阅读说明：本技术 七种虾类实时鉴定的原位快速蒸发电离质谱法 (In-situ rapid evaporation ionization mass spectrometry for real-time identification of seven shrimps ) 是由 沈清 卢蔚波 陈康 朱小芳 赵巧灵 王萍亚 于 2021-09-26 设计创作，主要内容包括：本发明公开了一种七种虾类实时鉴定的原位快速蒸发电离质谱法,包括以下步骤,a、获取七种虾,每种虾分成若干份；b、得到七种、每种若干份的虾肌肉,纯净水洗净；c、每份虾肌肉分别均质,得到七种、若干个虾滑样本；d、REIMS分析：形成七组、每组若干个REIMS光谱,并经MassLynx软件采集；e、数据分析与统计：计算每组REIMS光谱中的各个质谱数据变量的平均值和标准偏差；在无监督主成分分析和监督正交偏最小二乘判别分析的基础上,确定出七种虾之间的差异变量离子,f、根据差异变量离子建立比对模型,鉴别出虾产品的原料虾种类。本发明具有能对市场上最常见的七种虾类进行实时鉴定的优点,并且重复性好、可靠性好。(The invention discloses an in-situ rapid evaporation ionization mass spectrometry for real-time identification of seven shrimps, which comprises the following steps of a, obtaining seven shrimps, wherein each shrimp is divided into a plurality of parts; b. obtaining seven kinds of shrimp muscle, each kind of shrimp muscle is washed by purified water; c. homogenizing the muscles of each shrimp to obtain seven or a plurality of shrimp slide samples; d. REIMS analysis: forming seven groups of REIMS spectra in each group, and collecting the spectra by MassLynx software; e. data analysis and statistics: calculating the average value and the standard deviation of each mass spectrum data variable in each group of REIMS spectra; on the basis of unsupervised principal component analysis and supervised orthogonal partial least square discriminant analysis, determining difference variable ions among seven shrimps, and f, establishing a comparison model according to the difference variable ions to identify the raw shrimp species of the shrimp product. The invention has the advantage of real-time identification of seven most common shrimps in the market, and has good repeatability and reliability.)

1. The in-situ rapid evaporation ionization mass spectrometry method for real-time identification of seven shrimps is characterized by comprising the following steps of: comprises the following steps of (a) carrying out,

a. obtaining seven kinds of shrimps, wherein the seven kinds of shrimps comprise Thailand penaeus monodon, Hanshi imitated prawn, Pacific white shrimp, Sword-forehead penaeus, Chinese prawn, Japanese prawn and red prawn, and each kind of shrimp is divided into a plurality of parts;

b. removing hard shell, head and intestinal gland of each part of shrimp to obtain seven kinds of shrimp muscle, and cleaning with purified water;

c. homogenizing the muscles of each shrimp to obtain seven or a plurality of shrimp slide samples;

d. REIMS analysis: detecting lipidomics characteristics in each shrimp slide sample by using a REIMS system to form seven groups of REIMS spectra in each group, and collecting the spectra by MassLynx software; the REIMS system comprises an iKnife device and a commercial REIMS interface in a quadrupole rod which are coupled to form a time-of-flight mass spectrometer;

e. data analysis and statistics: calculating the average value and the standard deviation of each mass spectrum data variable in each group of REIMS spectra by using Microsoft excel software, and determining main components causing the lipid difference of seven shrimps by adopting PCA analysis; performing multivariate analysis on each group of REIMS spectra by using SIMCA-P on the basis of unsupervised principal component analysis and supervised orthogonal partial least square discriminant analysis aiming at the principal components to determine difference variable ions among seven shrimps;

f. and establishing a comparison model according to the difference variable ions, and comparing mass spectrum data of the shrimp products in real time by using LiveID software to identify the raw material shrimp species of the shrimp products.

2. The in-situ rapid evaporative ionization mass spectrometry for real-time identification of seven shrimps as claimed in claim 1, wherein: in the step d, detecting the lipidomics characteristics in the shrimp slide samples by cutting the corresponding shrimp slide samples by an iKnife device to generate corresponding aerosol containing gaseous compounds, wherein the cutting speed is 0.8-1.2cm/s, and the cutting length is 1.5-2.5 cm; the aerosol is transmitted into a mass spectrometer through a PTFE tube to form an REIMS spectrum; the aerosol is driven by a venturi pump of a nitrogen source and a PTFE tube is mounted on the interface of the mass spectrometer.

