1. Minczewski J, Chwastowska J, Dybczynski R (1982) Separation and preconcentration methods in inorganic trace analysis. Horwood, Chichester, p 97
2. Mizuike A (1983) Enrichment techniques for inorganic trace analysis. Springer, Berlin Heidelberg New York, p 30
3. Florence TM (1982) Talanta 29:345
4. N�rnberg HW (1983) Fresenius Z Anal Chem 316:557
5. Hunt DTE, Wilson AL (1986) The chemical analysis of water: general principles and techniques, 2nd edn. The Royal Society of Chemistry, Burlington House, London, p 559