CN103411953B - Method for rapidly detecting pesticide emulsifiable solution preparation on site - Google Patents

Abstract

The invention relates to the technical field of pesticide detection, in particular to a method for rapidly detecting a pesticide emulsifiable solution preparation on site, which is used for detecting active ingredients, whether forbidden ingredients are contained and ingredient concentrations of the pesticide emulsifiable solution preparation on site based on a Raman spectrum principle, wherein distinguishable ingredients comprise more than 30 common pesticides and more than 10 forbidden or limited pesticides, and single-sample test can be completed within 30 minutes. Through comparison and verification with objective results including detection results of pesticide detection authorities, the qualitative detection rate of the pesticide detection authority detection method reaches 76.7%, the total accuracy rate reaches 73.3%, the accuracy rate with the quantitative measurement error within 30% reaches 59.3%, and the accuracy rate with the quantitative measurement error within 20% reaches 48.1%. The method for comparing the chromatography and the mass spectrum in the test laboratory has the advantages of simple operation, capability of on-site test, short test time and the like.

Description

A method for on-site rapid detection of pesticide emulsifiable concentrate preparations

technical field

The invention relates to the technical field of pesticide detection, in particular to a method for on-site rapid detection of pesticide emulsifiable concentrate preparations.

Background technique

At present, there is still no rapid detection technology that can be used in the field of pesticide detection. The monitoring of pesticides on the market generally adopts the method of sampling and sending to the detection and experiment center of the agricultural department for detection. The main detection methods are chromatographs and chromatograms. Expensive, complex testing technology, and few qualified testing points. In many places, only prefecture-level cities or even provincial-level institutions can conduct testing, resulting in high cost of inspection and long feedback time, which seriously affects grassroots monitoring and law enforcement departments to crack down on illegal activities. The working efficiency of pesticides exceeding the standard.

Raman spectroscopy is a technology developed in the past 10 years. It has the advantages of fast, simple, non-destructive and direct detection of samples, and is very suitable as a rapid on-site detection method. The function is still limited to the category of pure substance identification, and cannot be directly used for the detection of mixtures such as pesticides. Most research institutes and colleges on the use of Raman spectroscopy for pesticide detection are still limited to preliminary feasibility studies on the qualitative and quantitative detection of a few types of pesticides with known components. , unknown, complex pesticides have the ability to detect and distinguish, and there is no systematic research report yet.

Therefore, there is an urgent need to address the defects of the prior art and provide a method for detecting multiple types of pesticides with unknown components and complex pesticides based on Raman spectroscopy.

Contents of the invention

The object of the present invention is to aim at the deficiencies of the prior art, and provide a method based on the principle of Raman spectroscopy, which can quickly detect pesticide emulsifiable concentrate preparations on site.

The present invention is achieved by the following technical inventions.

A method for on-the-spot rapid detection of pesticide emulsifiable concentrate preparations comprises the following steps:

a. Preparation: Collect the Raman features of several kinds of pesticide emulsifiable concentrate preparations in the solution system, assign distinguishing features to several kinds of pesticide emulsifiable concentrate preparations, store these features in the database, and use them for component identification by data processing software;

b. Prepare fluorescence eliminating agent and measure the density of pesticide emulsifiable concentrate preparation;

c. The first round of testing: Take the pesticide emulsifiable concentrate preparation into the sample bottle, add the fluorescence eliminating agent in multiples, and then start the test program of the Raman spectrometer to test the pesticide emulsifiable concentrate preparation; when the signal baseline level is close to 30,000, start the first round Test, test three times in a row and record the dilution factor, store the data;

d. The second round of testing: After the first round of testing is completed, add the fluorescence eliminating agent in multiples and test the pesticide emulsifiable concentrate preparation. When it is observed that the signal baseline level is close to 20,000, test three times in a row and record the dilution factor, and store the data;

e. Data processing and analysis: Process the data with data processing software to obtain the results of each qualitative test. If there are two or more results in a certain round of tests showing that a certain ingredient is contained, it is judged that the pesticide emulsifiable concentrate preparation contains this ingredient.

Wherein, in the step b, the preparation of the fluorescence elimination agent specifically includes: dissolving 50 mg of the original fluorescence elimination agent into 1 ml of water, injecting 9 ml of pure acetone after completely dissolving, mixing well, and preparing the fluorescence elimination agent. The original agent for fluorescence elimination is the product numbered YZ-903 provided by Shanghai Shenzhi Chemical Technology Co., Ltd., which is a high molecular sulfur silicon compound, and is a kind of fluorescent whitening agent widely used in the textile industry. It can react with fluorescent functional groups to convert them into non-fluorescent groups; it is white granular with a slightly pungent odor, water solubility can reach 20%, and the pH value of 1% aqueous solution is 6-7. It works better in acidic environment (pH 4) and higher water temperature (60°C).

Wherein, in the step b, measuring the density of the pesticide emulsifiable concentrate preparation is specifically: placing the sample bottle on an electronic balance, clearing 0, taking 1ml of the pesticide emulsifiable concentrate preparation, fully injecting it into the sample bottle, and recording the mass at this time; then clearing 0, After repeating the above steps twice, finally find the average value of the three times to obtain the density of the pesticide emulsifiable concentrate preparation.

Wherein, in the step c, the test procedure for starting the Raman spectrometer is specifically set: start the Raman spectrometer, open the test software interface, set the laser light intensity to 100%, and the integration time to 2×35000 milliseconds.

Further, after the step e, step f is also included to convert the concentration value: according to the dilution factor, the density of the pesticide emulsifiable concentrate preparation, the peak intensity provided by data processing, and the formula for the relationship between peak intensity and concentration, the concentration value of the pesticide emulsifiable concentrate preparation is converted .