3. The in-situ rapid evaporative ionization mass spectrometry for real-time identification of seven shrimps as claimed in claim 2, wherein: in the step d, leucine enkephalin is dissolved in 2-propanol, the concentration is adjusted to 1.5-2.5 ng/muL to obtain signal enhancement liquid, and when detection is carried out, the signal enhancement liquid is introduced into an REIMS interface (1/16 od,0.002 id) at the flow rate of 100 muL/min.

4. The in-situ rapid evaporative ionization mass spectrometry for real-time identification of seven shrimps as claimed in claim 2, wherein: in the step c, 8-12g of each shrimp slide sample; in the step d, the REIMS spectrum is obtained at a rate of 1scan/s in the mass-to-charge ratio m/z 100-1000 range, and the cutting power of the iKnife device is 35-45 w.

5. The in-situ rapid evaporative ionization mass spectrometry for real-time identification of seven shrimps as claimed in claim 1, wherein: and e, calculating the relative content of each ion in each shrimp sample by a peak area normalization method to obtain mass spectrum data.

Technical Field

The invention belongs to the field of shrimp identification, and particularly relates to an in-situ rapid evaporation ionization mass spectrometry method for identifying seven shrimps in real time.

Background

Seafood is a daily food and an important source of high-quality protein and other functional components. Shrimps belong to arthropoda, subclass of Crustacea and ten-poda, and become one of popular seafood due to their delicious taste and high nutritive value. The shrimp has low calorie and saturated fat content, and high contents of protein, n-3 polyunsaturated fatty acid (PUFA), B vitamins, ferrum and phospholipid. Shrimp from various sources and nutritional values around the world are sold as raw, frozen or processed shrimp products. Thailand Penaeus monodon (TBT), Penaeus harms (PSH), Penaeus pacificus (LSV), Penaeus Vannamei (MNS), Penaeus chinensis (PSC), Penaeus japonicus (PSJ), and Penaeus ruditanus (SAC) are the seven most common shrimp species in the market.

Due to the ever-increasing demand for good quality seafood and the globalization of markets and commerce, fraudulent activities of complex forms of seafood are occurring extensively. Typically, most shrimp species are identified by their full physical appearance. However, after removing the hard shell and head, it is visually difficult for consumers to distinguish the species, and this difficulty becomes more challenging when the shrimp are processed into shrimp slips. Shrimp product fraud is typically conducted by replacing high value species with cheaper ones and deliberately mislabeling geographical sources for economic benefit. Therefore, a rapid, accurate and reliable method for identifying and analyzing shrimp varieties is urgently needed, and the generation of fraudulent behaviors of shrimp products is reduced.

A common method for identifying marine product species is the detection of DNA-based biomarkers, such as multiplex real-time quantitative Polymerase Chain Reaction (PCR), polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and the like. However, for the genotyping method, when DNA contamination or the analyte is complex, the identification accuracy may be unstable. Recently, lipidomics approaches have proven to be an effective tool for monitoring adulteration and identifying different species, due to the lipid profile of each biological species, which is cheaper and more accurate than genotypic approaches. The lipidomics procedure was performed by detecting lipids using modern analytical methods. For example, ultra-high performance liquid chromatography-Triple time of flight tandem mass spectrometry (UPLC-Triple TOF-MS/MS) can be established to distinguish various shrimps according to different lipid contents, and for example, lipidomics fingerprints of rainbow trout and two kinds of salmon detected by hydrophilic interaction chromatography/mass spectrometry (HILIC/MS) are different. In addition, a variety of techniques have been successfully used to analyze lipid markers, such as gas chromatography/mass spectrometry (GC/MS), Nuclear Magnetic Resonance (NMR), matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF/MS), and the like. However, for the lipidomics approach described above, the sample preparation, analysis procedures and statistical steps are always labor intensive and time consuming.

