Characterization of nitrated phenolic compounds for their anti-oxidant, pro-oxidant, and nitration activities.

Coffee is one of the most widely consumed beverages worldwide. Evidence of the health benefits and the important contribution of coffee brew to the intake of anti-oxidants in the diet has increased coffee consumption. Chlorogenic acid (ChA) and caffeic acid (CaA) are the major phenolic compounds in coffee.

Quantification of reduced and oxidized thiols in mouse serum by column-switching hydrophilic interaction chromatography coupled with mass spectrometry.

An automated online solid-phase extraction method for the determination of the reduced and oxidized forms of thiols in mouse serum was developed and validated. Analysis was performed with column-switching hydrophilic interaction chromatography coupled with mass spectrometry (CS-HILIC-MS). The proposed CS-HILIC-MS method enabled the simultaneous determination of reduced and oxidized thiols in mouse serum samples.

Comparison of fluorescence reagents for simultaneous determination of hydroxylated phenylalanine and nitrated tyrosine by high-performance liquid chromatography with fluorescence detection.

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are well-known and important contributors to oxidative and nitrosative stress in several diseases. Hydroxylated phenylalanine and nitrated tyrosine products appear to be particularly susceptible targets of oxidative and nitrosative stress. We compared fluorescence reagents for their potential use in the analysis of hydroxylated phenylalanine and nitrated tyrosine products with a high-sensitivity and high-specificity HPLC-UV-FL technique.

A new strategy for ionization enhancement by derivatization for mass spectrometry.

Liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure ionization is drastically different from hitherto available analytical methods used to detect polar analytes. The electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) sources of MS have contributed to the advancement of LC-MS and LC-MS/MS techniques for the analysis of biological samples. However, one major obstacle is the weak ionization of some analytes in the ESI and APCI techniques.

Development and validation of a hydrophilic interaction chromatography-tandem mass spectrometry for quantification of nicotine and its metabolites in human maternal and cord sera.

A selective and sensitive HILIC-MS/MS method for the simultaneous quantification of nicotine and its metabolites in human maternal and cord sera was developed and validated. After solid-phase extraction, LC separation was achieved on a hydrophilic interaction chromatography. The validated method is capable of selective identification as well as accurate and sensitive quantification.

Chromatographic and mass spectrometric analysis of glutathione in biological samples.

Biological thiol compounds are classified into high-molecular-mass protein thiols and low-molecular-mass free thiols. Endogenous low-molecular-mass thiol compounds, namely, reduced glutathione (GSH) and its corresponding disulfide, glutathione disulfide (GSSG), are very important molecules that participate in a variety of physiological and pathological processes. GSH plays an essential role in protecting cells from oxidative and nitrosative stress and GSSG can be converted into the reduced form by action of glutathione reductase.