Gravimetric sampling procedure for aqueous ozone concentrations

Sampling procedures for the standard method for measuring dissolved ozone concentrations in water were modified by replacing narrow-necked volumetric flasks with wide-necked Erlenmeyer flasks, followed by gravimetric determination of sample volume. The intent of these modifications was to improve sampling ease, speed, and reproducibility when collecting large number of samples with highly variable and rapidly decaying dissolved ozone concentrations. Subsequent comparisons between samples collected by the standard method and the modified gravimetric method showed greater apparent ozone concentrations in samples collected by the modified method. This difference appears to result from negative sampling biases when using volumetric glassware under typical full-scale sampling conditions.