In-situ Rapid Evaporative Ionization Mass Spectrometry (REIMS) is a newly developed environmental ionization mass spectrometry technology, can realize biological tissue identification based on real-time lipidomics characteristics, and does not need sample pretreatment and chromatographic separation. The mass spectral signal is obtained by subjecting the cellular biomass to radio frequency alternating current by means of an electric knife "iKnife" causing local joule heating and cell disruption and desorption of charged and neutral particles. The entire REIMS analysis typically only requires a few seconds. At present, the REIMS method is successfully applied in the technical field of food science with excellent detection performance, for example, the REIMS method is used for distinguishing Chinese soft-shelled turtles cultured in different modes and food-grade meat products, but the real-time identification of the REIMS prawn cannot be realized at present.

Therefore, there is a need for an in situ rapid evaporative ionization mass spectrometry that can identify the seven most common shrimp species on the market in real time.

Disclosure of Invention

The invention aims to provide an in-situ rapid evaporation ionization mass spectrometry method for identifying seven shrimps in real time. The invention has the advantage of real-time identification of seven most common shrimps in the market, and has good repeatability and reliability.

The technical scheme of the invention is as follows: an in-situ fast evaporation ionization mass spectrometry method for real-time identification of seven shrimps comprises the following steps,

a. obtaining seven kinds of shrimps, wherein the seven kinds of shrimps comprise Thailand penaeus monodon, Hanshi imitated prawn, Pacific white shrimp, Sword-forehead penaeus, Chinese prawn, Japanese prawn and red prawn, and each kind of shrimp is divided into a plurality of parts;

b. removing hard shell, head and intestinal gland of each part of shrimp to obtain seven kinds of shrimp muscle, and cleaning with purified water;

c. homogenizing the muscles of each shrimp to obtain seven or a plurality of shrimp slide samples;

d. REIMS analysis: detecting lipidomics characteristics in each shrimp slide sample by using a REIMS system to form seven groups of REIMS spectra in each group, and collecting the spectra by MassLynx software; the REIMS system comprises an iKnife device and a commercial REIMS interface in a quadrupole rod which are coupled to form a time-of-flight mass spectrometer;

e. data analysis and statistics: calculating the average value and the standard deviation of each mass spectrum data variable in each group of REIMS spectra by using Microsoft excel software, and determining main components causing the lipid difference of seven shrimps by adopting PCA analysis; performing multivariate analysis on each group of REIMS spectra by using SIMCA-P on the basis of unsupervised principal component analysis and supervised orthogonal partial least square discriminant analysis aiming at the principal components to determine difference variable ions among seven shrimps;

f. and establishing a comparison model according to the difference variable ions, and comparing mass spectrum data of the shrimp products in real time by using LiveID software to identify the raw material shrimp species of the shrimp products.

In the in-situ rapid evaporation ionization mass spectrometry for real-time identification of seven shrimps, in the step d, the lipidomics characteristics in the shrimp slide sample are detected by cutting the corresponding shrimp slide sample by an iKnife device to generate corresponding aerosol containing gaseous compounds, wherein the cutting speed is 0.8-1.2cm/s, and the cutting length is 1.5-2.5 cm; the aerosol is transmitted into a mass spectrometer through a PTFE tube to form an REIMS spectrum; the aerosol is driven by a venturi pump of a nitrogen source and a PTFE tube is mounted on the interface of the mass spectrometer.

In the in-situ rapid evaporation ionization mass spectrometry for real-time identification of seven shrimps, in the step d, leucine enkephalin is dissolved in 2-propanol, the concentration is adjusted to 1.5-2.5 ng/muL to obtain a signal enhancement solution, and when detection is carried out, the signal enhancement solution is introduced into an REIMS interface (1/16 od,0.002 id) at the flow rate of 100 muL/min.

In the in-situ rapid evaporation ionization mass spectrometry for real-time identification of seven shrimps, in the step c, 8-12g of each shrimp slide sample is obtained; in the step d, the REIMS spectrum is obtained at a rate of 1scan/s in the mass-to-charge ratio m/z 100-1000 range, and the cutting power of the iKnife device is 35-45 w.

In the in-situ rapid evaporation ionization mass spectrometry for real-time identification of seven shrimps, in the step e, the relative content of each ion in each shrimp sample is calculated by a peak area normalization method to obtain mass spectrometry data.

