Ajh. Louter et al., FULLY AUTOMATED WATER ANALYZER BASED ON ONLINE SOLID-PHASE EXTRACTIONGAS-CHROMATOGRAPHY, The Journal of microcolumn separations, 5(4), 1993, pp. 303-315
An automated procedure for the analysis of aqueous samples by membrane
disk extraction coupled on-line to capillary gas chromatography (GC)
is presented. Organophosphorus pesticides are preconcentrated from aqu
eous samples on three 0.5 mm thick, 4.0 mm diameter XAD-2 membrane ext
raction disks which are mounted in a polymer holder for use in a PROSP
EKT sample processor. The layers are dried by a stream of nitrogen (30
min at ambient temperature). Desorption of the analytes is carried ou
t with ethyl acetate which is directly introduced into a retention gap
under partially concurrent solvent evaporation conditions, using an e
arly solvent vapor exit. The method is a fully software-controlled aut
omated system, and includes sample preparation, sample transfer and GC
analysis. The final analysis is carried out by GC with nitrogen-phosp
horus (NPD) or mass-selective detection. The technique is applied to t
he determination of a series of organophosphorus pesticides in tap wat
er and water from European rivers. With a sample volume of only 2.5 mL
, the detection limits achieved with the NPD were 20-50 ng L-1 in tap
water and 20-100 ng L-1 in river water.