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To figure out the reason for the drawback of the stored waveform inverse Fourier transform (SWIFT) waveform and realize the high-resolution ion isolation on the miniaturized linear ion trap mass spectrometer, we studied the efficiency that ions can be excited under different excitation durations and amplitudes at different frequencies and compared the overlap ratios of the effective excitation frequency bandwidths of the adjacent ions. According to this, we proposed a new coarse-to-fine isolation waveform named SWIFTSIN. By superposing one or more sinusoidal waveforms on the SWIFT waveform and modulating the phases of the superposed sinusoidal waveforms, the generated SWIFTSIN waveform can achieve unit mass isolation on the miniaturized linear ion trap mass spectrometer without reducing the intensity of the target ion. The isolation ability of the SWIFTSIN waveform was verified by isolating a single isotope peak in the mixed samples.

Inverse kinematics for all joint motions of parallel robot is the foundation for stiffness or dynamic analysis, and the prerequisite for motion monitoring during operation in case of collision or damage. The software equipped with a generalized inverse kinematic method is beneficial for the efficient motion solving of different parallel robots, and especially convenient for kinematic control development. Current inverse kinematic methods are either case-by-case studies or not amicable for programming. To tackle these problems, this paper proposes a generalized method to determine all the joint motions of parallel robot based on finite screw theory, including mechanism initialization, kinematic modeling and kinematic variable solving. Two parallel robots are taken as examples to verify the effectiveness and accuracy of the approach. After that, the method is applied for digital programming on the basis of computer technology, and a software is developed for the automatic inverse kinematic analysis. The advantages of this method lie in: the kinematic equation could be formulated in a general and concise manner independence of experience and observation; all the joint variables under given target pose are solved at the same time; it enables easy programming and realizes the automation of inverse kinematic analysis.

In the range of miniature mass spectrometers, the miniature ion trap mass spectrometer with continuous atmospheric pressure interface (CAPI) shows good performance potential and advantages due to its excellent sensitivity and analysis speed. However, in previous cases, placing the ion trap directly near the skimmer aperture means it will suffer high gas shock, which may affect performance. In this study, an improved miniature CAPI ion trap mass spectrometer was developed by gas flow optimization. According to the experimental results, excessive gas flow affects stability and resolution. The impact of the gas flow can be effectively reduced by reducing the inner diameter of the skimmer and adding an additional lens element to move the ion trap away from the skimmer aperture. However, this method will affect the sensitivity of the instrument to some extent, so a discontinuous subatmospheric pressure interface (DSPI) was developed to reduce the gas flow effects and improve the comprehensive performance. When using the DSPI system with a 0.4 mm skimmer and entrance lens, the resolution for roxithromycin was up to 2800 at a scanning speed of 1015 Th/s, which was 3.4-fold higher that without DSPI. The dynamic range of concentration reached 4 orders of magnitude and the detection limit for repaglinide was as low as 1 ng/mL. This study offers a new approach to develop better miniature ion trap mass spectrometers and to extend their practical application.

With the expansion of the functional food market, the qualification assessment of these products has become a major challenge, and efficient analytical tools are urgently needed. Here, a miniature mass spectrometer (MS) with self-aspiration capillary electrospray ionization (SACESI) source and ion trap analyzer was developed for rapid screening of various illegally added drugs in functional foods. No chromatographic separation was required, but a simplified two-step pretreatment method was developed to reduce the operational procedures and time consumption of the entire analysis. SACESI source uses capillary action to drive solution injection, which utilizes a simple structure and convenient operation to constitute a kind of disposable MS detection solution. To achieve accurate and automatic identification, an intelligent recognition algorithm with steps of spectrum preprocessing, characteristic peak matching, and support vector machine learning was constructed. The relative accuracy of rapid screening of 31 suspicious drugs in various samples is up to 99.78%. It achieves 100% correct identification for the 55 batches of actual samples captured by on-site inspection, which demonstrates the feasibility of the proposed analytical system and strategy in food safety applications.

