TY - JOUR A1 - van Wasen, S. A1 - You, Yi A1 - Beck, S. A1 - Riedel, Jens A1 - Volmer, D. A. T1 - Miniaturized Protein Digestion Using Acoustic Levitation with Online High Resolution Mass Spectrometry N2 - The combination of acoustically levitated droplets, mid-IR laser evaporation, and subsequent post-ionization by secondary electrospray ionization was applied for monitoring the enzymatic digestion of various proteins. Acoustically levitated droplets are an ideal, wall-free model reactor, readily allowing compartmentalized microfluidic trypsin digestions. Time-resolved interrogation of the droplets yielded real-time information on the progress of the reaction and thus provided insights into reaction kinetics. After 30 min of digestion in the acoustic levitator, the obtained protein sequence coverages were identical to the reference overnight digestions. Importantly, our results clearly demonstrate that the applied experimental setup can be used for the real-time investigation of chemical reactions. Furthermore, the described methodology only uses a fraction of the typically applied amounts of solvent, analyte, and trypsin. Thus, the results exemplify the use of acoustic levitation as a green analytical chemistry alternative to the currently used batch reactions. KW - Acoustic levitation KW - Protein analysis KW - Mass spectrometry PY - 2023 DO - https://doi.org/10.1021/acs.analchem.2c05334 VL - 95 SP - 4190 EP - 4195 PB - ACS Publications AN - OPUS4-57053 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Li, Xunyu A1 - Riedel, Jens A1 - You, Yi T1 - Determination of broadband-light atomic absorption through interferometric spectrometry with a spatial heterodyne spectrometer N2 - A spatial heterodyne spectrometer (SHS) was combined with a flame atomic absorption (FAA) setup to reveal the analytical potential of SHS to be used as a tool for high-resolution atomic absorption studies. Exploiting the advances in modern computational power, the spectral information encoded in the interferograms was extracted and separated. Consequently, unseeable interferometric ingredients corresponding to narrow-band absorption lines could be recognized. Namely, a single SHS absorption interferogram simultaneously contains both illumination background and absorption information, which can be distinguished through a series of computational steps. In the examples given by this work, we demonstrate the construction of Na absorbance spectra from a single image. The described single-image approach can be used to investigate highly dynamic systems, whereby background collections can be obviated. KW - Optical Spectrometry KW - Spatial Heterodyne Spectrometry KW - Atomic Absorption PY - 2023 DO - https://doi.org/10.1039/D2JA00367H VL - 38 IS - 5 SP - 1088 EP - 1096 PB - Royal Society of Chemistry (RSC) AN - OPUS4-58332 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - You, Yi T1 - Acoustic Ion Manipulation (AIM) N2 - The precise control of gaseous ions is a cornerstone in ion-based spectrometry and other disciplines such as materials processing. Traditional high-pressure ion optics rely on electrostatic and magnetic fields that often demand the use of intense electric fields, radio frequency activation, complex geometrical arrangements, or partially transmissive grids. Consequently, the efficiencies of such devices tend to be low or they require large footprints, as ion motions under ambient conditions are governed aerodynamically by collisions and fluid dynamics. However, from a different perspective and holistic reasoning, the limitations posed by collisions, aerodynamics, and other factors that hinder ion control in the open-air suggested an innovative direction for ion manipulation. Our study introduces a novel method that employs low-power standing acoustic waves to effectively manipulate ion beams. We observe that ions distinctively prefer traveling through areas of static pressure within the acoustic field, identified as "nodes." In contrast, neutral gases are unaffected by the acoustic field structure and continue to move along a straight trajectory. We have named this method Acoustic Ion Manipulation (AIM). Initial studies demonstrated selective and efficient manipulations of ion with AIM, including gating, redirection, regional dispersion, and focusing. This technique broadens the scope of ion manipulation strategies at high pressures while enriching our fundamental understanding of ion-acoustic kinetics. The potential applications of this method are vast, promising significant advancements in the fields of analytical chemistry, environmental science, and beyond. T2 - ANAKON 2025 CY - Leipzig, Germany DA - 10.03.2025 KW - Acoustic ion manipulation KW - Mass spectrometry PY - 2025 AN - OPUS4-64110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Saleh, Maysoon