CN112098502B - Detection method for calibrating ion mobility spectrometer by utilizing multiple ion peaks - Google Patents
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Abstract
A detection method for calibrating an ion mobility spectrometer by utilizing multiple ion peaks comprises the steps of obtaining a characteristic ion peak of an object to be detected and an ion mobility spectrogram of a characteristic ion peak of a calibration object under a first test environment; calculating the reduced mobility corresponding to the characteristic ion peak of the object to be detected and the characteristic ion peak of the calibration object; determining the reduced mobility corresponding to a characteristic ion peak of a standard product in a first test environment according to the reduced mobility corresponding to the characteristic ion peak of the calibration object and the reduced mobility corresponding to the characteristic ion peak of the calibration object in the standard detection database; and if the reduced mobility corresponding to the characteristic ion peak of the standard substance is consistent with the reduced mobility corresponding to the characteristic ion peak of the object to be detected, determining that the object to be detected is the standard substance. The invention improves the identification accuracy and the anti-interference capability, reduces the requirement on the drift gas environment in the drift tube, shortens the preheating time of the starting of the ion mobility spectrometer, and prolongs the service life of the dry filter material.
Description
Technical Field
The invention belongs to the field of rapid detection of trace substances, and particularly relates to a detection method for calibrating an ion mobility spectrometer by utilizing multiple ion peaks.
Background
Ion Mobility Spectrometry (IMS) is an analytical technique for separating and detecting chemical substances based on the difference in the migration velocity of different gas-phase ions in an electric field. Due to high sensitivity, high detection speed, small instrument volume and low cost, the ion mobility spectrometry technology is widely applied to the field rapid detection of chemical toxicants, explosives, drugs and other substances in the field of national defense safety. In recent years, with the rapid development of IMS technology, ion Mobility Spectrometers (IMS) are also gradually applied to trace pollutant monitoring in the environmental protection field, flavor detection in the food industry, breath detection in the biomedical field, and the like.
When the ion mobility spectrometry technology is used for detection, a detected object is firstly ionized to form characteristic ions, then the characteristic ions enter a drift region in the form of ion clusters (ion groups) through an ion gate, the ion clusters pass through the drift region at a constant speed under the combined action of a drift electric field and drift gas, and an ion current signal is obtained by detecting the ion clusters at the tail part of the drift region through a Faraday disc plasma detector. The drift velocity V (unit: cm/s) of ion clusters in a gas environment under the action of an electric field is proportional to the electric field intensity E (unit: V/cm):
v＝K·E
in the above formula, K is called the mobility coefficient of the ion (mobility, unit: cm) 2 /V·s)。
If the length of the drift region is L (unit: em), the drift voltage applied to the two ends of the drift region is V (unit: V), t d Is the time (unit: s) taken for the ion cluster to pass through the drift region. Then there are:
the mobility K of the ion clusters is related to the temperature T (unit: K) in the drift region and the drift gas pressure P (unit: pa), and for the purpose of comparing the mobility of different types of ion clusters, the mobility K is usually converted into a temperature 273K and a gas pressure of 1.013 × 10 5 Reduced mobility K at Pa 0 ：
The drift time T corresponding to the ion peak can be determined according to the length L of the drift region of the IMS, the voltage V applied to the drift region, the temperature T and the gas pressure P in the drift region, and d is obtained fromReduced mobility K of the seed 0 But due to drift region length L, temperature T and drift time T d Equal error, resulting in a calculated reduced mobility K of the ions 0 The error is large.
In order to increase the reduced mobility K of ions 0 The accuracy of (2) is usually calibrated for the ion mobility spectrometer using a calibration object with known ion reduced mobility, and the reduced mobility corresponding to the unknown ion peak is calculated using the following formula:
in the formula K 0(unknown) Reduced mobility, K, for unknown ion peaks 0(standard) Reduced mobility, t, for the calibrant ion peak d(unknown) Drift time, t, for unknown ion peaks d(standard) The drift time corresponding to the ion peak of the calibrator. According to the formula, the reduced mobility of the unknown ion peak is calculated by utilizing the ratio of the drift time of the standard ion peak to the drift time of the unknown ion peak and the reduced mobility of the standard ion peak, so that higher precision can be obtained.