This work reported an air atmospheric pressure plasma jet served as an ion source for nonvolatile solid analysis, which allows a unique capability to achieve thermal desorption and ionization simultaneously without complex devices, inert gas, or solvents. Owing to precise amount of heat generated by plasma jet, nonvolatile analytes were thermally released from solid surfaces without the assistance of secondary desorption equipment. According to the mass spectra and Fourier transform infrared spectrum, [M + H]+ and [M + NO3]− ions were the major analyte ions in the positive-ion and negative-ion modes, respectively. The applied voltages, discharge currents, and gas temperatures of plasma jet were measured, and found to be positively correlated with the mass spectra signal intensity of the samples, while the added resistances and gas flow rate were negatively correlated with the signal intensity. The influence mechanisms of analytes natures coupling physical parameters of plasma jet on detection performance were revealed. The prospect of quantitative testing was confirmed by the linear relationship between the peak intensity and sample mass.

The coupling of the microfluidic chip to mass spectrometry (MS) has attracted considerable attention in the area of chemical and biological analysis. The most commonly used ionization technique in the chip–MS system is electrospray ionization (ESI). Traditional chip-based ESI devices mainly employ direct electrical contact between the electrode and the spray solvent. In this study, a microchip ESI source based on a novel polarization-splitting approach was developed. Specifically, the droplet in the microchannel is first polarized by the electric field and then split into two sub-droplets. In this process, the charge generated by polarization is retained in the liquid, resulting in the generation of two charged droplets with opposite polarities. Finally, when these charged droplets reach the emitter, the electrospray process is initiated and both positive and negative ions are formed from the same solution. Preliminary experimental results indicate that the coupling of this polarization-splitting ESI (PS-ESI) chip with a mass spectrometer enables conventional ESI-MS analysis of various analytes.

Mass spectrometry is subject to matrix effects, which causes severe limitations on the analysis of live single cells in their native state. Here, we propose a three-phase droplet-based single-cell printing analysis system (TP-SCP), which can package, extract, separate, print, and analyze live single cells in saline matrixes (such as phosphate buffered saline) with matrix-assisted laser desorption/ionization mass spectrometry. This method can eliminate matrix effects to obtain information on a single cell in their native state. We report that a cell packaging percentage of 44% and single-cell packaging percentage of 88% can be achieved by TP-SCP. The system was capable of processing three to four single cells per second, which was 30 to 40 times higher than the traditional droplet-based microextraction (about 10 s/cell). Additionally, the MCF-7, A2780, 293, and 4T1 cells were screened in our system. The effect of cell viability and heterogeneity analysis was investigated, suggesting that the concentration of monounsaturated phosphatidylinositol and phosphatidylethanolamine both increase in cancer cells. Compared with conventional mass spectrometry, TP-SCP can ensure the accuracy of heterogeneity analysis of live single cells in their native state. Both a principal component analysis and a linear discriminant analysis were used to perform classification and identification of cells with an accuracy of 100%. This method provides an innovative framework for research on cell quality control, cell biology, cancer diagnosis, and prevention.

Ion funnels have been miniaturised and integrated into miniature ion trap mass spectrometers to improve instrument sensitivity. However, the ion discrimination effect of the ion funnel constrains its application. Previous research has generally reported that the ion discrimination is related mainly to the mass of the ions. In this paper, the Runge–Kutta algorithm was used to characterise the trajectories of ions in the funnel under collisions with gas molecules. It is theoretically and empirically proved that, in a continuous atmospheric-pressure-interfaced miniature mass spectrometer, ion discrimination in the funnel shows two aspects: mass discrimination and collision cross-section discrimination. It was found that DC gradient, RF amplitude and operating pressure of the ion funnel will affect ion transmission. Among these parameters, RF amplitude is the key parameter controlling ion discrimination. To weaken the ion discrimination, RF amplitude scanning method was introduced in the injection section of the ion trap to improve ion transmission efficiency over the entire mass range. After optimisation of the ion funnel, the dynamic range of the instrument concentration reached four orders of magnitude. The detection limit of roxithromycin reached a low level of 1 ng mL−1. The results of this study increase the theoretical understanding of the ion funnel, providing guidance for applying ion funnels in improving the sensitivity of miniature mass spectrometers and expanding their actual applicability.

