Evaluation of solvents used in summarized chromatograms

Analysis of some steroids by thin-layer chromatography using optimum mobile phases

The aim of this paper was the analysis of five androstane isomers by thin-layer chromatography (TLC). The choice of proper mobile phase and the optimization of the mobile phase composition are very important because the chromatographic separation is difficult to achieve. In the first step, the proper mobile phase system was chosen from seven elution systems presented in the literature using numerical taxonomy method. The proper solvent system was found to be the mixture of chloroform, acetone, and petroleum ether. In the second step the composition of mobile phase was optimized by "simplex" method and "prisma" method. The optimum TLC system can be applied for the separation of androstane isomers from real samples such as drug formulation, biological and natural sources.

Separation of N-alkyl phenothiazine sulfones by HPTLC using an optimum mobile phase

In high performance thin layer chromatography some form of optimization is necessary if complete separation of all components is required. The selection of mobile phase composition is one of the most important components of an optimization strategies. The aim of this paper is the separation of the N-alkyl phenothiazine sulfones by high performance thin layer chromatography using an optimum mobile phase system. The optimum composition of mobile phase (toluene-ethyl ether-chloroform, 30:50:20, v/v) are given by the maximum of objective function (F(obj)=10.6110).

How to approach substance identification in qualitative bioanalysis

The ultimate goal in qualitative analysis in the biosciences is to demonstrate with acceptable probability that for an unknown constituent in a sample only one substance comes into consideration and that all other substances can be rejected. In the biosciences, identification of relevant substances in complex matrices through database retrieval is frequently required. Yet, despite its importance, the subject has not received much attention, so that progress has been limited and relevant literature is scarce. As a result, one can conclude from many publications and reports that qualitative analysis in practice is often not being addressed properly. In this paper, some fundamental aspects of qualitative analysis will be discussed and a general approach is provided for the correct identification of organic substances in complex matrices through database retrieval. Special attention is given to the choice of proper analytical techniques and their inter-laboratory standard deviations, as well as to match factors and decision criteria based on applying multiple analytical techniques, also if the latter have different dimensions (e.g. retention data and spectral data). In addition, the requirements for suitable databases are outlined and the need for inter-laboratory cooperation is emphasized.

Application of numerical taxonomy techniques to the choice of optimum mobile phase in high-performance thin-layer chromatography (HPTLC)

A total of eight solvent systems used for the separation of 1,4-benzodiazepine mixtures were investigated. The classification of solvent systems was carried out by the numerical taxonomy technique. The selection of optimum solvent system was accomplished on the basis of information quantity and objective function. The method was found to be a rapid and efficient tool in the choice of optimum system solvent.