I. A1 - Rühle, Bastian A1 - Wang, Shu A1 - Radnik, Jörg A1 - You, Yi A1 - Resch-Genger, Ute T1 - Assessing the protective effects of different surface coatings on NaYF4:YB3+, Er3+, upconverting nanoparticles in buffer and DMEM N2 - We studied the dissolution behavior of β NaYF4:Yb(20%), Er(2%) UCNP of two different sizes in biologically relevant media i.e., water (neutral pH), phosphate buffered saline (PBS), and Dulbecco’s modified Eagle medium (DMEM) at different temperatures and particle concentrations. Special emphasis was dedicated to assess the influence of different surface functionalizations, particularly the potential of mesoporous and microporous silica shells of different thicknesses for UCNP stabilization and protection. Dissolution was quantified electrochemically using a fluoride ion selective electrode (ISE) and by inductively coupled plasma optical emission spectrometry (ICP OES). In addition, dissolution was monitored fluorometrically. These experiments revealed that a thick microporous silica shell drastically decreased dissolution. Our results also underline the critical influence of the chemical composition of the aqueous environment on UCNP dissolution. In DMEM, we observed the formation of a layer of adsorbed molecules on the UCNP surface that protected the UCNP from dissolution and enhanced their fluorescence. Examination of this layer by X ray photoelectron spectroscopy (XPS) and mass spectrometry (MS) suggested that mainly phenylalanine, lysine, and glucose are adsorbed from DMEM. These findings should be considered in the future for cellular toxicity studies with UCNP and other nanoparticles and the design of new biocompatible surface coatings. KW - Fluorescence KW - Lifetime KW - Method KW - Quantification KW - Stability KW - Coating KW - Surface chemistry KW - Lanthanide KW - Fluoride KW - Electrochemistry KW - ICP-OES KW - Upconversion KW - Nano KW - Particle KW - Aging KW - Quality assurance KW - Mass spectrometry KW - XPS PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515984 DO - https://doi.org/10.1038/s41598-020-76116-z SN - 2045-2322 VL - 10 IS - 1 SP - 19318-1 EP - 19318-11 PB - Springer Nature CY - London AN - OPUS4-51598 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - You, Yi T1 - Advanced Repetition-Rate Modulation and Computational Strategies for Background-Free LIBS Using Non-Gated Spectrometers N2 - Laser-induced breakdown spectroscopy (LIBS) is recognized for its rapid, direct elemental analysis capabilities. However, its general adoption is constrained by the reliance on expensive, high-power consumption, gated cameras such as intensified charge-coupled devices (CCDs). These devices, while sensitive, are expensive and possess low frame rates, limiting their efficacy in dynamic or challenging environments. Our study proposes an innovative approach that leverages non-gated spectrometers in conjunction with the framework of correlation spectroscopy to isolate analyte signals responsive to a specific repetition-rate modulation pattern, thereby yielding spectra with zero background. We utilized a diode-pumped solid-state laser, with repetition rates ranging from 10 Hz to 30 kHz, to induce plasma in aqueous solutions containing various alkaline and earth-alkaline metals. With a non-gated single-grating linear CCD spectrometer, we found that the continuum signal plateaued at approximately 7 kHz. In contrast, atomic emissions from the dissolved analytes showed continued increases. Notably, atomic emissions from the solvent (water) were observable only above 8.5 kHz, at a significant high rate of increase. Through computational synthesis of a modulation pattern, we determined an optimized scheme that effectively discriminates continuum and analyte signals; this pattern was optimized with a genetic algorithm. The spectral matrix correlating signal intensity with laser repetition rate and wavelength was used as the input of the model. Meanwhile, the fitness function that extracts the background-free spectra was built in-house and inspired by the Gardner transform, which exploits the power of Fourier transform, allowing for flagging and splitting analyte signal from other undesired features. This approach bypasses the limitations associated with gated cameras, while providing a cost-effective alternative for robust LIBS applications. This advancement is particularly relevant in field, portable and remote applications, aligning with the ongoing demand for accessible, high-performance analytical tools in diverse scientific fields. T2 - SCIX 2024 Conference CY - Raleigh, NC, USA DA - 20.10.2024 KW - LIBS KW - Data Processing KW - High Repetition Rate KW - Repetition Rate Modulation KW - Data-Oriented Experimental Design PY - 2024 AN - OPUS4-62137 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Danischewski, Julia