Selective preconcentration of chemical warfare agent degradation products using a zirconia preconcentration column

Zirconia (ZrO2) has strong Lewis acid sites which have an affinity for the strongly electronegative phosphonate group of organo-phosphates. To investigate whether this affinity can be used for selective preconcentration, the retention of methyl, ethyl, and propylphosphonic acid (MPA, EPA and PPA) and inorganic anion matrix components on ZrO2 was investigated. Only organo-phosphates and sulfate exhibited retention on zirconia. After preconcentration, the retained species were eluted from ZrO2 by 0.75 mM Na2CO3, and separated by a Dionex Ionpac AS11 anion-exchange column (250 mm × 2 mm I.D.) and a Hypercarb RPLC column (50 mm × 4.6 mm I.D., 3 μm) in series followed by suppressed conductivity detection. Calibration curve showed a linear response for MPA, EPA and PPA in the range of 0.01 μM to 1 μM (R2 > 0.9989). Detection limits after preconcentration of a 10 mL sample were 0.16, 0.19 and 0.16 μg/L for MPA, EPA, and PPA, respectively.