Wherein, in the conversion concentration value of the step f, the determination method of the relationship between the peak intensity and the concentration is specifically: dissolving the pure product agent of the pesticide original drug into the fluorescence eliminating agent, and making the concentrations respectively 0.5%, 1%, 2%, Five groups of solutions of 5% and 10%, each group of solutions were tested, repeated three times, and then each group of data was processed to obtain the peak value of the intensity measurement peak of each group of solutions, and the three average values were taken to obtain the strength of each group of solutions Measure the average peak value of the peak; also find the peak value of the internal standard peak signal 1706cm ^-1 of each group of solutions, get the average value three times, and divide the obtained average peak value by 9/10 to obtain the average peak value of acetone 1706cm ^-1 at 100% concentration; each group The ratio of the average peak value of the intensity measurement peak to the acetone ^1706cm average peak value of 100% concentration is the relative intensity of this group of solutions, get the relative intensity of five groups of solutions and the concentration of this group and carry out linear regression analysis, obtain peak intensity and concentration The relationship is linear.

Wherein, in the step f, the determination method of the relationship between the peak intensity and the concentration is specifically: dissolving the pure product agent of the pesticide original drug into the fluorescence eliminating agent, and making the concentrations respectively 0.5%, 1%, 2%, 5%, 10% and 25% of the six groups of solutions, each group of solutions were tested, repeated three times, and then each group of data was processed to find the peak value of the intensity measurement peak of each group of solutions, and the three average values were taken to obtain the strength of each group of solutions Measure the average peak value of the peak; also find the peak value of the internal standard peak signal 1706cm ^-1 of each group of solutions, get the average value three times, and divide the obtained average peak value by 9/10 to obtain the average peak value of acetone 1706cm ^-1 at 100% concentration; each group The ratio of the average peak value of the intensity measurement peak and the 1706 cm ^-1 average peak value of the acetone of 100% concentration is the relative intensity of this group of solutions, get the relative intensity of six groups of solutions and the concentration of this group to carry out linear regression analysis, obtain peak intensity and The linear relationship of the concentration relationship.

Wherein, in the step f, the conversion of the concentration value of the pesticide emulsifiable concentrate preparation is specifically as follows: according to the intensity value of the target signal peak, the diluted concentration value is converted by the peak relative intensity and concentration relationship formula, and the diluted concentration value is multiplied by The mass dilution factor gives the concentration value before dilution.

Wherein, the relative peak intensity is equal to the ratio of the intensity value of the target signal peak to the 1706cm ^-1 signal of acetone at 100% concentration; the volume ratio of acetone in the solution is calculated according to the dilution factor, and the measured signal intensity of acetone 1706cm ^-1 is divided by The volume ratio of acetone is converted to the intensity of the internal standard signal of 100% acetone at 1706 cm ⁻¹ ; wherein, the volume ratio of acetone is related to the dilution factor as follows: The relationship between the mass dilution factor and the dilution factor is

Wherein, in the step a, the pesticide emulsifiable concentrate preparation includes the following 49 kinds: DDT, dicofol, γ-HCH, DDT D, aldicarb, carbofuran, terbufos, methamidophos, isocarbosulfur Phosphorus, isofenphos-methyl, α-HCH, parathion-methyl, parathion, DDT E, fenvalerate, monocrotophos, phosphamide, fipronil, pyrimethanil, acetamide Phosphorus, dimethophos, malathion, fenitrothion, deltamethrin, cypermethrin, dichlorvos, dimethoate, fenpropathrin, chlorpyrifos, diazinon, profenofos, difenoconazole, Dowe, carbaryl, triazophos, imidacloprid, pyridaben, triadimefon, bifenthrin, diflubenzuron, phoxim, phosalthion, lambda-cyhalothrin, abamectin , procymidone, iprodione, vinclozolin, dicloprid, chlorothalonil.

Compared with the prior art, the present invention has the following advantages:

The method for on-site rapid detection of pesticide emulsifiable concentrate preparations of the present invention is based on the principle of Raman spectroscopy, on-site rapid detection of pesticide emulsifiable concentrate preparations, and on-site detection of the active ingredients of pesticide emulsifiable concentrate preparations, whether they contain prohibited ingredients and the concentration of ingredients, and the recognizable components include More than 30 commonly used pesticides and more than 10 banned or restricted pesticides (coverage can be expanded), single-sample testing can be completed within 30 minutes. Through comparison and verification with the objective results including the detection results of the pesticide detection authority, the qualitative detection rate of the present invention reaches 76.7%, the total accuracy rate reaches 73.3%, and the accuracy rate of the quantitative measurement error within 30% reaches 59.3%. The quantitative measurement error is within 20%, and the accuracy rate reaches 48.1%. Compared with the chromatographic and mass spectrometry methods in the test laboratory, it has the advantages of simple operation, on-site testing, and short testing time; compared with the traditional Raman spectroscopy technology, the present invention expands its substance identification function from pure substances to the category of mixtures, which is a good way for Raman A huge advance in the application of Mann spectroscopy.

Description of drawings

Fig. 1 is a graphic representation of the Raman shift value comparison between the Raman spectrum of 10% chlorpyrifos solution and the Raman spectrum of pure chlorpyrifos.

Figure 2 is a graphical representation of the Raman signal of 3% Metamiprid solution under different dilution conditions.

Figure 3 is an illustration of the dark signal obtained by the Raman spectrometer.

Figure 4 is a diagram of the original signal obtained by the Raman spectrometer.

Figure 5 is a signal diagram after subtracting the dark signal.

Figure 6 is a graphical representation of the signal before and after smoothing.

FIG. 7 is a graph showing the trend polarity of the spectral lines of the Raman spectrum.

Fig. 8 is a graphic representation of the relationship between the 658 cm ^-1 signal intensity and the concentration of pure dimethoate dissolved in dichlorprid solution and acetone.