However, the prior art still has the following problems:
(1) Difficulty in identifying the substance to be measured
The higher accuracy can be obtained by calculating the reduced mobility corresponding to the unknown ion peak by using the ion peak of the calibration object with the known reduced mobility, but it is still difficult to perform qualitative detection of the unknown object according to the reduced mobility, mainly because the reduced mobility of one substance characteristic ion is not constant in a strict sense, and is influenced by the ionization method, the drift gas type, the temperature and the content of water vapor and other interferents in the drift gas (as shown in fig. 1-2, the reduced mobility of several ions changes with the temperature and the content of water vapor of the drift gas). This results in different values of ions characteristic of a particular substance in different documents, which is not favorable for comparison of experimental results between different IMS instruments and different institutions. More seriously, even for the same IMS instrument, the drift gas temperature and the water vapor in the drift tubeAnd other interferent levels, the reduced mobility of the ions characteristic of the same species may vary over a range. The reduced mobility of some ions varies greatly as the IMS drift gas temperature and water vapor content change, e.g.
Reduced mobility of 3.02cm in dry nitrogen at 207 deg.C 2 V.s, water vapour content at 45 ℃ of less than 1 mg.m -3 Has an approximate mobility of 2.18-2.21cm in nitrogen 2 V.s. The water vapor content at 40 deg.C is 75 mg.m -3 Has reduced mobility of only 2.07cm in air 2 V.s. This poses certain difficulties in the qualitative identification of the measured object by means of the IMS technique: if the identification window of the characteristic ion reduced mobility is too small, the judgment is missed, and a specific measured object cannot be identified under certain conditions; if the identification window of the characteristic ion reduced mobility is too large, misjudgment is easily caused, and the interference component in the environment is identified as a specific measured object.
(2) High environmental requirement on the drift tube
In order to reduce K caused by unstable environmental parameters in IMS drift tube 0 Is required to take various measures to keep the environment inside the IMS drift tube stable. The method for keeping the drift tube working temperature stable is usually to make the drift tube work in a constant temperature state higher than room temperature, the method for keeping the drift gas component in the drift tube stable is usually to make the drift gas circularly flow in a closed system consisting of the drift tube and a gas drying and filtering device, and the content of water vapor and interferent in the drift gas is controlled in a very low range by utilizing a molecular sieve and the like in the gas drying and filtering device. The stable atmosphere environment in the IMS drift tube needs to be regularly replaced by dry filtering materials such as molecular sieves and the like, and in addition, when the IMS equipment stored for a long time is started, the starting preheating time is very long for reducing the content of water vapor and interferents in drift gas, so that great inconvenience is caused to the actual use of the IMS equipment.
Disclosure of Invention
In view of the above, one of the main objectives of the present invention is to provide a method for calibrating an ion mobility spectrometer by using multiple ion peaks, so as to at least partially solve at least one of the above technical problems.
In order to achieve the above object, as one aspect of the present invention, there is provided a detection method for calibrating an ion mobility spectrometer using multiple ion peaks, comprising:
(1) Acquiring an ion migration spectrogram of a characteristic ion peak of an object to be detected and a characteristic ion peak of a calibration object under a first test environment;
(2) Calculating the reduced mobility corresponding to the characteristic ion peak of the object to be detected and the characteristic ion peak of the calibration object;
(3) Determining the reduced mobility corresponding to the characteristic ion peak of a certain standard sample under the first test environment according to the reduced mobility corresponding to the characteristic ion peak of the calibration object and the reduced mobility corresponding to the characteristic ion peak of the calibration object in the standard detection database; wherein the standard detection database comprises reduced mobility of standard and calibration objects under different test environment parameters;
(4) And if the reduced mobility corresponding to the characteristic ion peak of the standard substance is consistent with the reduced mobility corresponding to the characteristic ion peak of the object to be detected, determining that the object to be detected is the standard substance.
As another aspect of the present invention, there is also provided a detection method for calibrating an ion mobility spectrometer by using multiple ion peaks, including:
(1) Acquiring ion migration spectrograms of characteristic ion peaks of an object to be tested and characteristic ion peaks of a calibration object under various test environments;
(2) Respectively calculating the reduced mobility corresponding to the characteristic ion peak of the object to be tested and the characteristic ion peak of the calibration object under different test environments;
(3) Determining the reduced mobility corresponding to the characteristic ion peak of a certain standard product under different test environments according to the reduced mobility corresponding to the characteristic ion peak of the calibration object and the reduced mobility corresponding to the characteristic ion peak of the calibration object in the standard detection database; wherein the standard detection database comprises reduced mobility of standard and calibration objects under different test environment parameters;
(4) And if the reduced mobility corresponding to the characteristic ion peak of the standard substance under different test environments is consistent with the reduced mobility corresponding to the characteristic ion peak of the object to be tested, determining the object to be tested as the standard substance.
