/L, and the like.

Preferably, the alkaline diluent comprises any one or a combination of at least two of sodium hydroxide, potassium hydroxide, sodium borohydride or potassium borohydride, such as a combination of sodium hydroxide and sodium borohydride, a combination of potassium hydroxide and potassium borohydride, a combination of sodium hydroxide and potassium borohydride, and the like, and any other combination can be used.

Preferably, the concentration of the sulfamic acid solution is 2-6g/L, such as 2g/L, 2.5g/L, 3g/L, 3.5g/L, 4g/L, 4.5g/L, 5g/L, 5.5g/L, 6g/L, and the like.

Preferably, the concentration of hydrogen ions in the distillation reagent is 5 to 12mol/L, such as 5mol/L, 6mol/L, 7mol/L, 8mol/L, 9mol/L, 10mol/L, 11mol/L, 12mol/L, etc., preferably 6 to 8 mol/L.

Preferably, the distillation reagent comprises any one or combination of at least two of phosphoric acid, hypophosphorous acid, sulfuric acid or hydrochloric acid, such as a combination of phosphoric acid and hypophosphorous acid, a combination of hypophosphorous acid and sulfuric acid, a combination of hypophosphorous acid and hydrochloric acid, and the like, and any other combination can be used.

Preferably, the distillation reagent further comprises sulfamic acid.

Preferably, the concentration of sulfamic acid in the distillation reagent is 1-5g/L, such as 1g/L, 1.5g/L, 2g/L, 2.5g/L, 3g/L, 3.5g/L, 4g/L, 4.5g/L, 5g/L, and the like.

Preferably, the temperature of the UV digestion is 20-85 deg.C, such as 20 deg.C, 25 deg.C, 30 deg.C, 35 deg.C, 40 deg.C, 45 deg.C, 50 deg.C, 55 deg.C, 60 deg.C, 65 deg.C, 70 deg.C, 75 deg.C, 80 deg.C, 85 deg.C, etc., preferably 40-60 deg.C.

Preferably, the distillation temperature is 110-.

Preferably, the separating of step (3) comprises: and (3) separating, condensing and absorbing the cyanide generated liquid obtained in the step (2) by a vapor-liquid separation device to obtain a cyanide ion solution.

Preferably, the absorption comprises mixing with an absorption solution.

Preferably, the concentration of hydroxide ions in the absorbing solution is 0.02 to 0.2mol/L, such as 0.02mol/L, 0.05mol/L, 0.07mol/L, 0.1mol/L, 0.12mol/L, 0.15mol/L, 0.17mol/L, 0.2mol/L, and the like.

Preferably, the absorption solution comprises sodium hydroxide and/or potassium hydroxide.

Preferably, the detecting of step (4) comprises: and (4) injecting the cyanide ion solution, the acidic diluent and the gas obtained in the step (3) into a detection system through a third sample injection unit, mixing with a chloramine T solution and a color developing agent in sequence, carrying out color development reaction, and detecting by using a spectrophotometry method to obtain the content of the water-soluble cyanide precursor in the tobacco.

Preferably, the acidic diluent has a pH of 5.1-5.3, e.g., 5.1, 5.2, 5.3, etc.

Preferably, the acidic diluent comprises any one or a combination of at least two of sodium dihydrogen phosphate, sodium hydrogen sulfate, sodium hydroxide and hydrochloric acid, the combination of at least two of sodium dihydrogen phosphate and sodium hydrogen phosphate, sodium dihydrogen phosphate and sodium hydrogen sulfate, sodium hydrogen phosphate and sodium hydrogen sulfate, and the like, any combination of the above methods can be used, and then the pH value of the acidic diluent is adjusted to the specified range by using sodium hydroxide or hydrochloric acid.

Preferably, the color developer comprises an isonicotinic-barbituric acid color developer or a pyridine-barbituric acid color developer.

Preferably, the temperature of the color reaction is 35-40 deg.C, such as 35 deg.C, 36 deg.C, 37 deg.C, 38 deg.C, 39 deg.C, 40 deg.C, etc.

The recitation of numerical ranges herein includes not only the above-recited values, but also any values between any of the above-recited numerical ranges not recited, and for brevity and clarity, is not intended to be exhaustive of the specific values encompassed within the range.

Compared with the prior art, the invention has the beneficial effects that:

firstly, the invention provides a detection system for water-soluble cyanide precursors in tobacco for the first time. The detection system for the water-soluble cyanide precursor in the tobacco belongs to a continuous flow analysis device, and firstly, compared with the detection of cyanide in a manual operation mode, the cyanide can be better prevented from diffusing in the operation process by using the continuous flow analysis device, so that the detection result is more accurate, and the safety of detection operation is improved. And the continuous flow analysis is characterized in that gas is introduced simultaneously in the sample introduction process, so that bubble intervals are formed in the liquid sample, the mixing of front and rear sample solutions is avoided, and the accuracy of the detection result is improved.

