Performance of 3­[4­(bromomethyl)phenyl]­7­(diethylamino) coumarin as a derivatization reagent for the analysis of medium and long chain fatty acids using HPLC with LIF detection.

Knowledge of the profile of fatty acids, including the profile of long chain fatty acids, is an important parameter for many areas like human health, food sciences, and the study of gene expression in plant tissues, among others. Moreover, very long chain fatty acids occur at low concentrations in many biological samples. The 3­[4­(bromomethyl)phenyl]­7­(diethylamino)coumarin (MPAC­Br) reagent is an improved version of the coumarin bromomethyl-type reagents, used for the fluorescent labeling of carboxylic acids in a variety of sample types. Derivatization reactions are always a matter of concern in routine analyses, as they are seen as a time demanding step and a source of errors in analytical chemistry. MPAC­Br is studied in the present work, including the robustness of its derivatization reaction, the stability of its derivatives, the limits of its detection and the repeatability of its results. An optimized version of its protocol was applied to determine the content and profiles of both medium and long chain fatty acids in eight samples of oils and fats. It was shown that the proposed derivatization reaction is a reliable, robust, fast and convenient method for the analysis of these compounds.

Analysis of sulfonamides by capillary electrophoresis.

The methods of analysis of sulfonamides (SFAs) using CE are reviewed. Sulfonamides were the first antimicrobial group of drugs used in medical treatment. These compounds are still used today in medicine and widely are employed in veterinary medicine, also for their growth promoter effects. Improved methods of analysis of sulfonamides are a constant challenge for researchers. CE is a new trend in the fields of pharmaceutical and food analyses. Several methods for the determination of SFAs by CE have been published in recent years, and the present review considers applications in quality control of pharmaceutical dosage forms, food analysis, determinations in serum, and other biological fluids as well as in electrophoresis experiments which examine the behavior of this class of compounds for theoretical studies of the technique. This review covers studies ranging from the pioneering works on sulfonamide analyses using classical electrophoresis to the more recent CE methods coupled to tandem mass spectrometers. The sections are divided following the EC modes like CZE, MEKC, and hyphenated methods (CE-MS, CE-MS/MS). A brief compilation of theoretical findings of sulfonamides electrophoretic behavior is also included. Parameters such as recoveries, LOD and LOQ, among others, are examined, covering works published until August 2008. This review can contribute to further research aimed to improve the analysis of SFAs by CE.

The propagator (retarded Green function) formalism as a new calculation method to predict the time evolution of bands in capillary electrophoresis and microchannels.

Capillary electrophoresis (CE) and microchannel (MC) techniques are important tools in chemical and biological sciences, mainly in the study of genomes, transcriptomes, proteomes, metabolomes, and organic as well as inorganic ions. The speed of DNA sequencing increased significantly during the last decade with the use of capillary electrophoresis (CE). The time evolution of the bands' spatial profile inside capillaries and channels is of paramount importance, since the main goal of these techniques is to maximize resolution (the ratio between the spacing of the peaks and their mean standard deviations). In the present work, the propagator (retarded Green function) formalism is applied to solve a few problems which are typical for CE and MC. We also apply this mathematical method to the problem of velocity gradients along the capillary, i.e., the time evolution of the bands is analyzed when they enter regions where they migrate with different velocities.

A review of DNA sequencing techniques.

The four best known DNA sequencing techniques are reviewed. Important practical issues covered are read-length, speed, accuracy, throughput, cost, as well as the automation of sample handling and preparation. The methods reviewed are: (i) the Sanger method and its most important variants (enzymic methods); (ii) the Maxam & Gilbert method and other chemical methods; (iii) the Pyrosequencing method--DNA sequencing in real time by the detection of released pyrophosphate (PPi); and (iv) single molecule sequencing with exonuclease (exonuclease digestion of a single molecule composed of a single strand of fluorescently labelled deoxynucleotides). Each method is briefly described, the current literature is covered, advantages, disadvantages, and the most suitable applications of each method are discussed.