Compared with the prior art, the method obtains spectra of seven most common shrimps in the market and a plurality of samples of each shrimp by using an iKnife-REIMS technology, determines main components causing the lipid difference of the seven shrimps by adopting PCA (principal component analysis), determines differential variable ions in the main components by multivariate analysis, establishes a comparison model by using the differential variable ions, compares mass spectrum data of the prawn products in real time, identifies the raw material shrimp species of the prawn products, does not need to make samples during mass spectrum of the prawn products, and can be realized by using the existing REIMS technology. The verification proves that the precision RSD in the day is less than 7.17 percent, the precision RSD in the day is within the range of 5.93-8.39 percent, and the repeatability is good; the overall real-time identification accuracy of the invention reaches 96.19 percent, and the reliability of the identification result is high. Therefore, the method has the advantage of identifying seven most common shrimps in the market in real time, and has good repeatability and reliability.

Drawings

Figure 1 is a REIMS spectrum of a shrimp slip sample of an MNS shrimp.

FIG. 2 is a graph showing a comparison of fatty acid ion REIMS spectra obtained from any one shrimp slide sample among seven kinds of shrimps.

FIG. 3 is a graph showing a comparison of the REIMS spectra of phospholipid ions obtained from any one shrimp slide sample of seven shrimps.

FIG. 4 is a graph of the overall identification results of a plurality of shrimp product samples identified according to the present invention.

FIG. 5 is a graph of the scores of phosphoric acid and fatty acid for each of seven shrimps.

Fig. 6 is a front view of the iknife cutting deck.

Fig. 7 is a left side view of the cartridge.

Fig. 8 is a front view of the doctor blade.

Fig. 9 is a left side view of the platen.

Detailed Description

The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.

Examples are given. An in-situ fast evaporation ionization mass spectrometry method for real-time identification of seven shrimps comprises the following steps,

a. seven kinds of shrimps including thailand penaeus monodon, han's imitated prawn, pacific white shrimp, prawns, penaeus chinensis, penaeus japonicus and red shrimp were obtained, and each shrimp was divided into several parts.

b. Removing hard shell, head and intestinal gland of each shrimp to obtain seven kinds of 18 kinds of shrimp muscle, and cleaning with purified water.

c. Each shrimp muscle was homogenized separately to give seven, 18 shrimp slide samples each, 8-12g, preferably 10 g.

d. REIMS analysis: detecting lipidomics characteristics in each shrimp slide sample by using a REIMS system (Vorte GmbH, Beijing, China) to form seven groups of REIMS spectra, wherein each group of REIMS spectra is collected by MassLynx software; the REIMS system includes an iKnife device (WSD151, Weller, germany) coupled to a commercial REIMS interface in a quadrupole to form a time-of-flight mass spectrometer (QTOF-MS, Xevo G2-XS); the REIMS spectrum is obtained at a rate of 1scan/s in the range of mass-to-charge ratio m/z 100-1000, and the cutting power of the iKnife device is 35-45 w; detecting lipidomic characteristics in the shrimp slide sample by cutting the corresponding shrimp slide sample by an iKnife device to generate corresponding aerosol containing gaseous compounds, wherein the cutting speed is 0.8-1.2cm/s, the optimal cutting speed is 1cm/s, the cutting length is 1.5-2.5cm, the optimal cutting length is 2cm, and the cutting depth is 1.2 mm; the aerosol is transmitted into a mass spectrometer through a PTFE pipe (the drift diameter is 2.53mm) to form a REIMS spectrum; the aerosol is driven by a Venturi pump of a 2bar nitrogen gas source, and a PTFE tube is arranged on an interface of a mass spectrometer; in order to subtract the spectrum background and improve the signal intensity, leucine enkephalin is dissolved in 2-propanol, the concentration is adjusted to 1.5-2.5 ng/muL, the optimal concentration is 2 ng/muL, and a signal enhancement solution is obtained, and when detection is carried out, the signal enhancement solution is introduced into an REIMS interface (1/16 'od, 0.002' id) at the flow rate of 100 muL/min. If no signal enhancement liquid is added during detection, the reliability of the identification of the invention is reduced by more than 10%.