Secondly, the continuous flow analyzer in the prior art is only suitable for detecting cyanide in a water sample with simple components, and the general process thereof is to perform a color reaction after digesting total cyanide compounds (including thiocyanate compounds, ferricyanide compounds and the like) in the water sample, thereby performing detection by a spectroscopic method. However, although the tobacco contains few total cyanide compounds, a large amount of organic components such as amino acids, water-soluble proteins, glycosides and organic acid ammonium are slightly converted into cyanide under a combustion state, and the tobacco also contains a large amount of water-soluble sugars and organic acids, so that the conversion of cyanide precursors cannot be realized if the cyanide precursors are directly digested, and therefore, the complex components need to be pretreated, and the process is often carried out under a high-temperature condition to facilitate the reaction. However, the sample solution generates bubbles at a temperature of 95 ℃ under normal pressure, so that the bubble intervals in the continuous flow analysis are disturbed, the detection result is affected, and if the temperature is higher, different sections of sample solutions are mixed, so that the measurement cannot be carried out. The invention creatively adds the pressurizing unit in the pretreatment module, and the saturated vapor pressure of the sample solution is increased in a pressurizing mode, so that bubbles and even boiling of the sample solution at high temperature are avoided, continuous flow analysis at high temperature is realized, and the full reaction is ensured.

Based on the detection system, the invention provides the method for detecting the water-soluble cyanide precursor in the tobacco for the first time, the method is simple to operate, high in stability, high in precision and high in accuracy, a new strategy is provided for evaluating the cyanide release amount of the cigarette smoke, and the method has important significance for controlling the quality of tobacco products.

Drawings

FIG. 1 is a schematic structural diagram of a system for detecting a water-soluble cyanide precursor in tobacco provided in example 1. Wherein, 1-a pressurizing unit; 2.1 and 2.2 are both heaters; 3.1, 3.2, 3.3, 3.4, 3.5, 3.6 and 3.7 are all 5 turns of spiral tubes; 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 and 4.10 are all pipeline joints; 4.11 is an h-shaped three-way pipeline joint; 5.1, 5.2 and 5.3 are all air inlet devices; 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8 and 6.9 are all liquid inlet devices; 7.1, 7.2, 7.3 and 7.4 are all waste liquid discharge devices; 8.1 and 8.2 are both bubble separation devices; 9.1 and 9.2 are both double liquid feeding devices; 10-ultraviolet digestion device; 11-a distiller; 12-a vapor-liquid separator; 13.1 and 13.2 are both water bath condenser pipes; 14-a colorimetric pool; 15 is a conduit which leads directly to the waste liquid bottle.

Fig. 2 is a schematic structural view of the pressurizing unit. The device comprises 31-a compressed air inlet device, 32-a pressure regulating valve, 33-a switch valve, 34-an air buffer pipe, 35-a pressurizing pipe, 36-a waste liquid discharge device and 37-a pressurizing interface.

Detailed Description

It should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "disposed," "connected" and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; the connection can be mechanical connection or chemical agent bonding connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

Example 1

The embodiment provides a detection system for a water-soluble cyanide precursor in tobacco, and fig. 1 is a schematic structural diagram of the detection system. The detection system for the water-soluble cyanide precursor in the tobacco comprises a pressurizing unit 1, heaters (2.1 and 2.2), spiral pipes (3.1, 3.2, 3.3, 3.4, 3.5, 3.6 and 3.7), pipeline joints (4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 and 4.10), h-type three-way pipeline joints (4.11), air inlet devices (5.1, 5.2 and 5.3), liquid inlet devices (6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8 and 6.9), waste liquid discharge devices (7.1, 7.2, 7.3 and 7.4), air bubble separation devices (8.1 and 8.2), re-feeding liquid devices (9.1 and 9.2), an ultraviolet digester 10, a distiller 11, a steam-dissolving device (12), a condensation pipe (1.2), a condensation pipe (13.2), a water bath (13.4) and a water bath (13), a water bath pool (13), and a water bath (15).

Wherein, the air inlet device 5.1, the liquid inlet device 6.1, the liquid inlet device 6.2 and the spiral pipe 3.1 are connected through a pipeline joint 4.1. The other end of the spiral tube 3.1 is connected with a heater 2.1 and a bubble separation device 8.1 in sequence. The other two interfaces of the bubble separation device 8.1 are respectively connected with the pressurizing unit 1 and the liquid re-feeding device 9.1. The other interface of the complex liquid inlet device 9.1 is connected with the spiral pipe 3.2 and the pipeline joint 4.3 through the pipeline joint 4.2. The other two interfaces of the pipeline joint 4.3 are respectively connected with a liquid inlet device 6.3 and an air inlet device 5.2. (it is stated that the two three-port connections 4.2 and 4.3 can also be replaced by a four-port connection, with the double feed 9.1, the inlet 6.3 and the inlet 5.2 being connected together and then leading to the spiral 3.2.) the other end of the spiral 3.2 is connected to the spiral 3.3 and the inlet 6.4 via a line connection 4.4. The other end of the spiral tube 3.3 is connected with an ultraviolet digestion device 10. The other end of the ultraviolet digester 10 is connected with a liquid inlet device 6.5 and a distiller 11 through a pipeline joint 4.5. The other end of the distiller 11 is connected with a vapor-liquid separator 12. The other two ends of the vapor-liquid separator 12 are respectively connected with a water bath condensation pipe 13.1 and a water bath condensation pipe 13.2. The other end of the water bath condenser pipe 13.1 is connected with a waste liquid discharge device 7.1 and a waste liquid discharge device 7.2 through an h-shaped three-way pipeline joint 4.11. The other end of the water bath condensation pipe 13.2 is connected with the liquid inlet device 6.6 and the bubble separation device 8.2 through the pipeline joint 4.6. The other two interfaces of the bubble separation device 8.2 are respectively connected with a waste liquid discharge device 7.3 and a liquid re-feeding device 9.2. The other port of the return inlet 9.2 is connected to the spiral pipe 3.4 and the line connection 4.8 via a line connection 4.7. The other two joints of the pipeline joint 4.8 are respectively connected with a liquid inlet device 6.7 and an air inlet device 5.3. The other end of the spiral pipe 3.4 is connected with a liquid inlet device 6.8 and the spiral pipe 3.5 through a pipeline joint 4.9. The other end of the spiral pipe 3.5 is connected with the liquid inlet device 6.9 and the spiral pipe 3.6 through a pipeline joint 4.10. The other end of the spiral tube 3.6 is connected with a heater 2.2, a spiral tube 3.7 and a colorimetric pool 14 in sequence. The other two ends of the colorimetric pool 14 are respectively connected with a waste liquid discharge device 7.4 and a conduit 15.

