Rapid, simultaneous and nanomolar determination of pyroglutamic acid and cis-/trans-urocanic acid in human stratum corneum by hydrophilic interaction liquid chromatography (HILIC)-electrospray ionization tandem mass spectrometry.
ABSTRACT A rapid, sensitive and specific hydrophilic interaction liquid chromatography coupled to tandem mass spectrometric (HILIC-MS/MS) method for the simultaneous determination of pyroglutamic acid, cis- and trans-urocanic acid in human skin stratum corneum (SC) were developed and validated. This method was carried out without derivatization or addition of ion-pair additives in mobile phase. The analytes were extracted by PBS buffer solution and analyzed using an electrospray positive ionization mass spectrometry in the multiple reaction monitoring (MRM) mode. Chromatographic separation was performed on an AQUITY UPLC amide column using gradient elution with the mobile phase of water and acetonitrile. The standard curves were linear over the concentration range of 1.0-250 ng/mL with a correlation coefficient higher than 0.999 with an LLOQ of 0.5 ng/mL. The lower limits of detection (LLOD) of these analytes were lower than 0.2 ng/mL. The intra- and inter-day precisions were measured to be below 7.7% and accuracies were within the range of 94.3-102.6%. The validated method was successfully applied to determine the level of pyroglutamic acid and cis-/trans-urocanic acid in the SC samples from forearm and forehead region of 19 human volunteers.
- Sensors and Actuators B Chemical 09/2013; 186:407-416. · 3.84 Impact Factor
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ABSTRACT: Ginkgo biloba leaf extract has been widely used in dietary supplements and more recently in some foods and beverages. In addition to the well-known flavonol glycosides and terpene lactones, G. biloba leaves are also rich in amino acids. To determine the content of free amino acids, a reliable method has been established by using hydrophilic interaction ultra-HPLC coupled with ESI-MS. 20 free amino acids were simultaneously determined without derivatization in 12 min. The proposed method was fully validated in terms of linearity, sensitivity, repeatability, as well as recovery. Furthermore, the principal component analysis was applied to different G. biloba leaves collected in November (after fruit harvest season), which revealed that the samples from different production areas exhibited regional disparity in different clusters in accordance with their various hydrophilic interaction chromatograms coupled with mass profiles. The established approach could be helpful for evaluation of the potential values as dietary supplements and the quality control of G. biloba leaves, which might also be utilized for the investigation of other medicinal herbs containing amino acids.Journal of Separation Science 09/2013; 36(17):2878-87. · 2.59 Impact Factor
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ABSTRACT: In recent years, the popularity of hydrophilic interaction chromatography (HILIC) in the analysis of small polar and ionizable molecules increased substantially. A large number of new stationary phases with sub-2-µm and superficially porous particles were developed and used in a applications, including pharmaceuticals, metabolites, biomarkers, amino acids and peptides. Applications of HILIC in ultra-high-pressure liquid chromatography (UHPLC) mode constitute only about 10% all current HILIC applications. This review presents an overview of UHPLC in HILIC mode, including the importance of the final sample diluent, a discussion on available stationary phases and approaches to detection, and a comparison of performance with other chromatographic modes.TrAC Trends in Analytical Chemistry 12/2014; · 6.61 Impact Factor