Fig. 9 is a graphical representation of the relationship between the volume ratio of acetone obtained by diluting xylene with acetone and the signal intensity at 1706 cm ⁻¹ .

Fig. 10 is a graphic representation of the relationship between the volume ratio of acetone obtained by diluting lambda-cyhalothrin emulsifiable concentrate (GLFQ) with acetone and the signal intensity at 1706 cm ⁻¹ .

Fig. 11 is a graphical representation of the relationship between the volume ratio of acetone obtained by diluting toluene with acetone and the signal intensity at 1706 cm ⁻¹ .

Fig. 12 is a graphic representation of the relationship between the relative strength and concentration of 658/1706 of pure dimethoate dissolved in dichlorprid solution and acetone.

Figure 13 is a graphical representation of the concentration curves of Metamiprid.

Figure 14 is a graphical representation of the concentration curve of chlorpyrifos.

Detailed ways

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

The invention includes a hardware device and a software system, and the hardware includes the following parts:

1. Portable Raman spectrometer 1

Parameters: excitation wavelength: 785nm±1nm, spectral range: 175cm ^-1 -3150cm ^-1 , spectral resolution 10cm ^-1 912nm, detector: TE cooled CCD array, pixel 2048×1 pixel 14μm×200μm each image Yuan, laser output power > 300mW, integration time 5 milliseconds - 2 minutes.

2. Several sample bottles and solvent bottles with a diameter of 22mm; one 5ml pipette equipped with several pipettes; one portable electronic balance; YZ-903 product), analytical grade acetone, some distilled water.

3. Test fixture.

A kind of concrete method step of the method that a kind of pesticide emulsifiable concentrate preparation of the present invention is carried out on-the-spot rapid detection is as follows:

a. Prepare:

Collect the Raman features of 49 kinds of pesticide emulsifiable concentrate preparations in the solution system, assign resolution features to the 49 kinds of pesticide emulsifiable concentrate preparations, and store these features in the database for use by data processing software for component identification.

The 49 kinds of pesticide emulsifiable concentrate preparations are: DDT T, dicofol, γ-666, DDT D, aldicarb, carbofuran, terbufos, methamidophos, isocarbophos, isofenphos-methyl, α -Hex, methylparathion, parathion, DDT E, fenvalerate, monocrotophos, phosphamide, fipronil, pyrimethanil, acephate, methapon, malathion Phosphorus, fenitrothion, deltamethrin, cypermethrin, dichlorvos, dimethoate, fenpropathrin, chlorpyrifos, diazinon, profenofos, difenoconazole, methomyl, carbaryl, triazole Phosphorus, imidacloprid, pyridaben, triadimefon, bifenthrin, diflubenzuron, phoxim, chlorthion, lambda-cyhalothrin, abamectin, procymidone, iprodione, Vinclozolin, Methamiprid, Chlorothalonil.

b. Prepare fluorescence eliminating agent and measure the density of pesticide emulsifiable concentrate preparation:

b1. Preparation of fluorescence elimination agent: Dissolve 50mg of the original fluorescence elimination agent into 1ml of water, inject 9ml of pure acetone after completely dissolving, and mix well to obtain a fluorescence elimination agent with a mass percentage of about 0.6% (hereinafter referred to as "0.6% fluorescence elimination agent ");

b2. Measure the density of the pesticide emulsifiable concentrate preparation: put the sample bottle loaded with the sample on the electronic balance, clear 0, take 1ml sample with a pipette, inject the sample bottle completely, record the mass at this time, then clear 0, and repeat the above steps Twice, the last three mass averages are the density of the pesticide emulsifiable concentrate preparation.

c. The first round of testing:

c1. Take the pesticide emulsifiable concentrate preparation into the sample bottle, and add the fluorescence eliminating agent in multiples;

Specifically: use a pipette to transfer 0.5ml of pesticide emulsifiable concentrate preparation to the sample bottle, and add fluorescence eliminating agent in multiples (the amount of fluorescence eliminating agent added each time is the multiple of pesticide emulsifiable concentrate preparation, such as 0.5ml, 1ml, 1.5ml , 2ml, etc.), put the sample bottle at the test point, and align the center of the laser window of the probe with the center line of the sample bottle. The sample should be allowed to stand for 1 minute after the elimination agent and before the test;

c2. Start the test program of the Raman spectrometer, turn on the Raman spectrometer, open the test software interface, set the laser light intensity to 100%, and the integration time to 2×35000 milliseconds;

c3. Test pesticide emulsifiable concentrate preparations; when the baseline signal level is observed to be close to 30,000, start the first round of testing, test three times in a row and record the dilution factor, and store the data; after each measurement, turn the sample bottle at an angle of about 90 degrees, and then proceed to the next step One measurement.

d. The second round of testing: After the first round of testing is completed, add the fluorescence eliminating agent in multiples and test the pesticide emulsifiable concentrate preparation. When it is observed that the signal baseline level is close to 20,000, test three times in a row and record the dilution factor, and store the data; After the first measurement, turn the sample bottle at an angle of about 90 degrees, and then proceed to the next measurement.

e. Data processing and analysis: Process the data with data processing software to obtain the results of each qualitative test. If there are two or more results in a certain round of tests showing that a certain ingredient is contained, it is judged that the pesticide emulsifiable concentrate preparation contains this ingredient.

f Converted concentration value: Calculate the concentration value of the pesticide emulsifiable concentrate preparation according to the dilution factor, the density of the pesticide emulsifiable concentrate preparation, the peak intensity provided by data processing, and the relationship formula between peak intensity and concentration.