Lipid imaging plays an important role in the research of some diseases, such as cancers. Unsaturated lipids are often present as isomers that can have different functions; however, traditional tandem mass spectrometry imaging (MSI) cannot differentiate between different isomers, which presents difficulties for the pathological study of lipids. Herein, we propose a method for the MSI of the C═C double-bond isomers of unsaturated lipids based on oxidative reactions coupled with air flow-assisted desorption electrospray ionization, which can conveniently achieve rapid MSI of unsaturated lipids at an isomeric level. Using this method, tissue sections can be scanned directly with MSI after only 10 min of accelerated oxidation. This method was used for the imaging of mouse lung cancer tissues, revealing a distributional difference in the unsaturated lipid isomers of normal and pathological regions. Through the MSI of unsaturated lipids at an isomeric level in tissues infected with cancer cells, the regions where the isomers were enriched were exhibited, indicating that these regions were the most concentrated regions of cancer cells. This method provides a convenient platform for studying the functional effects of the isomers of unsaturated lipids in pathological tissues.

Finite motion analysis and type synthesis of parallel mechanisms with parasitic motions are great challenges in the fields of mechanisms and robotics. This paper proposes a finite screw based approach to handle this problem by taking one translational and two rotational (1T2R) parallel mechanisms with parasitic motions as examples. Firstly, 1T2R finite motion of the moving platform is categorized into four cases whose finite motions are described by finite screw analytically and then the reasons for producing parasitic motions are explored in this process. Based on this, available limbs are obtained algebraically by deriving formulas formed by triangle screw product. Finally, the assembly conditions among limbs, fixed base and moving platform are acquired in an analytical manner, leading to synthesize 1T2R parallel mechanisms with parasitic motions systematically. This paper solves a long-term problem that describes and analyzes finite motions of parallel mechanisms with parasitic motions and synthesizes their topology structures.

In recent years, the development of unsaturated lipid isomeric imaging based on the Paterno–Buchi (PB) reaction has improved significantly. However, research on this imaging method in ambient conditions needs to expand. In this paper, a method of PB reaction in the solid phase in ambient conditions is developed, which is combined with air-flow-assisted desorption electrospray ionisation mass spectrometry (AFADESI-MS) to achieve in situ imaging of lipids at an isomeric level. Experiments showed that the efficiency of the PB reaction was much higher when spraying the reagent solution than when sprinkling the reactant powder directly, and it was not lower than that in the liquid phase. This method can simplify the reaction conditions in the imaging process and can be applied to tissue section samples with only 10 min of pre-processing. The study successfully demonstrated the spatial distribution of unsaturated lipid isomers, and the isomeric ratio corresponded to the lesion areas in mouse brain cancer tissues. Due to its simple operation and performance in ambient conditions, this method may be useful for future studies on lipid isomers in tissues.

In this paper, a novel mobile mechanism based on Bennett mechanism is proposed, which can realize self-crossing locomotion. Unlike the most of the self-crossing mechanisms, the proposed mechanism can be assembled modularly, which has better environment adaptability. Firstly, on the basis of revealing mechanism of the self-crossing movement, configuration of the self-crossing mechanism is designed. The mechanism consists of n Bennett mechanisms connected in series by 2(n-1) 3R limbs that are symmetrically distributed on both sides of n Bennett mechanisms. Then, kinematic analysis of the mechanism is carried out based on finite and instantaneous screw theory, including mobility analysis and gait analysis. For the former, the number of degrees of freedom that the mechanism can achieve self-crossing locomotion is obtained, and for the latter, the trajectory of end point of the mechanism in the self-crossing movement is obtained. Finally, On the basis of theoretical analysis, simulation is conducted, and the results show that the proposed novel mechanism can realize self-crossing locomotion without interference, which verified the rationality of the mechanism. This paper provides a useful reference for the design and analysis of self-crossing mobile mechanism.

