ION MOBILITY ANALYSIS APPARATUS
20220341874 · 2022-10-27
Inventors
Cpc classification
H01J49/004
ELECTRICITY
International classification
Abstract
A high duty cycle ion mobility analysis apparatus includes an ion source, first and second ion storage zones, and an ion mobility analyzer. The ion mobility analyzer includes first and second channels containing a gas flow coaxial with an ion migration direction and a direct current electric field in the opposite direction of the gas flow, and the direct current electric fields in the channels are different in strength. In a continuous scanning period, ions that have not reached appropriate scanning conditions or have missed the appropriate scanning conditions and thus are unable to pass through the mobility analyzer are temporarily stored in two independent ion storage zones without being lost to be analyzed by the mobility analyzer until conditions of the scanning period or a next scanning period are appropriate.
Claims
1. An ion mobility analysis apparatus, comprising: an ion source for continuously generating ions, which contain analyte ions; a first ion storage zone located downstream of the ion source; a second ion storage zone located downstream of the ion source; and an ion mobility analyzer located downstream of the ion source for receiving the ions generated by the ion source and performing mobility analysis; wherein the ion mobility analyzer scans at least one operating parameter f(t) in an operating period from t.sub.0 to t.sub.1, so that ions with different mobilities pass through the ion mobility analyzer sequentially, the operating parameter f(t) is a monotonic function of time t, the analyte ions can pass through the ion mobility analyzer in an operating parameter range of [f(t.sub.A), f(t.sub.B)], and t.sub.0<t.sub.A<t.sub.B<t.sub.1; the operating period is repeated multiple times, and in each operating period: in the stage of t.sub.0≤t<t.sub.A, at least part of the analyte ions filtered out by the ion mobility analyzer in the stage are transmitted and stored in the first ion storage zone; in the stage of t.sub.B<t≤t.sub.1, at least part of the analyte ions filtered out by the ion mobility analyzer in the stage are transmitted and stored in the second ion storage zone; in the stage of t.sub.A≤t≤t.sub.B, the analyte ions generated by the ion source, the analyte ions stored in the first ion storage zone in the same operating period, and the analyte ions stored in the second ion storage zone in the previous operating period can pass through the ion mobility analyzer to enter a next stage analysis apparatus or be detected by a detector.
2. The ion mobility analysis apparatus according to claim 1, wherein the ion mobility analyzer comprises a first channel and a second channel, and during mobility analysis, the ions generated by the ion source pass through the first channel and the second channel successively, and, only ions with mobility larger than a pre-set ion mobility K.sub.1 can pass through the first channel, and only ions with mobility smaller than a pre-set ion mobility K.sub.2 can pass through the second channel, wherein K.sub.1<K.sub.2, so that only ions with mobility between K.sub.1 and K.sub.2 can pass through the ion mobility analyzer; or only ions with mobility smaller than a pre-set ion mobility K.sub.1 can pass through the first channel, and only ions with mobility larger than a pre-set ion mobility K.sub.2 can pass through the second channel, wherein K.sub.2<K.sub.1, so that only ions with mobility between K.sub.1 and K.sub.2 can pass through the ion mobility analyzer.
3. The ion mobility analysis apparatus according to claim 2, wherein the first channel and the second channel contain a gas flow coaxial with an ion migration direction and a direct current electric field in the opposite direction of the gas flow, and the direct current electric field in the first channel and the direct current electric field in the second channel are different in field strength.
4. The ion mobility analysis apparatus according to claim 2, wherein the operating parameter f(t) is an electric field strength.
5. The ion mobility analysis apparatus according to claim 2, wherein the first ion storage zone is located in front of the second channel, and the second ion storage zone is located in front of the first channel.
6. The ion mobility analysis apparatus according to claim 2, wherein the first ion storage zone is located in front of the first channel, and the second ion storage zone is located in front of the second channel.
7. The ion mobility analysis apparatus according to claim 4, wherein the first channel and the second channel are both linear structures, and an included angle between the two channels is not less than 90 degrees.
8. The ion mobility analysis apparatus according to claim 5 wherein a radio frequency electric field and a direct current electric field are applied into the first ion storage zone and the second ion storage zone to store the ions.
9. The ion mobility analysis apparatus according to claim 4, wherein the mode of scanning the electric field strength is linear continuous scanning, curvilinear continuous scanning, segmented scanning or a combination of the above scanning mode.
