US EPA

4120360 

Technical Report 

Improved determination of dalapon residues in plant tissues and natural water by derivatization and electron capture gas chromatography 

Van der Poll, JM; De Vos, RH 

1980 

PESTAB/80/1493 

Chromatogr 

1 

PESTAB. The 3-phenylpropyl ester of dalapon was found to have good sensitivity and the highest retention time by gas-liquid chromatography (GLC) for use in measuring dalapon residues. Known amounts of dalapon were added to untreated plant and water samples. Plant tissue was treated with dilute o-phosphoric acid and 25% phosphotungstic acid, homogenized, and filtered; the filtrate and washings were saturated with NaCl and extracted with diethyl ether; and the extracts were dried over anhydrous Na2SO4. Natural water was treated in a similar manner. 3-Phenyl propanol-1 was added to the ether extract and the extracts were evaporated until no diethyl ether was left. The residue was saturated for 5 min with dry HCl gas; attached to a condenser and placed for 5 min in a steam bath. Hexane was added through the condenser after cooling and the tube was shaken. Water was then added and the tube shaken again. The mixture was separated; the hexane layer was extracted twice and filtered. After column clean-up, GLC with electron capture detection was performed on a 3% OV-210 packed Gas-Chrom Q column. Detection was linear up to nanogram amounts of the injected ester. Limits of detection were 0.2 mg dalapon/kg plant tissue and for water, 0.001 mg/l. Percent recoveries ranged from 86% for 0.16 mg dalapon/kg grasses to 103% for 0.05 mg dalapon/kg grasses.