PMID- 17723703
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20070830
LR  - 20070828
IS  - 1873-4324 (Electronic)
IS  - 0003-2670 (Linking)
VI  - 578
IP  - 2
DP  - 2006 Sep 25
TI  - Microwave-assisted extraction through an aqueous medium and simultaneous cleanup 
      by partition on hexane for determining pesticides in agricultural soils by gas 
      chromatography: a critical study.
PG  - 122-30
AB  - A simple microwave-assisted extraction and partitioning method (MAEP) using 
      water-acetonitrile and n-hexane for desorption and simultaneous partitioning, 
      respectively, together with gas chromatography (GC) was studied to determine 
      representative pesticides (trifluralin, metolachlor, chlorpyriphos and 
      triadimefon) with a broad range of physico-chemical properties in agricultural 
      soils. Three points were considered crucial in this study: instrumental and 
      sample-associated factors affecting extraction of the target compounds were 
      studied through experimental design; the spiking procedure at trace levels was 
      carried out to reproduce the solute-soil sorption taking place in the environment 
      as closely as possible; and results were analyzed taking into account the 
      adsorption behaviour of the compounds on different kinds of soils. The complete 
      analytical procedure proposed consisted of the MAEP of pesticides from 1.0 g of 
      soil with 1 mL of 1:1 water/acetonitrile mixture, and 5 mL of hexane for 
      trapping. The microwave heating program applied was 2 min at 250 W and 10 min at 
      900 W, and 130 degrees C maximum temperature. After extraction, the hexane layer 
      was evaporated to dryness; the residue was re-dissolved and directly analyzed by 
      gas chromatography electron capture detection (GC-ECD). Clean chromatograms were 
      obtained without any additional cleanup step. Besides the four pesticides used to 
      optimise MAEP, the method was applied to determine an additional group of 
      pesticides (triallate, acetochlor, alachlor, endosulphan I and II, endrin, 
      methoxychlor and tetradifon) in different soils. Most of the compounds studied 
      were recovered in good yields with relative standard deviations (R.S.D.s) below 
      9% and detection limits ranged from 0.004 to 0.036 microg g(-1). The described 
      method is efficient and fast to determine hydrophobic pesticides at ng g(-1) 
      level in soil with different clay-to-organic matter ratios.
FAU - Fuentes, Edwar
AU  - Fuentes E
AD  - Departamento de Quimica Inorganica y Analitica, Facultad de Ciencias Quimicas y 
      Farmaceuticas, Universidad de Chile, Santiago, Casilla 233, Chile. 
      edfuentes@ciq.uchile.cl
FAU - Baez, Maria E
AU  - Baez ME
FAU - Reyes, Dana
AU  - Reyes D
LA  - eng
PT  - Journal Article
DEP - 20060708
PL  - Netherlands
TA  - Anal Chim Acta
JT  - Analytica chimica acta
JID - 0370534
EDAT- 2007/08/29 09:00
MHDA- 2007/08/29 09:01
CRDT- 2007/08/29 09:00
PHST- 2006/02/24 00:00 [received]
PHST- 2006/07/03 00:00 [revised]
PHST- 2006/07/04 00:00 [accepted]
PHST- 2007/08/29 09:00 [pubmed]
PHST- 2007/08/29 09:01 [medline]
PHST- 2007/08/29 09:00 [entrez]
AID - S0003-2670(06)01489-9 [pii]
AID - 10.1016/j.aca.2006.07.007 [doi]
PST - ppublish
SO  - Anal Chim Acta. 2006 Sep 25;578(2):122-30. doi: 10.1016/j.aca.2006.07.007. Epub 
      2006 Jul 8.