Mass spectra were recorded in real time as slides were cut by the iKnife instrument and a large number of replicate spectra were obtained, such as the REIMS spectra of a slide from an MNS shrimp shown in fig. 1, where two major clusters of molecular ion peaks were observed in the ranges of m/z 200-. As shown in FIGS. 2 and 3, the REIMS spectra of the rest samples, in the ranges of m/z 200-. The m/z554.2615 ion peak generated from the internal standard leucine enkephalin was used for lock mass correction.

In seven kinds of shrimps, respectively taking the REIMS spectrum of a shrimp slide sample, integrating the peak areas of ions, calculating the relative content of the ions in two main molecular ion peak clusters by a peak area normalization method to obtain the results shown in tables 1 and 2, wherein the results shown in the table 1 show that the fatty acid ion compositions of the seven kinds of shrimps are remarkably different, and 19 kinds of fatty acids and oxygen-containing fatty acids are identified, the mass error is less than or equal to 5.05ppm and the fatty acids comprise saturated, monounsaturated and polyunsaturated fatty acid ions. Table 2 shows that the phospholipid molecules of seven kinds of shrimps and 45 kinds of phospholipid molecules detected in 7 kinds of shrimp slide samples are different, and the identification quality error is less than or equal to 9.30 ppm.

TABLE 1

TABLE 2

e. Data analysis and statistics: using Microsoft excel software to calculate the mean and standard deviation of each mass spectral data variable in each set of REIMS spectra, PCA analysis was performed and the variance of a large number of interrelated variables was converted into a small set of uncorrelated principal components, the first two principal components of PCA (fatty acids and phospholipids) were extracted and scored and as shown in fig. 5, the data points were well separated into seven feature clusters, meaning that the samples were well distributed spatially, demonstrating that the two principal components of the seven shrimp lipid component changes were fatty acids and phospholipids, i.e., these fatty acid ions and phospholipid ions in tables 1 and 2.

Multivariate analysis was performed on fatty acid and phospholipid ions in each set of REIMS spectra using SIMCA-P based on unsupervised principal component analysis and supervised orthogonal partial least squares discriminant analysis (i.e., OPLS-DA analysis). The statistical fatty acid ion data and phospholipid ion data are those in tables 1 and 2, but include all shrimp slip samples. As a result of analysis, the number of the differential variable ions among seven kinds of shrimps was 16, that of the fatty acid ions was 7, and that of the phospholipid ions was 9, and the most important of the 16 differential variable ions were m/z255.2, m/z 279.2, m/z 301.2, m/z 327.2, m/z 699.5, and m/z 742.5.

f. Establishing a comparison model according to six differential variable ions of m/z255.2, m/z 279.2, m/z 301.2, m/z 327.2, m/z 699.5 and m/z 742.5, and identifying the raw material shrimp species of the shrimp products by utilizing mass spectrum data of the LiveID software prawn products for real-time comparison. When the mass spectrum identification is carried out on the prawn product, the in-situ rapid evaporation ionization mass spectrum technology is adopted, and the raw material prawn species of the prawn product can be obtained by comparison without preparing a sample.

The method of the invention is repeatedly verified: the reproducibility and accuracy of the present invention was evaluated for iKnife-REIMS in terms of daytime and intra-day precision as expressed in Relative Standard Deviation (RSD), and the results are shown in table 3. LSV samples were used as representatives, fatty acid ions (m/z 255.2, 279.2, 301.2 and 327.2) and phospholipid ions (m/z 699.5)

And 742.5) was selected as the difference variable ion. The intra-day precision was calculated by the error of repeated ionization of the same shrimp sample batch, while the inter-day precision was calculated by sample analysis for three consecutive days. As shown in Table 3, the target ion has an intra-day precision RSD of less than 7.17% and an inter-day precision RSD in the range of 5.93-8.39%, indicating that the invention has good repeatability.

TABLE 3

The invention carries out reliability verification on the method: seven shrimp products were tested separately according to the above method, 15 samples each, as shown in fig. 4, the overall real-time recognition accuracy reached 96.19%, only three blind samples of all samples were misidentified, and all TBT, LSV, MNS, and SAC samples were correctly classified (100%). For PSH, PSC and PSJ, 93.33% of the samples were correctly identified because three of the samples (one sample per species) were misidentified as PSJ, TBT, PSH, respectively. The reliability of the invention for identifying shrimp products is high.