L. A1 - You, Yi A1 - Bauer, Lauren A1 - Riedel, Jens A1 - Shelley, Jacob T. T1 - Use of Resonant Acoustic Fields as Atmospheric-Pressure Ion Gates N2 - Ion optics are crucial for spectrometric methods such as mass spectrometry (MS) and ion mobility spectrometry (IMS). Among the wide selection of ion optics, temporal ion gates are of particular importance for time-of-flight MS (TOF-MS) and drift-tube IMS. Commonly implemented as electrostatic ion gates, these optics offer a rapid, efficient means to block ion beams and form discrete ion packets for subsequent analysis. Unfortunately, these devices rely on pulsed high voltage sources and are not fully transparent, even in their open state, which can lead to ion losses and contamination. Here, a novel atmospheric-pressure ion gate based on a resonant acoustic field structure is described. This effect was accomplished through the formation of a resonant, standing acoustic wave of alternating nodes and antinodes. Alignment of an atmospheric-pressure gaseous ion beam with an antinode, i.e. a region of transient pressure, of the acoustic structure acted as a gate and blocked ions from impinging on ion-selective detectors, such as a mass spectrometer and a Faraday plate. The velocity of the ion stream and acoustic power were found to be critical parameters for gating efficiency. In the presence of an acoustic field (i.e., a closed gate), ion signals decreased by as much as 99.8% with a response time faster than the readout of the ion-measurement devices used here (ca. 75 ms). This work demonstrates the basis for a low-cost, acoustic ion gate, which is optically transparent and easily constructed with low-power, off-the-shelf components, that could potentially be used with MS and IMS instrumentation. KW - Acoustic Ion Manipulation PY - 2025 DO - https://doi.org/10.1021/acs.analchem.4c05493 SN - 1520-6882 VL - 97 IS - 5 SP - 2890 EP - 2898 PB - American Chemical Society AN - OPUS4-62648 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Song, L. A1 - You, Yi A1 - Perdomo, R. A1 - Evans-Nguyen, T. T1 - Inexpensive Ultrasonic Nebulization Coupled with Direct Current Corona Discharge Ionization Mass Spectrometry for Liquid Samples and Its Fundamental Investigations N2 - The concept of direct mass-spectrometric analysis, especially exploited by ambient desorption/ionization (ADI) methods, provides numerous means for convenient sample analysis. While many simple and versatile ionization sources have been developed, challenges lay in achieving efficient sample introduction. In previous work, a sample introduction method employing direct current corona discharge (CD) coupled to a surface acoustic wave nebulization (SAWN) device enhanced sampling performance for both polar and nonpolar analytes by up to 4 orders of magnitude. In fact, the SAWN-CD method generated a multiply charged peptide ion signal comparable to that of conventional ESI. Unfortunately, the high cost of the SAWN devices themselves limits their accessibility. Herein, we report on an analogous implementation of CD with an inexpensive ultrasonic nebulizer (USN) on the basis of a commercial room humidifier demonstrating equivalent exemplary performance. We subsequently compare the two methods of SAWN-CD and USN-CD in a screening application of milk for the detection of two antibiotic drugs, ciprofloxacin and ampicillin. Finally, we further investigate the relative softness of these CD-coupled acoustic nebulization methods in comparison to that of ESI using a survival yield study of the thermometer ion nitrobenzylpyridinium. KW - Rapid Analysis KW - Ultrasonic Nebulization KW - Corona Discharge PY - 2020 DO - https://doi.org/10.1021/acs.analchem.0c00524 VL - 92 IS - 16 SP - 11072 PB - ACS Publication AN - OPUS4-51225 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - You, Yi A1 - Song, L. A1 - Young, M.D. A1 - van der Wielen, M. A1 - Evans-Nguyen, T. A1 - Riedel, Jens A1 - Shelley, J.T. T1 - Unsupervised Reconstruction of Analyte-Specific Mass Spectra Based on Time-Domain Morphology with a Modified Cross-Correlation Approach N2 - Concomitant species that appear at the same or very similar times in a mass-spectral analysis can clutter a spectrum because of the coexistence of many analyte-related ions (e.g., molecular ions, adducts, fragments). One method to extract ions stemming from the same origin is to exploit the chemical information encoded in the time domain, where the individual temporal appearances inside the complex structures of chronograms or chromatograms differ with respect to analytes. By grouping ions with very similar or identical time-domain structures, single-component mass spectra can be reconstructed, which are much easier to interpret and are library-searchable. While many other approaches address similar objectives through the Pearson’s