Based on the technical scheme, compared with the prior art, the detection method for calibrating the ion mobility spectrometer by utilizing the multi-ion peak has at least one of the following advantages:
1. the accuracy and the anti-interference capability of the identification are improved
The method adopts a plurality of calibration object ion peaks for calibration, further obtains the reduced mobility of the characteristic ions of the measured object under different detection environments, compares the reduced mobility with the reduced mobility data of the characteristic ions of a specific substance in different environments in a database, can more accurately judge whether the measured object is the specific substance, and improves the accuracy and the anti-interference capability of the ion mobility spectrometer for qualitatively identifying the measured object.
2. The requirements on the environment of drift gas in the drift tube are reduced, the preheating time of the starting of the ion mobility spectrometer is shortened, and the service life of a dry filter material is prolonged
The ion peaks of a plurality of calibration objects are adopted for calibration, so that the influence of the change of the environmental parameters in the IMS drift tube on the detection is reduced, the requirement on the stability of the environmental parameters in the drift tube is lowered, the pre-working time of the ion mobility spectrometer is greatly shortened, and the detection efficiency is improved; meanwhile, the service life of the molecular sieve and other dry filtering materials can be prolonged.
3. The method is used for rapid detection of the trace substance, can determine the type of the substance to be detected without knowing the parameters of the test environment, and can improve the rapid detection and identification capability of the ion mobility spectrometry on the trace substance.
Drawings
FIG. 1 is a graph of several ion reduced mobilities as a function of drift gas temperature;
FIG. 2 is a graph of the reduced mobility of several ions as a function of drift moisture content;
FIG. 3 is a block diagram of a calibration process in an embodiment of the invention;
FIG. 4 is a block diagram of a detection and identification process according to a first embodiment of the present invention;
FIG. 5 is a block diagram of a detection and identification process according to a second embodiment of the present invention;
fig. 6 is a block diagram of a detection and identification process in a third embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the accompanying drawings in combination with the embodiments.
The invention discloses a detection method for calibrating an ion mobility spectrometer by utilizing multiple ion peaks, which comprises the following steps:
(1) Acquiring an ion migration spectrogram of a characteristic ion peak of an object to be detected and a characteristic ion peak of a calibration object under a first test environment;
(2) Calculating the reduced mobility corresponding to the characteristic ion peak of the object to be detected and the characteristic ion peak of the calibration object;
(3) Determining the reduced mobility corresponding to a characteristic ion peak of a standard product in a first test environment according to the reduced mobility corresponding to the characteristic ion peak of the calibration object and the reduced mobility corresponding to the characteristic ion peak of the calibration object in the standard detection database; wherein the standard detection database comprises reduced mobility of standard and calibration objects under different test environment parameters;
(4) And if the reduced mobility corresponding to the characteristic ion peak of the standard substance is consistent with the reduced mobility corresponding to the characteristic ion peak of the object to be detected, determining that the object to be detected is the standard substance.
In some embodiments of the invention, the calibrant ion peak has at least two ion peaks;
in some embodiments of the present invention, the reduced mobility of at least one calibrant ion peak reflects a change in an environmental parameter within the drift tube of the ion mobility spectrometer.
In some embodiments of the invention, the test environment parameter comprises at least one of drift tube temperature, water content in drift gas, and interferent content.
In some embodiments of the present invention, the method for establishing the standard detection database includes:
(1) Sampling the standard substance and the calibration substance under a test environment parameter to obtain an ion migration spectrogram containing a characteristic peak of the standard substance and a characteristic peak of the calibration substance;
(2) Calculating reduced mobility corresponding to the standard substance characteristic peak and the calibration substance characteristic peak under the test environment parameters, and recording reduced mobility data corresponding to the standard substance characteristic peak and the calibration substance peak in an ion mobility spectrogram database;
(3) Changing the testing environment parameters, repeating the step (1) and the step (2) to obtain reduced mobility rates corresponding to the standard substance characteristic peak and the calibration object characteristic peak under different testing environment parameters, and recording the reduced mobility rates in an ion mobility spectrometry database;
(4) And when the scale of the ion mobility spectrogram database meets the preset scale, taking the ion mobility spectrogram database at the moment as a standard detection database.
In some embodiments of the present invention, in step (4), after the step of changing the test environment parameter if the reduced mobility corresponding to the standard article characteristic ion peak is identical to the reduced mobility corresponding to the object-to-be-tested characteristic ion peak, repeating steps (1) to (3) in the second test environment, and if the reduced mobility corresponding to the standard article characteristic ion peak obtained in the second test environment is identical to the reduced mobility corresponding to the object-to-be-tested characteristic ion peak, determining that the object-to-be-tested is the standard article.
