A sensitive, specific, accurate, and reproducible HPLC/MS-method for the simultaneous quantitative determination of niacin (NA) and its main metabolites niacinamide (NAM) and nicotinuric acid (NUR) in human plasma using chinolin-3-carboxylic acid as an internal standard was developed and validated according to international guidelines for method validation. All analytes and the internal standar...

Two modifications of the HPLC-ED method with respect to extraction procedure used have been developed for psilocin, the active metabolite of psilocybin, in human plasma using either liquid-liquid extraction (LLE) or automated on-line solid-phase extraction (on-line SPE). Each type of the sample preparation required a different HPLC system followed by electrochemical detection at 650 to 675 mV. ...

A molecular imprinted polymer (MIP) was computationally designed and synthesized for the selective extraction of metaproterenol (MTP), from human plasma. In this regards semi empirical MP3 and mechanical quantum (DFT) calculations were used to find a suitable functional monomers. On the basis of computational and experimental results, acrylic acid (AA) and DMSO:MeOH (90:10 %V/V) were found to b...

A laser ion source can provide high current, highly charged ions with a simple structure. However, it was not easy to control the ion pulse width. To provide a longer ion beam pulse, the plasma drift length, which is the distance between laser target and extraction point, has to be extended and as a result the plasma is diluted severely. Previously, we applied a solenoid field to prevent reduct...

The development of a high performance negative ion (NI) source constitutes a crucial step in the construction of Neutral Beam Injector of the future fusion reactor ITER. NI source should deliver 60 A of H (or 40 A D), which is a technical and scientific challenge, and requires a deep understanding of the underlying physics of the source including the role of the magnetic filter. The present kno...

Didanosine is an effective antiviral drug in untreated and antiretroviral therapy-experienced patients with Human Immunodeficiency Virus (HIV). An automated system using on-line solid extraction and High Performance Liquid Chromatography (HPLC) with ultraviolet (UV) detection was developed and validated for pharmacokinetic analysis of didanosine in dog plasma. Modifications were introduced on a...

The ability to use imprinted polymers for solid-phase extraction is demonstrated in a model pre-concentration of bupivacaine from human plasma samples prior to gas chromatography. Imprinting of the structural analogue pentycaine yielded a sorbent which efficiently extracted analyte and internal standard, while possible interference on analyte quantification from leakage of remaining template mo...

A sample preparation procedure using microwave energy is proposed for the determination of morphine, 6-acetylmorphine, codeine, cocaine, cocaethylene, benzoylecgonine, methadone, and 2-ethylene-1,5-dimethyl-3,3-diphenylpyrrolidine in human plasma. A screening asymmetrical factorial design was used to identify the most suitable extraction conditions as regards solvent, temperature, and extractio...

A specific, accurate liquid-chromatographic/mass-spectrometric (HPLC/MS) method for measurement of cholesterol sulfate in plasma from normal individuals and patients with recessive X-linked ichthyosis (RXLI) is described. The method is superior to previously described techniques because it measures the analyte intact rather than after hydrolysis. Traces of free cholesterol in the sample analyze...

Aims To evaluate whether plasma endothelin-1 (ET-1) is extracted or produced through the heart in patients with acute myocardial infarction (AMI), and the relationship between transcardiac extraction of plasma ET-1 and left ventricular (LV) remodelling. Methods and results We measured the plasma level of ET-1 in the aortic root (Ao) and coronary sinus (CS) in 48 consecutive patients, who receiv...