10. The ion mobility analysis apparatus according to claim 1, wherein further comprising a mass analyzer downstream of the ion mobility analyzer.
11. The ion mobility analysis apparatus according to claim 10, wherein the mass analyzer is a quadrupole mass filter or a magnetic mass analyzer.
12. The ion mobility analysis apparatus according to claim 10, wherein in the stage of t.sub.A≤t≤t.sub.B, the analyte ions pass through the ion mobility analyzer and enter the mass analyzer, at this time, the operating parameters of the mass analyzer are also set to be suitable for the analyte ions to pass through the mass analyzer.
13. An ion mobility analysis method, comprising: providing an ion source for continuously generating ions, which contain analyte ions; providing a first ion storage zone located downstream of the ion source; providing a second ion storage zone located downstream of the ion source; and providing an ion mobility analyzer located downstream of the ion source for receiving the ions generated by the ion source and performing mobility analysis; wherein the ion mobility analyzer scans at least one operating parameter f(t) in an operating period from t.sub.0 to t.sub.1, so that ions with different mobilities pass through the ion mobility analyzer sequentially, the operating parameter f(t) is a monotonic function of time t, the analyte ions can pass through the ion mobility analyzer in an operating parameter range of [f(t.sub.A), f(t.sub.B)], and t.sub.0<t.sub.A<t.sub.B<t.sub.1; the operating period is repeated multiple times, and in each operating period: in the stage of t.sub.0≤t<t.sub.A, at least part of the analyte ions filtered out by the ion mobility analyzer in the stage are transmitted and stored in the first ion storage zone; in the stage of t.sub.B<t≤t.sub.1, at least part of the analyte ions filtered out by the ion mobility analyzer in the stage are transmitted and stored in the second ion storage zone; in the stage of t.sub.A≤t≤t.sub.B, the analyte ions generated by the ion source, the analyte ions stored in the first ion storage zone in the same operating period, and the analyte ions stored in the second ion storage zone in the previous operating period can pass through the ion mobility analyzer to enter a next stage analysis apparatus or be detected by a detector.
14. The ion mobility analysis method according to claim 13, wherein the ion mobility analyzer comprises a first channel and a second channel, and during mobility analysis, the ions generated by the ion source pass through the first channel and the second channel in turn, and, only ions with mobility larger than a pre-set ion mobility K.sub.1 can pass through the first channel, and only ions with mobility smaller than a pre-set ion mobility K.sub.2 can pass through the second channel, wherein K.sub.1<K.sub.2, so that only ions with mobility between K.sub.1 and K.sub.2 can pass through the ion mobility analyzer; or only ions with mobility smaller than a pre-set ion mobility K.sub.1 can pass through the first channel, and only ions with mobility larger than a pre-set ion mobility K.sub.2 can pass through the second channel, wherein K.sub.2<K.sub.1, so that only ions with mobility between K.sub.1 and K.sub.2 can pass through the ion mobility analyzer.
15. The ion mobility analysis method according to claim 14, wherein the first channel and the second channel contain a gas flow coaxial with an ion migration direction and a direct current electric field in the opposite direction of the gas flow, and the direct current electric field in the first channel and the direct current electric field in the second channel are different in field strength.
16. The ion mobility analysis method according to claim 14 wherein the operating parameter f(t) is an electric field strength.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0016]
[0017]
[0018]
[0019]
[0020]
[0021]
[0022]
[0023]
[0024]
[0025]
REFERENCE NUMERALS
[0026] 1-ion source;
[0027] 2-first ion storage zone;
[0028] 3-second ion storage zone;
[0029] 4-ion mobility analyzer;
[0030] 5-detector;
[0031] 6-mass analyzer;
[0032] 40-first channel;
[0033] 41-second channel;
[0034] 7-U-shaped ion mobility analyzer;
[0035] 8-quadrupole mass filter;
[0036] 9-collision cell; and
[0037] 10-time of flight mass spectrometer.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Embodiments of the present invention are described below by specific embodiments, and other advantages and effects of the present invention can be easily known by those skilled in the art from the content disclosed in this specification.
