Positive Mass Spectrometry Research Articles

A differentially pumped windowless charge exchange cell (CEC) for investigating Positive Ion Mass Spectrometry (PIMS)

A windowless Charge Exchange Cell (CEC) is designed for the investigation of Positive Ion Mass Spectrometry (PIMS). In this method, positive ions are converted into negative ions via a double electron capture mechanism. By optimizing the operating conditions, including the type of gas, gas flow rate, gas pressure and ion velocity, high efficiency can be achieved for specific isotopes. In this paper, we outline the development and offline test results of the windowless gas cell system.

Deposition of Thin Films From HMDSO Utilizing the Vacuum UV Radiation From an Atmospheric Plasma

ABSTRACTThis study presents a source for studying thin‐film deposition utilizing vacuum UV (VUV) radiation from a remote argon or helium atmospheric plasma to initiate photochemistry in the precursor gas. We aim to assess how this radiation affects the deposition process and film structure while avoiding deposition inside the plasma source or particle formation. Deposition occurs where radiation interacts with the precursor and the growing film, as well as further downstream. The measured film properties clearly show that photon interaction with the film has a significant effect. Using hexamethyldisiloxane (HMDSO) as a precursor, we achieved nearly carbon‐free silicon dioxide () film growth due to photodesorption of hydrocarbons from the growing film, as confirmed by infrared spectra and positive ion mass spectrometry.

C− generation by charge exchange with non-metallic gas for positive ion mass spectrometry

Carbon positive ion mass spectrometry technology(C-PIMS) is a new type of mass spectrometry technology using the opposite charge exchange process of accelerator mass spectrometry (AMS). There is a plan at Peking University to build 14C-PIMS with the study of a compact 2.45 GHz ECR ion source for C2+ production and a charge exchange cell (CXC) for C2+ to C− conversion. In this paper, the profile of carbon ion source and CXC is introduced and the generation of C− ions is investigated. In experiment, five non-metallic gas targets are tested. 19 μA@90 keV C− beam is obtained from C2+ using the ethylene target. It is found that gas targets with low first ionization energy favor the generation of C−. In addition, the charge exchange efficiency at different beam energies (25 keV–90 keV) is investigated. In terms of theory, the mechanisms of resonant and non-resonant charge exchange processes are introduced to analyze the experimental results. Moreover, the charge exchange from C+ to C− is studied and the feasibility of C+-PIMS is discussed since 2.45 GHz ECR ion source produce more C+ ions. It is found that 139 μA@45 keV C− beam can be obtained from C+ using the methane target.

Feature-based molecular networking with MS2LDA to profile compounds in Lanbuzheng based on ultra-high-performance liquid chromatography-quadrupole Exactive Orbitrap high-resolution mass spectrometry.

Lanbuzheng (Geum japonicum Thunb. var. chinense Bolle), a plant found in Southwest China, is a traditional Chinese medicine that promotes hematopoiesis and antioxidant functions. Many of its chemical constituents remain unknown, posing challenges both to understanding its pharmacological mechanisms and to conducting quality control research. In this work, ultra-high performance liquid chromatography coupled with quadrupole Exactive Orbitrap high-resolution mass spectroscopy was used for profiling the composition of Lanbuzheng. Using positive ion mass spectrometry data enriched from Lanbuzheng extract, feature-based molecular networking (FBMN) was constructed and associated with Mass2Motifs substructures using MS2LDA. Prediction and validation of unknown constituents of Lanbuzheng using a custom-built compound library, SIRIUS, and network annotation propagation, achieved a semi-automated annotation of the molecular network. Based on the custom-built library comprising 206 compounds and the FBMN clustering results, the constituents in Lanbuzheng primarily include tannins, triterpenes, flavonoids, and phenolics. Using only 65 pre-identified compounds as references, 210 unknown compounds were annotated in various polarity regions of Lanbuzheng. Results of the current work indicate that molecular networks enable the efficient annotation of compounds in complex systems, laying the groundwork for the preliminary identification of pharmacologically active constituents of Lanbuzheng.