The pressurizing unit 1 has a structure as shown in fig. 2, and includes a compressed air inlet device 31, a pressure regulating valve 32, an on-off valve 33, an air buffer tube 34, a pressurizing tube 35, and a waste liquid discharge device 36, which are connected in sequence. Wherein the pressure pipe is further provided with a pressure interface 37 connected with the bubble separation device 8.1.

Example 2

This example provides a system for detecting a water-soluble cyanide precursor in tobacco, which is different from the system of example 1 only in that it does not include a pressurizing unit, and is otherwise the same as example 1.

Application example 1

The application example provides a method for detecting a water-soluble cyanide precursor in tobacco, wherein the method for detecting the water-soluble cyanide precursor in tobacco uses the detection system of embodiment 1 to carry out detection, and the method comprises the following specific steps:

(1) first stage reaction pipeline

1. Firstly, strong acid solution (2mol/L hydrochloric acid solution) is injected into the system through a liquid inlet device 6.1 according to a certain flow rate (1.0mL/min), and air is continuously injected through an air inlet device 5.1, so that continuous flowing liquid with bubble intervals is formed in the pipeline. Then, the sample solution is injected into the pipeline by the liquid inlet device 6.2 according to a certain flow rate (0.42mL/min), mixed with the strong acid solution and uniformly mixed by the rolling action of the spiral pipe 3.1.

The preparation method of the sample solution comprises the following steps:

according to YC-T31-1996 standards of preparation of tobacco and tobacco product samples and moisture determination oven method, tobacco leaves or tobacco shreds are ground into powder and the moisture content is determined. Weighing about 1.0g of powder sample, accurately obtaining the powder sample with the concentration of 0.1mg, placing the powder sample in a 100mL ground conical flask, accurately adding 40mL hydrochloric acid solution with the concentration of 0.1mol/L, carrying out ultrasonic treatment for 40min after plugging, and filtering the solution through quantitative filter paper to obtain a sample solution.

2. And then the mixed solution enters a heater 2.1, and is heated while rolling and mixing under the heating condition of 100 ℃, so that the acidolysis of the macromolecular organic components in the sample solution is completed. In order to ensure that the liquid does not generate bubbles and disturb the bubble intervals under the high-temperature condition, the pressure in the flow pipeline is improved by adopting a mode that an outlet end is connected with a pressurizing unit (the external pressure is adjusted to be 0.3 bar).

3. The sample solution after acidolysis is injected into the next stage reaction pipeline through a compound liquid inlet device 9.1 according to a certain flow (1.2mL/min) by adopting a compound sample injection mode.

(2) Second stage reaction pipeline

1. Alkaline diluted solution (40g/L sodium hydroxide +1.05g/L sodium borohydride) is injected into the process system through a liquid inlet device 6.3 according to a certain flow rate (2.0mL/min), air is continuously injected through an air inlet device 5.2, and continuous flowing liquid with bubble intervals is formed in the pipeline. Then, the alkaline diluted solution and the sample solution after acidolysis are uniformly mixed by the rolling action of the spiral tube 3.2, and neutralization and dilution are carried out.

2. Sulfamic acid solution (2g/L) is injected into the process system through a liquid inlet device 6.4 according to a certain flow (0.42mL/min) and is uniformly mixed with the neutralized and diluted sample solution through the rolling action of a spiral pipe 3.3 so as to ensure the subsequent ultraviolet digestion reaction.

3. The obtained solution enters an ultraviolet digestion device 10, and is subjected to ultraviolet irradiation while continuously rolling and mixing under the condition of heat preservation at 35 ℃ to obtain a sample solution subjected to ultraviolet digestion.

4. Injecting a distillation reagent (1.8 mol/L phosphoric acid, 0.2mol/L hypophosphorous acid and 1g/L sulfamic acid) into the process system according to a certain flow rate (1.0mL/min) through a liquid inlet device 6.5, and mixing the distillation reagent with the sample solution subjected to ultraviolet digestion.

