Application Of High-performance Chromatography Research Articles

Review of Chromatographic Methods Coupled with Modern Detection Techniques Applied in the Therapeutic Drugs Monitoring (TDM).

Therapeutic drug monitoring (TDM) is a tool used to integrate pharmacokinetic and pharmacodynamics knowledge to optimize and personalize various drug therapies. The optimization of drug dosing may improve treatment outcomes, reduce toxicity, and reduce the risk of developing drug resistance. To adequately implement TDM, accurate and precise analytical procedures are required. In clinical practice, blood is the most commonly used matrix for TDM; however, less invasive samples, such as dried blood spots or non-invasive saliva samples, are increasingly being used. The choice of sample preparation method, type of column packing, mobile phase composition, and detection method is important to ensure accurate drug measurement and to avoid interference from matrix effects and drug metabolites. Most of the reported procedures used liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) techniques due to its high selectivity and sensitivity. High-performance chromatography with ultraviolet detection (HPLC-UV) methods are also used when a simpler and more cost-effective methodology is desired for clinical monitoring. The application of high-performance chromatography with fluorescence detection (HPLC-FLD) with and without derivatization processes and high-performance chromatography with electrochemical detection (HPLC-ED) techniques for the analysis of various drugs in biological samples for TDM have been described less often. Before chromatographic analysis, samples were pretreated by various procedures—most often by protein precipitation, liquid–liquid extraction, and solid-phase extraction, rarely by microextraction by packed sorbent, dispersive liquid–liquid microextraction. The aim of this article is to review the recent literature (2010–2020) regarding the use of liquid chromatography with various detection techniques for TDM.

C-/O-GLYCOSYL FLAVONES OF SILENE ITALICA

Chemical research of Silene genus focused on the study of terpene compounds including ecdysteroids and triterpenoids, to the detriment of other classes of compounds. One of these poorly estimated group of substances are flavonoids, namely C-/O-glycosyl flavones, widely represented within the family Caryophyllaceae. Early studies revealed the presence of some C-glycosyl flavones (Zemtsova, Dzhumyrko, 1976; Darmogray, 1977), but a detailed study of the flavonoids was not conducted. Application of high performance chromatography with diode-array detection and electrospray ionization mass-spectrometry detection (HPLC-DAD-ESI-MS) allowed to found 14 flavonoids, which are C-, O- and C,O-glycosyl flavones in the aerial part of S. italica of Georgia origin. Ten components were discovered in S. italica for first time. The identified C-glycosides included monoglycosides as isoorientin, isovitexin, isoscoparin (chrysoeryol-6-C-glucoside) and diglycosides as carlinoside (luteolin-6-C-glucoside-8-C-arabinoside), schaftoside (apigenin-6-C-glucoside-8-C-arabinoside), isoschaftoside (luteolin-6-C-arabinoside-8-C-glucoside) and genkwanin-6-C-glucoside-8-C-arabinoside. Two O-glycosides, cosmosiin and cynaroside, and mixed C,O-glycosides as saponarin, isovitexin-2′′-O-arabinoside, isovitexin-6′′-O-arabinoside and O-hexosides od schaftosude and genkwanin-6-C-glucoside- 8-C-arabinoside were not previously identified in Silene genus. The known literature data (Mamadalieva et al., 2014) and the present data demonstrate the useful role of C-/O-glycosyl flavones in the systematics of the genus Silene.

Carbohydrate analysis with ion chromatography using Eurokat stationary phases : Preparative separation of monosaccharides and their fluorinated derivatives

The interaction of weakly acidic monosaccharides with a polystyrene sulphonate in the H + form resulted in unexpected selectivity for epimeric aldohexoses, deoxyaldohexoses and deoxyfluoroaldohexoses. This led to a new application of high-performance chromatography. The separation is dominated solely by the electrostatic interaction between carbohydrate oxygen atoms and H + of the stationary phase. Column heating was not required. High flow-rates in excess of 7 ml/min were possible, thus allowing preparative separations. Examples include 2-deoxy-2-fluoro- d-glucose, 2-deoxy-2-fluoro- d-mannose and 2-deoxy-2-fluoro- d-galactose.