| Sample matrix | Sample preparation | Assay procedurea | Limit of detection | Reference |
|---|---|---|---|---|
| Air | Collect vapours on polyurethane foam; extract with 5% diethyl ether in hexane Adsorb on XAD-2; desorb with toluene | GC/ECD GC/FPD | Not reported 0.2 μg/sample | US Environmental Protection Agency (1988a) US National Institute for Occupational Safety and Health(1979) |
| Water | Extract with dichloromethane; isolate extract; dry; concentrate with methyl tert-butyl ether | GC/NPD | 2.5 μg/1 | US Environmental Protection Agency(1988b) |
| Groundwater, soil, wastes | Extract with dichloromethane; dry; concentrate; clean-up using Florisil column or gel permeation; exchange into hexane | GC/MS | 0.1 μg/1 | US Environmental Protection Agency(1986) |
| Formulations | Dissolve in chloroform; concentrate using evaporation (baits & emulsifiable concentrate forms) Extract with sodium hydroxide; dry using anhydrous sodium sulfate (spray solutions & sprays in hydrocarbon solvents) | IR IR | Not reported Not reported | Williams (1984) Williams (1984) |
| Fruits and vegetables | Acidify with hydrochloric acid; extract with hexane; clean-up on silicic acid column | GC/MCD | 0.05 ppm (mg/kg) | US Food and Drug Administration (1989a) |
| Animal tissues, crops, milk | Acidify with hydrochloric acid; extract with hexane; clean-up with anhydrous sodium sulfate | GC/TD or GC/ECDb | 0.01–0.02 ppm (mg/1 or mg/kg) (milk & tissues) | US Food and Drug Administration (1989a) |
| Animal tissues, crops, eggs, milk | Extract into hexane; clean-up on silicic acid column with dichloro-methane:hexane (3:2) eluant | GC/FPD | 0.002 ppm (mg/1milk) | US Food and Drug Administration (1989b) |
Abbreviations: GC/ECD, gas chromatography/electron capture detection; GC/FPD, gas chromatography/ flame photometric detection; GC/MS, gas chromatography/mass spectrometry; GC/NPD, gas chromatography/nitrogen-phosphorus detection; GC/MCD, gas chromatography/microcoulometric detection; GC/TD gas chromatography/thermionic detection; IR, infrared spectrophotometry
Used if interfering organophosphorus or organochlorine pesticides are present
From: Dichlorvos
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