Characterization and identification of chemical components from Euodiae Fructus based on UHPLC-Q-TOF-MS

A sensitive and efficient ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry(UHPLC-Q-TOF-MS) approach was established. Based on the self-developed information library, the chemical components from Euodiae Fructus were systematically characterized and identified. The chromatographic separation conditions(e. g., stationary phase,mobile phase, column temperature, and elution gradient) and MS detection conditions(nozzle voltage, capillary voltage, fragmentor,and collision energy) were optimized. Ultimately, an HSS T3 column(2. 1 mm×100 mm, 1. 8 μm) maintained at 35 ℃ was used,and 0. 1% formic acid water-acetonitrile at the flow rate of 0. 4 m L·min~(-1) was used as the mobile phase. Electrospray ionization was adopted to collect the positive and negative ion mass spectrometry data in Auto MS/MS mode. According to the reference compound comparison, fragment ion information interpretation, literature, and retrieval in the self-developed information library, 92 compounds were characterized or derived from the decoction of Euodiae Fructus, including 33 alkaloids, 23 flavonoids, 12 terpenoids, 12phenylpropanoids, and 12 others. Among them, 17 compounds were identified by comparison with the reference compounds, and 11compounds were unreported from Euodiae Fructus. This study realizes the rapid characterization and identification of multi-class chemical components in the decoction of Euodiae Fructus and provides a reference for the studies regarding its effective substances and quality control.

An Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) Method for Qualifying DAPB in Rat Plasma and Application to Pharmacokinetic Studies.

DAPB, a new molecule including danshensu, borneol, and a mother nucleus of ACEI (Angiotensin-converting enzyme inhibitors), is being developed as an antihypertensive candidate compound. A rapid, accurate, and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was established and validated for the determination of DAPB in rat plasma. Chromatographic separation was performed on an Agilent SB-C18 column after protein precipitation by acetonitrile with a mobile phase consisting of acetonitrile and deionized water with 0.02% formic acid and 5 mM NH4F (v/v) at a flow rate of 0.2 mL/min. Quantification was performed using electrospray positive ionization mass spectrometry in the multiple reaction monitoring (MRM) mode. The method was linear over the range of 2-1000 ng/mL. The intra- and inter-day precision was within 12%, with accuracies less than 7%. Stability was within the acceptable limits under various storage and processing conditions. No apparent matrix effect was detected. The validated method was applied to the pre-clinical pharmacokinetic study of DAPB after oral administration of 30 mg/kg and intravenous administration of 6 mg/kg in rats.

New progress of a 2.45 GHz ECR ion source for carbon positive ion mass spectrometry

Positive ion mass spectrometry (PIMS) is a trace element measurement technique based on positive and negative ion conversion, which is contrary to conventional accelerator mass spectrometry (AMS). To precisely measure 14C, interference of molecular isobars (such as 12CH2 and 13CH) need to be suppressed in the ion source by generating multi-charged carbon ions, such as C2+ or C3+. At present, a high-frequency (> 7 GHz) electron cyclotron resonance (ECR) ion source is commonly used to generate C2+ or C3+ ions through CO2 discharge. At Peking University (PKU), we developed a compact permanent magnet 2.45 GHz ECR ion source attempting to produce C2+ ions. In this work, systematical experiments are performed to further improve the performance of the ion source for the application in PIMS. The results show that it can deliver 1.0 emA C2+ ions with an alumina ceramic liner, and its C consumption is about 10∼20 ng/s. Meanwhile, it is also proved that a certain proportion of He and CO2 mixing can improve the production efficiency of C2+ ions, and the consumption of C can be lower. Furthermore, results confirm that this ECR ion source with alumina liner has a lower memory effect, and the influence of original CO2 discharge can be eliminated by Ar plasma cleaning for several minutes. The experimental results show that the 2.45 GHz ECR ion source has the potential to be used in the PIMS system.

