Chromatographic Separations Coupled On-line to Atomic Spectrometry

2 Chromatographic Separations Coupled On-line to Atomic Spectrometry 

In the past, most analytical problems related to environmental or biological systems were addressed by measuring the total concentrations of the elements. However, at present, there is an increasing awareness of the importance of the chemical form in which an element is present (e.g. the oxidation state, the nature of the ligands or even the molecular structure) since its chemical, biological and toxicological properties critically depend on it. Hence there is a clear need for rapid and robust analytical tools to perform chemical speciation, and atomic spectroscopy is undoubtedly one of the most important tools for such studies. 

Many analytical strategies and methods have been described for elemental speciation. However, the so-called hyphenated (coupled or hybrid) techniques. 

The choice of the detector becomes crucial when the concentration of analyte species in the sample is very low and low limits of detection are required. For element-specific detection, the major atomic spectrometric techniques, flame AAS, OES, AFS and ICP-MS, are specially suited as chromatographic 

On-line coupling between a gas chromatograph and an atomic spectrometry detector is fairly simple. Typically, the output of the CG capillary column is connected to the entrance of the atomisation-ionisation system simply via a heated transfer line. When separation is performed by liquid chromatography (EC), the basic interface is straightforward a piece of narrow-bore tubing connects the outlet of the EC column with the liquid flow inlet of the nebuliser. Typical EC flow rates of 0.5-2 ml min are within the range usually required for conventional pneumatic nebulisation. 

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