In some embodiments of the invention, the calibrant in positive ion mode comprises at least one of 2, 6-di-tert-butylpyridine, 2,4-lutidine, dimethyl phosphate a, tetraalkylammonium, tetraethylammonium bromide, tetrapropylammonium bromide, tetrapentylammonium bromide, tetrabutylammonium iodide, nicotinamide, trimethylamine, triethylamine, dipropylene glycol methyl ether;
in some embodiments of the invention, the negative ion mode subscript comprises at least one of methyl salicylate, trinitrotoluene.
The invention also discloses a detection method for calibrating the ion mobility spectrometer by utilizing the multi-ion peak, which comprises the following steps:
(1) Acquiring ion migration spectrograms of characteristic ion peaks of an object to be detected and characteristic ion peaks of a calibration object under various test environments;
(2) Respectively calculating the reduced mobility corresponding to the characteristic ion peak of the object to be tested and the characteristic ion peak of the calibration object under different test environments;
(3) Determining the reduced mobility corresponding to the characteristic ion peak of a certain standard product under different test environments according to the reduced mobility corresponding to the characteristic ion peak of the calibration object and the reduced mobility corresponding to the characteristic ion peak of the calibration object in the standard detection database; wherein the standard detection database comprises reduced mobility of standard and calibration objects under different test environment parameters;
(4) And if the reduced mobility corresponding to the characteristic ion peak of the standard substance under different test environments is consistent with the reduced mobility corresponding to the characteristic ion peak of the object to be tested, determining the object to be tested as the standard substance.
In some embodiments of the present invention, after the step (2) is finished, before the step (3) is started, it is further determined whether the number of times of tests in different test environments reaches a preset value, and if no preset value exists, the test environments are changed to repeat the steps (1) and (2), until the number of times of tests reaches the preset value, the step (3) is performed.
In some embodiments of the invention, the calibrant ion peak has at least two ion peaks;
in some embodiments of the present invention, the reduced mobility of at least one of the calibrant ion peaks reflects a change in an environmental parameter within the drift tube of the ion mobility spectrometer.
In some embodiments of the invention, the test environment parameter comprises at least one of drift tube temperature, water content in drift gas, and interferent content.
In an exemplary embodiment, the detection method for calibrating an ion mobility spectrometer by using multiple ion peaks of the invention comprises a calibration process and a detection identification process; wherein, the calibration process mainly adopts two (or more) calibration object ion peaks A and B to calibrate the standard substance of the specific substance. The calibration process establishes a database (i.e., a standard detection database) containing the ion peaks of the calibration substance in various environments and the reduced mobility corresponding to the ion peaks characteristic of the calibration substance, wherein the reduced mobility of at least one ion peak of the calibration substance can reflect the change of the environmental parameters in the drift tube of the ion mobility spectrometer. And calibrating to realize calculation of the corresponding reduced mobility of the characteristic ion peaks of the measured object and qualitative identification of the measured object, wherein the ion peaks of the plurality of calibrated objects have different change rules along with the changes of environmental parameters such as temperature, water content in drift gas, interference object content and the like.
The detection and identification process comprises the following steps: (1) And obtaining an ion mobility spectrum of the characteristic ion peak of the object to be detected and the ion mobility spectrums of the ion peaks A and B of the calibration objects by using an ion mobility spectrometer, and further calculating the reduced mobility corresponding to the characteristic ion peak of the object to be detected and the two ion peaks of the calibration objects. (2) And determining the reduced mobility of a certain standard substance in the drift tube environment according to the ion mobility of the ion peaks A and B of the calibration object and a database (standard detection database) established in the calibration process. And (3) comparing the reduced mobility of the characteristic ion peak of the measured object obtained in the step (1) with the reduced mobility of the standard substance in the environment inquired from the database, and judging whether the measured object is a substance corresponding to the standard substance.
In some embodiments of the invention, the process of detecting identification may further comprise:
(1) And obtaining an ion mobility spectrum of the characteristic ion peak of the object to be detected and the ion mobility spectrums of the ion peaks A and B of the calibration objects by using an ion mobility spectrometer, and calculating the reduced mobility corresponding to the characteristic ion peak of the object to be detected and the characteristic ion peak of the calibration object.
