ENVIRONMENTAL SAMPLE TREATMENT - EVOLUTIO N AND PERSPECTIVES

Most environmental samples cannot be directly analysed without a previ ous sample pre-treatment because of the required low concentration lev els and the complexity of the matrices which we have to deal with (wat ers, soils, sediments, sludge, etc.). This sample pre-treatment has to be simple, fast, cost-effective, easy for automation in order to Limi t the risk of losses and of contamination and to gain in reproducibili ty. During a longtime, many sample pre-treatment methods such as liqui d-liquid extraction for water samples or Soxhlet extraction for soils and sediments have been used with the drawback of using large amounts of organic solvents. Due to more and more drastic environmental regula tions, Liquid-Liquid extraction is now replaced by solid-phase extract ion which is furthermore an efficient technique, considering the varie ty of commercially available sorbents. Nowadays, new solid-phase extra ction sorbents are being developed such as molecularly imprinted polym ers or immunosorbents which are used to selectively extract the target analytes. Derived from solid-phase extraction, the solid-phase microe xtraction (SPME) allows also to obtain very interesting results. For s olid matrices, recent techniques allow to minimise the use of organic solvents and can be easily automated to gain time and reproducibility. For instance, supercritical fluid extraction (SFE) is an all but solv ent-free technique and other techniques, which consume far less organi c solvent, can have their efficiency ensured and increased by the use of microwaves (MASE), ultrasound or high temperatures and pressures in order to keep the solvent in its liquid state (ASE).