5. The obtained solution enters a distiller 11, and is vaporized while continuously rolling and mixing under the heating condition of 110 ℃ to obtain a vaporized solution.

(3) Third stage reaction pipeline

1. And (4) condensing and recovering the vaporized solution by adopting a double-stage condensation pipe.

2. Firstly, most of the solution with higher boiling point is rapidly converted from gas state into liquid state and flows downwards after leaving the heating pipeline, then the temperature of the solution is reduced through the water bath condenser pipe 13.1, and the waste liquid is discharged through the waste discharge device.

3. Thereafter, a small part of the gaseous solution (including hydrogen cyanide) with a lower boiling point continues to follow the forward and upward pipeline, and is condensed at the second-stage condenser (i.e. the water bath condenser pipe 13.2) to be converted from a gaseous state into a liquid state.

4. And injecting the absorption solution (0.1mol/L sodium hydroxide) into the process system according to a certain flow (1.2mL/min), and mixing with the solution subjected to secondary condensation to obtain an alkaline cyanide ion solution.

(4) Fourth stage reaction pipeline

1. The acidic buffer solution (sodium dihydrogen phosphate buffer solution, pH 5.3) is injected into the process system through a liquid inlet device 6.7 according to a certain flow rate (0.23mL/min), and air is continuously injected through an air inlet device 5.3, so that continuous flowing liquid with bubble intervals is formed in the pipeline.

2. The cyanide ion solution is discharged with air bubbles through the air bubble separation device 8.2, then is injected into the process system through the composite liquid inlet device 9.2, and then is uniformly mixed with the buffer solution through the rolling action of the spiral pipe 3.4 so as to adjust the acidity and alkalinity of the cyanide ion solution.

3. Chloramine T solution (4g/L chloramine T trihydrate, sample introduction is carried out through a liquid inlet device 6.8) and color developing agent (isonicotinic acid-barbituric acid color developing agent, sample introduction is carried out through a liquid inlet device 6.9) are injected into the flow system in sequence according to a certain flow rate (all 0.23mL/min), and are uniformly mixed with the solution in the previous stage through the rolling action of a spiral pipe.

The preparation method of the isonicotinic acid-barbituric acid color developing agent comprises the following steps: 3.5g of sodium hydroxide was dissolved in about 450mL of distilled water, 8.4g of 1, 3-dimethylbarbituric acid and 6.8g of isonicotinic acid were added, and then the pH was adjusted to 5.3 with 1mol/L hydrochloric acid solution or 1mol/L sodium hydroxide solution, 0.5mL of Brij 35 was added and the volume was adjusted to 500 mL. And finally, violently and uniformly mixing for 1 hour at the temperature of 30 ℃, and filtering by using pleated filter paper to obtain the filter paper.

4. The solution mixed with the color developing agent enters a heater 2.2, and is heated while continuously rolling and mixing under the condition of heat preservation at 35 ℃ to complete the color development reaction of the cyanide component.

5. After the color reaction, the solution enters a colorimetric pool 14(50mm) after being cooled by a spiral tube 3.7, and quantitative detection is carried out at the wavelength of 580nm after air bubbles are discharged.

Application example 2

The application example provides a method for detecting a water-soluble cyanide precursor in tobacco, which adopts the detection system of embodiment 1 for detection, and specifically comprises the following steps:

(1) first stage reaction pipeline

1. Firstly, strong acid solution (1.5mol/L sulfuric acid solution) is injected into the system through a liquid inlet device 6.1 according to a certain flow rate (0.80mL/min), and nitrogen is continuously injected through an air inlet device 5.1, so that continuous flowing liquid with bubble intervals is formed in the pipeline. Then, the sample solution is injected into the pipeline by the liquid inlet device 6.2 according to a certain flow rate (0.60mL/min), mixed with the strong acid solution and uniformly mixed by the rolling action of the spiral pipe 3.1.

The preparation method of the sample solution comprises the following steps:

according to YC-T31-1996 standards of preparation of tobacco and tobacco product samples and moisture determination oven method, tobacco leaves or tobacco shreds are ground into powder and the moisture content is determined. Weighing about 0.5g of powder sample, accurately measuring to 0.1mg, placing in a 50mL ground conical flask, accurately adding 30mL of 5% acetic acid solution, heating at 40 ℃, oscillating and extracting for 30min to obtain an extract, filtering by quantitative filter paper, washing filter residue and filter paper by using 5% acetic acid solution, combining filtrates and fixing the volume to 50mL to obtain a sample solution.

2. And then the mixed solution enters a heater 2.1, and is heated while rolling and mixing under the heating condition of 95 ℃, so that the acidolysis of the macromolecular organic components in the sample solution is completed. In order to ensure that the liquid does not generate bubbles and disturb the bubble intervals under the high-temperature condition, the pressure in the flow pipeline is improved by adopting a mode that an outlet end is connected with a pressurizing unit (the external pressure is adjusted to be 0.1 bar).

3. The sample solution after acidolysis is injected into the next stage reaction pipeline through a compound liquid inlet device 9.1 according to a certain flow (1.5mL/min) by adopting a compound sample injection mode.

