A procedure for the determination of 13 organophosphate insecticides (OPs) in water, sediment and biota at low ppb
levels is described. Samples were extracted with dichloromethane or acetone/hexane and cleaned up with micro-column
silica gel chromatography. Measurements were made by dual capillary column gas chromatography using both
nitrogen-phosphorus (NPD) and electron capture (ECD) detection. Recoveries from fortified water samples ranged
from 76% to 102% for all sample types. Practical detection limits ranged between 0.003 and 0.029lg/l in natural water
samples, 0.0004–0.005lg/g w.w. for sediments, and 0.001–0.005lg/g w.w for biota using the NPD and ECD method.
Losses in sediments were experienced when sulphur was removed. Precision and accuracy were not affected in sediment
samples where sulphur was not removed.