No abstract

The sensitivity of detection of uric acid (H 2 U) in positive ion mode electrospray ionization mass spectrometry (ESI MS) was enhanced by uric acid oxidation during electrospray ionization. With a carrier solution of pH 6.3 > pK a1 ¼ 5.

No abstract

Summary: Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry allows fast and efficient analysis of complex synthetic polymers which always exhibit varying degrees of polydispersity including molar mass distribution and chemical composition distribution. Most commonly used with a time-of-flight (TOF) mass analyzer, MALDI MS is the workhorse in polymer mass spectrometry and can be used to 1) identify homopolymers, 2) determine the endgroups of macromolecules, 3) elucidate polymerization mechanisms, 4) analyze copolymers, 5) determine molecular structures, and 6) determine absolute molar masses of oligomers. This paper gives an overview of the mentioned applications of MALDI MS in polymer analysis.

High signal intensities of glutathione (GSH), [GSHþ (m/z 136), are observed in ESI MS with on-line electrochemistry (EC). Dimers formed by H-bonding, which are not electrochemical products, are detected asþ (m/z 271) together with disulfide dimers GSSG, CySSCy and hCySSCyh,When dopamine is present a thiol/dopamine quinone (DAQ) adduct is observed. Formation of this adduct is proposed to occur by an electrochemical mechanism during ESI. Catalysis of thiol oxidation and analysis of thiol mixtures is addressed.