ISO 18635:2016

Overview

ISO 18635:2016 specifies a validated analytical method for the quantitative determination of short‑chain polychlorinated alkanes (SCCPs) in environmental solid matrices. The method targets the sum of SCCPs in the carbon range n‑C10 to n‑C13 (chlorine mass fractions ~50–67 %) and covers mixtures containing many congeners (≈6 000 of ≈8 000). Applicable matrices include sediment, sewage sludge, suspended (particulate) matter and soil, with typical method applicability from about 0.03 µg/g to 3 µg/g total SCCPs. The technique uses gas chromatography–mass spectrometry with electron capture negative ionization (GC‑ECNI‑MS or GC‑ECNI-MS) plus specified extraction, clean‑up and calibration procedures.

Key Topics

• Scope and target analytes: Sum of SCCPs (n‑C10–n‑C13) in environmental solids; chlorine contents 50–67 %.
• Sample preparation: Fortification with internal standard and extraction (pressurized liquid extraction is recommended); non‑polar solvents such as n‑heptane.
• Clean‑up: Column chromatography and gel permeation chromatography options to remove matrix interferences; alternative clean‑ups provided in annexes.
• Instrumental analysis: Short capillary GC separation and MS detection in selected ion‑monitoring (SIM) using ECNI for enhanced sensitivity to chlorinated fragments.
• Calibration and quantification: Multiple linear regression based on at least three differently composed SCCP standard mixtures that mimic environmental distributions (examples: “Lake Ontario”, “Perch”, “Sediment Drevnice”). This approach accounts for varying C‑number and chlorine‑distribution patterns.
• Quality control: Blanks, recovery checks, and performance verification procedures are required; annexes include example chromatograms, performance data and QA solutions.
• Interferences: Guidance on common chlorinated mixtures and allowable interference levels; strategies to reduce matrix effects (e.g., mass resolution adjustments).

Applications and Users

Who uses ISO 18635:2016

• Environmental testing laboratories performing SCCP monitoring in sediments, sludges and soils.
• Regulatory agencies and monitoring programs assessing SCCP contamination and compliance.
• Research institutions studying SCCP fate, transport and ecotoxicology.
• Remediation and waste‑management professionals requiring reliable SCCP quantification.

Practical value

• Enables consistent, comparable SCCP measurements across labs.
• Supports contaminant inventories, risk assessments and regulatory enforcement.
• Delivers a reproducible protocol for trace‑level SCCP detection in complex solid matrices.

Related Standards

• ISO 12010 - SCCP determination in water (GC‑MS with NCI)
• ISO 5667 series (sampling guidance for sediments, sludges, suspended solids)
• ISO 8466‑1 - Calibration and evaluation of analytical methods
• ISO/TS 13530 - Guidance on analytical quality control for water chemistry

Keywords: ISO 18635:2016, SCCPs, short‑chain polychlorinated alkanes, GC‑ECNI‑MS, sediment analysis, sewage sludge testing, suspended particulate matter, environmental monitoring, pressurized liquid extraction.