The determination method of the relationship between the peak intensity and the concentration is as follows: dissolve the pure product agent of the pesticide original drug into the fluorescence eliminating agent, and make five groups of solutions with concentrations of 0.5%, 1%, 2%, 5%, and 10% respectively; The concentration of the pesticide emulsifiable concentrate preparation is higher, and the solution with a concentration of 25% is added. Each group of solutions is tested, repeated three times, then each group of data is processed, and the peak value of the intensity measurement peak of each group of solutions is obtained, and the average value of three times is obtained to obtain the average peak value of the intensity measurement peak of each group of solutions; The peak value of the internal standard peak signal 1706cm ^-1 of the group solution, get the average value of three times, the obtained average peak value is divided by 9/10 to obtain the acetone 1706cm ^-1 average peak value of 100% concentration; the average peak value of the intensity measurement peak of each group and 100% The ratio of the average peak value of the concentration of acetone at 1706cm ^-1 is the relative intensity of the solutions in this group. The relative intensity of five (six) groups of solutions and the concentration of this group are used for linear regression analysis to obtain the linear relationship between peak intensity and concentration.

The concentration value of the converted pesticide emulsifiable concentrate preparation is specifically: according to the intensity value of the target signal peak, the concentration value after dilution is converted by the peak relative intensity and concentration relationship formula, and the concentration value after dilution is multiplied by the mass dilution factor to obtain the concentration before dilution value.

Wherein, the relative peak intensity is equal to the ratio of the intensity value of the target signal peak to the 1706cm ^-1 signal of acetone at 100% concentration; the volume ratio of acetone in the solution is calculated according to the dilution factor, and the measured signal intensity of acetone 1706cm ^-1 is divided by The volume ratio of acetone is converted to the intensity of the internal standard signal of 100% acetone at 1706 cm ⁻¹ ; wherein, the volume ratio of acetone is related to the dilution factor as follows: The relationship between the mass dilution factor and the dilution factor is

The working principle of a method for on-site rapid detection of pesticide emulsifiable concentrate preparation of the present invention is as follows:

To detect whether a certain component is contained in the pesticide emulsifiable concentrate preparation, it is necessary to know the Raman characteristics of this component in the solution system. The Raman characteristics of the pure pesticide emulsifiable concentrate preparation will be partially covered in the solution system, but its main characteristics can still be revealed, and the Raman shift value is basically unchanged. The Raman spectrum and It can be seen from the Raman shift value comparison chart of the Raman spectrum of pure chlorpyrifos that the upper picture in Figure 1 is the Raman spectrum of 10% chlorpyrifos solution, and the lower picture is the Raman spectrum of pure chlorpyrifos.

The identification method of pesticide components adopted in the present invention is completely different from the traditional Raman spectrum technology for the full-spectrum identification method of pure substances. The identification of a certain component is based on several resolution features extracted from the Raman features of its solution system. , this method has high reliability in a limited range of detected substances, and the detection range can be extended as the distinguishing features of more kinds of substances are confirmed.

The present invention collects the Raman features of 18 prohibited and restricted pesticides and 31 commonly used pesticides in the solution system, and assigns distinguishing features to all pesticides, and these features are stored in the database for component identification by data processing software calls.

18 banned and restricted pesticides include: DDT, Dicofol, γ-Hexa, DDT D, Aldicarb, Carbofuran, Terbufos, Methamidophos, Isocarbophos, Isofenphos-methyl , α-666, methyl parathion, parathion, DDT E, fenvalerate, monocrotophos, phosphamide, fipronil.

31 commonly used pesticides include: pyrimethanil, acephate, methafos, malathion, fenitrothion, deltamethrin, cypermethrin, dichlorvos, dimethoate, fenpropathrin, chlorpyrifos, diazine Phosphorus, profenofos, difenoconazole, methomyl, carbaryl, triazophos, imidacloprid, pyridaben, triadimefon, bifenthrin, diflubenzuron, phoxim, sulfasulfur Phosphorus, lambda-cyhalothrin, abamectin, procymidone, iprodione, vinclozolin, dicloprid, chlorothalonil.

As an on-site rapid detection method, the present invention is equipped with a portable Raman spectrometer. Generally speaking, the test conditions of the portable Raman spectrometer are very wide, but due to the high signal-to-noise ratio required for the component analysis of the pesticide emulsifiable concentrate preparation , the present invention still performs necessary optimization and determination of test conditions, including light intensity, integration time, sample loading container, distance between probe and sample, test fixture, etc., and all additional conditions meet the requirements of on-site operation.

The optimized test conditions are 100% light intensity, 2×35 second integration time, loading samples with a sample bottle with a diameter of 22mm, and the probe is 2-3mm away from the sample bottle.

Most pesticide emulsifiable concentrate preparations contain a large amount of fluorescent substances, which will produce strong fluorescence when irradiated by the laser of the Raman spectrometer during the test, which will interfere or even cover up the Raman signal. The present invention uses the method of diluting the emulsifiable oil by adding a fluorescence eliminating agent to weaken or eliminate fluorescence. Compared with the polarization modulation method, frequency-shift excitation method, high-frequency modulation method, gating method, etc. commonly used in Raman spectrum testing, it is simple and effective. Good, no need to modify equipment and low cost. The formula of the fluorescence eliminating agent of the present invention is optimized for the effects of different ambient temperatures, and has stable properties and does not affect or interfere with the test results. Fig. 2 is the Raman signal diagram of 3% dichlorprid solution under different dilution conditions. Under the condition of 24-fold dilution, 3% metamiprid was diluted 10 times in the fluorescence eliminating agent (the curve marked with + in the figure), and 3% Metamiprid was diluted 20 times in the fluorescence eliminating agent (marked with ■ in the figure). The Raman signal of the curve), the test condition is 100% light intensity, 2×35 second integration time, showing the elimination effect of the fluorescence eliminating agent on the fluorescence.

Considering the difficulty of implementation, cost and other factors, the present invention uses a self-developed simple algorithm to process tasks such as signal smoothing, peak identification, baseline value calculation, peak intensity calculation, qualitative judgment, and quantitative calculation. This method has short operation time and is easy to realize automatic processing, and provides the unique function of cosmic ray remnant elimination, which is of great help in reducing misjudgment.