(3) Second stage reaction pipeline

1. Alkaline dilute solution (20g/L sodium hydroxide) is injected into the process system through a liquid inlet device 6.3 according to a certain flow rate (2.4mL/min), and nitrogen is continuously injected through an air inlet device 5.2, so that continuous flowing liquid with bubble intervals is formed in a pipeline. Then, the alkaline diluted solution and the sample solution after acidolysis are uniformly mixed by the rolling action of the spiral tube 3.2, and neutralization and dilution are carried out.

2. Sulfamic acid solution (5g/L) is injected into the process system through a liquid inlet device 6.4 according to a certain flow (0.23mL/min) and is uniformly mixed with the neutralized and diluted sample solution through the rolling action of a spiral pipe 3.3 so as to ensure the subsequent ultraviolet digestion reaction.

3. The obtained solution enters an ultraviolet digestion device 10, and is subjected to ultraviolet irradiation while continuously rolling and mixing under the condition of heat preservation at 60 ℃ to obtain a sample solution subjected to ultraviolet digestion.

4. Injecting a distillation reagent (4 mol/L sulfuric acid and 0.5mol/L hypophosphorous acid) into the flow system through a liquid inlet device 6.5 according to a certain flow rate (1.0mL/min), and mixing with the sample solution subjected to ultraviolet digestion.

5. The obtained solution enters a distiller 11, and is vaporized while continuously rolling and mixing under the heating condition of 140 ℃ to obtain a vaporized solution.

(3) Third stage reaction pipeline

1. And (4) condensing and recovering the vaporized solution by adopting a double-stage condensation pipe.

2. Firstly, most of the solution with higher boiling point is rapidly converted from gas state to liquid state and flows downwards after leaving the heating pipeline, and then the temperature of the solution is reduced through the water bath condenser pipe 13.1, and the waste liquid is discharged through the waste discharge device.

3. Thereafter, a small part of the gaseous solution (including hydrogen cyanide) with a lower boiling point continues to follow the forward and upward pipeline, and is condensed at the second-stage condenser (i.e. the water bath condenser pipe 13.2) to be converted from a gaseous state into a liquid state.

4. And injecting the absorption solution (0.1mol/L sodium hydroxide) into the process system according to a certain flow (1.5mL/min), and mixing with the solution subjected to secondary condensation to obtain an alkaline cyanide ion solution.

(4) Fourth stage reaction pipeline

1. Acidic buffer solution (sodium bisulfate and disodium hydrogen phosphate mixed buffer solution, pH 5.1) is injected into the process system through a liquid inlet device 6.7 according to a certain flow rate (0.42mL/min), and nitrogen is continuously injected through an air inlet device 5.3 to form continuous flowing liquid with bubble intervals in the pipeline.

2. The cyanide ion solution is discharged with air bubbles through the air bubble separation device 8.2, then is injected into the process system through the composite liquid inlet device 9.2, and then is uniformly mixed with the buffer solution through the rolling action of the spiral pipe 3.4 so as to adjust the acidity and alkalinity of the cyanide ion solution.

3. Chloramine T solution (4g/L chloramine T trihydrate, sample introduction is carried out through a liquid inlet device 6.8) and color developing agent (isonicotinic acid-barbituric acid color developing agent, sample introduction is carried out through a liquid inlet device 6.9) are injected into the flow system in sequence according to a certain flow rate (0.32mL/min), and are uniformly mixed with the solution in the previous stage through the rolling action of a spiral pipe.

The preparation method of the isonicotinic acid-barbituric acid color developing agent comprises the following steps: 3.5g of sodium hydroxide was dissolved in about 450mL of distilled water, and then 8.4g of 1, 3-dimethylbarbituric acid and 6.8g of isonicotinic acid were added, and then the pH was adjusted to 5.1 with 1mol/L hydrochloric acid solution or 1mol/L sodium hydroxide solution, and then 0.5mL of Brij 35 was added and the volume was adjusted to 500 mL. And finally, violently and uniformly mixing for 1 hour at the temperature of 30 ℃, and filtering by using pleated filter paper to obtain the nano-composite material.

4. The solution mixed with the color developing agent enters a heater 2.2, and is heated while continuously rolling and mixing under the condition of heat preservation at 40 ℃ to complete the color development reaction of the cyanide component.

5. After the color reaction, the solution enters a colorimetric pool 14(50mm) after being cooled by a spiral tube 3.7, and quantitative detection is carried out at the wavelength of 590nm after air bubbles are discharged.

Application example 3

The application example provides a method for detecting a water-soluble cyanide precursor in tobacco, which adopts the detection system of embodiment 1 for detection, and specifically comprises the following steps:

(1) first stage reaction pipeline

1. Firstly, strong acid solution (1mol/L phosphoric acid solution) is injected into the system through a liquid inlet device 6.1 according to a certain flow rate (1.2mL/min), and air is continuously injected through an air inlet device 5.1, so that continuous flowing liquid with bubble intervals is formed in the pipeline. Then, the sample solution is injected into the pipeline by the liquid inlet device 6.2 according to a certain flow rate (0.80mL/min), mixed with the strong acid solution and uniformly mixed by the rolling action of the spiral pipe 3.1.

