Characteristics of the Separation of Antibiotics using Supercritical Fluids

The main properties of SFC which significantly affect antibiotic separation are related to the high solvating power of supercritical fluids and their low viscosity, which yields high resolution power and throughput. This fact has two main consequences on this type of separation. Firstly, as already pointed out above, compounds like antibiotics can be analysed at lower temperatures than in gas chromatography, and in shorter times than in liquid chromatography, as a result of good solvating capacity. Secondly, SFC is able to resolve complex mixtures of not very volatile compounds, allowing the direct injection of samples

Sulfachlorpyridazine

Figure 1 Structures of eight sulfonamides determined by SFC

Sulfachlorpyridazine

Figure 1 Structures of eight sulfonamides determined by SFC

that contain antibiotics with little or no sample pre-treatment.

Some antibiotics may be degraded or lost during exposure to light, heat or extreme values of pH. In SFC, all these factors are avoided, providing separation under mild conditions that preserves the integrity of the sample.

Antibiotic determination presents some difficulties due to the complexity of the sample matrix and the relatively low concentration of the antibiotics in these samples. The whole procedure, including extraction and fractionation, is not only time-consuming and prone to error, but may degrade labile antibiotics and create artefacts. Consequently, new approaches have been developed in the last few years that avoid several or all of these questionable sample preparation steps by using multidimensional systems or even direct injection in SFC.

The analysis of antibiotics in human serum has been performed with both open tubular and packed-column SFC. With open tubular columns, it is possible to determine the antibiotic content with a simple liquid-liquid extraction. The use of a flame ionization detector has, however, not demonstrated satisfactory detection limits to date. Better results have been obtained with SFC and mass spectrometric detection, which thus provides a very useful method for the determination of low levels of impurities in macrolide

OCH3

Sulfadimethoxine

Sulfadimethoxine

Sulfaquinoxaline

Sulfaquinoxaline

Sulfathiazole (see chromatogram shown in Figure 2).

antibiotics, and presents an alternative approach to several LC-MS methods.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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