The quantitative measurement of the present invention is realized by calculating the characteristic peak intensity of the substance and converting it according to the relationship between the peak intensity and the concentration of the substance. During the research, it is found that different solution systems have a great influence on the relationship between the peak intensity and the concentration, and the internal standard method can be more effective. reduce this effect. The internal standard method used in the present invention is different from the commonly used method of adding a fixed internal standard in the system. It directly uses the characteristic signal of acetone 1706cm ^-1 of the fluorescence eliminating agent, and does not need to add an internal standard, which greatly simplifies the operation. However, the characteristic signal intensity is dynamic due to the change of the dilution factor. The present invention converts the signal intensity corresponding to the 100% concentration of acetone as an internal standard according to the proportional relationship between the characteristic signal intensity and the volume ratio of acetone in the solution system. signal strength to solve this problem.

The Raman spectrometer will also receive some signals when the laser is not turned on to irradiate the sample. The main source is high-energy spectral lines including cosmic rays, which are called "dark signals". Figure 3 is a diagram of the dark signal obtained by the Raman spectrometer . When the Raman spectrometer is tested, first scan the dark signal and record the signal when the laser is turned off, and then turn on the laser to scan the signal. The original signal obtained after deducting the dark signal is used as the final test signal. Figure 4 is the Raman Illustration of the raw signal acquired by the spectrometer. As shown in Figure 3, Figure 3 is a diagram of the dark signal obtained by the Raman spectrometer. It can be seen that some spectral lines with particularly high intensity in the dark signal are cosmic rays. . Since the integration time used in the present invention is relatively large, the interval between the dark signal scan and the signal scan is relatively large, which will cause the spectral lines of the dark signal of the two scans, especially the cosmic ray intensity values, to be unequal, resulting in remaining Negative or positive signal "remnants" affect the judgment of the signal, so try to eliminate it. In the presence of cosmic rays, the intensity increases abruptly in a single step (Raman shift) and then decreases abruptly in the next step. Therefore, it is possible to set a "dark signal intensity slope (DarkR)" that represents the rate of change of dark signal intensity. When the step DarkR is greater than r and the next step DarkR is less than -r, it is determined that cosmic rays occur in this step. For the step point where cosmic rays appear, no matter what the final signal strength is, it is rigidly set as the average of the strength of the previous step and the next step, so that the signal "remnant" can be effectively eliminated. Fig. 5 is the signal diagram after subtracting the dark signal, and Fig. 6 is the signal diagram after smoothing processing. It can be seen from Fig. 6 that the "remnants" caused by cosmic rays appearing at 1513cm ^-1 are processed by the above method "Erase".

For the "final signal" of other step points provided by the spectrometer, in order to eliminate some small jumps, the present invention adopts the following method for further smooth processing, setting In, In-1, and In+1 as the current step, the previous step, and the next step respectively. "Final signal" strength, the signal strength Ins of this step after rounding is: Ins=0.15×(In-1)+0.7×In+0.15×(In+1).

The identification of the peak is mainly done by judging whether the pattern formed by the polarity of the spectral line within a certain range meets the specified threshold requirement. First calculate the strength increase value (SLP) and strength increase rate (strength increase value divided by the distance between two steps, SLPR) of this step relative to the previous step, and then judge the trend polarity of this step according to the positive or negative of SLPR, SLPR is positive When it is negative, it is recorded as P, and when it is negative, it is recorded as N. Figure 7 is a polarity diagram of the trend of the spectral line of the Raman spectrum. When dealing with practical problems, you will find that there are some step points whose SLPR is very close to 0, about between -20 and 20, and it is difficult to judge whether it belongs to an upward or downward trend. If such a point appears at the top of the peak, it will often destroy the complete process of peak formation and affect peak identification, but in fact such a point is only caused by random fluctuations in the signal. Therefore the present invention stipulates a threshold p, when SLPR is between -p to p, the trend polarity of this step follows the previous step, greater than p is P, and less than -p is N, to avoid this effect.

After determining the trend polarity of each step, a series of polar patterns will be produced after examining a small section of the spectral line. For example, PPNN means two consecutive rising steps followed by two falling steps, and then set the polarity pattern for each pattern. By setting the corresponding threshold of SLP or SLPR, it is possible to judge whether the peak appears or not. The peak identification conditions currently used are shown in Table 1.

Table 1

polar pattern Conditions for peak appearance PNP The SLPR value of N is less than -150, and the SLPR value of the second P is greater than 75 NPN The SLPR value of P is greater than 150, and the SLPR value of the second N is less than -75 PPNN The sum of the SLP values of the two Ps is greater than 300, and the sum of the SLP values of the two Ns is less than -300 PPPNN The sum of the SLP values of the three Ps is greater than 225, and the sum of the SLP values of the two Ns is less than -225 PPPPNN The sum of the SLP values of the four Ps is greater than 150, and the sum of the SLP values of the two Ns is less than -150 PPPPNNNN The sum of the SLP values of the four Ps is greater than 150, and the sum of the SLP values of the three Ns is less than -150 PPNNN The sum of the SLP values of two Ps is greater than 225, and the sum of the SLP values of three Ns is less than -255 PPNNNN The sum of the SLP values of two Ps is greater than 150, and the sum of the SLP values of four Ns is less than -150 PPPNNNN The sum of the SLP values of the three Ps is greater than 150, and the sum of the SLP values of the four Ns is less than -150 .

