Automated Inline Chemistry Methods

Over the years, alternative approaches—such as matrix separation, analyte preconcentration, El, reductive precipitation, and hydride generation techniques— have been tried with limited success. However, none of these techniques could be considered truly routine because they were very labor intensive and also prone to contamination issues. As a result, they were only optimum for small numbers of samples and could not be applied to high-throughput analysis. 

This brand new technique offers up to three simultaneous modes of analysis, depending on the analytes of interest. They do not all need to be used together, but when combined, they offer a very powerful tool for the ultratrace analysis of seawater samples. The three fully automated modes are  

FIGURE 17.16 The automated inline combination of direct aspiration, matrix separation, analyte preconcentration, and hydride generation for the determination of 18 elements in seawater. (Courtesy of Elemental Scientific.) 

Preconcentration mode with an ion exchange column to preconcentrate analytes while allowing common seawater matrix ions such as Na Cl Mg +, Ca, and so forth to pass through to waste. The resin contains a mixture of iminodiacetic acid (IDA) and ethylenediaminetriacetic acid (EDTA), which complexes a wide variety of transition metals and rare earth elements (REEs). 

Hydride mode, which allows for inline, batch-mode hydride generation for elements forming volatile hydrides such as arsenic, selenium, and antimony. This step is also performed and the analyte measured during the preconcentration loading/washing step, so it does not add time to the analysis. 

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