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Accurate quantification of blood creatinine is important to estimate the glomerular filtration rate. Existing techniques using liquid chromatography tandem mass spectrometry (LC–MS/MS) have a high accuracy and eliminate most interferences encountered in routine enzymatic and Jaffé methods. However, they require laborious and time-consuming sample treatment and data acquisition. The aim of this study is to develop a fast and simple method to enable a direct analysis of whole blood creatinine with performance measures that are comparable to conventional LC–MS/MS. 5μL whole blood is formed as a three-dimensional spheroid on hydrophobic silanized paper substrates which then undergoes paper-spray ionization—tandem mass spectrometry (PSI–MS/MS). The method is validated using real human samples and compared with LC–MS/MS. PSI–MS/MS whole blood analysis exhibited a lower limit of quantification of 2.5 μg/mL, precision ≤ 6.3%, recovery in the range of 88–94% and excellent linearity (R2 > 0.99; 2.5—20 μg/mL) covering the normal range for creatinine levels. Creatinine levels were comparable to those measured by LC–MS/MS with small deviations of less than 0.3 μg/mL. This simple, fast and accurate microsampling technique for direct analysis of creatinine from whole blood shows promise for routine clinical screening and monitoring. This approach can be readily extended for other analytes of interest and, due to inherent advantages relating to cost, storability, speed, and simplicity, it can be especially advantageous for use in resource-limited settings. [ABSTRACT FROM AUTHOR]

Mitigation of the peroxide explosive threat, specifically triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD), is a priority among the law enforcement community, as scientists and canine (K9) units are constantly working to improve detection. We propose the use of paper spray ionization–high-resolution mass spectrometry (PSI-HRMS) for detection of peroxide explosives in biological matrices. Occurrence of peroxide explosives and/or their metabolites in biological samples, obtained from urine or blood tests, give scientific evidence of peroxide explosives exposure. PSI-HRMS promote analysis of samples in situ by eliminating laborious sample preparation steps. However, it increases matrix background issues, which were overcome by the formation of multiple alkali metal adducts with the peroxide explosives. Multiple ion formation increases confidence when identifying these peroxide explosives in direct sample analysis. Our previous work examined aspects of TATP metabolism. Herein, we investigate the excretion of a TATP glucuronide conjugate in the urine of bomb-sniffing dogs and demonstrate its detection using PSI from the in vivo sample. [ABSTRACT FROM AUTHOR]

Propofol is a widely used intravenous anesthetic agent in sedation and general anesthesia. To improve the safety and maintain the depth of anesthesia, it is important to develop a rapid, sensitive, and reliable method to monitor the concentration of propofol in blood during anesthesia continuously. Here, we present a novel strategy based on paper spray ionization-mass spectrometry (PSI-MS) to detect propofol. Samples (in 10 μL) were mixed with methanol as protein precipitation solvent and 2,6-dimethylphenol as internal standard. Protein micro-precipitation was achieved with methanol by vortexing and centrifuging for 5 s each, and propofol was extracted to the supernatant. PSI-MS was performed in negative ionization mode, and MS signal lasted for 1 min. The analysis of a single sample was completed within 2 min. The area ratios of propofol to internal standard were calculated for quantification. Limit of detection of 5.5 ng mL−1 and limit of quantification of 18.2 ng mL−1 were achieved for propofol in whole blood. Calibration curve was linear in the range of 0.02–10 μg mL−1. The developed method was used successfully in monitoring the propofol concentration in 3 patients' whole blood during anesthesia, showing its further application in controlling and feeding-back target concentration infusion. [ABSTRACT FROM AUTHOR]

In this paper, we establish an in situ visualization analysis method to image the spatial distribution of metabolites in different parts (sclerotium, coremium) and different microregions of Cordyceps cicadae (C. cicadae) to achieve the in situ visual characterization of tissues for a variety of metabolites such as nucleosides, amino acids, polysaccharides, organic acids, fatty acids, and so on. The study included LC–MS chemical composition identification, preparation of C. cicadae tissue sections, DEDI-MSI analysis, DESI combined with Q-TOF/MS to obtain high-resolution imaging of mass-to-charge ratio and space, imaging of C. cicadae in positive–negative ion mode with a spatial resolution of 100 μm, and localizing and identifying its chemical compositions based on its precise mass. A total of 62 compounds were identified; nucleosides were mainly distributed in the coremium, L-threonine and DL-isoleucine, and other essential amino acids; peptides were mainly distributed in the sclerotium of C. cicadae; and the rest of the amino acids did not have a clear pattern; sugars and sugar alcohols were mainly distributed in the coremium of C. cicadae; organic acids and fatty acids were distributed in the nucleus of C. cicadae more than in the sclerotium, and the mass spectrometry imaging method is established in the research. The mass spectrometry imaging method established in this study is simple and fast and can visualize and analyse the spatial distribution of metabolites of C. cicadae, which is of great significance in characterizing the metabolic network of C. cicadae, and provides support for the quality evaluation of C. cicadae and the study of the temporal and spatial metabolic network of chemical compounds. [ABSTRACT FROM AUTHOR]

This paper presents data on the mass spectrometric study of amino acids and dipeptides under electrospray ionization conditions. It is shown that the formation of a molecular ion depends not only on the nature of the ionizable compound, but also on its concentration in the solution under study. When registering mass spectra, the decay products of the studied molecules, as well as the products of their interaction with each other, were detected. It was shown that the nature of the mass spectrum can change depending on the concentration of the test compound. The main conclusions about the physicochemistry of the interaction of molecules in solution with each other are given. It is shown that the intensity of destruction and association of various molecules depends on the concentration of the substance in the solution and the geometry of the molecules. [ABSTRACT FROM AUTHOR]

In various methods to determine alpha-emitting radionuclides in matrices, alpha-particle spectrometry with alpha-emitting sources prepared by the electrodeposition has been widely used. Although there are several good review papers on alpha-particle spectrometry and preparation of electrodeposited alpha-emitting sources, the mechanism of analysis procedure and characterizations of alpha-emitting sources have not been reported well. These untouched subjects by other review papers are very significant to improve the analysis procedure. This review focuses on the mechanism of the electrodeposition of alpha-emitting radionuclides on the stainless steel disc, factors for the preparation of electrodeposited alpha-emitting layers, and various characterization methods. [ABSTRACT FROM AUTHOR]

The article presents an interview with Clint M. Alfaro, Doctor of Philosophy candidate in analytical chemistry at Purdue University. Topics discussed include he talks about motivation to do research on touch spray-mass spectrometry and its intraoperative applications; his valuable achievement in research was ambient ionization mass spectrometry results; and his future plans on becoming chemistry research faculty member and translational scientist.

Ultra high-resolution mass spectrometry (FT-ICR MS) coupled to electrospray ionization (ESI) provides unprecedented molecular characterization of complex matrices such as petroleum products. However, ESI faces major ionization competition phenomena that prevent the absolute quantification of the compounds of interest. On the other hand, comprehensive two-dimensional gas chromatography (GC × GC) coupled to specific detectors (HRMS or NCD) is able to quantify the main families identified in these complex matrices. In this paper, this innovative dual approach has been used to evaluate the ionization response of nitrogen compounds in gas oils as a case study. To this extent, a large gas oil dataset has been analyzed by GC × GC/HRMS, GC × GC-NCD and ESI(+/−)-FT-ICR MS. Then, the concentrations obtained from GC × GC-NCD have been compared to those obtained from FT-ICR MS hence proving that strong ionization competitions are taking place and also depending on the origin of the sample. Finally, multilinear regressions (MLR) have been used to quantitatively predict nitrogen families from FT-ICR MS measurements as well as start rationalizing the ionization competition phenomena taking place between them in different types of gas oils. [ABSTRACT FROM AUTHOR]

Deep understanding of the polymerization and transformation of tungstate species in aqueous solution is of great significance for hydrometallurgical and chemical separation processes, such as solvent extraction, membrane separation and crystallization. In order to study the polymerization and transformation of tungstate species, the semi-quantitative characterization method of electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) was developed. In this paper, the tungsten speciation in simulative leaching solution was investigated in detail between pH 2.5 and 7 under various conditions (e.g. acid species, initial concentration, pH), and the results indicated that HCl was more conducive than HNO3 for the polymerization of tungsten at the same pH, and HAc accelerated the polymerization of tungsten species, especially in acid solution at lower pH; the morphological changes of each tungsten species tended to be consistent with the increase of tungsten concentration; pH strongly influenced the distribution of tungsten species. Then, the polymerization and transformation laws of tungstate species are summarized. W1 (monomers) are dominant species in weak acid and neutral solution, and aggregate into oligomeric species (e.g. W2, W4, W6). Transformations also exist among W2, W4 and W6. The polymerization process from W4 and W6 species to higher poly-tungstate (W10–12) was observed with the consumption of H+. This work aims to understand the polymerization and transformation of tungsten speciation using ESI-TOF-MS, which should provide useful information for the understanding and optimizing of industrial production and environmental processes, building a bridge between micro tungsten speciation and macro industrial applications. [ABSTRACT FROM AUTHOR]

Over the past decade, mass spectrometry (MS)-based “shotgun lipidomics” has emerged as a powerful tool for quantitative and qualitative analysis of the complex lipids in the biological system. The aim of this critical review is to give the interested reader a concise overview of the current state of the technology, focused on lipidomic analysis by mass spectrometry. The pros and cons, and pitfalls associated with each available “shotgun lipidomics” method are discussed; and the new strategies for improving the current methods are described. A list of important papers and reviews that are sufficient rather than comprehensive, covering all the aspects of lipidomics including the workflow, methodology, and fundamentals is also compiled for readers to follow.ᅟ [ABSTRACT FROM AUTHOR]

This paper presents a multi-class target screening method for the detection of 105 veterinary drug residues from 11 classes in milk using ultra-high performance liquid chromatography electrospray ionization quadrupole Orbitrap mass spectrometry (UHPLC/ESI Q-Orbitrap). The method is based on a non-target approach of full mass scan and multiplexing data-independent acquisition (Full MS/mDIA). The veterinary drugs include endectocides, fluoroquinolones, ionophores, macrolides, nitroimidazole, NSAIDs, β-lactams, penicillins, phenicols, sulfonamides, and tetracyclines. Veterinary drug residues were extracted from milk using a salting-out and solid-phase extraction (SOSPE) procedure, which entailed the precipitation of milk proteins by an extraction buffer (oxalic acid and EDTA, pH 3) and acetonitrile, a salting-out acetonitrile/water phase separation using ammonium sulfate, and solid-phase extraction for clean-up using polymeric reversed-phase sorbent cartridges. The Q-Orbitrap Full MS/dd-MS2 (data-dependent acquisition) was used to acquire product-ion spectra of individual veterinary drugs to build a compound database and a mass spectral library, whereas its Full MS/mDIA was utilized to acquire sample data from milk for target screening of veterinary drugs fortified at 1.0 or 10.0 μg/kg. The in-spectrum mass correction or solvent background lock-mass correction was used to minimize mass error when building the compound database from experimental dd-MS2 accurate mass data. Retention time alignment and response threshold adjustment were used to eliminate or reduce false negatives and/or false positive rates. The validated method was capable of screening 58% and 96% of 105 veterinary drugs at 1.0 and 10.0 μg/kg, respectively, without manually evaluating every compound during data processing, which will reduce the workload in routine practice. [ABSTRACT FROM AUTHOR]

Real-time feedback about dissected tissue during the neurosurgical procedure is strongly requested. A novel direct ionization mass spectrometric method for identifying pathological differences in tissues is proposed. The method is based on simultaneous extraction of tissue lipids and electrospray ionization which allows mass spectrometric data to be obtained directly from soft tissues. The advantage of this method is the stable flow of solvent, which leads to stable time-dependent spectra. The tissues included necrotized tissues and tumor tissues in different combinations. Capability for direct analysis of samples of dissected tissues during the neurosurgical procedure is demonstrated. Data validation is conducted by compound identification using precise masses from the MS profile, MS/MS, and isotopic distribution structure analysis. The method can be upgraded and applied for real-time identification of tissues during surgery. This paper describes the technique and its application perspective. For these purposes, other methods were compared with the investigated one and the results were shown to be reproducible. Differences in lipid profiles were observed even in tissues from one patient where distinctions between different samples could be poor. The paper presents a proof of concept for the method to be applied in neurosurgery particularly and in tissue analysis generically. The paper also contains preliminary results proving the possibility of observing differences in mass spectra of different tumors. [ABSTRACT FROM AUTHOR]

Phytohormones are signaling and regulating metabolites involved in numerous plant processes, including growth, development, and responses to stress. Currently, the focus is on the analysis of multiple phytohormones in order to characterize crosstalk and hormone signaling networks. In this paper, representative phytohormones of the major classes are simultaneously determined in rice tissues by a generic solid-liquid extraction, followed by liquid chromatography and electrospray ionization high-resolution tandem mass spectrometry using a Q-Exactive™ instrument. After a thorough optimization of the sample preparation, the analytical method was fully validated toward the ultra-trace quantification of six a priori selected plant hormones using three scan modes of the quadrupole-Orbitrap instrument: full-scan high-resolution mass spectrometry, targeted single ion monitoring (t-SIM), and t-SIM followed by data-dependent tandem mass spectrometry. Overall, a similar quantitative performance was noticed for the different scan modes. The analytical method was successfully applied to measure basal phytohormone levels in six different rice accessions, comprising Oryza sativa ssp. japonica, indica, and Oryza glaberrima. Hormone concentrations were higher in shoots than in roots or at least similar. Except for a lower level of salicylic acid in shoots of O. glaberrima versus O. sativa, no other differences in hormone levels could be noticed that were dependent of the (sub)species assignment of the analyzed accessions. Making use of the benefits of full-scan high-resolution mass spectrometry, a first post-run suspect screening was performed, suggesting - based on accurate mass measurements and isotopic patterns - the possible presence of about 50 additional plant hormones in the rice tissues.ᅟ [ABSTRACT FROM AUTHOR]

Electrospray ionization mass spectra of biomolecules typically consist of a series of multiply charged ions because of the transfer of protons or other charge carriers between ions of biomolecules and the surrounding liquid or gas. The distribution of intensities of ions retained charge carriers contains information about the spatial structure of biomolecules. A new method is developed for the separation and decomposition of multidimensional charge distributions of ions bearing other charge carriers, such as alkali metal ions, along with protons. The proposed method ensures the estimation of the probability of charge carrier retention by separate functional groups for the selected conformations of biomolecules. The paper describes the application of this method to the analysis of a two-dimensional charge distribution of horse heart cytochrome C, resulting in the revelation of at least two its structural forms under the studied conditions. [ABSTRACT FROM AUTHOR]

This paper provides an efficient platform to diversify the structure and pharmaceutical potentials of known natural products. Seven metabolites were obtained via the biotransformation of cryptotanshinone by the fungus Mucor rouxii AS 3.3447, and assigned as 13 R-14 R-hydroxy-anhydride of 16 R-cryptotanshinone ( 1), 1 S-hydroxy-anhydride of 16 R-cryptotanshinone ( 2), 1 R-hydroxy-anhydride of 16 R-cryptotanshinone ( 3), 3 S-hydroxy-epicryptoacetalide ( 4), 3 S-hydroxy-cryptoacetalide ( 5), epicryptoacetalide ( 6), and cryptoacetalide ( 7). Among these compounds, 1- 5 are novel. The ortho-naphthoquinone chromophore of cryptotanshinone was degraded and rearranged by M. rouxii. 1 and 3 showed good anti-influenza A virus activities with the reduced cytotoxic activities compared to the parent substrate cryptotanshinone ( 8). The structures of all the new compounds were determined on the basis of HRESIMS (high-resolution electrospray ionization mass spectroscopy) spectrometry, NMR (nuclear magnetic resonance) spectroscopy, ECD (electronic circular dichroism) calculations, and the CD (circular dichroism) of 'in situ' method with [Rh(OCOCF)]. [ABSTRACT FROM AUTHOR]

In this paper, the effect of isotope-labeled analogs on the liquid chromatography-isotope dilution mass spectrometry (LC-IDMS) measurement was evaluated based on the comparison research of electrospray ionization responses (ESI) and matrix effect of melamine, C-melamine, C+N-melamine, and N-melamine. The isotope-labeled melamines had similar ionization efficiency with melamine in the electrospray ionization source, but the intensity of corresponding quantitative fragment ions had distinctive differences. Based on the density functional theory at the B3LYP/6-311+G** level, this phenomenon was explained very well. The rare cleavage pathways of melamine, which just could be exactly identified by N-labeled melamines, resulted in the difference of quantitative fragment ions between N-labeled melamines and melamine. The interaction of ESI response between melamine and isotope-labeled melamines was investigated using MRM monitor mode. N-labeled melamine had significant ion inter-suppression effect on melamine, while C-labeled melamine had little influence on melamine. Finally, the influence of different isotope-labeled melamines on the LC-IDMS result was evaluated using the IDMS correction factor ( θ). Taking the determination of melamine in milk powder as an example, the matrix effects of different isotope-labeled melamines and melamine had notable difference and the impact of this difference on the measurement results depended on the concentrations of analyte and matrix solution. It was worth noting that N-melamine exhibited significant ion suppression to melamine in matrix solution. The deviation of the results from IDMS method might reach 59% using N-melamine as internal standard in special matrix solution. [ABSTRACT FROM AUTHOR]

Many current tandem mass spectrometry (MS) methods for measuring phosphatidylcholines (PtdChos) rely only on precursor ion scanning of the common 184 m/z phosphocholine fragment with positive electrospray ionization (+ESI), and thus measure pools of PtdChos rather than specific isoforms. In this paper, we developed and compared an isotope dilution, tandem MS method capable of quantifying PtdChos based on specific fatty acid side-chains to the traditional 184 m/z method. The method is based on the detection of PtdCho ammonium formate (AmF) adduct as parent ions and fatty acid fragment daughter ions under negative electrospray ionization (−ESI). Accuracy, imprecision, and recovery were below 15 %, with acceptable linearity ( R > 0.99) up to 5 μg/mL. We used the method to analyze the distributions of PtdChos with common side-chain combinations among 60 subjects and showed that it was possible for two individuals to have the same PtdCho pool concentration based on detection of the 184 m/z fragment, but up to a fourfold difference in the levels of specific isoforms comprising the pool based on our method. We then compared the results of both methods across 572 patients with mild cognitive impairment (MCI), Alzheimer's disease (AD), or no impairment (NI), which showed that statistically significant associations between specific PtdCho isoforms and AD were masked with the 184 m/z method. Our findings demonstrate the importance of isoform specificity for quantifying PtdChos, and suggest caution when interpreting analytical data based on pools of biomarkers. [ABSTRACT FROM AUTHOR]

The present work reports a method for identification of Polish cochineal ( Porphyrophora polonica L.) in historical fabrics by the use of high-performance liquid chromatography coupled with diode array and tandem mass spectrometric detection with electrospray ionization (HPLC-DAD-ESI MS/MS). This hyphened technique allows detection and identification of 16 new minor colorants present in the discussed scale insect (including two previously observed by Wouters and Verhecken (Ann Soc Entomol Fr. ;25:393-410), but specified only as compounds of unknown structures) that do not occur (e.g., in American cochineal). The MS/MS experiments, complemented with UV-VIS data, enable identification of mono- and di-, C- and O-hexosides of kermesic and flavokermesic acids or their derivatives. The present paper introduces a fingerprint of color compounds present in Polish cochineal and defines them, particularly pp6 (ppI, O-hexoside of flavokermesic acid), as its markers allow distinguishing of Polish-cochineal reds from the American ones. Usefulness of the selected set of markers for identification of Polish cochineal has been demonstrated in the examination of textiles from the collection of the National Museum in Warsaw using the multiple reaction monitoring (MRM) method, originally elaborated on the basis of this study. [ABSTRACT FROM AUTHOR]

