Determination of high-energy fragmentation of protonated peptides using a beqq hybrid mass spectrometer

In recent years there has been a trend in the structure determination of reconstructed surfaces to use high energy electron diffraction techniques, and to employ a kinematic approximation in analyzing the intensities of surface superlattice reflections. Experimentally this is motivated by the great success of the determination of the dimer adatom stacking fault (DAS) structure of the Si(111) 7 × 7 reconstructed surface.While in the case of transmission electron diffraction (TED) the validity of the kinematic approximation has been examined by using multislice calculations for Si and certain incident beam directions, far less has been done in the reflection high energy electron diffraction (RHEED) case. In this paper we aim to provide a thorough Bloch wave analysis of the various diffraction processes involved, and to set criteria on the validity for the kinematic analysis of the intensities of the surface superlattice reflections.The validity of the kinematic analysis, being common to both the TED and RHEED case, relies primarily on two underlying observations, namely (l)the surface superlattice scattering in the selvedge is kinematically dominating, and (2)the superlattice diffracted beams are uncoupled from the fundamental diffracted beams within the bulk.

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A Rapid Method for Determination of Buprenorphine and Norbuprenorphine in Urine by UPLC-MS/MS

Current Pharmaceutical Analysis ◽

10.2174/1573412916999200627010536 ◽

2020 ◽

Vol 16 ◽

Author(s):

Aykut Kul ◽

Murat Ozdemir ◽

Selma Ozilhan ◽

Olcay Sagirli

Keyword(s):

Forensic Science ◽

Rapid Method ◽

Proficiency Testing ◽

Mass Spectrometer ◽

Illicit Market ◽

Analysis Methods ◽

Accuracy And Precision ◽

Lower Limits

Background: Buprenorphine is quite common in the illicit market. Buprenorphine-containing drugs abuse is frequently encountered in patients. The analysis methods used to determine the abuse of buprenorphine and norbuprenorphine are important for forensic science. Buprenorphine is metabolized to norbuprenorphine by the liver. Objective: Therefore, the determination of buprenorphine and norbuprenorphine in urine is one of the methods to determine the abuse of buprenorphine. Methods: In this study, we have developed a precise, simple, and rapid ultra-performance liquid chromatographytandem mass spectrometer method for the determination of buprenorphine and norbuprenorphine simultaneously. Results: The developed method was validated in terms of selectivity and linearity, which was in the range of 9–1800 ng/mL for both buprenorphine and norbuprenorphine. The intra-assay and inter-assay accuracy and precision were found within acceptable limits of the EMA guideline. Lower limits of quantitation were 9 ng/mL for both buprenorphine and norbuprenorphine. Conclusion: The developed method was successfully applied for the determination of both analytes in the proficiency testing samples.

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Thermal Dynamic Behavior in Bi-Zone Habitable Cell with and without Phase Change Materials

Proceedings ◽

10.3390/proceedings2020063041 ◽

2020 ◽

Vol 63 (1) ◽

pp. 41

Author(s):

Hanae El Fakiri ◽

Lahoucine Ouhsaine ◽

Abdelmajid El Bouardi

Keyword(s):

Thermal Behavior ◽

Thermal Comfort ◽

Phase Change ◽

Dynamic Behavior ◽

Phase Change Materials ◽

Energy Performance ◽

High Energy ◽

Water Heater ◽

Simplified Modeling

The thermal dynamic behavior of buildings represents an important aspect of the energy efficiency and thermal comfort of the indoor environment. For this, phase change material (PCM) wallboards integrated into building envelopes play an important role in stabilizing the temperature of the human comfort condition. This article provides an assessment of the thermal behavior of a “bi-zone” building cell, which was built based on high-energy performance (HEP) standards and heated by a solar water heater system through a hydronic circuit. The current study is based on studying the dynamic thermal behavior, with and without implantation of PCMs on envelope structure, using a simplified modeling approach. The evolution of the average air temperature was first evaluated as a major indicator of thermal comfort. Then, an evaluation of the thermal behavior’s dynamic profile was carried out in this study, which allowed for the determination of the PCM rate anticipation in the thermal comfort of the building cell.

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Advances in LC–MS/MS Methods for Allergen Testing, Meat Speciation, and Gelatin Speciation

Journal of AOAC International ◽

10.1093/jaoac/102.5.1309 ◽

2019 ◽

Vol 102 (5) ◽

pp. 1309-1315

Author(s):

Jianru Stahl-Zeng ◽

Ashley Sage ◽

Philip Taylor ◽

Jeremy Dietrich Netto ◽

Tuo Zhang

Keyword(s):

Mass Spectrometer ◽

Multiple Reaction Monitoring ◽

Proteome Analysis ◽

Food Product ◽

Transition Analysis ◽

Tandem Quadrupole Mass Spectrometer ◽

Signature Peptides ◽

Unique Markers ◽

Multiple Species

Abstract Background: Food authenticity is demanded by the consumer at all times. The consumer places trust in the manufacturer that the food product is genuine in terms of what is recorded on the packaging label. Objective: Recent advancements in LC–tandem MS methodology in the detection of allergens, meat, and gelatin speciation in raw food products and processed foods are detailed in this paper. Method: For each of the three methods, initial proteome analysis and the screening leading to the determination of unique tryptic peptides were conducted using a high-resolution, accurate tandem mass spectrometer. Having identified the unique markers, the method was transferred to a tandem quadrupole mass spectrometer for a higher-sensitivity quantitative study, multiple reaction monitoring transition analysis. Results: For the allergens method a detection limit of at least 10 ppm was attained across the 12 allergen peptides in this workflow. In the gluten workflow the resulting chromatograms show good detection down to 5 ppm, with no interference from the food matrices. The meat speciation method details that signature peptides could be readily identified at 1% w/w with no matrix interference. Conclusions: These single-injection workflows with cycle-time optimization enable wide coverage of analytes to identify multiple species within challenging matrix samples.

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