[0039] It should be noted that structures, proportions, sizes, etc. shown in the drawings and formulas of this specification are all only used to cooperate with the contents disclosed in this specification, so as to be understood and read by those who are familiar with the technology, are not used to limit the implementation conditions of the present invention, and thus do not have technically substantive significance, and any modification of the structure, changes of a proportional relationship or adjustment of the size, without affecting the effect that the present invention can produce and the purpose that the present invention can achieve, should still fall within the range of the technical content disclosed in the present invention. At the same time, the terms such as “up”, “down”, “left”, “right”, “middle” and “one” quoted in this specification are only for the clarity of description, and are not used to limit the implementable scope of the present invention, and the change or adjustment of the relative relationship thereof shall also be regarded as the implementable scope of the present invention without substantially changing the technical content.
[0040] “Mobility” or “mobility spectrometry” mentioned in this specification includes not only “mobility” or “mobility spectrometry” related to an ion collision cross section (CCS), but also “differential mobility” or “differential mobility spectrometry” which are related to an electric field strength. In this specification, the ions “pass through” a certain apparatus or analyzer, meaning that the ions can spatially pass through an operating zone of the apparatus or analyzer and be transmitted to a next stage apparatus.
[0041]
[0042] Any one operating period of this embodiment, such as the Nth period, can be divided into the following three stages.
[0043] The first stage is the stage of t.sub.0≤t<t.sub.A, at this time, conditions of the ion mobility analyzer 4 (such as electric field strength conditions) are not suitable for the target analyte ions to pass through, and the target analyte ions generated by the ion source in this stage may pass through a part of the ion mobility analyzer to enter the first ion storage zone 2, the stored target analyte ions are marked as “ions I.sub.1(N)”, the subscript 1 represents being stored in the first ion storage zone 2, and N represents that it is stored in the Nth period; at this time, the second ion storage zone 3 stores target analyte ions I.sub.2(N−1) stored in the previous period, and its generation and storage process will be described hereinafter.
[0044] The second stage is the stage of t.sub.A≤t≤t.sub.B, at this time, the conditions of the ion mobility analyzer 4 are suitable for the target analyte ions to pass through, and the target analyte ions generated by the ion source 1 in this stage, the target analyte ions I.sub.1(N) stored in the first ion storage zone 2 in the same period, and some kind of analyte ions I.sub.2(N−1) stored in the second ion storage zone 3 in the previous period will enter together and pass through the ion mobility analyzer 4 completely and then reach the detector 5 to be detected; after this stage is completed, the ions in the first ion storage zone 2 and the second ion storage zone 3 have been cleared.
[0045] The third stage is the stage of t.sub.B<t≤t.sub.1, at this time, the conditions of the ion mobility analyzer 4 become unsuitable for the target analyte ions to pass through, and the target analyte ions generated by the ion source 1 in this stage may pass through part of the ion mobility analyzer 4 to enter the second ion storage zone 3, and the stored target analyte ions are marked as “ions I.sub.2(N)”, while the first ion storage zone 2 still remains an ion cleared state.
[0046] In the next period, namely, the (N+1)th period, the three stages described above will be repeated, for example, in the first stage, the ions I.sub.1(N+1) will continue to be stored, in the second stage, the ions are transmitted completely, and in the third stage, the ions I.sub.2(N+1) will be stored. All the periods cycle in sequence until the end of this analysis.
[0047] In this embodiment, in the first period, I.sub.2(0) is actually an empty ion packet; and in the last period M, I.sub.2(M) will not have an opportunity to enter the ion mobility analyzer 4, so at the end of one analysis, a clearing stage can be additionally set to clear the I.sub.2(M) to avoid interference to next analysis.
[0048] In this embodiment, due to the use of the two ion storage zones, in one continuous operating period, ions that have not reached appropriate scanning conditions or have missed the appropriate scanning conditions and thus are unable to pass through the ion mobility analyzer 4 are temporarily stored in one of the two ion storage zones without being lost, and then the ions are transmitted out to be analyzed by the ion mobility analyzer 4 until conditions of the operating period or a next operating period are appropriate. By the above means, almost all the target analyte ions are finally analyzed and detected by the ion mobility analyzer 4, which effectively reduces an ion loss in a scanning process, so that the ion utilization efficiency, or the duty cycle of the ion mobility analysis apparatus, can reach a level close to 100%. However, in a traditional scanning process, the duty cycle depends on the proportion of a suitable ion transmission duration in the whole period, and this proportion is often negatively correlated with the resolution or scanning range, so to reach a higher resolution or wider scanning range, the duty cycle is often very low, thus limiting the sensitivity of the instrument.