It should be pointed out that the threshold set in the algorithm is an empirical value obtained by comparing the calculation results with the actual situation many times, and is not static. It should be adjusted according to changes in equipment status, spectral characteristics and other factors. If the laser power drops and the signal weakens after the equipment has been used for a long time, it may be considered to lower the threshold appropriately according to the test results of the standard sample. Another example is the spectral characteristics of the current system. The baseline after 1750cm ^-1 is simpler and flatter than before, and the fluctuation of the material characteristic peaks is also gentler. Therefore, a lower threshold for peak identification after 1750cm ^-1 can be considered. In short, the determination index of the threshold is to ensure that the calculation result is as close to the actual situation as possible, and it is adjustable, but at the same time, it must ensure that the standard used for inspection is stable and reliable. When designing algorithm software, it should be considered to store the threshold value in a reference database that can be easily modified.

After a component is qualitatively distinguished through the distinguishing features, to obtain its concentration, that is, to achieve quantitative measurement, it is necessary to know the peak intensity of a characteristic peak of it, and also know the corresponding relationship between peak intensity and concentration, in order to convert concentration. When discussing the relationship between peak intensity and concentration, the first question raised by the present invention is which factors affect the relationship between peak intensity and concentration? According to the principle of Raman spectroscopy, Raman scattering spectroscopy is not only related to the composition of the sample, but also to factors such as structure and shape. For the actual commercial pesticide emulsifiable concentrate preparation to be measured, even if it is the same active ingredient, other adjuvant formulas are also quite different, so for the entire solution system, the composition, structure, and shape are very different, and the same ingredient has a large difference. It is entirely possible that its signal strength may be affected in the background. In order to confirm this theory, the present invention dissolves dimethoate pure product respectively in pure acetone and through the dichlorprid solution of fluorescence elimination treatment (diluted with 0.6% fluorescence elimination agent), then measures dimethoate 658cm at different concentration levels ^-1 signal strength. Fig. 8 is the diagram showing the relationship between the ^{658cm -1} signal intensity and the concentration of dimethoate pure product dissolved in dichlorprid solution and acetone, as can be seen from Fig. The relationship between the concentration (the line marked with ■ in the figure) formula is y=5E- ^06x +0.006, R ² =0.99; Marked line) formula is y=4E-06x+0.001, R ² =0.998. As shown in Table 2, at different concentration levels, dimethoate has a large difference in the ^658cm signal intensity of the two solution systems, which confirms that different solution systems do have an effect on the signal intensity of the components dissolved therein. Influence.

Table 2

concentration Methamiprid 658cm ^-1 average strength Acetone 658cm ^-1 average intensity deviation 0.2% - 530 - 0.5% - 967 - 1.0% 1453 1999 37.6% 2.0% 2152 4160 93.3% 5.0% 9337 12886 38.0% 10.0% 19465 24840 27.6% .

For the influence caused by the fluctuation of the internal or external factors of the measurement system, the internal standard method is often used to eliminate or offset the test technology. The principle is to select the internal standard signal inherent in the system as a reference signal, and form a relative signal strength with the target signal. . When the system factor changes, its effect on the target signal also acts on the reference signal, so the effect on the relative signal strength will be weakened. In the present invention, due to the use of the fluorescence eliminating agent, acetone is used as the internal standard, and the 1706 cm ^-1 signal of acetone is very suitable as the internal standard reference signal because it has no overlap with other known characteristic peak signals.

However, the content of the general internal standard in the system is constant, and the concentration of acetone in the system varies with the required dilution factor (volume ratio of acetone in the system), how to obtain the signal intensity from the actual measurement What about the corresponding fixed concentration (100%) signal value?

The relationship between the volume ratio of acetone obtained by diluting toluene, xylene, and lambda-cyhalothrin emulsifiable concentrate (GLFQ) with acetone and the signal intensity at 1706cm ^-1 was studied. Figures 9 to 11 show the intensity and volume ratio of acetone at 1706cm ^-1 It can be seen from the data in Figures 9 to 11 that, for different solutions, the volume ratio of acetone has a good linear proportional relationship with the signal intensity of 1706 cm ^-1 . Figure 9 is the relationship between the volume ratio of acetone obtained by diluting xylene with acetone and the signal intensity at 1706cm ^-1 (the line marked with ■ in the figure). The formula is y=37404x, R ² =0.960; The relationship between the volume ratio of acetone and the signal intensity at 1706cm ^-1 obtained from cyanothrin emulsifiable concentrate (GLFQ) (the line marked with ▲ in the figure) is y=38773x, R ² =0.909; Figure 11 is obtained by diluting toluene with acetone The formula for the relationship between the volume ratio of acetone and the signal intensity at 1706cm ^-1 (the line marked with ◆ in the figure) is y=38164x, R ² =0.956. Therefore, as long as the volume ratio of acetone in the measured solution is known, the signal value of 1706 cm ^-1 of 100% acetone under this condition can be given as the internal standard reference signal value.

Adopt internal standard method to process the data of dimethoate again, obtain the result shown in Fig. 12, Fig. 12 is the 658/1706 relative intensity and the concentration diagram of dimethoate pure product being dissolved in dichlorprid solution and acetone, dimethoate The relationship between the 658/1706 relative strength and the concentration of the pure product dissolved in the dichlorprid solution (the line with the ▲ mark in the figure) formula is y=0.148x+0.007, R ² =0.991; The formula for the relationship between relative intensity and concentration of 658/1706 (the line marked with ◆ in the figure) is y=0.142x+0.001, R ² =0.999. It can be seen from Table 3 that when the concentration is higher (5%, 10%), the deviation is significantly reduced when the internal standard method is used.

table 3

concentration Methamiprid 658/1706 Average Strength Acetone 658/1706 Average Strength deviation 0.2% - 1.4% - 0.5% - 2.6% - 1.0% 3.8% 5.5% 44.9% 2.0% 5.5% 11.4% 107.8% 5.0% 30.9% 34.1% 10.4% 10.0% 61.5% 69.0% 12.1% .

