Solid-state extraction of plasma or serum offers significant advantages over traditional liquid-liquid methods in cortisol determinations by liquid chromatography (HPLC). Sample preparation is facilitated and HPLC column contamination is minimized. Extract yield from the solid-state columns is enhanced by sample pretreatment with methanol. Cortisol values by solid-state extraction/HPLC correlat...

Hexazinone has been detected at levels ranging from 0.2 to 50 micrograms/L in many groundwater samples from eastern Maine over the past decade. A rapid and inexpensive direct-injection high-performance liquid chromatographic (HPLC) method has been developed to monitor contamination levels of the herbicide. The method is sensitive (limit of quantitation = 0.33 microgram/L) and is linear to 33.0 ...

front matter & 2009 a.2010.01.002 author. : diegochiappetta@y Abstract Objective: Two carvedilol aqueous solutions and one carvedilol aqueous suspension for paediatric oral use (1mg/ml) were studied to determine their stability. Method: All samples were stored at 4, 25 and 401C. Carvedilol content of each of the three formulations was tested using high performance liquid chromatography (HPLC). ...

A review of indirect photometric and fluorometric detection in high-performance liquid chromatography (HPLC) is presented. A functional definition of indirect detection, somewhat broader and simpler than what was often used to characterize these techniques, was employed for this review. Emphasis was placed on distinguishing different approaches to indirect photometric and fluorometric detection...

When analyses of mixtures of small molecules are carried out at mobile phase velocities close to (for isocratic runs) or somewhat above (for gradient runs) the optimum velocity, the eddy diffusion term contributes to at least 75% of the band broadening. Future improvements in column performance may come only from a reduction of the eddy diffusion term. The classical models of axial dispersion o...

We describe an HPLC method for quantifying creatinine, separating the analyte from other compounds in serum and urine by cation-exchange chromatography and measuring its absorbance at 234 nm. The precision of the method (CV) varied from 2.9% (mean creatinine concentration, 31 mumol/L) to 1.7% (361 mumol/L) within a series of assays and from 3.9% (34 mumol/L) to 2.4% (391 mumol/L) between series...

A three-dimensional high-performance liquid chromatography (HPLC) method is described for the determination of cyclosporine A in human skin. The method allows to determine at least 3 ng cyclosporine A in 10 mg skin (total sample amount needed) and is suitable for cyclosporine A level monitoring in the skin of psoriatic patients.

A chemometric tool based on the Function of Mutual Information (FUMI) theory can provide a relative standard deviation (RSD) without repetitive measurements in high-performance liquid chromatography with electrochemical detection (HPLC-ECD). Two parameters: precision (= information content) phi and efficiency (= information content/time) theta, which were calculated from predicted RSD based on ...

High-performance liquid chromatography is a technic that has recently been applied to the diagnosis of hemoglobinopathies and thalassemias. Its advantages over other methods include increased sensitivity, resolution and simplicity, as well as speed. In this report, the authors present an HPLC procedure that uses a weak cation exchange column and a gradient elution system for the diagnosis of he...

conclusions this method could be feasibly used for purification of large quantities of allicin from garlic extract. results semi-preparative hplc yielded a distinct peak with a retention time of 12.28 minutes. the purity (≥ 95%) and biological activity (p > 0.05) of purified allicin were comparable to the standard allicin. purified allicin produced same peak areas compared to the standard allic...