(2) And determining the reduced mobility of a certain standard substance in the drift tube environment according to the ion mobility of the ion peaks A and B of the calibration object and a database established in the calibration process. Comparing whether the reduced mobility of the characteristic ion peak of the object to be measured obtained in the step (1) is consistent with the reduced mobility of the standard substance in the environment inquired from a database, and if the reduced mobility is inconsistent, judging that the object to be measured is not the substance corresponding to the standard substance; and if the reduced mobility is consistent, performing the next detection.
(3) Changing the working parameters (including drift gas flow, drift tube temperature and the like) of the ion mobility spectrometer, obtaining the ion mobility spectrograms of the characteristic ion peak of the object to be measured and the ion peaks A and B of the calibration objects again under the second environment of the drift tube different from the drift tube in the step (1), and further calculating the reduced mobility corresponding to the characteristic ion peak of the object to be measured and the characteristic ion peak of the calibration objects.
(4) And determining the reduced mobility of a certain standard substance in the drift tube environment according to the ion mobility of the ion peaks A and B of the calibration object and a database established in the calibration process. Comparing the reduced mobility of the characteristic ion peak of the measured object obtained by measurement in the step (3) with the reduced mobility of the standard substance in the second environment inquired from the database, and if the reduced mobility is not consistent, judging that the measured object is not the substance corresponding to the standard substance; if the reduced mobility rates are consistent, the detected object is judged to be the substance corresponding to the standard product, or the processes (3) and (4) are repeated to further improve the detection reliability and the anti-interference capability.
Wherein the ion peak of the label under positive ion mode can be selected from the group consisting of 2, 6-di-tert-butylpyridine (2, 6-DTBP, CAS No. 585-48-8), 2, 4-dimethylpyridine (2, 4-lutidine,2,4-DMP, CAS No. 108-47-4) dimethyl phosphate grade A (DMMP, CAS No. 756-79-6), tetraalkylammonium (tetraalkylammonium, including but not limited to tetrabutylammonium bromide, CAS No. 1643-19-2, tetraethylammonium bromide, CAS No. 71-91-0, tetrapropylammonium bromide, CAS No. 1941-30-6, tetrapentylammonium bromide, CAS866-97-7, tetrabutylammonium iodide, CAS No. 311-28-4), nicotinamide (Nicotinamide, CAS No. 98-92-0), trimethylamine (TMA, CAS No. 75-50-3), triethylamine (TEA, CAS No. 121-44-8), dipropylene glycol methyl ether (DPGME, CAS No. 94-348), etc. The ion peak of the fixer under the negative ion mode can be selected from substance characteristic ion peaks such as methyl salicylate (CAS number 119-36-8), trinitrotoluene (TNT CAS number 118-96-7) and the like.
Wherein, the monomer ion peak and dimer ion peak of a calibrator (including but not limited to dimethyl methylphosphonate) can be selected as the calibrator ion peak respectively. A reactant ion (including but not limited to hydrated protons, hydrated ammonia ions, hydrated acetone ions, hydrated chloride ions) peak may also be used as one of the calibrant ion peaks.
In which a plurality of drift tubes having different internal environments (temperature, water content in drift gas, content of interfering substances, etc.) can be used to operate in parallel. In some embodiments of the present invention, single drift tube operation may also be used, with varying drift tube temperature, varying drift gas circulation flow, or varying the moisture and other interfering species content in the drift gas by switching gas paths, among other means.
The technical solution of the present invention is further illustrated by the following specific embodiments in conjunction with the accompanying drawings. It should be noted that the following specific examples are given by way of illustration only and the scope of the present invention is not limited thereto.
The chemicals and raw materials used in the following examples were either commercially available or were prepared by a known preparation method.
In order to improve the accuracy of the IMS equipment for identifying the measured object by using the reduced mobility and reduce the requirement on the environment in the IMS drift tube so as to shorten the starting time of the IMS, the invention calibrates the ion mobility spectrometer by adopting a plurality of calibration object ion peaks and realizes the calculation of the reduced mobility corresponding to the characteristic ion peaks of the measured object and the qualitative identification of the measured object. The ion peaks of the calibration substances have different change rules along with the change of temperature, water vapor in drift gas, content of interferents and other environmental parameters.