Detection and mass spectral characterization of carbofuran and its degradation product

Carbofuran is an N-methyl carbamate pesticide that is extensively used to control insects and nematodes on a range of farming crops because of its wide-ranging biological activity & relatively low persistence when compared to other pesticides. It is highly toxic to birds, mammals, fish and wildlife due to its anticholinesterase activity. In humans, Carbofuran is associated with endocrine disrupting activity, reproductive disorders, cytotoxic and genotoxic abnormalities. In biological and environmental conditions Carbofuran tend to undergo degradation. The screening, identification and characterization of the Carbofuran and its degradation product in biological samples are an important task in the area of forensic toxicology. In a case study Carbofuran and its degradation product Carbofuran phenol were detected and identified by Gas Chromatography Mass Spectrometry. The present study deals with the successful detection & characterization of the Carbofuran and its degradation product under positive ion Electron Ionization (EI) mass spectrometry. The EI mass spectra of the Carbofuran and its degradation product showed the stable molecular ion [M+•] peaks in addition to the other diagnostic fragment ions that enable unambiguous identification of Carbofuran and its Carbofuran phenol. The general fragmentation patterns of these two compounds are discussed in detail. Carbofuran showed an ion at m/z 164 as the base peak corresponds to loss of Methylisocyanato group (CH3NCO) from the [M+•] ion, which was formed by the Mclafferty rearrangement. Carbofuran phenol showed a more stable Molecular ion [M+•] peak compared to Carbofuran and showed a major peak at m/z 149 corresponds to the loss of methyl group from the [M+•] ion. The detection and identification of these compounds will be an invaluable support during investigation and in conviction of criminal cases in courts of law in Carbofuran poisoning cases.

Preliminary results of positive ion mass spectrometry based on a 2.45 GHz ECR ion source and a non-metallic gas target

Positive-ion mass spectrometry (PIMS) is a positive-to-negative ion conversion metrology that just operated on the opposite of traditional accelerator mass spectrometry (AMS) on high-precision radiocarbon dating. With a higher efficient simple structure plasma ion sources instead of AMS sputter ion sources, lower ion energy (tens keV) in place of MeV, and limited footprint facility, PIMS will be a powerful competitor to AMS in the future. To precisely measure 14C, interference of molecular isobars (such as 12CH2, 13CH) will be eliminated with higher charged ions (charge state ≥ 3; molecular cations 12CH2 2+ is metastable, can be eliminated by higher stripping pressure.), nitrogen will be eliminated inside the charge-exchange cell (CXC) through charge exchanging with target gas. To demonstrate the probability of PIMS with a 2.45 GHz ECR ion source, an experiment was launched at Peking University (PKU). A compact permanent magnet 2.45 GHz ECR ion source is designed to produce carbon ions from CO2. A CXC unit was installed after the extraction system and ethylene is chosen as charge exchange gas. Preliminary experiments prove that more than hundreds of microamp of C2+ beam can be produced with this ECR source. By injecting ethylene into CXC, several microamp C- beam was detected and the C2+ ions charge exchange efficiency to C- ions can reach close to 5%.

Estimation of minoxidil in human plasma using UHPLC-MS/MS and its application in pharmacokinetic study

Measurement of drug concentration in biological matrices (such as serum, plasma, blood, urine, and saliva) is important to determine Bioavailability (BA) and/or Bioequivalence (BE) of a drug product which are required during the drug product development and approval process to support applications for new active substances (INDs, NDAs) and generic (ANDAs) drug products to make critical decisions on safety and efficacy. Because of their vital role, bioanalytical methods should be well-characterized, fully validated and documented to yield reliable results. In present work, a simple, specific, high throughput, accurate and sensitive UHPLC–MS/MS method has been developed and validated for quantification of Minoxidil in human plasma. The analyte and the internal standard were extracted from plasma by Liquid-Liquid Extraction using ethyl acetate. The chromatographic separation was achieved on Thermo Hypersil Gold column (4.6x50mm, 5μm) using acetonitrile-0.1% formic acid in water (60:40, v/v) at a flow rate of 0.400 ml/min. Detection by turbospray positive ionization mass spectrometry in the multiple reaction monitoring mode with a mass transition ion-pair of m/z 210.152 → 163.965 (Minoxidil) and m/z 220.267 → 169.089 (Internal Standard-Minoxidil D10) was found to be linear over the concentration range of 1.280 to 151.075 ng/ml. The method was fully validated as per USFDA guidelines and the results were within regulatory limits. The inter and intra-day precision ranged from 5.42 to 9.27% and 2.55–9.42% respectively. The inter and intra-day accuracy ranged from 89.2 to 98.9% and 102–105% respectively. The method was successfully applied to a BE study involving human volunteers.

