Determination of ethylene by field asymmetric ion mobility spectrometry

A planar high field asymmetric waveform ion mobility spectrometer (PFAIMS) with a micro-machined drift tube was characterized as a detector for capillary gas chromatography. The performance of the PFAIMS was compared directly to that of a flame ionization detector (FID) for the separation of a ketone mixture from butanone to decanone. Effluent from the column was continuously sampled by the detector and mobility scans could be obtained throughout the chromatographic analysis providing chemical inforrmation in mobility scans orthogonal to retention time. Limits of detection were approximately I ng for measurement of positive ions and were comparable or slightly better than those for the FID. Direct comparison of calibration curves for the FAIMS and the FID was possible over four orders of magnitude with a semi-log plot. The concentration dependence of the PFAIMS mobility scans showed the dependence between ion intensity and ion clustering, evident in other mobility spectrometers and atmospheric pressure ionization technologies. Ions were identified using mass spectrometry as the protonated monomer and the proton bound dimer of the ketones. Residence time for column effluent in the PFAIMS was calculated as approximately 1 ms and a 36% increase in extra-column broadening versus the FID occurred with the PFAIMS.

Rapid Determination of Phenylalanine by Micro-chip Based Field Asymmetric Waveform Ion Mobility Spectrometry Technology

A non-contact method for analyzing of explosives traces from surfaces was developed. The method is based on the laser desorption of analyzed molecules from the surveyed surfaces followed by the laser ionization of air sample combined with the field asymmetric ion mobility spectrometry (FAIMS). The pulsed radiation of the fourth harmonic of a portable GSGG: Cr3+ :Nd3+ laser (λ = 266 nm) is used. The laser desorption FAIMS analyzer have been developed. The detection limit of the analyzer equals 40 pg for TNT. The results of detection of trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX) and cyclotetramethylenetetranitramine (HMX) are presented. It is shown that laser desorption of nitro-compounds from metals is accompanied by their surface decomposition. A method for detecting and analyzing of small concentrations of explosives in air based on the laser ionization and the FAIMS was developed. The method includes a highly efficient multipass optical scheme of the intracavity fourthharmonic generation of pulsed laser radiation (λ = 266 nm) and the field asymmetric ion mobility (FAIM) spectrometer disposed within a resonator. The ions formation and detection proceed inside a resonant cavity. The laser ion source based on the multi-passage of radiation at λ = 266 nm through the ionization region was elaborated. On the basis of the method the laser FAIMS analyzer has been created. The analyzer provides efficient detection of low concentrations of nitro-compounds in air and shows a detection limit of 10-14 - 10–15 g/cm3 both for RDX and TNT.

The ways for increasing the distance of non-contact sampling up to 40 cm for a field asymmetric ion mobility (FAIM) spectrometer are formulated and implemented by the use of laser desorption and active shaper of the vortex flow. Numerical modeling of air sampling flows was made and the sampling device for a laser–based FAIM spectrometer on the basis of high speed rotating impeller, located coaxial with the ion source, was designed. The dependence of trinitrotoluene vapors signal on the rotational speed and the optimization of the value of the sampling flow were obtained. The effective distance of sampling is increased up to 28 cm for trinitrotoluene vapors detection by a FAIM spectrometer with a rotating impeller. The distance is raised up to 40 cm using laser irradiation of traces of explosives. It is shown that efficient desorption of low-volatile explosives is achieved at laser intensity 10⁷ W / cm² , wavelength λ=266 nm, pulse energy about 1mJ and pulse frequency not less than 10 Hz under ambient conditions. The ways of optimization of internal gas flows of a FAIM spectrometer for the work at increased sampling distances are discussed.

A new optical multipass scheme for laser field asymmetric ion mobility spectrometry (FAIMS) has been proposed and implemented. The scheme and the gas-analyzer system developed include both intracavity multiphoton laser ionization and FAIMS detection of the analyte. The computation and experimental results show multifold growth of the laser intensity in the FAIMS ion source, as well as the amplitude of ion signal. The gas phase detection threshold achieved is estimated to be 10−14 to 10–15 g cm−3. Further development of the proposed approach is discussed.

采用热解析-高场非对称波形离子迁移谱（FAIMS）技术快速检测柯衣定、孔雀石绿、罗丹明B和甲基红4种合成色素. 通过对热解析温度和载气流量进行优化，确定了不同色素的离子特征信号. 在最佳分析条件下，热解析温度为160 ℃，载气流量为1.6 L/min，采用不同模式下补偿电压（CV）值定性，以FAIMS在正模式下检测柯衣定（CV=0.41 V）和罗丹明B（CV=-0.89 V），在负模式下检测甲基红（CV=-0.67 V）和孔雀石绿（CV=0.02 V）；用外标法定量检测了样品中的4种合成色素，线性关系 R 2 ≥0.9967，检出限为2.5～10 μg/L，定量限为5～20 μg/L，加标回收率≥78.2%，相对标准偏差RSD≤8%. 本文为FAIMS技术快速检测合成色素提供了一定的技术基础.