As can be seen from the above discussion, in order to reduce the influence of the background solution on the peak intensity, when carrying out the determination of the relationship between the peak intensity and the concentration of each pesticide emulsifiable concentrate preparation sample, the solution used should be as close as possible to the solution during the actual measurement, because the actual measurement must use 0.6% fluorescence elimination agent dilutes the pesticide emulsifiable concentrate preparation to eliminate the influence of fluorescence, and the dilution factor is more than 3 times in most cases, and the solution will contain a large amount of fluorescence elimination agent composition during actual measurement, so the present invention selects 0.6% fluorescence elimination agent as solution for measurement.

The Raman characteristic peak signal used for quantitative measurement is selected from a certain feature in the resolution feature. The principle of selection is that the peak signal must be strong and stable and not susceptible to interference, and the peak selection between the components should not overlap too much. Because if two components with overlapping intensity measurement peaks appear at the same time, it will directly affect the measurement accuracy. Of course, the probability of this is not too high.

The determination method of the relationship between peak intensity and concentration is as follows: dissolve the pure product into 0.6% fluorescence eliminating agent, first prepare a 0.5% concentration solution and test according to the optimized conditions, repeat three times, and then gradually increase the concentration. Generally, it is divided into 5 groups of 0.5%, 1%, 2%, 5%, and 10%. If the concentration of the pesticide emulsifiable concentrate preparation is high, the 25% concentration group will be added for testing. Each set of data is processed to find the peak value of the intensity measurement peak and take the average of three times. Also calculate the internal standard peak signal 1706cm ^-1 peak value, and take the average of three times. Since the ratio of 0.6% fluorescence eliminating agent water to acetone is 1:9, the obtained average peak value has to be divided by 9/10 to obtain the 1706cm ^-1 peak value of acetone at 100% concentration. The ratio of the average peak value of the intensity measurement peak to the average peak value of 1706cm ^-1 is the relative intensity of the group. Taking 5 groups (or 6 groups) of relative intensity and corresponding concentration for linear regression analysis, the linear relationship between the two can be obtained as shown in the figure 13, 14 shown. For the 50 pesticide ingredients, most of them have a good linear relationship, and R ² is generally above 0.95. The linear relationship formula of each component is obtained for the concentration conversion of the actual measurement.

During the actual measurement, as long as the intensity value of the target signal peak is known, the concentration value can be converted by the peak intensity and concentration relationship formula. During the conversion process, of course, the volume ratio of acetone in the solution must be calculated according to the dilution factor, and then converted The intensity of the internal standard signal corresponding to 1706cm ^-1 at 100% concentration. For the case of using 0.6% fluorescence eliminating agent, the relationship between the volume ratio of acetone and the dilution factor is as follows:

The concentration value converted by the above steps is after dilution, and needs to be multiplied by the dilution factor to obtain the concentration value of the stock solution. In actual operation, for convenience, the quantitative method by volume is adopted, that is, a certain volume of 0.6% fluorescence eliminating agent is diluted with a pipette, and the general concentration value is measured by mass, so the volume The dilution factor is converted into the mass dilution factor, which requires knowing the density of the original pesticide emulsifiable concentrate preparation and 0.6% fluorescence eliminating agent. The density of 0.6% fluorescence eliminating agent is basically constant and known, and the density of the stock solution pesticide emulsifiable concentrate preparation needs to be measured. The method is to take 1ml emulsifiable concentrate with a pipette, weigh its mass with a portable electronic balance, and repeat three times to get the average value. This method can also be implemented in the field.

A method for rapid on-site detection of pesticide emulsifiable concentrate preparations of the present invention was used to quickly detect and verify 37 kinds of pesticide samples, among which 9 commercially available pesticide emulsifiable concentrate preparations were tested qualitatively according to their nominal components. In addition, 8 commodity pesticide emulsifiable concentrate preparations purchased in the market and 13 commercial pesticide emulsifiable concentrate preparations regularly inspected by a certain agricultural inspection institute were first tested by the present invention, and then submitted to a certain agricultural inspection institute for qualitative and quantitative determination. The qualitative determination used a chromatographic mass spectrometer. There are 7 commercial pesticide samples purchased in the market, mixed with a certain amount of pure samples of different types of banned pesticides, and self-tested for quantitative and qualitative testing. The results are summarized in Table 4.

Table 4

According to test result, can make following judgment and evaluation to the present invention:

The detection rate of the present invention is 76.7% (missing rate: 23.3%), the accuracy rate after detection is 95.7% (false alarm rate: 4.3%), and the total qualitative accuracy rate is 73.3%. The main reason for the underreporting is the low concentration of the stock solution or diluted components.

There are 3 samples containing 3 or 4 active ingredients (both containing pyridaben and fipronil), and the qualitative test is correct except for one ingredient which cannot be detected, showing that the present invention has a better effect on multi-component mixed solutions. detection and resolution capabilities.

It has a strong detection ability for the components whose resolution characteristics are above 1750cm ^-1 , such as metamiprid, fipronil, chlorothalonil, etc. For example, in the 9 qualitative detections of fipronil, there was 1 false positive (the concentration of the stock solution was only 0.05%) and 2 false positives (one of which was found on the chromatographic linkage instrument to be very close to the interference peak of fipronil peak 17.19 , the fipronil peak is 17.22), and the detection limit can reach 3% of the stock solution.

