Drug deconjugation-assisted peptide mapping by LC-MS/MS to identify conjugation sites and quantify site occupancy for antibody-drug conjugates.

Antibody-drug conjugates (ADCs) are a heterogeneous mixture of conjugated species with varied drug loadings. Depending on conjugation sites, linkers and drugs can exhibit different stability as influenced by the solvent-accessibility and local charge, resulting in different ADC efficacy, pharmacokinetics, and toxicity. Conjugation site analysis is critical for ADC structural characterization to assure product quality and consistency.

Migration time correction for dual pressure capillary electrophoresis in semi-targeted metabolomics study.

Migration time fluctuation strongly affects peak alignment and identification of unknown compounds, making migration time correction an essential step in capillary electrophoresis (CE)-based metabolomics. To obtain more reliable information, metabolites with different apparent mobilities are analyzed by tandem mass spectrometry. Applying a small pressure is a common practice for reducing the analysis time of anions in a positive mode CE, known as the pressure-assisted CE.

Capillary electrophoresis-mass spectrometry analysis of bisphenol A and its analogues in bottled tea beverages with dynamic pH focusing.

A simple and sensitive method for the determination of bisphenol A and its analogues at the ng/mL level in bottled tea beverages is presented. This method utilized a dynamic pH junction to focus the analyte into a more concentrated zone, based on the electrophoretic mobility difference of analytes in the sample matrix and background electrolytes in capillary electrophoresis coupled to mass spectrometry (CE-MS). The optimised analyte focusing led to enhanced signal detection with average peak heights for five bisphenols of 53-170 folds higher than conventional injections.

Enantioselective analysis in complex matrices using capillary electrophoresis-mass spectrometry: A case study of the botanical drug Corydalis Rhizoma.

Enantioselective analysis is critically important in the pharmaceutical and agricultural industries. However, most of the methods reported were developed for the analysis of pure racemates acquired from chemical synthesis or purification. Direct analysis of chiral enantiomers in complex matrices has rarely been reported.

Determination of urinary prostaglandin E as a potential biomarker of ureteral stent associated inflammation.

Ureteral stents are the most widely used surgical implant in urology. However, they may cause adverse effects to patients, including pain, discomfort, and inflammation. In this work, the inflammatory effect of stent placement and the associated elevation of cyclooxygenase-2 (COX-2) expression were observed.

Application of multisegment injection on quantification of creatinine and standard addition analysis of urinary 5-hydroxyindoleacetic acid simultaneously with creatinine normalization.

In this paper, the development of a simple dilute-and-shoot method for quantifying urinary creatinine by CE-ESI-MS was described. The creatinine analysis time was about 7 min/sample by conventional single injection (SI) method and can be significantly reduced to less than 2 min/sample with multi-segment injection (MSI). In addition, the standard addition analysis of 5-hydroxyindole-3-acetic acid (5-HIAA) and creatinine normalization was performed within one run by the MSI technique, and the total analysis time was 14-min faster compared to the SI method for analyzing the same set of samples.

Review of recent developments in determining volatile organic compounds in exhaled breath as biomarkers for lung cancer diagnosis.

Lung cancer is the most common cause of cancer deaths, its global incidence is rising, and continuing rises are predicted. The potential to diagnose lung cancers based on the determination of volatile organic compounds (VOCs) in human breath has been attracting increasing attention with the development of new techniques and methodologies. However, despite many reports of VOC profiling in lung cancer patients, little is known about how specific biomarkers relate to the biochemical pathways involved in lung cancer development, and there is still no reliable method for diagnosing lung cancer at the early stages.

Synthesis of Cyclic Vinylidene Complexes and Azavinylidene Complexes by Formal [4+2] Cyclization Reactions.

Reactions of the hydrido-butenylcarbyne complex [OsHCl2(≡CC(PPh3)=CHEt)(PPh3)2]BF4 (1) with nitriles RC≡N (R=2-cyclopropyl-2-oxopropyl, 3-amino-2-oxobutyl) lead to six-membered cyclic vinylidene complexes 3 and azavinylidene complexes 4, that is, iso-osmapyridiniums. Treatment of 1 with excess 2-formylbenzonitrile at reflux temperature in CHCl3 in the presence of air produces a fused osmapyridinium 8, which is first oxidized to the tricyclic iso-osmapyridinium derivative 7, then to iso-osmapyridinium 9, which contains a fused naphthalenone fragment. The conversion of iso-osmapyridinium 9 (with a vinylidene segment) to the iso-osmapyridinium compounds 10 and 11 (with azavinylidene segments) was achieved in the presence of a hydrogen halide, such as HCl or HI.

Conversions of osmabenzyne and isoosmabenzene.

We report herein the first example of the conversion of metallabenzyne II and isometallabenzene III. The osmium hydride vinylidene complex 1 reacts with HC≡CCH(OEt)(2) to give osmabenzyne 3 via isoosmabenzene 2. Compound 3 exhibits high thermal stability in air.