Trace metal automated preconcentration

Katarina, R.K., N. Lenghor, and S. Motomizu. 2007. On-line preconcentration method for the determination of trace metals in water samples using a fully automated pretreatment system coupled with ICP-AES. Anal. Sci. 23 343-350. 

Although the automated, trace-metal preconcentration system has undergone a number of design changes, the major characteristics are summa-... 

The chromatographic procedure intially investigated was reverse-phase liquid chromatography (RPLC) using Cig-bonded silica gel. This technique has been used previously for the preconcentration of trace metals from seawater prior to analysis by atomic absorption spectrophotometry (23, 24) and for the isolation of organically bound copper from seawater (4). These methods were modified and adapted for automation. 

The authors thank Alfred K. Hanson, Jr. and Francis J. Pickles for their cooperation and help in developing the automated trace-metal preconcentration procedure. The support of the U.S. Office of Naval Research through Contract N00014-81-C-0062 is gratefully acknowledged. 

The application of the ASV technique to the analysis of seawater has been reviewed (6-9). Its advantages over other trace-metal methods are several (1) sea salts do not interfere (2) a high degree of sensitivity and selectivity can be achieved through electrolytic preconcentration, thus the analysis can be carried out directly in seawater, and few or no reagents need to be added (3) the measurement is easily automated (4) relatively inexpensive, rugged, and portable instrumentation can be built for field use (5) more than one metal may be measured at one time with a sensitivity approaching parts per trillion. 

Packer, A. P., Gine, M. E, Miranda, C. E. S., and Dos Reis, B. F. (1997). Automated on-line preconcentration for trace metals determination in water samples by inductively coupled plasma mass spectrometry.J. Anal. At. Spectrom. 12(5), 563. 

Fig. 4.14 Flow-injection assemblies for ion-exchange preconcentration of metal traces prior to introduction into an atomic absorption spectrometer. (A) Single-line manifold (B) three-valve system for upstream elution (C) automated assembly with intermittent pumping. (Reproduced from [11] with permission of the Royal Society of Chemistry).

SPE is one of the most important preconcentration/separation procedures to trace heavy-metal ions and organic pollutants, due to its simplicity and limited usage of the organic solvents. Among many others, ion exchange and selective resins are very popular methods due to their applicability to both preconcentration and separation. The implementation of highly selective columns to flow-based methodologies allowed the automation of many analytical methods. 

Keil,0.,Dahmen,J.,andVolmer, D.A. (1999). Automated matrix separation and preconcentration for the trace level determination of metal impurities in ultrapure inorganic salts by high-resolution ICP-MS. Fresenius J.Anal. Chem. 364(8), 694. 

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