O. Zuloaga et al., Optimization of focused microwave-assisted extraction of DDT and derivatives from soil samples, HRC-J HIGH, 23(12), 2000, pp. 681-687
Optimization of focused microwave (FMW)-assisted extraction of 4,4'-DDE, 4,
4'-DDD, and 4,4'-DDT from soil samples was carried out using central compos
ite designs. All the extracts were analyzed with GC/MS and some of them als
o with GC/AED using columns of different polarities for each of the techniq
ues, The extraction of the analytes was carried out in two ways: with aceti
c acid as microwave radiation absorbent solvent and n-decane to concentrate
the analytes and with reagent water and iso-octane as solvents. In the fir
st case, the influence of the extraction temperature, the extraction time,
and the addition of sodium chloride were studied and the optimum conditions
for the extraction of 1 g of soil with 5 mL of acetic acid and 2 mL of n-d
ecane were 1.30 mol L-1 sodium chloride at 98 degreesC for 9.3 min. In the
second case, the temperature was kept constant (94 degreesC) and the influe
nce of the concentration of sodium chloride and the extraction time were st
udied. The optimum conditions were 5 mL of a 2.0 mol L-1 sodium chloride to
gether with 2 mL of iso-octane for 15 min, The recoveries obtained by water
-FMW extraction were significantly lower than those obtained by the acetic
acid-FMW procedure. These last recoveries were in good agreement with those
obtained by closed microwave assisted-extraction with acetone-n-hexane as
solvent.