Analysis of cycloheximide in rat specimens using liquid chromatography with tandem mass spectrometry detection

The development of a selective and sensitive high-performance liquid chromatographic tandem mass spectrometric method for the determination of cycloheximide (CHX) in rat blood and plasma is described. The extraction of CHX and colchicine as internal standard from blood fluid (0.1 mL) was achieved using n-hexane: dichloromethane: isopropanol (20:10:1 v/v/v). The mobile phase, a combination of methanol:10 mM ammonium acetate (85:15, v/v), was pumped at 0.2 mL/min through a C18 analytical column with a run time of 3.5 min. Detection was carried out by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring (MRM) mode. The assay exhibited excellent linearity (r2 > 0.999) in peak area response over the concentration ranges of 2–1000 ng CHX /mL blood fluid. The mean absolute recoveries for 20, 100 and 500 ng/mL CHX in blood fluid using the present extraction procedure were > 97%. The intra- and inter-day coefficients of variation in the plasma and blood and mean error were < 13% at different concentrations. Samples had limited stability at room temperature, and speedy processing is needed. After intravenous administration, rats had measurable concentrations of CHX for up to 24 h after dosing with 1 mg/kg of cycloheximide. The method displayed a high caliber of sensitivity and selectivity for detecting very low concentrations of CHX in rats.

Study on titanium dioxide nanoparticles as MALDI MS matrix for the determination of lipids in the brain

Abstract The structures of lipids are diverse, and thus, lipids show various biological functions. Systematic determination of lipids in organisms has always been a concern. In this paper, a methodology on the matrix-assisted laser desorption ionization mass spectrometry (MALDI MS), with titanium dioxide nanoparticles (TiO2 NPs) as the matrix, was studied for lipid determination. The results showed that the following conditions were preferable in the determination of small-molecule lipids (such as hypoxanthine, guanosine, uridine, and cytidine), lipid standards (such as GC, GM, TG, phosphatidylethanolamine, phosphatidylcholine, and ceramide), and mixed lipids (extracted from brain homogenate with methanol alone and with the B&amp;D method): TiO2 NPs as the matrix, absolute ethanol as the solvent, 1 mg of TiO2 NPs dispersed in 1 mL of absolute ethanol as the matrix solution, NaCl as the ionization reagent, and positive mass spectrometry (MS) as the mode. Modified TiO2 NP as a new matrix for MALDI MS will be a future research direction; in addition, the characteristics of TiO2 NPs make it a potential matrix for imaging MS.

Molecular Characterization of NSO Compounds and Paleoenvironment Implication for Saline Lacustrine Oil Sands by Positive-Ion Mass Spectrometry Coupled with Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry.

NSO compounds mainly exist in geological bodies in the form of nonhydrocarbons and asphaltenes with abundant geological and geochemical information. Combined with the gas chromatography mass spectrometry (GC–MS) technology, positive-ion electrospray ionization Fourier-transform ion cyclotron resonance MS (FT-ICR MS) was used to understand the composition and distribution characteristics of NSO compounds in the oil sands of the Dongpu Depression and to explore their paleoenvironmental significance. The results show that n-alkanes are characterized by an even carbon number and phytane dominance, suggesting a saline lacustrine environment. Certain abundance of nC37 and β-carotane, high gammacerane content, and low diasterane content are detected in the analyzed samples, reflecting the saline-reducing paleoenvironment for the organic matter. Nine types of heteroatom compounds are detected: N1, N1O1, N1S1, O1, O1S1, O2, O2S1, S1, and S2. The main compounds are S1 and N1 compounds, followed by O1S1 compounds. The double-bond equivalent (DBE) value of S1 compounds is mainly distributed between 3 and 12, and the carbon number is mainly distributed between 18 and 35. The DBE value of N1 compounds is mainly distributed between 4 and 14, and the carbon number is mainly distributed in the range 15–35. Among the S1 compounds, DBE3 compounds (thiophenes) have relatively more sulfur-containing carotenoids (C40). The abundance of C40 S1 and the ratio of pyridine and its homologue DBE4–8/DBE9–12 N1 compounds show a good contrast with the paleoenvironment indicators of gammacerane/C30 hopane and diasterane/regular sterane. They can be used as a reference for the paleoenvironment index. Maturity is another factor affecting the distribution of NSO heteroatoms in the oil sands. NSO compounds are enriched in the DBE area with higher condensation, and the main peak carbon shifts forward. As the maturity increases, the relative abundance of N1 compounds increases, the aromatization intensifies, and carbon is broken into short chains. The research results shed light on the potential application of NSO compounds in petroleum exploration based on FT-ICR MS.