With the development of instrumental miniaturization, the portable mass spectrometer is becoming a new tool for on-site rapid analysis of environmental samples. Membrane inlet (MI) and photoionization (PI) are two commonly used sampling and ionization techniques, respectively, as they both exhibit detection selectivity for volatile organic compounds (VOCs). In this paper, a membrane inlet photoionization ion trap mass spectrometer was developed for the direct analysis of VOCs in gaseous samples. With the new structure and timing design, various operation modes were proposed and tested. In particular, the use of pulse carrier gas can integrate the appropriate pressure conditions required by each module, thus improving the efficiency of analyte transport, ionization, and mass analysis. The detection limit of sub-ppb was obtained, and the response time can be greatly reduced by increasing the sample flow rate. Furthermore, the capability of selective enrichment for organic analytes was also realized by using a special accumulation mode with a modified sequence, which is easy to operate because no additional devices are needed.

RATIONALE Secular frequency scanning is a mass spectrometry (MS) analysis method in which the frequency of the auxiliary alternating current (AC) signal is scanned. It has low requirements for radio-frequency (RF) power, which is beneficial for the miniaturization of the mass spectrometer. In this study, the MS performance in the reverse secular frequency scanning (RSFS) mode is optimized for a rectilinear ion trap (RIT), and a method for rapid MS analysis using continuous secular frequency scanning (CSFS) is proposed. METHODS A RIT mass spectrometer with an auxiliary AC frequency scanning function was built. The resolution, tandem mass spectrometry (MS/MS) and quantitation capability in the RSFS mode were characterized and optimized. Operation in the CSFS mode was then performed by scanning the frequency of the auxiliary AC signal continuously and periodically while maintaining the RF signal and the front Z electrode in the ion injection state, so that the ion injection and cooling were performed at the same time as the mass analysis. RESULTS With this system, the RSFS mode achieved unit mass resolution at 332 Th, and the MS/MS analysis was completed without changing the RF amplitude at q = 0.4583 for reserpine. The limit of quantitation for imatinib was about 250 ng/mL with the determination coefficient R2 = 0.9981. In the CSFS mode, a single analysis cycle of less than 20 ms could be achieved, which is 14 times faster than the traditional sweep modes. In addition, 100% ion utilization can theoretically be achieved in the CSFS mode. CONCLUSIONS The CSFS mode is different from the traditional phased sequential operation mode of an ion trap mass spectrometer. By periodic scanning of the auxiliary AC frequency while maintaining ion injection, it is possible to improve the analysis efficiency of the mass spectrometer, which has the prospect of useful application in the field of rapid MS monitoring. Copyright © 2017 John Wiley & Sons, Ltd.

This paper proposes topology design and kinematic optimization of cyclical 5-degree-of-freedom (DoF) parallel manipulator with proper constrained limb. Firstly, a type of cyclical 5-DoF parallel manipulators with proper constrained limb is proposed by analyzing DoF of the proper constrained limb within workspace. Exampled by a cyclical 5-DoF parallel manipulator with the topology 4-UPS&1-RPS, its motion mapping model is formulated. By taking the reciprocal product of a wrench on a twist as the generalized virtual power, the local and global kinematic performance indices are provided. Then, on the basis of the actuated and constrained singularity analysis of the 4-UPS&1-RPS parallel manipulator within the position and pose workspace, the topology design of the manipulator without singularity is carried out, and its reachable and prescribed workspaces are obtained. Finally, by maximizing the global kinematic performance index and subjecting to a set of appropriate constraint conditions, the kinemati...

