Ekstraksjon av fosfonsyrer fra vannfase ved hjelp av fast fase ekstraksjon

Methylation of methylphosphonic acids with diazometane gives good results, even if the eluate is acidic. Extraction of methylphosphonic acids from water using solid phase extraction has been tested with three differents columns, SAX, DEA and NH2. The SAX columns give highest recoveries. Different solvents for eluation were tested, and methanol with at least 0,6 % HBr in the eluent show the best recovery rates. Variation in pH does not infuece the recovery rates. Different contents of salt in the sample were also tested. If the sample volumes are between 50 and 100 ml, the capacity of solid phase column has to be at least 500 mg. Amounts of methylphoshonic acids in samples below about 700 ng/ml will decrease the recovery rate. The limit of quatification for this method is less then 100 ng/ml with standard deviation less then 10 %