At present, when the iKnife is used for cutting, a person holds a pen-shaped cutter bar on the iKnife to cut, the cutting length, depth and speed are difficult to control, the top surface of an object to be cut is often uneven, the cutting depth is more easily difficult to be uniform, when a repeatability test or a contrast test is carried out, the cutting length, depth and speed of each cutting are difficult to keep the same, variable factors are increased, the test is easy to be inaccurate, and even completely different test results are produced.

An iknife cutting platform, as shown in fig. 6-9, comprises a bottom plate 1, wherein the bottom of the bottom plate 1 is provided with a supporting leg 2, a straight beam 3 is arranged above the bottom plate 1, two ends of the straight beam 3 are both provided with a stand column 4 connected with the bottom plate 1, one side of the straight beam 3 is provided with a slide rail 5, the slide rail 5 is provided with a slide block 6, the slide block 6 is provided with an air cylinder 7, the output end of the air cylinder 7 is provided with a transfer block 8, one side of the transfer block 8 is provided with a scraper 9, the scraper 9 is provided with a vertical long hole 38, a pin shaft 39 connected with the transfer block 8 is arranged in the long hole 38, the end of the pin shaft is provided with a guide plate 40 for limiting the scraper 9, the lower end of the scraper 9 is bent and inclined, the transfer block 8 is provided with a chuck 10 for fixing a cutter bar, the chuck 10 is tubular, and the side wall of the chuck 10 is provided with a compression screw 11; the straight beam 3 is provided with a first motor 12, the first motor 12 is a stepping motor with a driver, the output end of the first motor 12 is provided with a screw 13, the screw 13 is provided with a nut 14, and the nut 14 is connected with the sliding block 6 through a bracket 15;

a bedplate 16 for placing a sample to be cut is arranged on the bottom plate 1, a baffle plate 17 is arranged on the bedplate 16, a movable plate 18 and a fixed plate 19 are sequentially arranged on one side of the baffle plate 17, the baffle plate 17 and the movable plate 18 are equal in height, the top surface of the baffle plate 17 is equal in height with the lower end of the scraper 9, a guide shaft 20 is arranged on one side of the movable plate 18, one end of the guide shaft 20 penetrates through the fixed plate 19, a spring 21 sleeved on the guide shaft 20 is arranged between the movable plate 18 and the fixed plate 19, and a limit block 22 is arranged between the baffle plate 17 and the movable plate 18;

a first rotating cylinder 23 with an open top and a second rotating cylinder 24 with an open top are sequentially arranged on one side of the bedplate 16, the first rotating cylinder 23 and the second rotating cylinder 24 both extend downwards through the bottom plate 1, and the first rotating cylinder 23 and the second rotating cylinder 24 are both rotationally connected with the bottom plate 1 through a bearing 25; a first gear 26 is arranged on the first rotary drum 23, a second gear 27 connected with the first gear 26 is arranged on the second rotary drum 24, the diameter of the first gear 26 is 1/2 of the second gear 27, a rotating shaft 28 is arranged at the bottom of the second rotary drum 24, a driven wheel 29 is arranged on the rotating shaft 28, the driven wheel 29 is connected with a driving wheel 31 through a belt 30, and a second motor 32 with an output end connected with the driving wheel 31 is arranged on the bottom plate 1; abrasive particles 34 with the diameter of 0.3-0.5mm are arranged in the first rotary drum 23, alcohol 35 is arranged in the second rotary drum 24, a sponge plate 36 is arranged on the liquid level of the alcohol 35, and limiting rings 37 fixed with the second rotary drum 24 are arranged on the upper side and the lower side of the sponge plate 36.

The device also comprises a controller 33 of the PLC, the first motor 12 and the second motor 32 are both connected with the controller 33, the cylinder 7 is connected with a high-pressure air source through an electromagnetic valve, and the electromagnetic valve is connected with the controller 33; a retro-reflection type photoelectric sensor 34 is arranged above the first rotating drum 23 and the second rotating drum 24, the photoelectric sensor 34 is fixed at the bottom of the straight beam 3, and the photoelectric sensor is connected with the controller 33.

