Current Analytical Chemistry - Volume 10, Issue 3, 2014

In the present study we report the first automated flow-based derivatization method for the determination of the anti-spastic active pharmaceutical ingredient baclofen. The analyte reacts on-line with o-phthalaldehyde in the presence of N-acetylcysteine in a sequential injection manifold to form a highly fluorescent derivative (340 / 455 nm). The various instrumental (flow rate, volumes of sample and reagents, length of reaction c Read More

In this work, an overview of analytical methods employing derivatization reactions in chemiluminescence detection is presented. Method development, instrumental configurations and hyphenated manifolds, specifically designed or implemented to accommodate CL detection, along with their analytical applications for the determination of a wide variety of organic compounds such as biochemically active substances, Read More

We have developed a sensitive, simple and cheap method for determination of lipoic acid in urine and dietary supplement tablets. The method is based on conversion of lipoic acid to its thiol counterpart – dihydrolipoic acid – by reductive cleavage with tris(2-carboxyethyl)phosphine hydrochloride prior to precolumn derivatization with 1-benzyl-2- chloropyridinium bromide, followed by ion-pairing reversed-phase liquid Read More

A new, simple HPLC method is described for the isocratic separation of biogenic monoamines, in milk samples, in the presence of hexylamine as the internal standard, after pre-column derivatization with naphthalene-2,3- dicarboxaldehyde /cyanide ions. The derivatization reaction variables including buffer pH and concentration, reaction time, naphthalene-2,3-dicarboxaldehyde (NDA) and cyanide concentrations were optimi Read More

Flow Injection analysis (FIA) has been established as a useful tool for the automation of chemical analysis. In principle, analytes are injected as a discrete zone into a flowing stream followed by physical/chemical processing that is governed by the dispersion mechanism. The products/complexes/ derivatives or detectable species are measured in a continuous mode. However, in many instances the reactions p Read More

A determination method for amino acids in mouse plasma was developed by HPLC with fluorescence detection. The developed methodology is based on a pre-column derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) carried out in the sample injection loop. The optimized derivatization time and temperature were 10 min and 60 °C, respectively. The separation of 21 amino acid derivatives was achieved on Read More

The problems and risks associated with mycotoxin contamination of foods and feedstuffs have led to the development of a variety of confirmatory analytical methods for their determination, based on chromatographic techniques and capillary electrophoresis. In this paper, an overview of the analytical methods developed in the last decade and based on post-column derivatization coupled with high-performance liquid chromat Read More

A new UHPLC protocol for the determination of amino acids after pre-column derivatization with 6- aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) was presented. Applying a simple and easy to prepare binary eluent system, the 20 major proteinogenic amino acids were separated in about 7 min with a total runtime of 10.5 min until the next injection. Since AQC amino acid derivatives were primarily desig Read More

An accurate, simple and sensitive method for determination of tiopronin (TP, N-(2-mercaptopropionyl)- glycine, Thiola) in human urine has been devised. Tiopronin is an important compound and is mainly used as a drug to prevent kidney stones. It works by removing the extra cystine from the body. Therefore, the reliable assay of tiopronin in biological matrices and pharmaceutical preparations is highly desirable. The propo Read More

High-performance liquid chromatography coupling with atmospheric pressure ionization mass spectrometry (LC–API–MS) has been widely used in the pharmaceutical industry, clinical research, environmental science, metabolomics studies and so on. However, LC-API-MS often suffers from the matrix effect in its applications in complex samples. Matrix effects can heavily affect reproducibility, linearity, and accuracy of the metho Read More

The Schiff bases are formed by condensation of different β-diketones, salicylaldehydes or 2-hydroxyacetophenes with various amines. These bases react with metal and oxo-metal cations to form stable metal chelates which absorb/fluoresce in UV or visible region of light. The Schiff bases have been used in the determination of metal ions by spectrophotometry, spectrofluorimetry, gas chromatography, liquid chromatography a Read More

The absorption of the diatomic molecule AlF in the C2H2/N2O flame at 227.66 nm reveals an interesting feature. The calibration curve of the AlF absorption plotted against a rising concentration of hydrofluoric acid in solutions of constant aluminum content consists of two subsequent linear sections of different slopes. The bend position is reproducibly found at a molar fluorine-to-aluminum ratio of 3, calculated from the com Read More

The molecular absorption of the diatomic AlF molecule in the C2H2/N2O flame was studied using a highresolution continuum source flame atomic absorption spectrometer. AlF has a structured absorption spectrum in the range of 227.30 nm and 227.80 nm. From this band system, the remarkably narrow absorption band at 227.66 nm proved to be the optimum for analytical purposes. The signal intensity was studied as Read More

In this report we aimed to examine the effect of metal / metal oxide nano / micro particles on the electrochemical responds of composite, carbon paste electrode (CPE) and solid glassy carbon electrode (GCE). Therefore, three different configurations of CPE modified with titanium (IV) oxide micro particles (TiO2-µp) and gold nanoparticles (Au-np) and three different configurations of GCE including TiO2-µp, Au-np and mangan Read More

An innovative microbiological assay was developed for the determination of colistin sulphate at various concentrations (192-469 IU/mL); using Bordetella bronchiseptica ATCC 4617 as microorganism test. This assay revealed subtle changes not demonstrated by chemical methods, such as chemical degradation and low of potency, but by evaluating the potency of colistin, which is very important for the analysis of antibiotics Read More