A Novel Liquid Chromatography-Tandem Mass Spectrometry Method for Simultaneous Quantification of Telmisartan and Chlorthalidone in Rat Plasma and its Application to a Pharmacokinetic Study

A selective, sensitive, rapid, and stable liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay method has been developed for the simultaneous quantification of chlorthalidone (CLT) and telmisartan (TEL) in rat plasma. Sample preparation involved liquid-liquid extraction by ethyl acetate. Analytes and internal standard (IS) were separated on Gemini C18 (50 x 4.6 mm, 5 μm) using a mixture of methanol-2 mM ammonium acetate (80:20 v/v) as the mobile phase at a flow rate of 0.4 mL/min. Hydrochlorothiazide (HCTZ) was used as an internal standard. Detection was carried out using Electrospray positive and negative ionization mass spectrometry using multiple reaction monitoring of the transition at m/z 515.90→276 for TEL and m/z 337.1→190.05 for CLT, m/z 296.1→205.3 for HCTZ respectively. For TEL and CLT, the method was linear (R2 ≥ 0.995) within the range of 6-1200 ng/mL and 3-600 ng/mL respectively. The retention time for TEL, CLT, and IS was found to be 3.65±0.03 min, 1.83±0.02 min, and 1.76±0.01 min. The mean recovery for both analytes and IS was greater than 70 %. The developed method was validated according to the USFDA guideline. The quantitative method was validated for specificity, linearity, accuracy, precision, recovery, dilution integrity, matrix effect, and analyte stability. The method was successfully applied to a pharmacokinetic study in rat plasma following oral administration.

Characterisation of an algerian asphaltene by 1H and 13C CPMAS NMR, DEPT and ESI mass spectroscopy

Quantitative liquid 1H and solid 13C CPMAS NMR spectroscopy were used in combination with qualitative DEPT (Distortionless Enhancement by Polarization Transfer) and liquid 13C NMR to investigate the molecular structural parameters of an Algerian asphaltenes. The molecular weight of the asphaltene ionisable species determined by positive Electro Spray Ionization mass spectrometry ESI was around 390 Da. The results indicate that the representative molecular structure of the asphaltenes contains PAH (Poly-aromatic hydrocarbon) core of 4–5 rings. The combination of 13C NMR/DEPT constitutes a good route for characterizing the chemical functions of asphaltenes.

Comparison of sensitivity for methods of positive and negative ion mass spectrometry, exemplified by nitrotoluenes

For a model series of nitro aromatic compounds comprising mono-, di- and trinitrotoluenes, and dinitrobenzene, using the same commercial experimental set up consisting of gas chromato-graphy/mass spectrometry (GC/MS) instrument equipped with a quadrupole analyzer, the two types of mass spectra were recorded, of positive ions (in the conventional, standard mode of electron ionization at 70 eV) and of negative ions (NI, generated at low, pre-ionization electron energies by resonant electron capture, REC). The comparative analysis of characteristic fragmentation processes was carried out for molecular ions of both signs. The sensitivity of REC NI MS method was established to enhance upon increasing the number of electron-withdrawing nitro groups, reaching or even outperforming that of the classical method of electron ionization (EI). Thus, the detection limit for trinitrotoluene in a solution was estimated as 5 ppm, which is by an order of magnitude lower as compared to the conventional EI mode of analysis. Comparison of the ion composition of NI mass spectra and of the relative intensities of ion peaks with the corresponding data obtained previously for the studied group of compounds by means of different types of mass spectrometers, has revealed a satisfactory inter-instrumental reproducibility of the NI mass spectra. The results reported herein indicate that the NI generation/registration mode, which can technically be readily available even without modifications of design of commercial GC/MS instrument in their basic configuration, is suitable to be introduced in laboratory practice as the additional tool for increasing the selectivity and reliability in detection/identification of trace amounts of compounds possessing a high electron af nity and for solving extraordinary structural and analytical problems.