Aiming at obtaining lower-mobility parallel mechanisms (PMs) in a topological and direct manner, this paper intends to propose an approach for configuration evolution of Stewart Platform and its variations. Firstly, the finite motion of Stewart Platform is described by utilizing finite screw and the motion mapping with lower-mobility PMs is formulated. Then the relationship between motion and topology is revealed in an analytical form. Following with these work, the principles for removing motions and their according topological manipulations are derived. A two-step method for configuration evolution is proposed. Finally, two examples as spatial translational and planar motion PMs are taken to show the concise process of the method and target PMs with closed-loop limbs are obtained. The principles involved in this approach are proved algebraically, but they are easy to be performed by simple topological manipulations such as synchronously driving and locking joints without any calculations even mathematic knowledge. This method facilitates the concise acquirement of lower-mobility PMs, especially 3-degree-of-freedom (DoF) PMs in the engineering.

Baseline correction is an indispensable step in the signal processing of chemical analysis instruments. With the increasing demand for on-site applications, a variety of analytical instruments require a more friendly, rapid and adaptive baseline correction method. In this paper, a data-driven and coarse-to-fine (DD-CF) baseline correction scheme mainly based on the empirical mode decomposition (EMD) algorithm is proposed. For eliminating the mode-mixing effect of the original EMD, the proposed method firstly obtains a coarse baseline estimation using automatic peak detection, elimination and interpolation; and the EMD is applied on the coarse baseline to get a fine baseline finally. We have compared this method with the adaptive iteratively reweighted Penalized Least Squares algorithm (airPLS) and the sparse representation baseline correction methods using simulated signals and experimental signals from different analytical instruments. Results indicate that the proposed DD-CF scheme can effectively estimate the baseline more accurate than the comparing methods for varies of analytical signals such as mass spectrometer, ion mobility spectrometer, gas chromatograph, etc. Furthermore, with signals of different length, different peak distributions and even from totally different instruments, the proposed method requires minimal user intervention, in which the parameters of the comparing methods should be adjusted for a wide range.

To improve tracking precision against complex external forces in the working environment, dynamic model-based control algorithms are widely used in tracking mechanisms. As a foundation of the real-time dynamic control system, this paper focuses on the complete predicted dynamic modelling and dynamic parameter identification of a 2-DoF over-constrained tracking parallel mechanism. Firstly, the kinematic model is obtained by differential mapping of the topology models based on finite and instantaneous screws (FIS). Referred to virtual work principle, dynamic equation is constructed. To reduce the computation cost in practice, a linear model involving inertial and friction parameters is formulated for dynamic identification. A direct identification method is applied and all the parameters are obtained at the same time. Experiments are performed to show the accuracy and efficiency of the identification results. The contributions of the paper lie in 1) a concise method for constructing velocity and acceleration models of components is provided without tedious analysis 2) complete dynamic model of an over-constrained tracking parallel mechanism is developed 3) practical dynamic identification process is carried out compromising between precision and efficiency.

Determining the motions and constraints of serial kinematic chains in a concise and visual way is an inevitable step in the analysis and design of both serial and parallel mechanisms. The now most used method is the numerical approach which resorts to solving linear equations. By introducing Clifford algebra, this paper intends to propose an analytical approach to determine the unknown 6- n ( n

The rectilinear ion trap (RIT) has always been one of the ideal candidates for mass analyzer miniaturization because of its simple configuration. In this work, the effect of the ejection-slit dimensions on the ion ejection efficiency of a miniature rectilinear ion trap (mRIT) with full-scale dimensions of 5 mm × 4 mm × 25 mm was investigated by using SIMION8.1 simulation. Six mRITs with the same dimensions as those simulated and with different slit widths, whose X electrodes were fabricated by the stainless steel chemical etching process, were tested and characterized on a homemade mass spectrometer platform. It is shown that the ejection slit dimensions have a significant impact on both the signal intensity and mass resolution. For an mRIT with these full-scale dimensions, the optimized slit dimensions are 0.6 mm × 18 mm. The optimized mRIT demonstrated capabilities including a mass/charge range of over 1000 Th, unit mass resolution at m/z 332, and a passable tandem mass spectrometry capability, which are better than the non-optimized RIT with the same dimensions.