The detection method for detecting a certain substance comprises two processes of calibration and detection identification. The calibration process is shown in figure 3, the specific substance standard is calibrated by mainly adopting two calibration object ion peaks A and B, and the reduced mobility rates corresponding to the calibration object ion peaks A and B are influenced differently by the temperature of the drift tube, the water vapor content of drift gas and the content of interferents. The calibration process specifically comprises the following steps:
(1) Sampling a standard substance and two calibration substances;
(2) Obtaining an IMS spectrogram containing a standard substance characteristic peak and two calibration object peaks under the test environment condition;
(3) Calculating the reduced mobility corresponding to the characteristic peak of the standard substance and the peaks of the two calibration substances;
(4) Increasing the approximate mobility of the standard substance peak and the standard substance characteristic peak under the condition in an IMS spectrogram database;
(5) Judging whether the scale of the IMS spectrogram database meets the preset scale or not, if so, saving the IMS spectrogram database as an ion mobility spectrogram database in the subsequent detection process; and (3) if the preset scale is not met, changing the working parameters such as the temperature of the drift tube, the water vapor content in the drift gas, the content of the interferent and the like, and returning to the step (2) again until the scale of the IMS spectrogram database meets the preset scale.
As a special case, the reduced mobility corresponding to the ion peak a of the calibration material is slightly influenced by the temperature of the drift tube, the water vapor content of the drift gas and the content of the interferent, and can be considered as a constant in a certain range; the reduced mobility corresponding to the calibration material ion peak B is affected by the drift tube temperature, the drift gas water content, the interferent content, and the like, and can be regarded as a function of the environmental parameters such as the drift tube temperature, the drift gas water content, the interferent content, and the like. By adjusting the drift gas flow and the working temperature plasma mobility spectrometry working parameters, the reduced mobility corresponding to the ion peaks A and B of the two calibration objects and the ion peak of the standard substance of the measured object under various environments is obtained. Establishing a database containing various environmental standard ion peaks and reduced mobility corresponding to the standard characteristic ion peaks, wherein the reduced mobility of at least one standard ion peak can reflect changes of environmental parameters (including but not limited to temperature, drift gas water vapor content, interferent content and the like) in the drift tube of the ion mobility spectrometer.
In the first embodiment, the process of detecting and identifying the object to be detected is shown in fig. 4, and mainly includes:
(1) And obtaining the ion mobility spectrograms of the characteristic ion peak of the measured object and the ion peaks A and B of the calibration objects by using an ion mobility spectrometer, and further calculating the characteristic ion peak of the measured object and the reduced mobility corresponding to the two ion peaks of the calibration objects.
(2) And determining the reduced mobility of a certain standard substance in the drift tube environment according to the ion mobility of the ion peaks A and B of the calibration object and a database established in the calibration process. And (3) comparing the reduced mobility of the characteristic ion peak of the measured object obtained in the step (1) with the reduced mobility of the standard substance in the environment inquired from the database, and judging whether the measured object is a substance corresponding to the standard substance.
In a second embodiment, another process of detecting and identifying a detected object is shown in fig. 5, which mainly includes:
(1) And obtaining the ion mobility spectrograms of the characteristic ion peak of the measured object and the ion peaks A and B of the calibration objects by using an ion mobility spectrometer, and calculating the corresponding reduced mobility.
(2) And determining the reduced mobility of a certain standard substance in the drift tube environment according to the ion mobility of the ion peaks A and B of the calibration object and a database established in the calibration process. Comparing the reduced mobility of the characteristic ion peak of the measured object obtained by measurement in the step (1) with the reduced mobility of the standard substance in the environment inquired from a database, and if the reduced mobility is not consistent, judging that the measured object is not the substance corresponding to the standard substance; and if the reduced mobility is consistent, performing the next detection.
(3) Changing the working parameters (including drift gas flow, drift tube temperature and the like) of the ion mobility spectrometer, obtaining the ion mobility spectrograms of the characteristic ion peak of the object to be measured and the ion peaks A and B of the calibration objects again under the second environment of the drift tube different from that of the drift tube in the step (1), and further calculating the corresponding reduced mobility.
(4) And determining the reduced mobility of a certain standard substance under the drift tube environment according to the ion mobility of the ion peaks A and B of the calibration object and a database established in the calibration process. Comparing the reduced mobility of the characteristic ion peak of the measured object obtained by measurement in the step (3) with the reduced mobility of the standard substance in the second environment inquired from the database, and if the reduced mobility is not consistent, judging that the measured object is not the substance corresponding to the standard substance; if the reduced mobility is consistent, the measured object is judged to be the substance corresponding to the standard product or the processes (3) and (4) are repeated so as to further improve the reliability and the anti-interference capability of the detection.