The preparation method of the sample solution comprises the following steps:

according to YC-T31-1996 standards of preparation of tobacco and tobacco product samples and moisture determination oven method, tobacco leaves or tobacco shreds are ground into powder and the moisture content is determined. Weighing about 0.25g of powder sample, accurately obtaining the powder sample with the weight of 0.1mg, placing the powder sample in a 100mL conical flask with a ground opening, accurately adding 50mL of deionized water, carrying out ultrasonic treatment for 60min after plugging, and filtering through quantitative filter paper to obtain a sample solution.

2. And then the mixed solution enters a heater 2.1, and is heated while rolling and mixing under the heating condition of 115 ℃, so that the acidolysis of the macromolecular organic components in the sample solution is completed. In order to ensure that the liquid does not generate bubbles and disturb the bubble intervals under the high-temperature condition, the pressure in the flow pipeline is increased by connecting an outlet end with a pressurizing unit (the external pressure is adjusted to be 0.8 bar).

3. The sample solution after acidolysis is injected into the next stage reaction pipeline through a compound liquid inlet device 9.1 according to a certain flow (1.0mL/min) by adopting a compound sample injection mode.

(4) Second stage reaction pipeline

1. Alkaline diluted solution (80g/L potassium hydroxide +2g/L potassium borohydride) is injected into the process system through a liquid inlet device 6.3 according to a certain flow rate (1.8mL/min), air is continuously injected through an air inlet device 5.2, and continuous flowing liquid with bubble intervals is formed in the pipeline. Then, the alkaline diluted solution and the sample solution after acidolysis are uniformly mixed by the rolling action of the spiral tube 3.2, and neutralization and dilution are carried out.

2. Sulfamic acid solution (3g/L) is injected into the process system through a liquid inlet device 6.4 according to a certain flow (0.32mL/min), and is uniformly mixed with the neutralized and diluted sample solution through the rolling action of a spiral pipe 3.3 so as to ensure the subsequent ultraviolet digestion reaction.

3. The obtained solution enters an ultraviolet digestion device 10, and is subjected to ultraviolet irradiation while continuously rolling and mixing under the condition of 80 ℃ heat preservation, so that a sample solution subjected to ultraviolet digestion is obtained.

4. Injecting a distillation reagent (5 mol/L of hydrochloric acid, 1mol/L of hypophosphorous acid and 2g/L of sulfamic acid) into the flow system through a liquid inlet device 6.5 according to a certain flow rate (2.0mL/min), and mixing with the sample solution subjected to ultraviolet digestion.

5. The obtained solution enters a distiller 11, and is vaporized while continuously rolling and mixing under the heating condition of 160 ℃ to obtain a vaporized solution.

(3) Third stage reaction pipeline

1. And (4) condensing and recovering the vaporized solution by adopting a double-stage condensation pipe.

2. Firstly, most of the solution with higher boiling point is rapidly converted from gas state to liquid state and flows downwards after leaving the heating pipeline, and then the temperature of the solution is reduced through the water bath condenser pipe 13.1, and the waste liquid is discharged through the waste discharge device.

3. Thereafter, the small part of the solution with lower boiling point (including hydrogen cyanide) continues to follow the forward and upward pipeline and is condensed at the second-stage condenser (i.e. the water bath condenser pipe 13.2) to be converted from gas state to liquid state.

4. And injecting the absorption solution (0.15mol/L potassium hydroxide) into the flow system according to a certain flow (1.6mL/min), and mixing with the solution subjected to secondary condensation to obtain an alkaline mixed solution.

(4) Fourth stage reaction pipeline

1. The acidic buffer solution (sodium dihydrogen phosphate buffer solution, pH 5.2) is injected into the process system through a liquid inlet device 6.7 according to a certain flow rate (0.32mL/min), and air is continuously injected through an air inlet device 5.3, so that continuous flowing liquid with bubble intervals is formed in the pipeline.

2. Cyanide ion solution discharges bubbles through bubble separator 8.2, and then pours into the process system through compound inlet means 9.2, then mixes with the buffer solution evenly through the rolling action of spiral pipe 3.4 to adjust the pH value of solution.

3. Chloramine T solution (4g/L chloramine T trihydrate, sample introduction is carried out through a liquid inlet device 6.8) and color developing agent (isonicotinic acid-barbituric acid color developing agent, sample introduction is carried out through a liquid inlet device 6.9) are injected into the flow system in sequence according to a certain flow rate (0.32mL/min), and are uniformly mixed with the solution in the previous stage through the rolling action of a spiral pipe.

The preparation method of the isonicotinic acid-barbituric acid color developing agent comprises the following steps: 3.5g of potassium hydroxide was dissolved in about 450mL of distilled water, and 8.4g of 1, 3-dimethylbarbituric acid and 6.8g of isonicotinic acid were added, and then the pH was adjusted to 5.2 with 1mol/L hydrochloric acid solution or 1mol/L potassium hydroxide solution, and 0.5mL of Brij 35 was added to make a volume of 500 mL. And finally, violently and uniformly mixing for 1 hour at the temperature of 30 ℃, and filtering by using pleated filter paper to obtain the filter paper.