Odor quality in the cabin air of automobiles can be a significant factor in the decision to purchase a vehicle and the overall customer satisfaction with the vehicle over time. A current standard practice uses a human panel to rate the vehicle cabin odors on intensity, irritation, and pleasantness. However, human panels are expensive, time-consuming, and complicated to administer. To address this issue, we present a machine olfaction approach to assess odors inside automobiles. The approach uses a field asymmetric ion mobility spectrometer and a photoionization detector to measure volatile organic compounds, and a multivariate technique to map sensor data into human ratings. Validation on an experimental dataset of odors from ten different vehicles shows a correlation (0.67–0.84) between model predictions and ground truth from a trained human panel. These results support the feasibility of replacing human panel assessments by objective instrumental means for quality control tasks in the production process.

Colorectal cancer (CRC) is a leading cause of cancer related death in Europe and the USA. There is no universally accepted effective non-invasive screening test for CRC. Guaiac based faecal occult blood (gFOB) testing has largely been superseded by Faecal Immunochemical testing (FIT), but sensitivity still remains poor. The uptake of population based FOBt testing in the UK is also low at around 50%. The detection of volatile organic compounds (VOCs) signature(s) for many cancer subtypes is receiving increasing interest using a variety of gas phase analytical instruments. One such example is FAIMS (Field Asymmetric Ion Mobility Spectrometer). FAIMS is able to identify Inflammatory Bowel disease (IBD) patients by analysing shifts in VOCs patterns in both urine and faeces. This study extends this concept to determine whether CRC patients can be identified through non-invasive analysis of urine, using FAIMS. 133 patients were recruited; 83 CRC patients and 50 healthy controls. Urine was collected at the time of CRC diagnosis and headspace analysis undertaken using a FAIMS instrument (Owlstone, Lonestar, UK). Data was processed using Fisher Discriminant Analysis (FDA) after feature extraction from the raw data. FAIMS analyses demonstrated that the VOC profiles of CRC patients were tightly clustered and could be distinguished from healthy controls. Sensitivity and specificity for CRC detection with FAIMS were 88% and 60% respectively. This study suggests that VOC signatures emanating from urine can be detected in patients with CRC using ion mobility spectroscopy technology (FAIMS) with potential as a novel screening tool.

Since the development of electrospray ionization (ESI) for ion mobility spectrometry mass spectrometry (IMMS), IMMS have been extensively applied for characterization of gas-phase bio-molecules. Conventional ion mobility spectrometry (IMS), defined as drift tube IMS (DT-IMS), is typically a stacked ring design that utilizes a low electric field gradient. Field asymmetric ion mobility spectrometry (FAIMS) is a newer version of IMS, however, the geometry of the system is significantly different than DT-IMS and data are collected using a much higher electric field. Here we report construction of a novel ambient pressure dual gate DT-IMS coupled with a FAIMS system and then coupled to a quadrupole ion trap mass spectrometer (QITMS) to form a hybrid three-dimensional separation instrument, DT-IMS-FAIMS-QITMS. The DT-IMS was operated at ~3 Townsend (electric field/number density (E/N) or (Td)) and was coupled in series with a FAIMS, operated at ~80 Td. Ions were mobility-selected by the dual gate DT-IMS into the FAIMS and from the FAIMS the ions were detected by the QITMS for as either MS or MSn. The system was evaluated using cocaine as an analytical standard and tested for the application of separating three isomeric tri-peptides: tyrosine-glycine-tryptophan (YGW), tryptophan-glycine-tyrosine (WGY) and tyrosine-tryptophan-glycine (YWG). All three tri-peptides were separated in the DT-IMS dimension and each had one mobility peak. The samples were partially separated in the FAIMS dimension but two conformation peaks were detected for the YWG sample while YGW and WGY produced only one peak. Ion validation was achieved for all three samples using QITMS.

