ISO 7981-2:2005

Overview

ISO 7981-2:2005 specifies a laboratory method for determining six priority polycyclic aromatic hydrocarbons (PAH) in water using liquid–liquid extraction (LLE) followed by high-performance liquid chromatography (HPLC) with fluorescence detection. The procedure targets mass concentrations above 0.005 µg/L and is intended for drinking, mineral and table waters, groundwater and surface waters. With modifications it can also be applied to moderately polluted waste waters.

Key PAHs covered:

• Fluoranthene
• Benzo[b]fluoranthene
• Benzo[a]pyrene
• Benzo[k]fluoranthene
• Indeno[1,2,3-cd]pyrene
• Benzo[ghi]perylene

Keywords: ISO 7981-2:2005, water quality, PAH determination, HPLC fluorescence, liquid-liquid extraction, benzo[a]pyrene.

Key Topics and Technical Requirements

• Sampling and sample handling: Whole-sample analysis is specified because PAHs adsorb to particulates; avoid plastics and light exposure; follow good laboratory practice.
• Extraction and cleanup: PAHs are extracted by LLE using solvents such as cyclohexane, hexane or dichloromethane; extracts are concentrated by evaporation and, for surface/contaminated samples, cleaned on silica.
• Chromatography and detection: Separation by HPLC (isocratic conditions) with fluorescence detection using fixed excitation/emission settings; identification and quantification via retention times and fluorescence response.
• Calibration and quality control: Use certified single- and multi-substance stock solutions and prepare at least five calibration levels; perform blank measurements and determine recovery to validate results.
• Reagents and apparatus: Specifies HPLC-grade solvents (methanol, acetonitrile, tetrahydrofuran) and laboratory equipment (autosampler vials, silica cartridges, degassing assembly, fluorescence detector, temperature-controlled column).
• Safety and interferences: Notes carcinogenicity of some PAHs and hazards of solvents (e.g., acetonitrile, hexane); warns about fluorescent interferences and peak co-elution.
• Performance and reporting: Clauses cover calculation, expression of results and method accuracy (statistical evaluation referenced to ISO 8466-1).

Applications and Practical Use

• Routine monitoring of drinking water quality for regulatory compliance and public health protection.
• Environmental surveillance of surface water and groundwater for contamination by combustion-derived PAHs.
• Source-water and treatment-plant monitoring by water utilities, environmental laboratories and consultants.
• Screening of moderately polluted industrial or municipal wastewaters after method adjustments.

Who Would Use This Standard

• Accredited environmental testing laboratories
• Water utilities and treatment operators
• Environmental regulators and public health agencies
• Consultants performing watershed and pollution assessments

Related Standards

• ISO 7981-1 (Part 1 - HPTLC option)
• ISO 8466-1 (calibration and statistical evaluation)
• ISO 5667-2 / ISO 5667-3 (sampling guidance)

ISO 7981-2:2005 is a practical, well-defined method for reliable PAH quantification in water using HPLC-fluorescence and is suited to labs implementing routine monitoring and regulatory compliance programs.