4. The solution mixed with the color developing agent enters a heater 2.2, and is heated while continuously rolling and mixing under the condition of heat preservation at 35 ℃ to complete the color development reaction of the cyanide component.

5. After the color reaction, the solution enters a colorimetric pool 14(30mm) after being cooled by a spiral tube 3.7, and quantitative detection is carried out at the wavelength of 600nm after air bubbles are discharged.

Application example 4

The application example provides a method for detecting a water-soluble cyanide precursor in tobacco, which adopts the detection system of the embodiment 2 to detect, and the detection method refers to the application example 2.

Application example 5

The application example provides a method for detecting water-soluble cyanide precursors in tobacco, which adopts the detection system of the embodiment 1 to carry out detection, and the detection method is only different from the detection system of the application example 2 in that 95 ℃ heating in a first-stage reaction pipeline is changed into 90 ℃ heating, and other reference is made to the application example 2.

Test example

The content of the water-soluble cyanide precursor in five tobacco samples is detected by the detection methods of application examples 1-5 respectively, each sample is detected for 5 times, and the relative standard deviation is calculated to reflect the precision of the method.

The detection results are as follows:

TABLE 1

The results show that: the RSD of the results of each application example is less than 11 percent, wherein the RSD of the results of application examples 1-3 and 5 is less than 8 percent, which shows that the detection system and the detection method for the water-soluble cyanide precursor in the tobacco provided by the invention have high precision of the detection result, the detection conditions are changed within a certain range, the obtained results are relatively consistent, and the stability of the detection method is high. The precision of the detection method of application example 4 is inferior to that of application example 2 because the sample solution generates bubbles at a high temperature of 95 ℃ under normal pressure (because a small amount of air can be dissolved in water, and the small bubbles act as nuclei for gasification, the solubility of water to air decreases with the increase of temperature, when water is heated, bubbles are first generated on the wall of the heated surface, after the bubbles are generated, because water is continuously heated, a superheated water layer is formed near the heated surface, which continuously evaporates water vapor into the small bubbles, so that the pressure in the bubbles, i.e., the sum of air pressure and vapor pressure, is continuously increased, as a result, the volume of the bubbles is continuously expanded, the buoyancy force applied to the bubbles is also increased, and when the buoyancy force applied to the bubbles is larger than the adhesive force between the bubbles and the wall, the bubbles leave the wall and start to float upwards), causing the bubble separation in continuous flow analysis to be disturbed, thereby influencing the detection result (shown as that small peak protrusion or depression appears at the peak top of the absorption peak obtained by spectrophotometry). The detection result of the detection method of application example 5 is smaller than that of the detection method of application example 2, which shows that when the reaction temperature of the acidification treatment is not high enough, the acidolysis of the organic matter is insufficient, and the detection result is also influenced.

To reflect the accuracy of the method (in application example 1), the standard recovery test was performed using a cyanogen standard (national second-order standard) in water having a cyanogen ion content of 50.0. mu.g/mL. The results are as follows:

TABLE 2

The results show that: the result of the standard recovery rate test is within the range of 89-108%, which indicates that the method has good accuracy.

The applicant states that the present invention is described in the above embodiments and application examples to describe a system and a method for detecting a water-soluble cyanide precursor in tobacco, but the present invention is not limited to the above embodiments and application examples, which means that the present invention is not limited to the above embodiments and application examples. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

Claims (10)

1. A detection system for water-soluble cyanide precursor in tobacco is characterized by comprising a pretreatment module, a cyanide generation module, a separation module and a detection module which are sequentially connected;

the pretreatment module comprises a reaction unit, and the reaction unit comprises a heating device.

2. The system for detecting the water-soluble cyanide precursor in the tobacco as claimed in claim 1, wherein the pretreatment module comprises a first sample introduction unit, a reaction unit, a separation unit and a pressurization unit, the first sample introduction unit is connected in series with the reaction unit and is connected in parallel with the pressurization unit through the separation unit;

preferably, the first sample introduction unit comprises a liquid inlet device and a gas inlet device which are connected in sequence;

preferably, the reaction unit comprises a blending device and a heating device which are connected in sequence;

preferably, the separation unit comprises a bubble separation device.

3. The detection system for the water-soluble cyanide precursor in the tobacco as claimed in claim 1 or 2, wherein the cyanide generation module comprises a second sample introduction unit, a digestion reaction unit and a distillation reaction unit which are connected in sequence;

preferably, the second sample introduction unit comprises a re-feeding device, an air inlet device, a liquid inlet device and a blending device which are connected in sequence;

preferably, the digestion reaction unit comprises a liquid inlet device, a uniform mixing device and an ultraviolet digestion device which are connected in sequence;

preferably, the distillation reaction unit comprises a liquid inlet device and a distillation device which are connected in sequence.

4. The system for detecting the water-soluble cyanide precursor in tobacco as claimed in any one of claims 1-3, wherein the separation module comprises a separation reaction unit, a waste discharge unit and an absorption unit;

preferably, the waste discharge unit comprises a condensing device and a waste discharge device which are connected in sequence;

preferably, the absorption unit comprises a condensing device, a liquid inlet device and a bubble discharging device which are connected in sequence;

preferably, the separation reaction unit comprises a vapor-liquid separation device, and the vapor-liquid separation device is simultaneously connected with the condensing device in the waste discharge unit and the condensing device in the absorption unit.