Introduction This is an investigation of the capability of FAIMS (Field Asymmetric Ion Mobility Spectrometry) technology as a tool for non-invasive detection of Colorectal Cancer (CRC) through urinary volatile organic compound analysis. It expands on "Detection of Colorectal Cancer (CRC) by Urinary Volatile Organic Compound Analysis" (Ramesh P. Arasaradnam et al, 2014) with an increased sample population and local to Japan, also comparing in-house data of CA19-9 and carcinoembryonic antigen (CEA) markers. Experiment Conducted at Nippon Medical School Chiba Hokusoh Hospital, urine samples were collected and frozen at -80°C from 139 patients at various stages of CRC and 78 healthy control samples. The samples were thawed in batches and placed in ice hours prior to testing. 2 ml of each urine sample was aliquoted into 10 ml vials for processing with the commercial FAIMS device (Lonestar, Owlstone, UK). Each vial was heated in the device to 40°C to create headspace with sufficient VOCs then a carrier gas (clean dry air) delivered the headspace (0.5 L/min) diluted with a make-up flow (2 L/min). The FAIMS device was set to scan at 0 to 100% electric dispersion field in 51 steps and compensation voltage between -6 V and +6 V in 512 steps, producing data matrices for each sample's analysis. Principal Component Analysis (PCA) followed by Partial Least Squares Discriminant Analysis (PLS-DA) of each sample was conducted using SIMCA 13 (Umetrics, Sweden). See Table Conclusions FAIMS technology achieved a high rate of separation between the CRC and healthy control urine samples with 64.7% sensitivity and 82.1% specificity overall. As the CRC stage advances the sensitivity increased from 27.3% to 100%. Results show excellent potential to use FAIMS technology as an early screening tool for CRC, particularly impressive compared to in-house sensitivity data of CA19-9 and CEA markers. Further research into FAIMS screening of other cancer types through VOC biomarker analysis of urine, breath, and feces is recommended. >Detection ResultsCRC STAGEFAIMSOTHER MARKERSCA19-9CEATrue PositiveFalse NegativeSensitivityFalse PositiveTrue NegativeSpecificityNo. of SamplesSensitivitySensitivityI123227.3%146482.1%434.7%18.6%II181260.0%146482.1%3116.1%32.3%III45590.0%146482.1%5219.2%36.5%IV150100%146482.1%1735.3%64.7%ALL904964.7%146482.1%14316.1%33.6% Citation Format: Christopher Psutka, Marina Yamada, Akihisa Matsuda, Kazuya Yamahatsu, Satoshi Matsumoto, Toshihiko Kitayama, Nobuo Nakano, Jyunichi Koyano, Tohru Mikoshiba, Masao Miyashita. FAIMS technology in urinary volatile organic compound analysis to detect colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5303. doi:10.1158/1538-7445.AM2017-5303

Ion mobility spectrometry is a powerful and low-cost technique for the identification of chemical warfare agents, toxic chemicals, or explosives in air. Drift tube ion mobility spectrometers (DT-IMS) separate ions by the absolute value of their low field ion mobility, while field asymmetric ion mobility spectrometers (FAIMS) separate them by the change of their ion mobility at high fields. However, using one of these devices alone, some common and harmless substances show the same response as the hazardous target substances. In order to increase the selectivity, orthogonal data are required. Thus, in this work, we present for the first time an ambient pressure ion mobility spectrometer which is able to separate ions both by their differential and low field mobility, providing additional information for selectivity enhancement. This novel field asymmetric time of flight ion mobility spectrometer (FAT-IMS) allows high repetition rates and reaches limits of detection in the low ppb range common for DT-IMS. The device consists of a compact 44 mm drift tube with a tritium ionization source and a resolving power of 70. An increased separation of four substances with similar low field ion mobility is shown: phosgene (K0 = 2.33 cm2/(V s)), 1,1,2-trichlorethane (K0 = 2.31 cm2/(V s)), chlorine (K0 = 2.24 cm2/(V s)), and nitrogen dioxide (K0 = 2.25 cm2/(V s)). Furthermore, the behavior and limits of detection for acetonitrile, dimethyl methylphosphonate, diisopropyl methyl phosphonate in positive polarity and carbon dioxide, sulfur dioxide, hydrochloric acid, cyanogen chloride, and hydrogen cyanide in negative polarity are investigated.