In the third embodiment, the detection process may also first perform (1) and (3) to obtain the reduced mobility of the ion peak of the calibration object and the characteristic peak of the object under various environments, and then perform (2) and (4) to determine whether the object is the substance corresponding to the standard. Only if the reduced mobility of the characteristic peak of the measured object detected in various environments is consistent with the value inquired from the database, the measured object can be judged to be the substance corresponding to the standard product, otherwise, the measured object is judged not to be the substance corresponding to the standard product. (see FIG. 6)
The ion peaks A and B of the calibration objects are characteristic ion peaks of two calibration objects. Under the positive ion detection mode, 2, 6-di-tert-butylpyridine (2, 6-DTBP, CAS number 585-48-8) and 2,4-lutidine (2, 4-1 lutidine,2,4-DMP, CAS number 108-47-4) can be selected as calibration substances, wherein the reduced mobility corresponding to the characteristic ion peak of the 2,6-DTBP is slightly influenced by the temperature of an IMS drift tube, the content of water vapor and interferents in drift gas and can be considered as constant in a certain range, the reduced mobility corresponding to the characteristic ion peak of the 2,4-DMP is changed along with the temperature of the drift tube, the water content of the drift gas and the content of the interferents, and the change of the numerical value reflects the change of environmental parameters in the drift tube of the ion mobility spectrometer.
The positive ion mode subscript may also be selected from dimethyl phosphate grade (DMMP, CAS number 756-79-6), tetraalkylammonium (tetraalkylammonium, including but not limited to tetrabutylammonium bromide, CAS number 1643-19-2, tetraethylammonium bromide, CAS number 71-91-0, tetrapropylammonium bromide, CAS number 1941-30-6, tetrapentylammonium bromide, CAS866-97-7, tetrabutylammonium iodide, CAS number 311-28-4), nicotinamide (Nicotinamide, CAS number 98-92-0), trimethylamine (TMA, CAS number 75-50-3), triethylamine (TEA, CAS number 121-44-8), dipropylene glycol methyl ether (DPGME, CAS number 34590-94-8), and the like.
The negative ion mode marker can be methyl salicylate (CAS number 119-36-8), trinitrotoluene (TNT CAS number 118-96-7), etc.
In the method of the invention, the ion peaks A and B of the markers can adopt the following alternative technical scheme besides the characteristic ion peaks of two different markers:
(1) The monomer ion peak and dimer ion peak of a calibration material are respectively selected as calibration material ion peaks A and B.
If dimethyl methyl phosphate is used as a calibration material in a positive ion mode, the reduced mobility corresponding to a dimer ion peak of the dimethyl methyl phosphate is slightly influenced by the temperature of an IMS drift tube, the content of water vapor and interferents in drift gas, and can be considered as a constant in a certain range, while the reduced mobility corresponding to a monomer ion peak of the dimethyl methyl phosphate is changed along with the temperature of the drift tube, the water content of the drift gas and the content of the interferents, and the change of the numerical value reflects the change of environmental parameters in the drift tube of the ion mobility spectrometer.
(2) And selecting a calibration substance ion peak and a reactant ion peak as a calibration substance ion peak A and a calibration substance ion peak B respectively.
As in the positive ion detection mode, the general ion mobility spectrometry uses hydrated protons, hydrated ammonia ions, or hydrated acetone ions as reactant ions, and uses hydrated chloride ions as reactant ions in the negative mode. The reduced mobility of the reactive ions also changes along with the temperature of the drift tube, the water content of drift gas and the content of interferent, the numerical change reflects the change of environmental parameters in the drift tube of the ion mobility spectrometer, and the numerical change can be used as a calibration object ion peak B. The effect of the method can be achieved only by selecting a calibration object ion peak A which is slightly influenced by the temperature of the IMS drift tube, the water vapor in the drift gas and the content of the interferent.
The number of marker ion peaks in the method of the present invention can also be more than two to more accurately reflect the effects of drift tube temperature, drift gas water content, and the content of various interferents.
(2) Number of ion peaks of calibration object
(3) Method for changing working parameters of ion mobility spectrometer
In order to obtain ion migration spectrograms of characteristic ion peaks of a measured object and ion peaks of a calibration object under various environments, a plurality of drift tubes with different internal environments (temperature, water content in drift gas, content of interferent and the like) can be used for working in parallel; the single drift tube can also be used for working, and the content of water vapor and other interferent in drift gas can be changed by changing the temperature of the drift tube, changing the circulating flow of the drift gas, or changing the gas path by switching and the like.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A detection method for calibrating an ion mobility spectrometer by utilizing multiple ion peaks comprises the following steps:
(1) Acquiring a characteristic ion peak of an object to be detected and an ion migration spectrogram of at least two characteristic ion peaks of a calibration object under a first test environment;
(2) Calculating the reduced mobility corresponding to the characteristic ion peak of the object to be measured and the characteristic ion peak of the calibration object;
(3) Determining the reduced mobility corresponding to a characteristic ion peak of a standard product in a first test environment according to the reduced mobility corresponding to the characteristic ion peak of the calibration object and the reduced mobility corresponding to the characteristic ion peak of the calibration object in the standard detection database; wherein the standard detection database comprises reduced mobility of standard and calibration objects under different test environment parameters;
(4) If the reduced mobility corresponding to the characteristic ion peak of the standard substance is consistent with the reduced mobility corresponding to the characteristic ion peak of the object to be detected, determining the object to be detected as the standard substance;
the characteristic ion peak of the calibrator comprises any one of the following:
characteristic ion peaks of at least two different calibrators;
a monomeric ion peak and a dimeric ion peak of a calibrator;
the reduced mobility of the characteristic ion peak of the calibration object reflects the change of environmental parameters in the drift tube of the ion mobility spectrometer;
the test environment parameters comprise the temperature of the drift tube, the water content in the drift gas and the content of interferents;
and (3) changing the test environment parameters after the step of the step (4) is finished if the reduced mobility corresponding to the standard substance characteristic ion peak is consistent with the reduced mobility corresponding to the object characteristic ion peak, repeating the steps (1) to (3) in a second test environment, and determining that the object to be detected is the standard substance if the reduced mobility corresponding to the standard substance characteristic ion peak obtained in the second test environment is consistent with the reduced mobility corresponding to the object characteristic ion peak.
2. The detection method according to claim 1,
the standard detection database establishing method comprises the following steps:
(1) Sampling a standard substance and a calibration substance under a test environment parameter to obtain an ion migration spectrogram containing a characteristic peak of the standard substance and a characteristic peak of the calibration substance;
(2) Calculating reduced mobility corresponding to the standard substance characteristic peak and the calibration substance characteristic peak under the test environment parameters, and recording reduced mobility data corresponding to the standard substance characteristic peak and the calibration substance peak in an ion mobility spectrogram database;
(3) Changing the testing environment parameters, repeating the step (1) and the step (2) to obtain reduced mobility rates corresponding to the standard substance characteristic peak and the calibration object characteristic peak under different testing environment parameters, and recording the reduced mobility rates in an ion mobility spectrometry database;
(4) And when the scale of the ion mobility spectrogram database meets the preset scale, taking the ion mobility spectrogram database at the moment as a standard detection database.
3. The detection method according to claim 1,
the calibration substance in the positive ion mode comprises at least one of 2, 6-di-tert-butylpyridine, 2, 4-dimethylpyridine, dimethyl phosphate, tetraalkylammonium, tetraethylammonium bromide, tetrapropylammonium bromide, tetrapentylammonium bromide, tetrabutylammonium iodide, nicotinamide, trimethylamine, triethylamine and dipropylene glycol methyl ether;
the negative ion mode subscript includes at least one of methyl salicylate and trinitrotoluene.
4. A detection method for calibrating an ion mobility spectrometer by using multiple ion peaks comprises the following steps:
(1) Acquiring ion migration spectrograms of characteristic ion peaks of an object to be detected and characteristic ion peaks of a calibration object under various test environments;
(2) Respectively calculating the reduced mobility corresponding to the characteristic ion peak of the object to be tested and the characteristic ion peak of the calibration object under different test environments;
(3) Determining the reduced mobility corresponding to the characteristic ion peak of a certain standard product under different test environments according to the reduced mobility corresponding to the characteristic ion peak of the calibration object and the reduced mobility corresponding to the characteristic ion peak of the calibration object in the standard detection database; wherein the standard detection database comprises reduced mobility of standard and calibration objects under different test environment parameters;
(4) And if the reduced mobility corresponding to the characteristic ion peak of the standard substance under different test environments is consistent with the reduced mobility corresponding to the characteristic ion peak of the object to be tested, determining the object to be tested as the standard substance.
5. The detection method according to claim 4,
and (3) after the step (2) is finished and before the step (3) is started, judging whether the testing times of different testing environments reach preset values or not, if not, changing the testing environments to repeat the step (1) and the step (2) until the testing times reach the preset values, and then carrying out the step (3).
6. The detection method according to claim 4,
the calibrant ion peak has at least two ion peaks;
the reduced mobility of at least one of the calibrant ion peaks is reflective of a change in an environmental parameter within the drift tube of the ion mobility spectrometer.
7. The detection method according to claim 4,
the test environment parameters comprise at least one of drift tube temperature, water content in drift gas and interferent content.
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