[0049]
[0050] At the beginning of scanning (t=t.sub.0), E.sub.S1=E.sub.0, and E.sub.S2=E.sub.0+ΔE, as shown by thick dashed lines in
[0051] In the stage from t.sub.A to t.sub.B, if the ion mobility analysis apparatus is suitable for the target analyte ions to pass through, the target analyte will pass through the first channel 40, then is deflected to the right end of the second channel 41, continues to pass through the second channel 41 to the left, and finally, enters the next stage through an exit of the second channel 41; this state continues until t=t.sub.B, at this moment, E.sub.S1=E.sub.B, and E.sub.S2=E.sub.B+ΔE.
[0052] In the stage from t.sub.B to t.sub.1, E.sub.S1 is scanned to increase from E.sub.B to E.sub.1, at this stage, for the analyte ions, the magnitude of an acting force exerted by the field strength in the first channel 40 on the ions has exceeded the influence of the gas flow, and the analyte ions are repulsed leftwards to the tail end of the left side by the field strength to be lost as soon as they enter the first channel 40.
[0053] In the present invention, referring to
[0054] At the beginning of scanning (t=t.sub.0), E.sub.S1=E.sub.0, E.sub.S2=E.sub.0+ΔE, a field strength in the second ion storage zone 3 is E.sub.0, a field strength in the first ion storage zone 2 is E.sub.1, then E.sub.S1 and E.sub.S2 are synchronously scanned to enhance until t=t.sub.A, E.sub.S1=E.sub.A, E.sub.S2=E.sub.A+ΔE=E.sub.B, and in the field strength scanning enhancement process of the above-mentioned channel zone, the field strength in the ion storage zone remains unchanged; in the stage from t.sub.0 to t.sub.A, due to an insufficient field strength in the channel, the target analyte ions will be carried by the gas flow to pass through the first channel 40, and are transmitted to a right end of the second channel 41 by a deflecting electric field, since the field strength in the first storage zone 2 at this position is strong, its acting force on the ions is greater than that generated by the gas flow, and the analyte ions can not escape out of the zone, and the field strength in the second channel 41 is still relatively weak and thus cannot continue to transmit ions to the left, so the ions will be stored in the first ion storage zone 2.
[0055] In the stage from t.sub.A to t.sub.B, the ion mobility analysis apparatus is suitable for the target analyte ions to pass through, then the target analyte ions entering from the ion source 1 will pass through the first channel 40, and then are U-deflected to the second channel 41, at this time, the ions stored in the first storage zone 2 are also released at the same time, and these ions pass through the second channel 41 together, and then enter a next stage through the exit of the second channel 41; this state continues until t=t.sub.B, at this moment, E.sub.S1=E.sub.B, and E.sub.S2=E.sub.B+ΔE.
[0056] In the stage from t.sub.B to t.sub.1, E.sub.S1 is scanned to increase from E.sub.B to E.sub.1, at this stage, for the analyte ions, the field strength in the first channel 40 has exceeded the influence of the gas flow, and the analyte ions are repulsed leftwards to the left side by the field strength as soon as they enter the first channel 40, but in the second ion storage zone 3 on the left side, the field strength is very low and cannot continue to push the ions, so the ions will be stored in the second ion storage zone 3 and these ions will be released from the second ion storage zone 3 in the stage from t.sub.A to t.sub.B in the next period, and pass through the first channel 40 and the second channel 41 together with the ions entering from the ion source 1 to be analyzed.
[0057] In actual analysis, there may be more than one kind of target analyte ions, or sometimes it is non-target analysis, and the present invention is also completely applicable to these situations.
[0058]
[0059]
[0060]
[0061] As a variant of the present invention, the ion mobility analysis apparatus may have only the first ion storage zone 2, or only the second ion storage zone 3, or, the first ion storage zone 2 and the second ion storage zone 3 are merged into the same zone. Compared with the prior art, the duty cycle can still be increased even a single ion storage zone is used, and these conditions are also within the protection scope of the present invention.
[0062] The above-mentioned embodiments merely illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above embodiments without departing from the spirit or scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present invention shall still be covered by the claims of the present invention.