A 2.45 GHz microwave ion source for carbon positive-ion mass spectrometry

Carbon positive-ion mass spectrometry (C-PIMS) is a two stage mass spectrometer by producing high charge state carbon ions (C2+/C3+) directly in the ion source to eliminate molecular interferences and by converting the beam (C2+/C3+) to C− ions in a charge exchange cell to eliminate 14N interference. It has been proven that C-PIMS is an effective method for the detection of radiocarbon at low levels. This article will focus on the multiply charged carbon ion generation. Based on the fact that a C-PIMS system is usually equipped with high frequency electron cyclotron resonance (ECR) ion sources. It is significant to investigate if the simple and low-cost 2.45 GHz ECR ion source is an optional choice for the C-PIMS. At Peking University (PKU), a 2.45 GHz microwave ion source with minimum-B magnetic field configuration is designed for the production of intense C2+ beam. Preliminary experiments have proved that the 2.45 GHz microwave ion source can produce up to 40 μA@40 keV C2+ beam. In addition, it was found that argon could increase the decomposition efficiency of CO2, which can eliminate CO2+ ions of the extracted beam.

Identification and Determination of the Molecular Structure of Phosphate Esters by the Joint Application of Positive Ion and Negative Ion Electron Ionization Mass Spectrometry

The decay paths of negative molecular ions of phosphate esters, formed under the conditions of resonance electron capture, are of the same type and, therefore, predictable. A combination of mass spectra of the studied substances obtained by this method with the mass spectra of positive ions recorded in the convential electron ionization mode significantly expands the possibilities of their identification and determination of the characteristics of their molecular structures. In this case, only one mass spectrometer can be used, quickly switched from one mode to another.

Quantification of 4-Methylimidazol in NMRI Mice Plasma and Cerebrospinal Fluid (CSF) by Using Liquid Chromatography Tandem Mass Spectrometry.

A sensitive method using ion-pair extraction was developed by liquid chromatography tandem mass spectrometry (LC–MS/MS) for measurement of 4-methylimidazole (4-MI) in NMRI mice plasma and cerebrospinal fluid (CSF). Detection was done by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring (MRM) mode. The validation method was applied to quantification of 4-MI in plasma and CSF samples using oral doses of 100, 200, and 300 mg/kg in NMRI mice. The efficiency of the method was evaluated in terms of linearity (R 2> 0.99), recovery (98–107%, 3 levels) and precision (8–10%, 3 levels, n = 6). Limit of detection (LOD) and limit of quantification (LOQ) were 25 ng/mL and 50 ng/mL, respectively. The results obtained showed that the exposure to oral doses of 4-MI in mice makes different concentrations in plasma and CSF and causes significant changes in mice. This study was the first report for determination of 4-MI in plasma and CSF samples in mice. Our results suggest that LC-MS/MS-based on ion-pair extraction is a robust method with high detection ability for measurement of 4-MI in plasma and CSF samples. Therefore, the developed method can be useful for evaluation and monitoring of imidazole derivatives in biological samples.

Gaining of analytical information about a compound for structural group analysis using mass spectra of negative ions

Successful functioning of expert systems designed for determination of the molecular structure of organic compounds by spectral characteristics requires the availability of most complete initial analytical information. Successful functioning of expert systems designed for determination of the molecular structure of organic compounds by spectral characteristics requires the availability of most complete initial analytical information which necessitates summarizing and using data gained in different analytical methods. We consider prospects of gaining new information about test compounds by the method of resonant electron capture negative ion mass spectrometry using a serial quadrupole mass-spectrometer. A number of phosphorus-containing organic compounds are used to demonstrate a possibility of recording mass spectrum peaks of deprotonated molecules, which is rather important for determination of the molecular mass and, hence, correct identification of the compound. Examples of successful detection of the fragments with positive electron affinity present in the structure of compounds under study are listed. The obtained results substantially differ from that obtained by the “classical” method of electron ionization positive ion mass spectrometry and can be considered as a complementary data about the structure of compounds for the purposes of structural group analysis., We also present the results of experiments in which mass spectra of negative ions were obtained using the advanced cathode power supply device via multiple change in the energy of ionizing electrons during the analysis. The possibility of implementing both analytical methods on the same device is an additional advantage of this approach.