correlation coefficient, we explore an alternative method based on a modified cross-correlation algorithm to compute a metric that describes the degree of similarity between features inside any two ion chronograms. Furthermore, an automatic workflow was devised to be capable of categorizing thousands of mass-spectral peaks into different groups within a few seconds. This approach was tested with direct mass-spectrometric analyses as well as with a simple, fast, and poorly resolved LC–MS analysis. Single-component mass spectra were extracted in both cases and were identified based on accurate mass and a mass-spectral library search. KW - Mass-Spectral Reconstruction KW - Mass Spectrometry KW - Correlation PY - 2021 DO - https://doi.org/10.1021/acs.analchem.0c04396 VL - 93 IS - 12 SP - 5009 EP - 5014 PB - ACS AN - OPUS4-52467 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - You, Yi A1 - Bierstedt, Andreas A1 - Riedel, Jens T1 - Spatial, temporal, and spectral characterization and kinetic investigations of a high repetition-rate laser-induced micro-plasma in air N2 - Advances in laser-induced plasmas have enabled various rapid and simple analytical applications. Especially, their uses in the analyses of condensed-phase samples have drawn significant attention in the past few decades. Depending on the laser energy per pulse, various analytical goals can be achieved. Laser-induced airborne plasmas allow direct analysis of species in ambient air. Importantly, all of these applications are based on a fundamental understanding of the laser–medium interaction. Recent developments of diode-pumped solid-state lasers offer an alternative to conventional powerful, yet bulky lasers, which can specifically operate at high Repetition rates. Although these lasers deliver much lower power per pulse (mJ compared to mJ), the outstanding repetition rates offer significant improvement to meet statistical needs in some cases. In the present work, a mJ-laserinduced airborne plasma was characterized through optical emission analysis. By using a ns-timegated image detector coupled with specific bandpass filters, spatially, temporally, and spectrally resolved plasma images were recorded. Compared to conventional mJ-laser-induced plasmas, the one induced by mJ-lasers demonstrated unique features during its evolution. Specifically, measurements of the distribution of ionic and atomic species revealed distinctive energy/matter transfer processes during early ignition of the plasma. Meanwhile, dynamic investigations suggested subsequent matter transport in the later stage. KW - Laser-induced plasma KW - Plasma KW - DPSS-laser PY - 2019 UR - https://pubs.rsc.org/en/content/articlehtml/2019/ja/c9ja00163h DO - https://doi.org/10.1039/C9JA00163H SN - 0267-9477 VL - 34 IS - 8 SP - 1618 EP - 1629 PB - Royal Society of Chemistry CY - London AN - OPUS4-48622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Li, Xunyu A1 - Riedel, Jens A1 - You, Yi T1 - Practical high-resolution spectroscopy with a spatial heterodyne spectrometer: Determination of instrumental function for lineshape recovery N2 - The spatial heterodyne spectrometer (SHS) is a well-recognized platform for its high resolving power in various use cases of spectroscopy. Same as other spectrometer topologies, the SHS, unfortunately, also suffers from classical challenges such as distorted lineshape due to the instrumental function. The goal of this work is to tackle this persisting issue through a simple numerical approach. With the inherent characteristics of an SHS interferogram, we report the direct extraction and determination of the instrumental function in its numerical representation from an SHS interferogram; this instrumental function was further used for spectral data processing that enables significant improvements in spectral resolution through deconvolution algorithms.Here, we systematically discuss the recognition of the embedded instrumental function among various ingredients within an interferogram. To verify the numerical approach, lithium was chosen as the model sample, resembling the use of SHS in an isotopic analysis application. Specifically, the resonance transition of lithium D-lines (2P1/2,3/2 ← 2S1/2) was selected to assess the performance of the spectral processing. With the spectral deconvolution, the spectral features that represent the 6Li and 7Li were nearly baseline-separated, allowing for the accurate measure of the isotopic abundance without external references or algorithm adjustments (e.g., curve fitting). KW - SHS KW - Isotopic analysis KW - High Resolution PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-613401 DO - https://doi.org/10.1016/j.sab.2024.107053 SN - 0584-8547 VL - 221 SP - 1 EP - 5 PB - Elsevier AN - OPUS4-61340 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -