RATIONALE Ambient ionization mass spectrometry (AIMS) delivers realistic data from samples in their native state. In addition, AIMS methods reduce time and costs for sample preparation and have less environmental impact. However, AIMS data are often complex and require substantial processing before interpretation. METHODS We developed an interactive R script for the guided processing of mass spectrometry (MS) data. The ‘MQ_Assistant’ is based on MALDIquant, a popular R package for MS data processing. In each step, the user can try and pre-view the effect of chosen parameters before deciding on the values with the best result and proceeding to the next stage. The outcome of the MQ_Assistant is a feature matrix that can be further analyzed in R and statistics tools such as MetaboAnalyst. RESULTS Using 360 AIMS example spectra, we demonstrate the step-by-step processing for creating a feature matrix. In addition, we show how to visualize the results of tree biological replicates of a plant-microbe interaction between Arabidopsis and Trichoderma as a heatmap using R and upload them to MetaboAnalyst. The final parameter set can be saved for reuse in MALDIquant workflows of similar data. CONCLUSIONS The MQ_Assistant helps novices and experienced users to develop workflows for (AI)MS data processing. The interactive procedure supports the quick finding of appropriate settings. These parameters can be exported and reused in future projects. The step-wise operation with visual feedback also suggests the use of the MQ_Assistant in education.

The researcher will introduce the way of effective liquid chromatography tandem mass spectrometric method (HPLC-MS) which is quick, sensitive, and alternative to determine the (E)-3-(3,4-dihydroxyphenyl) -2-(3-(3,4-dihydroxyphenyl)acrylamido)propanoic acid (A1) and rosmarinic acid (RA) of the plasma in rats. The analyses were divided into a C18 column (1.9 μm, 2.1 mm × 100 mm) with a security guard C18 column (5 μm, 2.1 mm × 10 mm) and a triple-quadrupole mass spectrometry with an electrospray ionization (ESI) ion-source generates ions. With Pseudoephedrine hydrochloride being a standard, the sample pretreatment is relevant to the one-step protein precipitation with isopropanol: ethyl acetate (v/v, 20:80). This method presented a linear relationship within ranges of the concentration of 5–750 ng/ml for RA and A1. Relative standard deviations (RSD) in daily courses stood less than 15% and the relative errors (RE) registered within 15%. The means adopted in this research makes the RA’s and A1’s unambiguous quantification and identification and in vivo possible. And this study can be the first one to focus on determining the A1 and RA of rat plasma with administration orally. The results served as a significant basis to evaluate the medicine’s applications in the clinic.

A document by Colette LaMonica Kelly. Click on the document to view its contents.

RATIONALE: Selective derivatization of peptide N-terminus with 4-formyl-benzenesulfonic acid (FBSA) enables chemically activated fragmentation in ESI+/- (positive and negative ion mode) under charge reduction conditions. Overlapped positive and negative tandem mass spectra pinpoint b-ions making the assignment of b-ion series fragments easy and accurate. METHODS: We developed a FBSA-peptide microwave assisted derivatization procedure. Derivatized and non-derivatized bovine serum albumin tryptic peptides and insulin non-tryptic peptide were compared after MS/MS analysis in positive and negative ion mode. High-quality dataset of sulfonated b-ions obtained in negative tandem mass spectra of singly charged FBSA-peptides were matched to detected b-ions in positive MS/MS spectra. Moreover, negative spectra signals were converted and matched against y-ions in positive tandem mass spectra to identify complete peptide sequences. RESULTS: The FBSA derivatization procedure produced a significantly improved MS/MS dataset (populated by high-intensity signals of b- and y-ions) in comparison to commonly used N-terminal sulfonation reagents. Undesired side reactions do not occur and the procedure reduces the derivatization time. It was found that b-ions comprise 15% and 13% of all fragment ions generated in positive and negative ion mode, respectively. High visibility of b-ion series in negative ion mode can be attributed to the N-terminal sulfonation which had no effect on the production of b-ion series in positive ion mode. CONCLUSIONS: The FBSA derivatization and de novo sequencing approach outlined here provides a reliable method for accurate peptide sequence assignment. Increased production of the b-ions in positive and negative ion mode greatly improves peak assignment and thus enables accurate sequence reconstruction. Implementation of the named methodology would improve the quality of de novo sequencing data and reduce the number of misinterpreted spectra.

Rationale: The fundamental understanding of Grignard-type organolanthanides(III) is still in its infancy. Decarboxylation of metal carboxylate ions is a powerful method to obtain organometallic ions which are well suited for gas-phase investigation by using ESI-MS in combination with DFT calculations. Methods： (RCO2)LnCl3- (R = CH3, Ln = La-Lu except Pm; Ln = La, R = CH3CH2, CH2CH, CHC, C6H5 and C6H11) ions were produced via ESI of LnCl3 and RCO2H/RCO2Na in methanol. Collision-induced dissociation (CID) was employed to examine whether RLnCl3- can be obtained via decarboxylation of (RCO2)LnCl3-. With the aid of DFT calculations, the influences of Ln and R on the formation of RLnCl3- can be uncovered. Results: When R was fixed as methyl, CID of (CH3CO2)LnCl3- (Ln = La-Lu except Pm) all gave (CH3)LnCl3- and LnCl3·- with a variation in the relative intensity ratio of (CH3)LnCl3-/LnCl3·-. The trend is following as (CH3)EuCl3-/EuCl3·- < (CH3)YbCl3-/YbCl3·- ≈ (CH3)SmCl3-/SmCl3·- < other (CH3)LnCl3-/LnCl3·-, which generally complies with the trend of Ln(III)/Ln(II) reduction potentials. When Ln was fixed as La and R groups were varied as CH3CH2, CH2CH, CHC, C6H5 and C6H11, the fragmentation behaviors of these (RCO2)LaCl3- are diverse. Except for (C6H11CO2)LaCl3-, the rest four (RCO2)LaCl3- ions all underwent decarboxylation to give RLaCl3-. The relative intensities of RLaCl3- compared to (RCO2)LaCl3- decrease as follow: CHC > CH2CH > C6H5 > CH3 > CH3CH2 >> C6H11 (not visible). Conclusion： A series of Grignard-type organolanthanide(III) ions RLnCl3- (R = CH3, Ln = La-Lu except Pm; Ln = La, R = CH3CH2, CH2CH, CHC and C6H5) were generated from (RCO2)LnCl3- via CO2 loss while (C6H5)LaCl3- not. The experimental and theoretical results suggest that the reduction potentials of Ln(III)/Ln(II) couples as well as the bulkiness and hybridization of hydrocarbyl groups play crucial roles in promoting or limiting the formation of RLnCl3- via decarboxylation.

RATIONALE Boron isotopes are a powerful tool for pH reconstruction in marine carbonates and as tracer for fluid-mineral interaction in geochemistry. Micro-analytical approaches based on laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) often suffer from effects induced by the sample matrix. In this study, we investigated matrix-independent analyses of B isotopic ratios and applied this technique to cold-water corals. METHODS We employed a customized 193 nm femtosecond laser ablation system (Solstice, Spectra-Physics) coupled to a MC-ICP-MS (Nu Plasma II, Nu Instruments) equipped with electron multipliers for in situ measurements of B isotope ratios (11B/10B) at the micron-scale. We analyzed various reference materials of silicate and carbonate matrices using non-matrix match calibration without employing any correction mode. This approach was then applied to investigates defined increments in coral samples from a Chilean fjord. RESULTS We obtained accurate B isotope ratios with a precision of ± 0.9‰ (2 SD) for various reference materials including silicate glasses (GOR132-G, StHs6/80-G, ATHO-G, and NIST SRM 612), clay (IAEA-B-8) and carbonate (JCp-1) using the silicate glass NIST SRM 610 as calibration standard, which shows that neither laser-induced nor ICP-related matrix effects are detectable. The application to cold-water corals (Desmophyllum dianthus) reveal little intra-skeleton variations in δ11B with average values between 23.27 and 26.09‰. CONCLUSIONS Our instrumental set-up provides accurate and precise B isotopic ratios independently of the sample matrix at the micron-scale. This approach opens a wide field of application in geochemistry, including pH reconstruction in biogenic carbonates and deciphering processes related to fluid-mineral interaction.

Rationale. Femtoamp and picoamp electrospray ionization characteristics of a non-polar solvent were explored. The direct ESI-MS analysis of chloroform extract solution enabled rapid analysis of perfluorinated sulfonic acid (PFS) analytes in drinking water. Methods. Neat chloroform solvent and extracts were directly used in a typical wire-in ESI setup using micrometer emitter tips. Ionization currents were measured with femtoamp sensitivity while ramping the spray voltage from 0 to -5000 V. Methanol was used to illustrate the characteristics of spraying chloroform. The effect of spray voltage and inlet temperature was studied. A liquid-liquid extraction workflow was developed to analyze PFOS in drinking water using an ion trap mass spectrometer. Results. The ionization onset of chloroform solution was 41 ± 17 fA at 300 V. The ionization current gradually increased with voltage while remaining below 100 pA when using voltage up to -5000 V. PFOS ion signal was significantly enhanced to improve the detection limit to 25 ppt in chloroform. Coupled with a liquid-liquid extraction workflow, detection limits of 0.38-5.1 ppt, and a quantitation range of 5-400 ppt were achieved for perfluorinated sulfonic compounds in 1 mL drinking water samples. Conclusions. Femtoamp and picoamp modes expand the solvent compatibility range of electrospray ionization and can enable quantitative analysis in ppt concentrations.

Rationale: IMS has been widely used for the on-site detection of explosives. Air sampling method is applicable only when the concentration of explosive vapor is considerably high in the air, but vapor pressures of common explosives such as TNT, RDX, and PETN are very low. A test method for analyzing the vapor detection efficiency of explosives with low vapor pressure via IMS was developed using artificial vapor and collection matrices. Methods: Artificial explosive vapor was produced by spraying an explosive solution in acetone. Fifteen collection matrices of various materials with woven or nonwoven structure were tested. Two arrangements of horizontal and vertical positions of the collection matrices were employed. Explosive vapor collected in the matrix was analyzed through IMS. Results: Only three collection matrices of stainless steel mesh (SSM), polytetrafluoroethylene sheet (PFS), and lens cleansing paper (LCP) showed the TNT and/or RDX ion peaks at explosive vapor concentration of 49 ng/L. There was no collection matrix to detect PETN vapor at lower than 49 ng/L. For the PFS, TNT and RDX were detected at 49 ng/L vapor concentration. For the LCP, TNT and RDX were detected at vapor concentrations of 14 and 49 ng/L, irrespectively. Conclusions: The difference in the explosive vapor detection efficiencies could be explained by the adsorption and desorption capabilities of the collection matrices. The proposed method can be used for evaluating the vapor detection efficiency of hazardous materials with low vapor pressure.

Rationale: Position-Specific (PS) δ13C values of propane has proven its ability to provide valuable information on evolution history of natural gases. Two major approaches to measure PS δ13C values of propane are quantitative NMR (qNMR) and GC-Py(rolysis)-GC-IRMS. The qNMR has verified measurement accuracy, however, required large sample size and long experimental time limit its applications. The GC-Py-GC-IRMS is more versatile method with small sample size, but its accuracy has not been demonstrated. Methods: We measured PS δ13C values of propane from nine natural gases, using the both methods and evaluated the accuracy of GC-Py-GC-IRMS method. Results: The results show that large carbon isotope fractionations occurred for the both terminal and central carbons within propane during pyrolysis. The isotope fractionations during the pyrolysis are reproducible at optimum conditions, but vary between the two GC-Py-GC-IRMS systems tested, affected by experimental conditions (e.g., pyrolysis temperature, flow rate, and reactor conditions). Conclusions: Therefore, it is necessary to evaluate and calibrate each GC-Py-GC-IRMS system using propane gases whose PS δ13C values are accurately determined. This study also highlights a need of PS isotope standards for propane and other molecules.

Chlorinated aromatics and alkanes have important use value because of their flame retardancy，but they need to be monitored when used in recycled pulp. This paper report the use of palladium acetate/ Activated carbon activated by nitric acid as an online catalyst in the determination of chlorinated aromatics and chlorinated alkanes in recycled paper products with Gas Chromatography-Tandem Mass Spectrometry method, by which significantly improve the sensitivity of the method and dramatically lower the detection limits.