The working principle of the iknife cutting platform is as follows: the movable plate 18 is pushed to move the movable plate 18 away from the baffle 17, the cut object is placed between the movable plate 18 and the baffle 17, the movable plate 18 is loosened, the movable plate 18 moves back under the action of the spring 21 until the movable plate contacts with the limiting block 22, the cut object is extruded to be higher in height and longer in length, and the cut object with the higher height is higher than the baffle 17. According to the required iknife cutting length, the cut object is cut off correspondingly by a prepared blade, and the cut part is removed. According to the required iknife cutting depth, the compression screw 11 is loosened, and the height of the cutter bar is adjusted. The controller 33 is used to set the cutting speed of iknife.

The controller 33 is started, the controller 33 outputs a first signal to the second motor 32, the second motor 32 is started, the second motor drives the driving wheel 31 to rotate, the driving wheel 31 drives the driven wheel 29 to rotate through the belt 30, the driven wheel 29 drives the second drum 24 to rotate through the rotating shaft 28, the second drum 24 drives the second gear 27 to rotate, and the second gear 27 drives the first drum 23 to rotate through the first gear 26.

The controller 33 outputs a second signal to the first motor 12, the second motor 12 drives the screw rod 13 to rotate, the nut 14 moves horizontally, the nut 14 drives the sliding block 6 to move through the support 15, the scraper 9 and the cutter bar move synchronously, the scraper 9 firstly passes through the cut object to scrape the upper end of the cut object, and then the cutting end at the lower end of the cutter bar passes through the cut object at a constant speed. When the cylinder 7 passes the photoelectric sensor 34 above the first drum 34, the photoelectric sensor 34 generates a third signal and sends the third signal to the controller 33, and the controller 33 sends a fourth signal, a fifth signal, a sixth signal and a seventh signal to the first motor 12, respectively, to the electromagnetic valve 12. The first motor 12 is turned off after receiving the fourth signal; the electromagnetic valve is opened after receiving the fifth signal, so that the air cylinder extends out, the cutting end of the guide rod extends into the first rotary cylinder 34, and residual substances on the surface are primarily wiped off by the abrasive particles 34; the electromagnetic valve is closed after receiving the sixth signal, and the air cylinder contracts; the first motor 12 is started by receiving the seventh signal, and the air cylinder 7 continues to move horizontally.

When the cylinder 7 moves to the photoelectric sensor 34 above the second drum 24, the photoelectric sensor 34 generates an eighth signal and sends the eighth signal to the controller 33, the controller 33 sequentially sends a fourth signal to the first motor 12, a fifth signal to the electromagnetic valve, a sixth signal to the electromagnetic valve and a ninth signal to the first motor 12, and the first motor 12 is turned off after receiving the fourth signal; the electromagnetic valve is opened after receiving the fifth signal, so that the air cylinder extends out, the cutting end of the cutter bar extends into the first rotary drum 34 and is continuously scrubbed by the sponge plate 36, and the cleanness of the cutting end of the cutter bar is ensured; the electromagnetic valve is closed after receiving the sixth signal, and the air cylinder contracts; the first motor 12 receives the ninth signal and reverses to drive the nut 14 back to the home position.

The iknife cutting platform has the advantages that when repeatability and contrast experiments are carried out, the cutting length, the depth and the speed of cutting at each time can be guaranteed to be the same, the cutting end head which finishes cutting at each time can be automatically cleaned, uncertain factors are further reduced, the accuracy of the experiments is improved, the structure is simple, the failure rate is low, and the use is convenient. When cleaning the cutting end, the rotating abrasive particles 34 are used for removing sinter on the cutting end, and the sponge board soaked in alcohol is used for further taking out dust on the cutting end, so that high cleaning degree is ensured. Set up the sponge board on alcohol, and need not the direct cutting end that washs of alcohol, because alcohol spills over easily under the rotation, the sponge board has played the effect of baffle to reduce alcohol and volatilize, reduce the cost, reduce the supplementary step of adding of alcohol. When the cutting end descends into the first drum 23 or the second drum 24, the scraper 9 is blocked by the corresponding drum and cannot enter, at this time, the pin 39 moves downwards continuously in the long hole 38, and the scraper 9 does not collide with the corresponding drum and is only attached.