This paper proposes a geometric algebra (GA) based approach to carry out inverse kinematics and design parameters of a 2-degree-of-freedom parallel mechanism with its topology structure 3-RSR&SS for the first time. Here, R and S denote respectively revolute and spherical joints. The inverse solutions are obtained easily by utilizing special geometric relations of 3-RSR&SS parallel positioning mechanism, which are proven by calculating relations among point, line and plane in virtue of operation rules. Three global indices of kinematic optimization are defined to evaluate kinematic performance of 3-RSR&SS parallel positioning mechanism in the light of shuffle and outer products. Finally, the kinematic optimal design of 3-RSR&SS parallel positioning mechanism is carried out by means of NSGA-II and then a set of optimal dimensional parameters is proposed. Comparing with traditional kinematic analysis and optimal design method, the approach employing GA has following merits, (1) kinematic analysis and optimal design would be carried out in concise and visual way by taking full advantage of the geometric conditions of the mechanism. (2) this approach is beneficial to kinematic analysis and optimal design of parallel mechanisms in automatic and visual manner using computer programming languages. This paper may lay a solid theoretical and technical foundation for prototype design and manufacture of 3-RSR&SS parallel positioning mechanism.

Finite motion analysis of parallel mechanisms (PMs) denotes formulating the map between finite motion of end-effector and those of its component limbs. By employing conformal geometric algebra (CGA), this paper presents an analytical and accurate method to analyze the finite motions of PMs with parasitic motions. Herein, parasitic motions are defined as the dependent motions in the constraint Degrees-of-Freedom (DoFs) of PMs. Firstly, description of rigid body transformations based on CGA is reviewed. Then, the intersection algorithm of finite motions is introduced by exploiting the algebraic properties of CGA. Based on this, a method to formulate the finite motions of PMs with parasitic motions is proposed. Finally, Z3 mechanism is sketched as example by utilizing the approach. This method facilitates the invention of new mechanisms and can also be applied in the finite motion analysis of other kinds of PMs.

A fiber-capacitive drop analyzer is an instrument which monitors a growing droplet to produce a capacitive opto-tensiotrace (COT). Each COT is an integration of fiber light intensity signals and capacitance signals and can reflect the unique physicochemical property of a liquid. In this study, we propose a solution analytical and concentration quantitative method based on multivariate statistical methods. Eight characteristic values are extracted from each COT. A series of COT characteristic values of training solutions at different concentrations compose a data library of this kind of solution. A two-stage linear discriminant analysis is applied to analyze different solution libraries and establish discriminant functions. Test solutions can be discriminated by these functions. After determining the variety of test solutions, Spearman correlation test and principal components analysis are used to filter and reduce dimensions of eight characteristic values, producing a new representative parameter. A cubic spline interpolation function is built between the parameters and concentrations, based on which we can calculate the concentration of the test solution. Methanol, ethanol, n-propanol, and saline solutions are taken as experimental subjects in this paper. For each solution, nine or ten different concentrations are chosen to be the standard library, and the other two concentrations compose the test group. By using the methods mentioned above, all eight test solutions are correctly identified and the average relative error of quantitative analysis is 1.11%. The method proposed is feasible which enlarges the applicable scope of recognizing liquids based on the COT and improves the concentration quantitative precision, as well.

