Overview
ISO 24758-2:2025 - Fine bubble technology - Evaluation method for determining the reactive oxygen species in ultrafine bubble dispersions - Part 2: APF (3'-(p-aminophenyl) fluorescein) assay defines a standardized fluorescence-based method for detecting and quantifying reactive oxygen species (ROS) generated in microbubble (MB) and ultrafine bubble (UFB) dispersions. The document specifies use of the APF assay to evaluate ROS relevant to pollutant abatement and FB-facilitated advanced oxidation treatments, with sensitivity down to submicromolar levels.
Key topics and technical requirements
- Scope and targets: Procedures for measuring ROS such as hydroxyl radical (·OH), superoxide anion (O2·−), singlet oxygen (1O2), hydrogen peroxide (H2O2) and dissolved ozone in UFB/MB systems.
- Principle: APF (3'-(p-aminophenyl) fluorescein) is a fluorescein-based probe that becomes highly fluorescent after oxidation (O-dearylation) by strong oxidants; fluorescence intensity correlates with ROS concentration.
- Reagents and controls: Lists required chemicals, positive controls and methods for generating representative ROS (hydroxyl radicals, superoxide, singlet oxygen, H2O2) for calibration.
- Apparatus & environment: Requirements for measuring instruments, sample preparation, and environmental conditions to ensure reproducible fluorescence readings.
- Procedure: Stepwise method including standard curve development for individual ROS, fluorescence response characterization (·OH, dissolved ozone, H2O2, superoxide, singlet oxygen), ROS identification protocols, and interpretation guidelines.
- Reporting: Required result formats and testing condition documentation; annexes provide example test results (e.g., H2O2 detection after UFB + plasma treatment).
Practical applications
- Evaluating advanced oxidation processes (AOPs) and pollutant abatement in water and wastewater treatment using fine bubble technology.
- Assessing disinfecting and oxidation performance of ozone UFBs and other FB-enabled treatments.
- Research into biological effects of ROS in agriculture (plant and aquaculture systems) where UFBs influence growth or stress responses.
- Quality control and R&D for manufacturers of UFB generators, oxygenation systems, and environmental treatment equipment.
Who should use this standard
- Environmental and water treatment engineers
- Analytical and research laboratories working on AOPs or FB technologies
- Agricultural and aquaculture researchers studying oxidative effects
- Manufacturers and conformity assessment bodies involved in fine bubble products
Related standards
- ISO 24758-1 (probe‑based kinetic models for ROS measurement) - complements Part 2
- ISO 23015 - Fine bubble measurement techniques
- ISO 20480-1:2017 - Fine bubble terminology and general principles
Keywords: ISO 24758-2:2025, APF assay, ultrafine bubble (UFB), reactive oxygen species, fine bubble technology, hydroxyl radical, hydrogen peroxide, pollutant abatement, advanced oxidation.
Open preview (PDF)Fine bubble technology — Evaluation method for determining the reactive oxygen species in ultrafine bubble dispersions — Part 2: APF (3'-(p-aminophenyl) fluorescein) assay
