Ozone-scavenging reagents suitable for use in the quantitative determination of aldehydes as the O-(2,3,4,5,6-pentafluorobenzyl) oximes by GC-ECD

Previously, we reported interference due to several ozone-scavenging reagents (OSRs) in the quantitation of aldehydes using O-(2,3,4,5,6-pentafluorobenzyl)oxylamine (PFBOA) in the analysis of ozonated waters. Scavenging ozone is essential if ozonation byproduct concentrations are to be fixed in time, which is required in a study of formation as a function of time; otherwise, additional redox reactions can take place prior to analysis. We have since determined that triphenylphosphine and indigo-5,5′,7-trisulfonate can be satisfactory OSRs. Both PPh3 and indigo-5,5′,7-trisulfonate react rapidly with ozone, i.e., within 10 s. Triphenylphosphine is insoluble in water and must be dissolved in an appropriate organic solvent (e.g., benzene) that can be dispersed into the sample. When PFBOA is added directly, several minutes must elapse to completely scavenge the ozone, making this approach unsatisfactory. Procedures for using these OSRs are described, and quantitative results are explained. Although PPh3 and indigo-5,5′,7-trisulfonate produce deviations relative to controls devoid of OSRs, the biases are precise and therefore readily corrected for by subjecting calibration standards and analyte-fortified (spiked) samples to the same analytical procedure.