Secular frequency scanning is a mass spectrometry (MS) analysis method in which the frequency of the auxiliary alternating current (AC) signal is scanned. It has low requirements for radio-frequency (RF) power, which is beneficial for the miniaturization of the mass spectrometer. In this study, the MS performance in the reverse secular frequency scanning (RSFS) mode is optimized for a rectilinear ion trap (RIT), and a method for rapid MS analysis using continuous secular frequency scanning (CSFS) is proposed.A RIT mass spectrometer with an auxiliary AC frequency scanning function was built. The resolution, tandem mass spectrometry (MS/MS) and quantitation capability in the RSFS mode were characterized and optimized. Operation in the CSFS mode was then performed by scanning the frequency of the auxiliary AC signal continuously and periodically while maintaining the RF signal and the front Z electrode in the ion injection state, so that the ion injection and cooling were performed at the same time as the mass analysis.With this system, the RSFS mode achieved unit mass resolution at 332 Th, and the MS/MS analysis was completed without changing the RF amplitude at q = 0.4583 for reserpine. The limit of quantitation for imatinib was about 250 ng/mL with the determination coefficient RThe CSFS mode is different from the traditional phased sequential operation mode of an ion trap mass spectrometer. By periodic scanning of the auxiliary AC frequency while maintaining ion injection, it is possible to improve the analysis efficiency of the mass spectrometer, which has the prospect of useful application in the field of rapid MS monitoring. Copyright © 2017 John WileySons, Ltd.

This paper proposes CGA based approach to determine motions and constraints, analyze mobility, identify singularity of parallel mechanisms, which is perfectly demonstrated by taking 3-RSR&SS parallel positioning mechanism as an example. By introducing CGA, which combining elements of geometry and algebra, the motions and constraints are expressed as simple formulas and their relations are calculated by means of outer product with clear physical meaning, these lead to the motions and constraints are determined in a visual, concise and efficient way, and the number and type of DoF and accessible motions are obtained readily. The inverse and forward position solutions are obtained easily utilizing special geometric relations of 3-RSR&SS parallel positioning mechanism, which are proven by calculating relations among point, line and plane in virtue of CGA operation rules. Two indices of singularity are defined to identify singular configurations of 3-RSR&SS parallel positioning mechanism in the light of the shuffle and outer products. The work of this paper lay a solid theoretical and technical foundation for the prototype design and manufacture of 3-RSR&SS parallel positioning mechanism.

Interlayer spray is proposed as a convenient ionization source for direct analysis by mass spectrometry. Two slices of non-absorbent substrate hold the liquid sample to form a sandwich structure. By applying a high voltage to the sample, spray is generated at the tip of the substrate. The sampling procedure can be operated easily in an open condition and the spray is processed in a semi-enclosed condition, which leads to a relatively stable process. An ultralow amount (

The rectilinear ion trap (RIT) has gradually become one of the preferred mass analyzers for portable mass spectrometers because of its simple configuration. In order to enhance the performance, including sensitivity, quantitation capability, throughput, and resolution, a novel RIT mass spectrometer with dual pressure chambers was designed and characterized. The studied system constituted a quadrupole linear ion trap (QLIT) in the first chamber and a RIT in the second chamber. Two control modes are hereby proposed: Storage Quadrupole Linear Ion Trap-Rectilinear Ion Trap (SQLIT-RIT) mode, in which the QLIT was used at high pressure for ion storage and isolation, and the RIT was used for analysis; and Analysis Quadrupole Linear Ion Trap-Rectilinear Ion Trap (AQLIT-RIT) mode, in which the QLIT was used for ion storage and cooling. Subsequently, synchronous scanning and analysis were carried out by QLIT and RIT. In SQLIT-RIT mode, signal intensity was improved by a factor of 30; the limit of quantitation was reduced more than tenfold to 50 ng mL−1, and an optimal duty cycle of 96.4% was achieved. In AQLIT-RIT mode, the number of ions coexisting in the RIT was reduced, which weakened the space-charge effect and reduced the mass shift. Furthermore, the mass resolution was enhanced by a factor of 3. The results indicate that the novel control modes achieve satisfactory performance without adding any system complexity, which provides a viable pathway to guarantee good analytical performance in miniaturization of the mass spectrometer.