5. The detection system for the water-soluble cyanide precursor in the tobacco as claimed in any one of claims 1 to 4, wherein the detection module comprises a third sample feeding unit, a color development reaction unit and a detection unit which are connected in sequence;

preferably, the third sample feeding unit comprises a re-feeding device, an air inlet device, a liquid inlet device and a blending device which are connected in sequence;

preferably, the color reaction unit comprises a liquid inlet device, a blending device and a heating device;

preferably, the detection unit comprises a cuvette and a waste.

6. A method for detecting water-soluble cyanide precursors in tobacco, which comprises the steps of using the detection system for water-soluble cyanide precursors in tobacco as claimed in any one of claims 1 to 5, and comprises the following steps:

(1) pretreatment: injecting the tobacco sample solution to be detected into a pretreatment module for heating treatment to obtain a pretreatment solution;

(2) cyanide formation: the pretreatment solution enters a cyanide generation module to react to obtain cyanide generation solution;

(3) separation: separating the cyanide generated liquid by a separation module to obtain cyanide ion solution;

(4) and (3) detection: and detecting the content of cyanide ions in the cyanide ion solution in a detection module to obtain the content of water-soluble cyanide precursors in the tobacco.

7. The method for detecting water-soluble cyanide precursors in tobacco as claimed in claim 6, wherein the method for preparing the tobacco sample solution to be detected comprises: mixing the tobacco sample with a solvent, filtering, and collecting filtrate to obtain the tobacco extract;

preferably, the solvent comprises pure water or an acidic aqueous solution;

preferably, the concentration of hydrogen ions in the acidic aqueous solution is 0.005-1mol/L, preferably 0.05-0.2 mol/L;

preferably, the mixing temperature is 15-40 ℃, and the mixing time is 20-60 min;

preferably, the mixing means comprises any one or a combination of at least two of oscillation, vortexing or sonication;

preferably, the pretreatment of step (1) comprises: injecting the tobacco sample solution to be detected, the strong acid solution and the gas into a detection system through a first sample introduction unit, mixing and heating to obtain a pretreatment solution;

preferably, the concentration of hydrogen ions in the strong acid solution is 1-3 mol/L;

preferably, the strong acid comprises any one of hydrochloric acid, sulfuric acid or phosphoric acid or a combination of at least two thereof;

preferably, the gas comprises nitrogen or air;

preferably, the heating temperature is 95 to 125 ℃, preferably 95 to 115 ℃.

8. The method for detecting a water-soluble cyanide precursor in tobacco according to claim 6 or 7, wherein the cyanide formation in step (2) comprises: injecting the pretreatment liquid, the alkaline diluent and the gas obtained in the step (1) into a detection system through a second sample injection unit, mixing, adding a sulfamic acid solution, performing ultraviolet digestion, adding a distillation reagent, and distilling to obtain a cyanide generation liquid;

preferably, the concentration of hydroxide ions in the alkaline diluent is 0.5-2 mol/L;

preferably, the alkaline diluent comprises any one or a combination of at least two of sodium hydroxide, potassium hydroxide, sodium borohydride or potassium borohydride;

preferably, the concentration of the sulfamic acid solution is 2-6 g/L;

preferably, the concentration of hydrogen ions in the distillation reagent is 5-12mol/L, preferably 6-8 mol/L;

preferably, the distillation reagent comprises any one of phosphoric acid, hypophosphorous acid, sulfuric acid or hydrochloric acid or a combination of at least two thereof;

preferably, the distillation reagent further comprises sulfamic acid;

preferably, the concentration of sulfamic acid in the distillation reagent is 1-5 g/L;

preferably, the temperature of the ultraviolet digestion is 20-85 ℃, and preferably 40-60 ℃;

preferably, the temperature of the distillation is 110-180 ℃, preferably 140-160 ℃.

9. The method of detecting a water-soluble cyanide precursor in tobacco according to any one of claims 6-8, wherein the separating of step (3) comprises: separating, condensing and absorbing the cyanide generated liquid obtained in the step (2) by a vapor-liquid separation device to obtain cyanide ion solution;

preferably, the absorbing comprises mixing with an absorbing solution;

preferably, the concentration of hydroxide ions in the absorption solution is 0.02-0.2 mol/L;

preferably, the absorption solution comprises sodium hydroxide and/or potassium hydroxide.

10. The method for detecting a water-soluble cyanide precursor in tobacco according to any one of claims 6-9, wherein the detecting in step (4) comprises: injecting the cyanide ion solution, the acidic diluent and the gas obtained in the step (3) into a detection system through a third sample injection unit, mixing with a chloramine T solution and a color-developing agent in sequence, carrying out color development reaction, and detecting by a spectrophotometry method to obtain the content of the water-soluble cyanide precursor in the tobacco;

preferably, the pH of the acidic diluent is 5.1 to 5.3;

preferably, the color developer comprises an isonicotinic acid-barbituric acid color developer or a pyridine-barbituric acid color developer;

preferably, the temperature of the color reaction is 35-40 ℃.

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