Hs. Dorea et Fm. Lancas, Matrix solid-phase dispersion extraction of organophosphorus and syntheticpyrethroid pesticides in cashew nut and passion fruit, J MICROCOL, 11(5), 1999, pp. 367-375
A multiresidue extraction method based on matrix solid-phase dispersion (MS
PD) and capillary gas chromatography-electron capture detection for quantif
ication of five widely used organophosphorus insecticides (diazinon, malath
ion, parathion, methidathion, and pyrazophos) and one synthetic pyrethroid
(permethrin) in Brazilian fruits is described. Cashew nut and passion fruit
are plants native to South America. Capillary gas chromatography with mass
selective detection was also utilized to confirm the pesticides through ma
ss spectra. Different parameters were optimized, such as the solid phase an
d dispersant used, amounts, type of eluant and volume, and sample amount. T
he best results were obtained using a silica gel cartridge column and Flori
sil as dispersant. The eluant was ethyl acetate. Analysis of fortified frui
t (n = 3) shows an average recovery of 101.4% for cashew nut and 97.8% for
passion fruit at 0.3-1.0-mg/kg levels. Detection limits ranged from 0.2 to
0.4 pg for the compounds studied using l-g samples. The linearity, repeatab
ility, and recoveries of the method are presented. This MSPD method was com
pared with solid-phase extraction (SPE) for cleanup, using an alumina-silic
a gel (1:1) cartridge column and ethyl acetate as eluant. Analysis of forti
fied fruit (n = 3) shows an average recovery of 104.9% for cashew nut and 1
06.8% for passion fruit at 0.1-0.6-mg/kg levels. Detection limits ranged fr
om 0.2 to 0.6 pg for the compounds studied using 25-g samples. The combined
use of C-18 and silica (or Florisil) makes this extraction system unsuitab
le for these fruits matrixes. The cleanest extracts are obtained using two
polar (Florisil and silica) solid phases. In conclusion, the proposed MSPD
method described here can be applied to extract five organophosphorus pesti
cides and permethrin in 1 g of fruit. It is advantageous because it uses et
hyl acetate as the only solvent, is faster and uses less solvent than SPE m
ethods, and requires only small sample sizes. (C) 1999 John Wiley & Sons, I
nc.