Catalyst could significantly improve thermal decomposition performance of energetic materials. However, different approaches for dispersing catalyst into energetic materials lead to quite different results. Generally, improved homogeneity of the mixture always results in better performance. In this paper, a novel method was applied on synthesizing nanoceria; at the same time, electrospray method was introduced to produce homogenous RDX/ceria micropowder. The mixture was characterized and tested by scanning electron microscope-energy-dispersive spectroscopy and differential scanning calorimetry-thermogravimetry. Kissinger method was employed to calculate activation energy of different specimens according to DSC data. Results indicated that with electrospray formation, catalyst (nanoceria) could be evenly dispersed into RDX. In contrast to pure RDX, RDX/ceria mixture could decompose at a lower temperature and has lower activation energy. The calculation results of critical explosion temperature indicated that the mixture is safe for storage and process operation. This study points out a potential way to develop new method to make energetic/catalyst mixture. [ABSTRACT FROM AUTHOR]

Desorption electrospray ionization (DESI) mass spectrometry is an emerging technology for direct therapeutic drug monitoring in dried blood spots (DBS). Current DBS methods require manual application of small molecules as internal standards for absolute drug quantification. With industrial standardization in mind, we superseded the manual addition of standard and built a three-layer setup for robust quantification of salicylic acid directly from DBS. We combined a dioctyl sodium sulfosuccinate weave facilitating sample spreading with a cellulose layer for addition of isotope-labeled salicylic acid as internal standard and a filter paper for analysis of the standard-containing sample by DESI-MS. Using this setup, we developed a quantification method for salicylic acid from whole blood with a validated linear curve range from 10 to 2000 mg/L, a relative standard deviation (RSD%) ≤14 %, and determination coefficients of 0.997. The limit of detection (LOD) was 8 mg/L and the lower limit of quantification (LLOQ) was 10 mg/L. Recovery rates in method verification by LC-MS/MS were 97 to 101 % for blinded samples. Most importantly, a study in healthy volunteers after administration of a single dose of Aspirin provides evidence to suggest that the three-layer setup may enable individual pharmacokinetic and endpoint testing following blood collection by finger pricking by patients at home. Taken together, our data suggests that DBS-based quantification of drugs by DESI-MS on pre-manufactured three-layer cartridges may be a promising approach for future near-patient therapeutic drug monitoring. [ABSTRACT FROM AUTHOR]

Abstract: Materials emitting white luminescence are receiving increasing attention due to their potential applications in electroluminescent devices, information displays and fluorescent sensors. To produce white light, one must have either three primary colors, blue, green and red or two colors, blue and orange. In this paper, we have used thiol/phosphine protected red luminescent silver nanoclusters (Ag NCs), [Ag29(BDT)12(PPh3)4]3-(BDT=1,3-benzenedithiol), [AuxAg29-x(BDT)12(PPh3)4]3- and Ag29(LA)12 (LA=lipoic acid) as one of the fluorophores for white light emission. These clusters are mixed with blue luminescent silicon nanoparticles (Si NPs) and green luminescent fluorescein isothiocyanate (FITC). The mixtures show white luminescence with CIE coordinates of (0.31, 0.34), (0.33, 0.35) and (0.29, 0.31) which are in good agreement with pure white light (0.33, 0.33). The other clusters with yellow, blue, orange, etc., luminescence can also be used to make white light. This work provides a prospective pathway for white light emission based on atomically precise noble metal NCs.Graphical abstract: Synopsis Monolayer protected noble metal nanoclusters such as [Ag29(BDT)12(PPh3)4]3-(BDT=1,3-benzenedithiol), [AuxAg29-x(BDT)12(PPh3)4]3- and Ag29(LA)12 (LA=lipoic acid) are used as red luminophores which can produce white light emission when mixed with blue luminescent silicon nanoparticles (Si NPs) and green luminescent fluorescein isothiocyanate (FITC). The mixtures produce white luminescence with CIE (Commission Internationale d’Eclair) coordinates of (0.31, 0.34), (0.33, 0.35) and (0.29, 0.31), respectively. All-cluster-based white light emission is indeed possible. [ABSTRACT FROM AUTHOR]