Transforming growth factor-β superfamily members, such as myostatin, growth/differentiation factor 11, and activin A, negatively regulate skeletal muscle mass. Inhibitors targeting these cytokines or activin receptor type IIB have the potential to treat muscular diseases and enhance physical performance. However, because of their effects on muscle mass and potential misuse, they are strictly prohibited in sports. Given the high potential for misuse as a doping agent in sports, effective analytical methods for these prohibited antibodies targeting these specific cytokines or their receptor are critically needed. In this study, we aimed to develop and validate a multitarget method to detect the prohibited transforming growth factor-β superfamily-targeting monoclonal antibodies, such as landogrozumab, domagrozumab, and the activin receptor type IIB-targeting antibody, bimagrumab, in human plasma and dried blood spot (DBS) samples using liquid chromatography-tandem mass spectrometry. Antibodies were purified from both the DBS and plasma samples using protein G magnetic beads and field-asymmetric ion mobility spectrometry (FAIMS) to minimize interference, followed by liquid chromatography-tandem mass spectrometry analysis. The validation process included tests for specificity, selectivity, linearity, limit of detection (LOD), limit of identification, precision, recovery, carryover effect, and matrix effect. The LODs for the target antibodies were identical in both DBS and plasma samples at 0.1 µg/mL for landogrozumab heavy and light chains, as well as 0.25 µg/mL for the domagrozumab light chain and 0.25 µg/mL for the bimagrumab heavy chain. However, the heavy chain of domagrozumab exhibited an LOD of 0.5 µg/mL in DBS and 1 µg/mL in plasma. The analytical method demonstrated strong linearity, with R² values greater than 0.99 for both plasma and DBS, and no carryover effect. Precision (CV%) was below 15 % at both middle (1 or 5 µg/mL; specific to the heavy chain of domagrozumab in plasma) and high (10 µg/mL) concentrations and was less than 20 % at the LOD. The selectivity and specificity indicated no interference in the analysis of target mAbs in different blood samples. Recovery was 31.6–49.8 % for DBS and 51.4–85.3 % for plasma, with no significant matrix effect. This study provides an effective method for doping analysis and novel protein detection.

In this paper we study the influence of the carrier and drift gas composition on ionization processes taking place inside drift chamber of field asymmetric ion mobility spectrometer with laser ionization. Solid state nanosecond laser of YAG:Nd 3+ type with fourth harmonic unit (λ = 266 nm, τpulse = 6 ns, E pulse = 700 – 2500 μJ, ν = 10 – 20 Hz) was used for negative ion generation. In this study we experimentally discover the features of laser ionization of four nitro-compounds: cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitramine (HMX), pentaerythritol tetranitrate (PETN), trinitrotoluene (TNT) explosives. Drift and sample carrier gas were prepared by mixing purified air with different amounts of water vapor and organic dopants. Ion mobility increments were calculated after calibration of field asymmetric ion mobility spectrometer (FAIMS) based on published data for TNT and Iodine and measured alternating separation field waveform. The experimental setup also included drift time ion mobility spectrometer (IMS) which was used to verify linear ion mobility spectra to supplement ion mobility increment values, obtained by FAIMS. Previous studies of laser ionization with optimization of intensity and pulse repetition rates gave LOD values well below 10−15 g/cm3: 3 × 10−15 g/cm3 for RDX, 8 × 10−15 g/cm3 for PETN and less than 3 × 10−15 g/cm3 for HMX. Common ideas about ionization mechanisms of nitro-based explosives propose that indirect processes with ion-molecular reactions substantially contribute to negative ion formation as well as resonant enhanced multi photon ionization (REMPI) direct processes. Ionization process starts with electron generation by organic impurities in atmospheric air. These organic compounds have low ionization energy and require less than two photons to ionize. Current research involves doping air sample with such substances as: toluene acetone, naphthalene and chloroform at different UV irradiation modes. Such compounds can act as electron source for rising TNT and RDX ion signal levels above background. Such selectivity enhancement can be a step on the way to achieving even lower detection limits to sense trace explosive vapor concentrations in real conditions.

The field asymmetric ion mobility spectrometry(FAIMS) technique was used for the rapid analysis of diethanolamine( DEA). The ion characteristic signal of DEA was acquired by FAIMS with the direct thermal desorption method for sampling,which was compared with the result of gas chromatograph-mass spectrometer(GC-MS). The concentration of DEA gas was controlled by the polytetrafluoroethene(PTFE) diffusion tube method. The DEA gas samples with different concentrations were detected by FAIMS technique. The dependence of the integrated ion current on DEA gas concentration was obtained,and the limit of detection for DEA gas is 0. 02 μg / L. This study has laid a foundation for the application of FAIMS technique to on-site rapid detection of DEA.

The approaches for increasing a contact-free sampling distance up to 40 cm for a field asymmetric ion mobility spectrometer were investigated and implemented by use both the vortex flow made by a rotating impeller and the laser desorption of traces of low volatile explosives. The sampling device for a laser-based field asymmetric ion mobility spectrometer including a high-speed rotating impeller was designed and built with help of computer simulation of vortex and analytical flows. The dependence of a signal of trinitrotoluene vapors on a rotational speed of an impeller was obtained. The optimization of analytical flow was performed. The effective sampling distance is increased up to 28 cm for trinitrotoulene vapors detection by a field asymmetric ion mobility spectrometer equipped with a rotating impeller. The distance can be increased up to 40 cm using laser irradiation of objects with traces of explosives. It was shown that under ambient conditions the efficient desorption of low-volatile explosives is achieved at laser intensity 107 W/cm2, wavelength λ = 266 nm, pulse energy about 1 mJ and pulse frequency not less than 10 Hz.