7 samples adulterated with prohibited ingredients (respectively 40% Liben Phoxim mixed with 26% monocrotophos, 40% methapion mixed with 9.7% dicofol, 5% Methamiprid-NYJC12154 mixed 8.7% γ-HCH, 48% chlorpyrifos, 48% chlorpyrifos, 15.5% methyl parathion, 40% methapion, 21.1% isofenphos-methyl, 5% dichlorpyrifos -5 of NYJC12154 mixed with 23.2% aldicarb, 2.5% Longxin lambda-cyhalothrin mixed with 28.4% carbofuran) could be detected (monocrotophos and aldicarb were not detected) , it can be seen that the present invention has better detection ability for pesticides doped with prohibited components.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that Modifications or equivalent replacements are made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims (6)

1. farm chemical emulsion preparation is carried out to a method for field quick detection, it is characterized in that: it comprises the following steps:

A. prepare: collect the raman signatures of several farm chemical emulsion preparation at solution system, differentiate feature for several farm chemical emulsion preparation distributes, by these features stored in database, call when carrying out composition identification for data processing software;

B. prepare Fluorescence Quenching Agent, measure the density of farm chemical emulsion preparation; Preparation Fluorescence Quenching Agent is specially: 50mg fluorescence is eliminated former medicament and dissolves in 1ml water, injects 9ml pure acetone, fully mix, be mixed with Fluorescence Quenching Agent after dissolving completely;

C. first round test: get farm chemical emulsion preparation to sample bottle, add Fluorescence Quenching Agent by multiple, then start the test procedure of Raman spectrometer, test farm chemical emulsion preparation; When observe signal base line be on close level 30000 time, start the first round test, follow-on test three times also records extension rate, store data;

D. second take turns test: after the first round tested, then add Fluorescence Quenching Agent by multiple and farm chemical emulsion preparation is surveyed in examination, when observe signal base line be on close level 20000 time, follow-on test three times also records extension rate, stores data;

E. Data Management Analysis: by data processing software process data, obtain each qualitative test result, taking turns test if a certain to have twice or more result display containing certain composition, then judge that farm chemical emulsion preparation contains this composition;

F. converted score value: according to extension rate, the peak intensity that the density of farm chemical emulsion preparation and data processing provide, and peak intensity and concentration relationship formula, converse the concentration value of farm chemical emulsion preparation, in described step f converted score value, the assay method of peak intensity and concentration relationship is specially: pesticide original medicine sterling is dissolved in Fluorescence Quenching Agent, be made into concentration respectively and be respectively 0.5%, 1%, 2%, 5%, five groups of solution of 10% or be made into concentration respectively and be respectively 0.5%, 1%, 2%, 5%, 10%, six groups of solution of 25%, test often organizing solution, in triplicate, then process often organizing data, obtain the peak value at the ionization meter peak often organizing solution, get the average peak that three mean value draws the ionization meter peak often organizing solution, obtain the interior mark peak-to-peak signal 1706cm often organizing solution equally ^-1peak value, get three mean values, averaging of income peak value obtains the acetone 1706cm of 100% concentration divided by 9/10 ^-1average peak, the average peak at the ionization meter peak often organized and the acetone 1706cm of 100% concentration ^-1the ratio of average peak is the relative intensity of this group solution, and the concentration of the relative intensity and this group of getting five groups of solution or six groups of solution carries out linear regression analysis, obtains the linear relationship of peak intensity and concentration relationship.

2. a kind of method of farm chemical emulsion preparation being carried out to field quick detection according to claim 1, it is characterized in that: in described step a, described farm chemical emulsion preparation comprises following 49 kinds: D.D.T. (dichloro-diphenyl-trichloroethane) T, dicofol, γ-benzene hexachloride, D.D.T. (dichloro-diphenyl-trichloroethane) D, Aldicarb, carbofuran, terbufos, acephatemet, isocarbophos, Isofenphos methyl, α-benzene hexachloride, parathion-methyl, parathion, D.D.T. (dichloro-diphenyl-trichloroethane) E, fenvalerate, Azodrin, phosphamidon, ethiprole, phonetic mould amine, orthene, methidathion, malathion, fenifrothion, decis, cypermethrin, DDVP, Rogor, Fenpropathrin, chlopyrifos, diazinon, Profenofos, Difenoconazole, Methomyl, carbaryl, Hostathion, Imidacloprid, pyridaben, triazolone, Biphenthrin, diflubenzuron, phoxim, Phosalone, gamma cyhalothrin, Avermectin, procymidone, iprodione, vinclozolin, determine worm amidine, Bravo.

3. a kind of method of farm chemical emulsion preparation being carried out to field quick detection according to claim 1, it is characterized in that: in described step b, the density measuring farm chemical emulsion preparation is specially: sample bottle is placed on electronic balance, clear 0, get 1ml farm chemical emulsion preparation, inject sample bottle completely, record now quality; Then clear 0, repeat above step twice, finally ask the mean value of three inferior qualities to draw the density of farm chemical emulsion preparation.

4. a kind of method of farm chemical emulsion preparation being carried out to field quick detection according to claim 1, it is characterized in that: in described step c, the test procedure starting Raman spectrometer is specially setting: start Raman spectrometer, open testing software interface, setting laser light intensity is 100%, and integral time is 2 × 35000 milliseconds.

5. a kind of method of farm chemical emulsion preparation being carried out to field quick detection according to claim 1, it is characterized in that: in described step f, the concentration value conversing farm chemical emulsion preparation is specially: according to the intensity level at echo signal peak, concentration value after going out to dilute by peaks relative intensities and concentration relationship formula scales, the concentration value after dilution is multiplied by quality extension rate and obtains the concentration value before diluting.

6. a kind of method of farm chemical emulsion preparation being carried out to field quick detection according to claim 5, is characterized in that: described peaks relative intensities equals the intensity level at echo signal peak and the acetone 1706cm of 100% concentration ^-1the ratio of signal; The acetone volume accounting in solution is extrapolated, the acetone 1706cm of actual measurement according to extension rate ^-1signal intensity just converses the acetone 1706cm of 100% concentration divided by acetone volume accounting ^-1the intensity of interior mark signal; Wherein, acetone volume accounting and extension rate close and are ; Quality extension rate and extension rate close and are .