A Liquid Chromatography (LC) method using volatile ion pairing agents and E
vaporative Light Scattering Detector (ELSD) was developed. The separation o
f a series of three common inorganic anions (Cl-, NO3- and SO42-) and three
organophosphonic anions (Methyl, ethyl and propylphosphonic acids) was ach
ieved on a reversed-phase C-18 column with pentylammonium or heptylammonium
formiate as ion pairing agent.
This method provides good linearity of the calibration curve and enables a
limit of detection to be reached of 4 mg/L and 3.12 mg/L for alkylphosphoni
c anions and inorganic anions respectively.
The separation for methyl and ethylphosphonic acids, which are poorly resol
ved in the LC systems commonly used, was successfully achieved.